# Roll Call: Who's building, built, or thinking of building a beta22?



## Nebby

I've seen more than a few posts about the beta22 pop up recently, so I figure I'm not the only one getting ready to build one 
	

	
	
		
		

		
			





 Post here if you're thinking of building one, currently building one, or already built one! If you already built one, pics and specs would be handy!

 I'm planning on building one, but it seems my laundry list of wanted features will have to be pruned down a bit for practicality's sake. On a more positive note, I think I've figured out how to mount the six beta22 boards I have planned in a nice and efficient manner with bigger heatsinks


----------



## Uncle Erik

I've got a box of boards and parts, but haven't gotten around to it yet. I've got what I need to build a fully-balanced one, with four amp boards and two power supplies. I will get to it, but there's a tube amp I'm dying to build. And work has been keeping me late, as well. But I will build it, sooner or later.


----------



## beerad

I will build one late this summer/early fall, but I have a couple of other amps to build first, both for education and experience. I find that the more experience I get, the better job I do, and I want the B22 to be done right. Also, I'd like to have some understanding of it while I build it.


----------



## gates_2

I'm currently in the ordering stages of building a B22 for my friend... Gonna try that jason tree relay-based attenuator- should be fun


----------



## kklee

I've built two of them, both active ground using AMB's backplane. They sound awesome!

 Pictures of my build are on AMB's gallery (which I can't link to for some reason). Here's an alternate link:
http://kklee.smugmug.com/gallery/2538766#142082532

 I highly recommend reading through the build threads on Headwize. Even though the build is straight forward, the sheer number of parts involved makes it easy to make mistakes (and hard to troubleshoot).


----------



## gmckay

Still trying to finish my build- I'm about 90% finished.

 I've taken the harder route...separate power supplies and transformers for each of the channels . Each amp and power supply is mounted directly on large off-board Conrad heatsinks.

 I'm planning on using this amp for headphone and speaker use.


----------



## TheRobbStory

I've started collecting parts, but I doubt I'll actually heat up a soldering iron for it within the next four months. There are a few other projects I need to finish first before tackling the β22. I spent a few hours last night reading through the AMB guide on it. It's definitely something I want to build.


----------



## Nebby

Quote:


  Originally Posted by *gmckay* /img/forum/go_quote.gif 
_Still trying to finish my build- I'm about 90% finished.

 I've taken the harder route...separate power supplies and transformers for each of the channels . Each amp and power supply is mounted directly on large off-board Conrad heatsinks.

 I'm planning on using this amp for headphone and speaker use._

 

This is pretty much what I'm planning on doing, so I apologize in advance for asking so many questions. Are you using 4 channels? How did you mount the Conrad heatsinks, and which Conrad heatsink did you use? Also, which transformers did you use? Do you have any pictures of your current setup?

 Thanks in advance for any questions you can answer 
	

	
	
		
		

		
		
	


	




  Quote:


  Originally Posted by *gates_2* /img/forum/go_quote.gif 
_I'm currently in the ordering stages of building a B22 for my friend... Gonna try that jason tree relay-based attenuator- should be fun_

 

are you talking about the Joshua Tree attenuator? I think I will be using that for my balanced pot, and standard pots for my SE outputs.


----------



## thrice

Just finished a 6-channel balanced in two cases. There are pics:














 I've since added the ground boards to the amp and single-ended inputs.


----------



## Ferrari

My β22 amplifier is built as 3-channel active-ground configuration and is housed in an ATI-737U enclosure.
 The β22 boards are mounted on a ε22 backplane board to reduce wirings and keep the internal of the amp tidy.
 All electrolytic capacitors used on the amplifier boards are Black Gate Std. and the small values capacitors are MKT, MKP and polystyrene. Manganin 1% resistors (type PBH) are used at the output while Vishay-Dale RN55D resistors are used on the remaining part of the amp. All BJT’s are matched within 5%. The gain is set to 5. The volume control is an Alps RK40 "Black Beauty" and the 50mm knop from DACT.


----------



## MisterX

A passive ground version in dual Hammond enclosures complete's the trilogy.


----------



## Tedro

Sorry, Camera phone picture:


----------



## fierce_freak

I finished my balanced one earlier today (had to change the gain). Well, it's mostly done...I still don't have any knobs, lol. That's it, though. It's fully functional.

 -edit- didn't see the joshua tree attenuator until after i built my pair of stepped attenuators. wish i had, though...it looks pretty cool (and would have helped with wiring a bit (no backplane board).


----------



## bryerd

I'm planning to build both the β22 and Millett Max, but have much on my plate to finish first though. My Dynalo is running and two Dynahi's are just about populated but have not been fired up yet. All three cases are just about done and are awaiting paint. I'm also in the process of looking for a house and selling mine, so DIY projects are on hold until the move is over.

 However, I have ordered the Millett Max pcb and β22 backplane pcb, but not the other parts. Looking forward to hearing all 4 amps for a side-by-side comparison (hopefully near the end of the year)!

 Dave...


----------



## thrice

Quote:


  Originally Posted by *bryerd* /img/forum/go_quote.gif 
_I'm planning to build both the ?22 and Millett Max, but have much on my plate to finish first though. My Dynalo is running and two Dynahi's are just about populated but have not been fired up yet. All three cases are just about done and are awaiting paint. I'm also in the process of looking for a house and selling mine, so DIY projects are on hold until the move is over.

 However, I have ordered the Millett Max pcb and ?22 backplane pcb, but not the other parts. Looking forward to hearing all 4 amps for a side-by-side comparison (hopefully near the end of the year)!

 Dave..._

 

Yep, can you see the eyes?....he's got it, the sickness. With only 11 posts too, man you're hooked bad


----------



## threEchelon

I'm planning on building one this summer if I get the money for it fast enough. I also need to work out a crazy switch setup too.


----------



## n_maher

(click pictures for larger versions)

 Single-ended, active ground beta/sigma combo. Uses an alps RK40 pot, has two switched inputs, speaker binding posts (not shown in pictures) and otherwise is pretty much stock.

 Planning for my balanced beta gets underway this weekend.


----------



## el_matt0

im just about to start building the S22 for a B22 that will EVENTUALLY come . im building it in its own par-metal 20 series enclosure and throwing a 100VA transformer in, as im planning (or at least at THIS point), to build the 4 channel balanced b22. ill definitely post further as i make progress!


----------



## mb3k

Nice to see everyone building/planning!
 It'll be in my books also. I think I've decided on the case for the Beta and Sigma.


----------



## el_matt0

hey mb3k, fill us in, what cases have u decided on?? OK, this is probably a good place to ask this question, for the umbilical between S22 and B22 housed in separate enclosures, two things. what is a good cable for that umbilical. can someone recommend something that is available to order (to canada please) in short enough lengths for just this purpose (i dont want a ton of extra)!, or do you guys just find using something like 18AWG hookup wire, braided and in techflex or w/e, is ok? also, link to some of those amphenol tuchel detachable connectors for the panels and the umbilical? THANKS guys


----------



## Nebby

quoting from Amb's post over at headwize about his dynahi build, I suspect the same connectors could be used for the beta22:

  Quote:


 I received several queries about the Amphenol connectors that I used for the umbilical cable between the PSU and amp cases. Here is the detailed info. Two of each is needed:

 Amphenol-Tuchel T3108 001
 (male, cable-mount, Digikey 361-1026-ND or Mouser 523-T3108-001)
 Amphenol-Tuchel T3111 000
 (female, panel-mount, Digikey 361-1032-ND or Mouser 523-T3111-000) 
 

Given I'm planning a 6 board setup I think I may have to get more than 2 umbilical cords


----------



## luvdunhill

Quote:


  Originally Posted by *el_matt0* /img/forum/go_quote.gif 
_for the umbilical between S22 and B22 housed in separate enclosures, two things. what is a good cable for that umbilical._

 

I'd recommend the Neutrik SpeakON connectors!


----------



## el_matt0

ok thanks, im all clear about the connectors now, seems striaghtforwards...now about the wire? what do you guys find has worked best for you, braiding hookup wire of your own, or using _____ cable? (thats where you insert a link to a good cable !) cheers everyone


----------



## MASantos

Quote:


  Originally Posted by *thrice* /img/forum/go_quote.gif 
_Just finished a 6-channel balanced in two cases. There are pics:














 I've since added the ground boards to the amp and single-ended inputs._

 

Does your setup use 3 boards per channel n the balanced mode? Or is the 3rd board in each channel used to make 2x single ended active ground amps?


----------



## Nebby

Quote:


  Originally Posted by *MASantos* /img/forum/go_quote.gif 
_Does your setup use 3 boards per channel n the balanced mode? Or is the 3rd board in each channel used to make 2x single ended active ground amps?_

 

I am planning to use this configuration so I think I can answer this one...but correct me if I'm wrong thrice 
	

	
	
		
		

		
		
	


	




 In balanced mode only four boards are used, while in single ended mode it runs as two separate SE active ground amps.


----------



## el_matt0

Quote:


  Originally Posted by *luvdunhill* /img/forum/go_quote.gif 
_I'd recommend the Neutrik SpeakON connectors!_

 

these speakON connectors are just a suitable replacement for the amphenol tuchel connectors right? what kind of cable should i be looking to use FOR the umbilical though? braid something myself out of hookup wire and then techflex it..or do you guys prefer an already insulated and shielded pre-twisted cable?


----------



## naamanf

Just started my B22 build. I hope to have it all soldered up waiting for the backplane board by next week. Then comes the joy of finding a case I like


----------



## mb3k

Quote:


  Originally Posted by *el_matt0* /img/forum/go_quote.gif 
_hey mb3k, fill us in, what cases have u decided on?? OK, this is probably a good place to ask this question, for the umbilical between S22 and B22 housed in separate enclosures, two things. what is a good cable for that umbilical. can someone recommend something that is available to order (to canada please) in short enough lengths for just this purpose (i dont want a ton of extra)!, or do you guys just find using something like 18AWG hookup wire, braided and in techflex or w/e, is ok? also, link to some of those amphenol tuchel detachable connectors for the panels and the umbilical? THANKS guys_

 

I'll be using the HiFi2000 Galaxy Max cases with the 10mm faceplates.
 230x230x80 for the Sigma22 and 330x280x80 for the 3-channel Beta22 w/ backplane.

 I've been fooling around with AutoCAD tonight to come up with a way to mount the NJ3FP6C Neutrik jack from behind the panel. Here's some prelim screens






 You can see that the back of the panel has to be milled out enough for the jack to poke out.


----------



## el_matt0

Quote:


  Originally Posted by *el_matt0* /img/forum/go_quote.gif 
_what kind of cable should i be looking to use FOR the umbilical though? braid something myself out of hookup wire and then techflex it..or do you guys prefer an already insulated and shielded pre-twisted cable?_

 

anyone? quick answer


----------



## mb3k

Quote:


  Originally Posted by *el_matt0* /img/forum/go_quote.gif 
_anyone? quick answer _

 

The Belden 83803 power cable was something I was looking at. Still undecided if I would go for the Belden, or twist my own.


----------



## el_matt0

where were you considering ordering from? do any of the main online suppliers carry it? is this the route that most people go...or is twisting their own? or is it simply preference...?


----------



## threEchelon

Quote:


  Originally Posted by *luvdunhill* /img/forum/go_quote.gif 
_I'd recommend the Neutrik SpeakON connectors!_

 

What about the PowerCon connectors?


----------



## Nebby

Quote:


  Originally Posted by *threEchelon* /img/forum/go_quote.gif 
_What about the PowerCon connectors?_

 

powercon connectors are great, if you only need three prongs per connector, I like the speakon's because they have a 8 prong version....that'll reduce the umbilicals I will have to use, and that's a good thing


----------



## el_matt0

for those of you that have built or are building b22 or s22s, when mounting your PCB to your enclosure using standoffs, are the male/female brass standoffs the ticket (you drill out the bottom side of the enclosure so male end goes down?), or do you guys find that using female/female standoffs and simply crazy gluing the bottom end down to the bottom of the enclosure suffices, so that you dont have holes visible from the bottom? not that that much matters...


----------



## MisterX

lol @ crazy glue. 

 I works for the led's but not much else.


----------



## thrice

yeah what you need to do is place the pcb on the bottom of the enclosure, line it all up and mark the holes. then drill holes and screw the standoffs down to the bottom of the enclosure. don't use crazy glue....now liquid nails


----------



## thrice

Quote:


  Originally Posted by *MASantos* /img/forum/go_quote.gif 
_Does your setup use 3 boards per channel n the balanced mode? Or is the 3rd board in each channel used to make 2x single ended active ground amps?_

 

No the balanced setup uses 4 boards and the third board per side is to have 2 3-channel single-ended amps......you know should that prove useful someday :0


----------



## fierce_freak

I went female to female, matt0.

 Here's some pics of my mostly finished build (still need knobs for it, haha...also thinking of making a wood panel for the front):

 Man, guess I should have wiped it down to get rid of the fingerprints and smears on the aluminum front. The flash on my camera is a killer.















 don't mind the rats' nest -.-















 ^stepped attenuators i made


----------



## el_matt0

k got it...crazy glue..no go. thats what i figured, so just drilling it out and having a few tiny holes visible from the bottom, not a big deal, and much more secure. what was that about liquid nails thrice? i should use those either though should i...? lol


----------



## el_matt0

wow fierce, thats looking VERY nice man, i wish i could give it a spin! so what did you use for your standoffs...female female and crazy glue or liquid nails 
	

	
	
		
		

		
		
	


	




 (dont let thrice hear that! haha!) reaaally nice work though man, dang, hopefully a month or so from now ill be somewhere near that!


----------



## fierce_freak

I actually used female to female standoffs and used a bolt from the bottom of the case and threaded it all the way through the standoff, so I could place the board down on the exposed ends of the bolts and then put nuts down on top of that. Maybe I can take a picture later to explain what I mean.

 Word of advice, though: Take your time with the build, especially if this is one of your first projects. My first build was a CMOY that was never cased, second was this one - so it can be done if you take your time and really pay attention to what you're doing, double and triple check. Patience is certainly a virtue in DIY (something I don't have a lot of when it comes to stuff like this, haha).


----------



## n_maher

One other piece of advice:

 The beta/sigma projects are not really of the intro to DIY caliber. I've noticed at least a couple of folks posting in this thread who don't appear to have built anything else. While things might go fine the odds of success are certainly stacked against you. Several very experienced builders have had issues with this build which is not surprising given the parts count and complexity. 

 Just my 2¢,

 Nate


----------



## fierce_freak

I agree. If I could do it over again (and had the cash), I would definitely have done a couple of other projects before this one.


----------



## el_matt0

hey fierce, ya i definitely understand exactly what you did, i guess using male/female would be just as fine of an alternative to that. ive had several people forewarn about doing this as one of my earlier projects in DIY, however at the same time ive also had several people tell me that other than the # of parts, this really isnt too much more difficult than other circuits. i realize obviously the complexity is greater, but having built a few BASIC amps and cables, i think im ready to tackle this as a big project - might as well make it worth it IMHO. i generally find that as long as one is careful and checks (and double checks) everything first, things SHOULD turn out a-ok in the end


----------



## thrice

Quote:


  Originally Posted by *el_matt0* /img/forum/go_quote.gif 
_k got it...crazy glue..no go. thats what i figured, so just drilling it out and having a few tiny holes visible from the bottom, not a big deal, and much more secure. what was that about liquid nails thrice? i should use those either though should i...? lol_

 

No, you shouldn't...that was just a joke....although liquid nails is great. It's a waterproof adhesive (usually used in plumbing...etc.) that you can adjust after you set it...so you glue to pieces together and then you can wiggle it into place up to an hour or so after gluing...it allows for some adjustment. Then when it's dried (24 hours or so) it's never going to move again....use wisely.


  Quote:


  Originally Posted by *fierce_freak* /img/forum/go_quote.gif 
_I went female to female, matt0.

 Here's some pics of my mostly finished build (still need knobs for it, haha...also thinking of making a wood panel for the front):

 Man, guess I should have wiped it down to get rid of the fingerprints and smears on the aluminum front. The flash on my camera is a killer.















 don't mind the rats' nest -.-















 ^stepped attenuators i made




_

 

Fierce-freak...nice build man, I can't wait to hear it at the MD meet.

  Quote:


  Originally Posted by *fierce_freak* /img/forum/go_quote.gif 
_I actually used female to female standoffs and used a bolt from the bottom of the case and threaded it all the way through the standoff, so I could place the board down on the exposed ends of the bolts and then put nuts down on top of that. Maybe I can take a picture later to explain what I mean.

 Word of advice, though: Take your time with the build, especially if this is one of your first projects. My first build was a CMOY that was never cased, second was this one - so it can be done if you take your time and really pay attention to what you're doing, double and triple check. Patience is certainly a virtue in DIY (something I don't have a lot of when it comes to stuff like this, haha)._

 

Yes on all of this. I like to use male/female standoffs since you can screw the standoffs to the bottom of the case and then just sit the boards on them while you're wiring and casing. It's easier to get the boards in and out of the case that way...then when you're done, just get some nuts and secure the boards to th standoffs. makes it easier for servicing too.

  Quote:


  Originally Posted by *n_maher* /img/forum/go_quote.gif 
_One other piece of advice:

 The beta/sigma projects are not really of the intro to DIY caliber. I've noticed at least a couple of folks posting in this thread who don't appear to have built anything else. While things might go fine the odds of success are certainly stacked against you. Several very experienced builders have had issues with this build which is not surprising given the parts count and complexity. 

 Just my 2¢,

 Nate_

 

Yep..patience is a virtue and read everything amb's site says aout this amp...twice, no.....maybe _thrice*_ before you fire up your iron.






 *oh, come on, you know you were thinking it!


----------



## fierce_freak

**we were...but gods, man! ha

 Thanks for the compliment. I'm looking forward to hearing your insane B22, too (is that enough 2's?). Too bad n_maher can't make it with his great looking 3-channel B22 (love the front panel!).


----------



## Nebby

I'm taking and planning everything very carefully before I even start ordering parts. I've learned quite a bit already and I haven't even touched the soldering iron for this planned project 
	

	
	
		
		

		
			





 I learned to triple-check everything the hard way last weekend when I measured the width of a speaker wrong twice and cut a hole too big in a perfectly good piece of cherry 
	

	
	
		
		

		
		
	


	







 I know now to check it....._thrice_.
	

	
	
		
		

		
		
	


	




  Quote:


  Originally Posted by *thrice* /img/forum/go_quote.gif 
_Yep..patience is a virtue and read everything amb's site says aout this amp...twice, no.....maybe thrice* before you fire up your iron.

 *oh, come on, you know you were thinking it!_


----------



## el_matt0

ok all my b22 gurus...heres a question. im considering going w/ the ATI 649

http://www.atiresearch-anodized.com/ATI-649PR.html

 cases for my sigma and beta 22. i THINK, this size should be able to fit my 4 channel balanced config (i dont have it yet which is why im unsure, just trying to think ahead), without the backplane boards. my question is, if i wanted identical cases for my psu etc (just for aesthetics), is tehre any disadvantage to using a "larger" case than is needed, as i know this case in specific is far bigger than is "NEEDED" for my basic 100VA sigma22.


----------



## Nebby

Quote:


  Originally Posted by *el_matt0* /img/forum/go_quote.gif 
_ok all my b22 gurus...heres a question. im considering going w/ the ATI 649

http://www.atiresearch-anodized.com/ATI-649PR.html

 cases for my sigma and beta 22. i THINK, this size should be able to fit my 4 channel balanced config (i dont have it yet which is why im unsure, just trying to think ahead), without the backplane boards. my question is, if i wanted identical cases for my psu etc (just for aesthetics), is tehre any disadvantage to using a "larger" case than is needed, as i know this case in specific is far bigger than is "NEEDED" for my basic 100VA sigma22._

 

Disadvantages to using a larger case? It's more expensive, is heavier, and takes up more space


----------



## el_matt0

i should be able to fit a 4 channel balanced, without the backplane boards, into a 16.7" X 2.3" X 10.4" enclosure shouldnt i?


----------



## Nebby

um....board dimensions are on amb's site


----------



## lcp12345

PCB had been received for month. Still collecting the componets


----------



## n_maher

I highly suggest mocking up your proposed configuration on a piece of large paper prior to ordering any cases. I did and I still didn't properly account for the size of the stepped attenuator that I wanted to use and this caused me to have to order a different volume control part way through the build. 

 And just a word of warning about ATI, the last couple of times that I've thought about ordering from them they haven't had the case that I wanted in stock. I'd send them an email before doing a whole lot of planning.


----------



## luvdunhill

Quote:


  Originally Posted by *n_maher* /img/forum/go_quote.gif 
_And just a word of warning about ATI, the last couple of times that I've thought about ordering from them they haven't had the case that I wanted in stock. I'd send them an email before doing a whole lot of planning. 
	

	
	
		
		

		
		
	


	


_

 

ditto ...


----------



## el_matt0

alright ya i did that, they DO have those in stock in fact. about my question regarding the dimensions...my calculations read that it SHOULD fit OK, my only concern is the height. with the heatsinks that come in jeff rossels kit, the default size i think, will 2.3" be enough clearance including the board and spacers?


----------



## fierce_freak

You should be fine, but hopefully someone with some experience with it can pitch in on that. I'm pretty sure Jeff includes the 1.5" heatsinks in his kit, add 1/4" for spacers, another 1/8" or so for board thickness...you still have space.


----------



## n_maher

Quote:


  Originally Posted by *el_matt0* /img/forum/go_quote.gif 
_the heatsinks that come in jeff rossels kit, the default size i think, will 2.3" be enough clearance including the board and spacers?_

 

 Quote:


  Originally Posted by *n_maher* 
_I highly suggest mocking up your proposed configuration on a piece of large paper prior to ordering any cases._

 

My advice still sands and I would suggest that you find out if the 2.3" is the outside or inside dimension. It could make a world of difference.


----------



## el_matt0

yet another stupid noob question from me. im looking over my options for my panel mount XLRs, mouser labels some as being PCB mount style, and others as being panel or chassis mount. WHICH do i want..one would think it should obvious, but..well. you know me 
	

	
	
		
		

		
		
	


	




! the two model #s i had in mind are:
 1) NC3FD-V , my first choice, will this work ("PCB mount")
 OR
 2) NC3FD-LX (panel mount)


----------



## n_maher

Quote:


  Originally Posted by *el_matt0* /img/forum/go_quote.gif 
_yet another stupid noob question from me._

 

You said it, not me. 
	

	
	
		
		

		
		
	


	




 The answer _is_ obvious if you just look at the data sheets and/or Neutrik's website.


----------



## thrice

Quote:


  Originally Posted by *el_matt0* /img/forum/go_quote.gif 
_yet another stupid noob question from me. im looking over my options for my panel mount XLRs, mouser labels some as being PCB mount style, and others as being panel or chassis mount. WHICH do i want..one would think it should obvious, but..well. you know me 
	

	
	
		
		

		
		
	


	




! the two model #s i had in mind are:
 1) NC3FD-V , my first choice, will this work ("PCB mount")
 OR
 2) NC3FD-LX (panel mount)_

 

Technically either one will work, but unless you have PCB holes specifically designed for those jacks (hint: you don't), I would go with the panel mount ones

  Quote:


  Originally Posted by *n_maher* /img/forum/go_quote.gif 
_You said it, not me. 
	

	
	
		
		

		
		
	


	




 The answer is obvious if you just look at the data sheets and/or Neutrik's website._

 

Ease up there N, perhaps you should focus on remembering your wedding anniversary....................................... .................................................. .................................................. .................................................. .................................................. .................................................. .................................................. .................................................. .................................................. .................................................. .................................................. .................................................. .................................................. .................................................. .................................................. .................................................. .................................................. .................................................. .................................................. .................................................. .................................................. .................................................. .................................................. .................................................. .................................................. .................................................. .................................................. .................................................. .................................................. .................................................. .................................................. .................................................. .................................................. .................................................. .................................................. .................................................. .................................................. .................................................. .................................................. .................................................. .................................................. .................................................. .................................................. .................................................. .................................................. .................................................. .................................................. .................................................. .................................................. .................................................. .................................................. .................................................. .................................................. .................................................. .................................................. .................................................. .................................................. .................................................. .................................................. .................................................. .................................................. .................................................. .................................................. .................................................. .................................................. .................................................. .................................................. .................................................. .................................................. .................................................. .................................................. .................................................. .................................................. .................................................. .................................................. .................................................. .................................................. .................................................. .................................................. .................................................. .................................................. .................................................. .................................................. .................................................. .................................................. .................................................. .................................................. .................................................. .................................................. .................................................. .................................................. .....Oh no he DIDN'T!

 I kid, i kid


----------



## el_matt0

lol i love posting KNOWING nate is gunna hound me for whatever it is...its ok I DONT hate you for it...!


----------



## mb3k

Quote:


  Originally Posted by *el_matt0* /img/forum/go_quote.gif 
_lol i love posting KNOWING nate is gunna hound me for whatever it is...its ok I DONT hate you for it...!_

 

Nate has taught us ALL.
 Don't feel bad


----------



## el_matt0




----------



## n_maher

Quote:


  Originally Posted by *mb3k* /img/forum/go_quote.gif 
_Nate has taught us ALL.
 Don't feel bad_

 

me, teaching, bwaaaaaaaaaahahahahaha. I guess I teach by bad example, if that's what you mean. 
	

	
	
		
		

		
		
	


	




 I just want matt to learn how to solve some of these problems on his own so then he can share his _learned_ knowledge with others. I too was reminded of how important this type of learning was early in my DIY career and I'm thankful that I was. I'll never design my own circuits but I'm starting to get the hang of some of this after 3 or so years and 50 or so amps.


----------



## n_maher

Quote:


  Originally Posted by *thrice* /img/forum/go_quote.gif 
_Ease up there N, perhaps you should focus on remembering your wedding anniversary_

 

Note to self...

 lose Stephen's e22 order, permanently.


----------



## naamanf

Quote:


  Originally Posted by *n_maher* /img/forum/go_quote.gif 
_Note to self...

 lose Stephen's e22 order, permanently. 
	

	
	
		
		

		
		
	


	





_

 

Oh man that's rough.


----------



## el_matt0

Quote:


  Originally Posted by *n_maher* /img/forum/go_quote.gif 
_I too was reminded of how important this type of learning was early in my DIY career and I'm thankful that I was._

 

as am I!!


----------



## khbaur330162

el_matt0: Maybe you could help others out after all. You should think about making an all-encompassing thread titled "el_matt0 ß22 Build Thread" or something similar so that you can ask all the questions your heart desires concerning the ß22 while keeping them together and organized in a single kind of database. Your questions when scattered through random threads makes research much more difficult for others who may wish to follow in your footsteps, and it takes previous threads, such as this one, completely off topic.

 Good luck with your ß22 build, btw.


----------



## Nebby

Quote:


  Originally Posted by *mb3k* /img/forum/go_quote.gif 
_Nate has taught us ALL.
 Don't feel bad_

 

so true...so true


----------



## thrice

Quote:


  Originally Posted by *n_maher* /img/forum/go_quote.gif 
_me, teaching, bwaaaaaaaaaahahahahaha. I guess I teach by bad example, if that's what you mean. 
	

	
	
		
		

		
		
	


	




 I just want matt to learn how to solve some of these problems on his own so then he can share his learned knowledge with others. I too was reminded of how important this type of learning was early in my DIY career and I'm thankful that I was. I'll never design my own circuits but I'm starting to get the hang of some of this after 3 or so years and 50 or so amps._

 

Yeah me too. Essentially someone told me in no uncertain terms....DIY means DO IT YOURSELF...LOL

  Quote:


  Originally Posted by *n_maher* /img/forum/go_quote.gif 
_Note to self...

 lose Stephen's e22 order, permanently. 
	

	
	
		
		

		
		
	


	





_

 

That's cool man...I'll get that paypal dispute started then


----------



## amb

Quote:


  Originally Posted by *khbaur330162* /img/forum/go_quote.gif 
_el_matt0: Maybe you could help others out after all. You should think about making an all-encompassing thread titled "el_matt0 ß22 Build Thread" or something similar so that you can ask all the questions your heart desires concerning the ß22 while keeping them together and organized in a single kind of database._

 

There are already "stickied" β22 threads at headwize.
β22 part 1
β22 part 2
σ22 PSU thread


----------



## fierce_freak

I just got done staining the wooden front panel I made, so hopefully I'll have a screenshot sometime on Sunday (still have to put a protecting coat on it). I've been DIY'ing a lot of stuff I've never done before and having to make do with the tools I have (making the panel out of a drill, a dremel, and a file was fun 
	

	
	
		
		

		
		
	


	




).


----------



## n_maher

Quote:


  Originally Posted by *naamanf* /img/forum/go_quote.gif 
_Oh man that's rough._

 

Don't fear for Captain Rockhopper, he's got so much dirt on me after NYC (and I on him) that we exist in a sort of mutually assured destruction type of permanent peace.


----------



## thrice

Quote:


  Originally Posted by *n_maher* /img/forum/go_quote.gif 
_Don't fear for Captain Rockhopper, he's got so much dirt on me after NYC (and I on him) that we exist in a sort of mutually assured destruction type of permanent peace. 
	

	
	
		
		

		
		
	


	


_

 

Hey that girl told me she was old enou.........nevermind.

 Good thing you didn't come to the Tampa meet....I'd be in real trouble then


----------



## Nebby

Quote:


  Originally Posted by *fierce_freak* /img/forum/go_quote.gif 
_I just got done staining the wooden front panel I made, so hopefully I'll have a screenshot sometime on Sunday (still have to put a protecting coat on it). I've been DIY'ing a lot of stuff I've never done before and having to make do with the tools I have (making the panel out of a drill, a dremel, and a file was fun 
	

	
	
		
		

		
		
	


	




)._

 

Oh man, I've done that before, and when I went to the wood shop for my latest project it was so ridiculously easy to do everything in comparison I was amazed


----------



## fierce_freak

Yeah, I'm sitting here spending all this time to do something that seems would be so easy to do if I had the right tools (table saw, drill press, a unibit)...oh well


----------



## DigiPete

I would have to hear a balanced Beta22 against my Dynamite,
 before I commited the funds to build one.


----------



## khbaur330162

Quote:


  Originally Posted by *amb* /img/forum/go_quote.gif 
_There are already "stickied" β22 threads at headwize.
β22 part 1
β22 part 2
σ22 PSU thread_

 

Yet the man is still asking questions out the wazoo. 
	

	
	
		
		

		
		
	


	




 He might as well keep them compiled in a single location as he asks them, no?


----------



## Nebby

Quote:


  Originally Posted by *khbaur330162* /img/forum/go_quote.gif 
_Yet the man is still asking questions out the wazoo. 
	

	
	
		
		

		
		
	


	




 He might as well keep them compiled in a single location as he asks them, no?_

 

I agree.....one central thread would be a good idea


----------



## el_matt0

ok ok, next "question" i have to ask will be in a new thread called b22 questions or matts b22 questions or something...then those of you that are disgusted by my frequent questions dont even hafta open the thread up! :/


----------



## tomb

This is just a comment in general - nothing personal - but I don't understand why many are reluctant to post on another site, period. I know this to be true, because of certain Group Buys that were conducted on both forums. There are entire groups of people who post on one forum, but apparently refuse to post on the other and vice versa.

 I don't understand it, though - even when specific URL's are listed for purposes such as the one in this thread, the choice is often made to just start another thread. Again, no personal criticism against the OP or other posters for this; it's a phenomenon that exists for many users.


----------



## Nebby

Quote:


  Originally Posted by *tomb* /img/forum/go_quote.gif 
_This is just a comment in general - nothing personal - but I don't understand why many are reluctant to post on another site, period. I know this to be true, because of certain Group Buys that were conducted on both forums. There are entire groups of people who post on one forum, but apparently refuse to post on the other and vice versa.

 I don't understand it, though - even when specific URL's are listed for purposes such as the one in this thread, the choice is often made to just start another thread. Again, no personal criticism against the OP or other posters for this; it's a phenomenon that exists for many users._

 

I mostly post here and lurk over there, though I've poked my head in on other forums to ask noob questions every once in a while


----------



## fierce_freak

I got the wooden front panel done, so I thought I'd post a pic. I also made the flexy rack over the weekend 
	

	
	
		
		

		
		
	


	














 I'm putting the dac I'm building in a Par-Metal 20 series case, too, so I'll finish it in the same fashion as the Beta22.


----------



## naamanf

Looks great. I can't wait to get mine done. I have kick***** piece of cocabolo thats going on the front. How long did it take to get the Par-Metal case in?


----------



## fierce_freak

I bought mine off the ebay store (extremely limited selection), so I got it in about a week.

 Nice wood. I just used a crappy piece of ~$2 aspen and stained it.


----------



## naamanf

Have the sellers name or link for the ebay store?


----------



## fierce_freak

http://stores.ebay.com/Antek-inc_Enc...QQftidZ2QQtZkm


----------



## el_matt0

fierce that looks AWESOME man..although..what happend to the knob on your zhaolu??


----------



## fierce_freak

lol...I removed the original analog section and the headphone amp to put a Zapfilter into it. Sounds great.

 Thanks for the compliment 
	

	
	
		
		

		
		
	


	




 I'm thinking of adding a couple LEDs to the front panel to indicate power.


----------



## The Burn Pt.2

Mines just an acrylic "platter" with everything mounted on top


----------



## khbaur330162

Cases are nice and all, but how's it sound?


----------



## el_matt0

guys, for hooking up a power entry module to the transformer, i know its recommended to use something like fastON connectors etc, but is this just for ease, or for safety etc as well? would it not be suitable to just do a careful job with well insulated 16 AWG wire and heatshrink the connections nicely?


----------



## n_maher

If I'm understanding you correctly you're asking about using faston connectors to wire your trafo to the power inlet module. If that's the case, yes it would be suitable to do as you describe and just direct solder the wires to the module and insulate them with shrink. The only issue you could face is if you ever need to remove the trafo it's a much more arduous task dealing with the soldered connections.


----------



## threEchelon

Quote:


  Originally Posted by *The Burn Pt.2* /img/forum/go_quote.gif 
_



_

 

nm


----------



## gates_2

i'm getting a dc offset on one of my boards of 58mV. The Jfets were matched by jeff(ordered a kit from him), so I don't think thats the problem. Should i just get a lower value resistor for R13 and extend the trimpot range?


----------



## gates_2

well, i swapped q3 and q4, got the dc offset down, but now something weird happened...

 measuring across r34, wasn't getting a reading, so i fiddled with VR2, and got the number up some, but it was fluctuating quite a bit, up and down, up and down. Went back, fixed vr1 so was reading 4.5 V across R9, then when i went to mess with VR2 again, no reading....(in mV, of course)

 did I fry my jfets desoldering them?(I hope not)


 EDIT:
 Another interesting note, i hooked up a source and some crappy earbuds, and i get music with little hum (odd...)


----------



## n_maher

1. I wouldn't trust crappy earphones when testing for hum. I've had little buds that hummed regardless of how quiet an amp was with my ER4Ps. Some headphones/earbuds really do just suck. If you amp tests fine with regards to DC offset you don't have all that much to worry about.

 2. You may or may not have fried the fets in the solder/desolder cycle. However, given the intermittent characteristic it would make a lot of sense to reflow all of the joints from the swap since you might have a cold joint.


----------



## el_matt0

well. just an update..got my s22 finished and mounted along with the trafo in my par-metal case (black anodized, 16"x16"x4"), ya its a beast. lol. everythings goin smoothly so far, rest of my b22 boards probably populated later this week. man, although im relatively new to the circuitry stuff and thats DEFINITELY my weakness (as uve all noticed by now 
	

	
	
		
		

		
		
	


	




), im GLAD that casework and carpentry type work was my strong suit coming into this project, because i would NOT want to do this casing without experience! man, i can not speak enough for how handy the drill press in the basement has been! quickie question, i dont (yet?) have a nice big stepped drill bit, so for getting the really large holes, ie for the power entry module etc, any tricks? would drilling out a series of smaller holes and then dremmelling or something probably be my best bet?


----------



## kklee

Quote:


  Originally Posted by *el_matt0* /img/forum/go_quote.gif 
_ would drilling out a series of smaller holes and then dremmelling_

 

That's the approach I used. Measure carefully and it's okay to be a little on the smaller side since you can always file to fit.


----------



## el_matt0

yep exactly what im ABOUT to do. smaller is always better. i imagine TOO big would be no good 
	

	
	
		
		

		
		
	


	




. it would definitely suck to hafta shop around to find a power entry module to fit a botched hole lol!


----------



## Clutz

I'm planning on starting to build my Beta22 (for the second time, I buggered it the first time) tonight after work. 
	

	
	
		
		

		
		
	


	




 I'm hoping to have enough time to finish one board completely.


----------



## Clutz

So far I've got all the diodes, all the resistors, and all the CRDs installed. I've also got all the JFETs, and have the BJTs installed. I've been going at this for about 4 hours so far, and I'm starting to go a bit stir crazy.


----------



## naamanf

I like doing all the same component on all the boards at the same time. That way as long as your doing it right all the boards should get built the same. Well except for the ground board but that is only a couple components different. Plus I think it saves time in the long run because you only have to reference and pull out the parts one time.


----------



## Clutz

Woot. Well, I finished getting all the BJTs installed. All I have left are the POTs, the capacitors and the mosfets. If I can get another 4-6 hour chunk of time free, I should be able to finish get all the soldering done and get the set up and biasing done.


----------



## jarthel

Quote:


  Originally Posted by *gates_2* /img/forum/go_quote.gif 
_I'm currently in the ordering stages of building a B22 for my friend... Gonna try that jason tree relay-based attenuator- should be fun_

 

be careful though. I have ask Russ White about the *joshua* tree attentuator and it seems to be similar to a shunt attenuator not series/ladder.


----------



## jarthel

even with parts count, this is an easy project. you have a PCB provided with labels for components. how hard can it be?

 if you can read, you can built this one!


----------



## n_maher

Quote:


  Originally Posted by *jarthel* /img/forum/go_quote.gif 
_even with parts count, this is an easy project. you have a PCB provided with labels for components. how hard can it be?
 if you can read, you can built this one! 
	

	
	
		
		

		
		
	


	


_

 

You might be able to build it, but if you have any issues you might have a hard time fixing it. And there are a lot of similarly shaped components which has been known to throw the novice builder. 

  Quote:


  Originally Posted by *jarthel* /img/forum/go_quote.gif 
_be careful though. I have ask Russ White about the *joshua* tree attentuator and it seems to be similar to a shunt attenuator not series/ladder._

 

I'm curious, what is your concern here?


----------



## gates_2

Quote:


  Originally Posted by *n_maher* /img/forum/go_quote.gif 
_You might be able to build it, but if you have any issues you might have a hard time fixing it. And there are a lot of similarly shaped components which has been known to throw the novice builder. 

 I'm curious, what is your concern here?_

 


 x2 I was about to order one for the b22 i'm building, thinking it would be cheaper/better than a standard stepped attenuator....


----------



## Nebby

As for the similarly shaped parts issue, it's really a non-issue with the way Twisted Pear labels their kits, every part is labeled with a label stating the Part number that's silk screened on the actual pcb and item description. Makes stuffing the pcb a simple affair of connect-the-dots, imo


----------



## kklee

Quote:


  Originally Posted by *jarthel* /img/forum/go_quote.gif 
_even with parts count, this is an easy project. you have a PCB provided with labels for components. how hard can it be?

 if you can read, you can built this one! 
	

	
	
		
		

		
		
	


	


_

 

As Nate said, the sheer parts count drives up the odds for mixing up parts, but it also means higher odds for having bad solder joints. I spent two days assembling boards for two 3-channel amps. I consider myself a seasoned pro when it comes to soldering (been doing it for over 30 years) and I still managed to miss one solder joint on a board.

 As evidenced by some of the posts over on Headwize, troubleshooting this amp isn't easy.


----------



## jarthel

Quote:


  Originally Posted by *n_maher* /img/forum/go_quote.gif 
_
 I'm curious, what is your concern here?_

 

shunt attenuators works differently than your ordinary log pot or series/ladder attenuator. check goldpt.com for explanation


----------



## jarthel

Quote:


  Originally Posted by *gates_2* /img/forum/go_quote.gif 
_x2 I was about to order one for the b22 i'm building, thinking it would be cheaper/better than a standard stepped attenuator...._

 

looking at percy's catalog, he sells an elma switch + a set of holco resistors for only $76. definitely cheaper than the joshua tree (by $6) and less real estate too 
	

	
	
		
		

		
		
	


	




 up to you I suppose, it's your project 
	

	
	
		
		

		
		
	


	




http://www.goldpt.com/how.html


----------



## Nebby

Is the elma switch usable for a 4 channel balanced beta22? That's the main reason I've been looking at the JT attenuator, doesn't seem balanced stepped attenuators come very cheap....


----------



## fierce_freak

I have two elma stereo switches I stuffed with resistors for my Beta22 (ask jrossel about it).


----------



## Nebby

Ah yes, but I want a single volume knob for my balanced output, and two separate volume knobs for the SE outputs.....at least that's what I'm dreaming of. How, to get there....I'm still researching


----------



## n_maher

Quote:


  Originally Posted by *jarthel* /img/forum/go_quote.gif 
_shunt attenuators works differently than your ordinary log pot or series/ladder attenuator. check goldpt.com for explanation 
	

	
	
		
		

		
		
	


	


_

 

I'm aware of the differences and based on my understanding I don't see any reason why the JT attenuator wouldn't work fine on the input of a beta. Granted, I'm not the most technically inclined person so any further explanation would be greatly appreciated.


----------



## n_maher

Quote:


  Originally Posted by *Nebby* /img/forum/go_quote.gif 
_Ah yes, but I want a single volume knob for my balanced output, and two separate volume knobs for the SE outputs.....at least that's what I'm dreaming of. How, to get there....I'm still researching 
	

	
	
		
		

		
		
	


	


_

 

I'm sure it _can_ be done, but it doesn't strike me as at all practical or elegant.


----------



## Nebby

Quote:


  Originally Posted by *n_maher* /img/forum/go_quote.gif 
_I'm sure it can be done, but it doesn't strike me as at all practical or elegant._

 

pretty much what I've come to conclude, but I can always dream in the mean time


----------



## jarthel

Quote:


  Originally Posted by *n_maher* /img/forum/go_quote.gif 
_I'm aware of the differences and based on my understanding I don't see any reason why the JT attenuator wouldn't work fine on the input of a beta. Granted, I'm not the most technically inclined person so any further explanation would be greatly appreciated._

 

the question has nothing to do with the preamp/headphone amp. It has something to do with the source.

 since a shunt attenuator input impedance varies, the load seen by the source varies as well. it's easier for a source to drive 100K vs 10k input impedance. the sound *might* sound different (not just louder or softer) as well when changing position.

 if you want something similar to series/ladder, try electronics.dantimax.dk. I bought his RelVol1C. cheaper than the joshua tree too


----------



## gates_2

picked up the Relvol1c.... looks cool, and you can use a remote control with it :-D


----------



## jarthel

Quote:


  Originally Posted by *gates_2* /img/forum/go_quote.gif 
_picked up the Relvol1c.... looks cool, and you can use a remote control with it :-D_

 

lots of people in diyaudio has used his kits and I've only seen good feedback. and he is very helpful 
	

	
	
		
		

		
			





 3 things I like about the dantimax kit:
 1. constant input impedance
 2. small size
 3. cheaper


----------



## MrMajestic2

Im thinking of building a balanced b22, but I want to be able to run in single ended mode also. How do I wire that up, and what do I have to think about? I bet there are more than a few pitfalls with this setup 
	

	
	
		
		

		
		
	


	




 Also, would a 10K pot be sifficient for the b22?


----------



## amb

Quote:


  Originally Posted by *MrMajestic2* /img/forum/go_quote.gif 
_Im thinking of building a balanced b22, but I want to be able to run in single ended mode also. How do I wire that up,_

 

See "Other options" section at the β22 webste.
  Quote:


 Also, would a 10K pot be sifficient for the b22? 
 

See "Parts list" section at the β22 website.


----------



## MrMajestic2

Quote:


  Originally Posted by *amb* /img/forum/go_quote.gif 
_See "Other options" section at the β22 webste.

 See "Parts list" section at the β22 website._

 


 Thanks AMB, I found it after posting the question. Next time Ill know better 
	

	
	
		
		

		
		
	


	




 I found a quad Alps RK27 on german ebay that is only available in 5 or 10K. Pretty good price too:

http://stores.ebay.com/familygate


----------



## Dorder

Quote:


  Originally Posted by *amb* /img/forum/go_quote.gif 
_See "Other options" section at the β22 webste._

 

hey amb,
 i saw that in your schematics for combined balanced and single-ended operation the bal. and SE inputs are shorted, without a switch. wouldn't that create the problem of the sources "driving" eachother and causing potential damage, due to the amps high input- and the sources' lower output impedance?


----------



## itsborken

Have the boards for a se b22 but am revisiting building a balanced/se combo in its place. Might as well go all out on it and the reviews are great.


----------



## naamanf

I am working on a three channel version. Received my E22 backplanes this weekend and hope to have it up and running sometime this week.


----------



## amb

Quote:


  Originally Posted by *Dorder* /img/forum/go_quote.gif 
_i saw that in your schematics for combined balanced and single-ended operation the bal. and SE inputs are shorted, without a switch. wouldn't that create the problem of the sources "driving" eachother and causing potential damage, due to the amps high input- and the sources' lower output impedance?_

 

The balanced and unbalanced inputs are not meant to be used simultaneously. If you want to have them plugged in at the same time, then a switch should be used.


----------



## GlendaleViper

Selling my little Eddie Current to build this amp/PS. Should be a great project for the impending winter (yes, in Canada we think about that early).

 Regarding the full kits available, is it worth it to purchase the kits (from Glass Jar Audio) if I know I'm likely to tinker with upgraded or just plain different parts?


----------



## KerryKing

In the building process 
	

	
	
		
		

		
		
	


	



 Cant wait to lift the Solder iron again


 To bad I am missing parts for the s22 so i cant test it 
	

	
	
		
		

		
		
	


	



 Especially since I am missing the CR1-4 that is almost impossible to source in Sweden 
	

	
	
		
		

		
		
	


	




 (at least to normal prices without super high postage costs)


----------



## MrMajestic2

Quote:


  Originally Posted by *KerryKing* /img/forum/go_quote.gif 
_In the building process 
	

	
	
		
		

		
		
	


	



 Cant wait to lift the Solder iron again


 To bad I am missing parts for the s22 so i cant test it 
	

	
	
		
		

		
		
	


	



 Especially since I am missing the CR1-4 that is almost impossible to source in Sweden 
	

	
	
		
		

		
		
	


	




 (at least to normal prices without super high postage costs)_

 

Guess what, Im placing an order with Mouser again


----------



## KerryKing

Ah sweet music for my ears 
	

	
	
		
		

		
		
	


	




 guess who is joining


----------



## Grahame

Received my E22 backplanes.
 Still doing my due diligence / background reading.

 Thinking about a 6 channel - balanced / dual SE setup hence the need for 2 backplanes.

 Investigating volume control switching options + casework.

 Came across these sweet cases - but two E22s won't fit in a stereo case, nor one in a mono - the quest continues. 

 Also to fit into a standard audio rack the clearance with two boards will be tight.

 Q: Anyone know of any cases that could fit two E22's side by side yet not add too much to the total size of the package - suggestions welcome. 

 Also looking into seeing if remote control of switching / volume is a realistic option - I only intend to do this once, I might as well do it right!

 The remote control is overkill for a headphone rig, I know - but this might be a speaker amp as well - hence the remote control being a nice to have.


----------



## amb

Grahame, have a look at thrice's balanced β22 with two ε22 backplane boards (the pics were taken when only four channels were populated, now he has all six):
http://www.head-fi.org/forums/showpo...postcount=2162

 It's a wide case but does fit two backplane boards comfortably.

 Here is info about the case:
http://www.head-fi.org/forums/showpo...postcount=2170


----------



## MrMajestic2

Quote:


  Originally Posted by *Grahame* /img/forum/go_quote.gif 
_Received my E22 backplanes.
 Still doing my due diligence / background reading.

 Thinking about a 6 channel - balanced / dual SE setup hence the need for 2 backplanes.

 Investigating volume control switching options + casework.

 Came across these sweet cases - but two E22s won't fit in a stereo case, nor one in a mono - the quest continues. 

 Also to fit into a standard audio rack the clearance with two boards will be tight.

 Q: Anyone know of any cases that could fit two E22's side by side yet not add too much to the total size of the package - suggestions welcome. 

 Also looking into seeing if remote control of switching / volume is a realistic option - I only intend to do this once, I might as well do it right!_

 

Wow, those cases look really cool. Too bad the prices are uncool.

 To answer one of your questions:
 I was checking out some volume options when I stumbled upon a quad version of the Alps Blue velvet on ebay. Its also available in a motorized version.
http://stores.ebay.com/familygate


----------



## Grahame

Thanks for the info guys, more options to consider.
 Choices, Choices!


----------



## Nebby

I didn't realize you were a soldering fool too Grahame! I'm also building a beta22 that will likely be a speaker amp too


----------



## fierce_freak

I have a bit of a problem 
	

	
	
		
		

		
		
	


	




 I was testing out a couple different connectors, and I think I managed to bridge ground and the - output of one channel (balanced amp). The sinks on the - board for that channel aren't getting warm now. Is it possible I just killed a couple of parts on the board, or am I going to have to put together a whole new one?

 -edit- just took a closer look...R34 is burnt up, so is it possible that's the only part that bit it?


----------



## el_matt0

quickie update to anyone that was interested/cared. finally got all 4 b22 boards populated, my s22 populated and wired up/ mounted. and just actually currently sitting here with a file doing some of my panel components. im working on the square hole for the power entry currently. ugh. not fun. quick 2 side questions ive got. currently ive got 2 blue LEDs per board. im mounting this all in a big par metal case which has a vented top. u guys think i would get enough light simply spilling from the vents (seeing that there are 10 something LEDs inside) that i wouldnt need a power LED front and center on the front panel? might try and go for a simplistic looking front panel and just cut it out if its deemed unecessary. also, hmm, for case feet, anyone know of a good place to order? the type i have in mind are (gunna do my best to describe) low and cylindrical. basically like flat circles, maybe 1cm or so high, usually either in chrome or black? thx guys and gl with all of YOUR b22 builds. im gunna need it for the nastiness of wiring and biasing - the part where all my inexeprience will undoubtedly come back to bite me


----------



## SilverTrumpet999

MrMajestic2 and Grahame: Where are you getting your E22 boards, as I am pretty sure AMB's stock has been out for some time? Were you in on n_maher's group buy for the 1.1 version? 

 If so, I'm jealous as I missed that one by mere days... that's what I get for going on vacation


----------



## threEchelon

Quote:


  Originally Posted by *el_matt0* /img/forum/go_quote.gif 
_quickie update to anyone that was interested/cared. finally got all 4 b22 boards populated, my s22 populated and wired up/ mounted. and just actually currently sitting here with a file doing some of my panel components. im working on the square hole for the power entry currently. ugh. not fun. quick 2 side questions ive got. currently ive got 2 blue LEDs per board. im mounting this all in a big par metal case which has a vented top. u guys think i would get enough light simply spilling from the vents (seeing that there are 10 something LEDs inside) that i wouldnt need a power LED front and center on the front panel? might try and go for a simplistic looking front panel and just cut it out if its deemed unecessary. also, hmm, for case feet, anyone know of a good place to order? the type i have in mind are (gunna do my best to describe) low and cylindrical. basically like flat circles, maybe 1cm or so high, usually either in chrome or black? thx guys and gl with all of YOUR b22 builds. im gunna need it for the nastiness of wiring and biasing - the part where all my inexeprience will undoubtedly come back to bite me_

 

Dude, you need to use paragraphs and proper writing conventions. No one wants to read that.


----------



## colonelkernel8

Quote:


  Originally Posted by *threEchelon* /img/forum/go_quote.gif 
_Dude, you need to use paragraphs and proper writing conventions. No one wants to read that. 
	

	
	
		
		

		
		
	


	


_

 

Yeah, thats kind of a "voice of the mind" typing style.


----------



## threEchelon

Quote:


  Originally Posted by *colonelkernel8* /img/forum/go_quote.gif 
_Yeah, thats kind of a "voice of the mind" typing style._

 

"Stream of consciousness" it's called.


----------



## MrMajestic2

Quote:


  Originally Posted by *SilverTrumpet999* /img/forum/go_quote.gif 
_MrMajestic2 and Grahame: Where are you getting your E22 boards, as I am pretty sure AMB's stock has been out for some time? Were you in on n_maher's group buy for the 1.1 version? 

 If so, I'm jealous as I missed that one by mere days... that's what I get for going on vacation 
	

	
	
		
		

		
		
	


	


_

 

Im not getting a E22 board. Im most likely building the four-board balanced version, so its of no use to me.


----------



## Grahame

Quote:


  Originally Posted by *Nebby* /img/forum/go_quote.gif 
_I didn't realize you were a soldering fool too Grahame!_

 

You might be half right!


----------



## el_matt0

currently ive got 2 blue LEDs per board. im mounting this all in a big par metal case which has a vented top. u guys think i would get enough light simply spilling from the vents (seeing that there are 10 something LEDs inside) that i wouldnt need a power LED front and center on the front panel? might try and go for a simplistic looking front panel and just cut it out if its deemed unecessary. 

 also, hmm, for case feet, anyone know of a good place to order? the type i have in mind are (gunna do my best to describe) low and cylindrical. basically like flat circles, maybe 1cm or so high, usually either in chrome or black?


----------



## n_maher

You'll get quite a bit of light out of all those blue LED's, it would probably serve as enough of a reminder that the amp is on without having a front panel LED.

 Can't say I've seen the feet that you're looking for but feet seem like knobs to me, the good places to buy them are few and far between.


----------



## dsavitsk

Quote:


  Originally Posted by *el_matt0* /img/forum/go_quote.gif 
_also, hmm, for case feet, anyone know of a good place to order? the type i have in mind are (gunna do my best to describe) low and cylindrical. basically like flat circles, maybe 1cm or so high, usually either in chrome or black?_

 

The Cary feet (as seen here: http://caryaudio.com/graphics/produc..._front_800.jpg ) can be purchased from http://www.audioelectronicsupply.com...m=FOOT_LRG_BSS


----------



## MisterX

Like these?


----------



## el_matt0

YES misterx. exactly liek those. where to get em? lol, tease! those cary feet look ok too, given that my case is black they would probably do the job and look quite inconspicuous. although...if misterx lets me know where those ones can be found i may just holdout for those


----------



## n_maher

http://www.jaycar.com.au 

 Your webstalking skills need work, el_matt0.


----------



## MisterX

The image came from Jaycar electronics. 

 You can get plain rubber ones just about anywhere.


----------



## el_matt0

thanks guys. i KNOW nate its true, im a horrible webstalker. care to gimme any advice from the pros? i do use the search feature etc a ton but id say about 90% of the time just turn up either jibberish or useless threads!


----------



## MisterX

Quote:


 care to gimme any advice from the pros? 
 

google


----------



## Nebby

Quote:


  Originally Posted by *MisterX* /img/forum/go_quote.gif 
_google_

 

All hail the power of google!


----------



## el_matt0

ugh, soo, thought i was all finished up populating the boards and mounting them to the case etc when i realized that i mounted q1-q4 as the silkscreen indicated - incorrectly 
	

	
	
		
		

		
			





. think im just gunna order up a new batch and wait the week rather than try and refit these already trimmed ones. 

 on a different note, has anyone had any experience with http://www.partsconnexion.com/catalo...s/image006.jpg 
 the foculpods by spectra dynamics? what kind of mounting system do they employ..?


----------



## MrMajestic2

Quote:


  Originally Posted by *el_matt0* /img/forum/go_quote.gif 
_on a different note, has anyone had any experience with http://www.partsconnexion.com/catalo...s/image006.jpg 
 the foculpods by spectra dynamics? what kind of mounting system do they employ..?_

 

http://www.tnt-audio.com/accessories/deflex_e.html

 Havent tried them though.


----------



## KerryKing

Backplane arrived today,
 now i have to start building seriously 
	

	
	
		
		

		
		
	


	




 Great day


----------



## gates_2

got the boards installed on the backpane... everything sounds/looks good... John from par-metal never responded to my email

 seems like I'll have to give him a ring


----------



## el_matt0

ya dont bother emailing john lol. i tried about 5 times to no avail. calling on the other hand - very good idea. if not his secretary, you'll probably be able to get john himself on the phone. ordering from par-metal was very straightforward..they took about a week to ship once i ordered, at which point i was billed. delivery took about 1.5 weeks to BC canada.


----------



## colonelkernel8

Quote:


  Originally Posted by *threEchelon* /img/forum/go_quote.gif 
_"Stream of consciousness" it's called. 
	

	
	
		
		

		
		
	


	


_

 

Thats it! I couldnt remember so I made up my own phrase. The original one is better.


----------



## el_matt0

wow, seems like this thread has been absolutely dead with my absence of silly questions! anyways, heres one more "classic" from myself. im just in the stages that im about to begin the wiring up of my 4 channel b22, i was originally planning to use just 2 balanced inputs and 2 balanced outputs. however, after thinking about it more, i think i definitely want at least a few RCA inputs as well as either 1 or 2 SE outputs. is this just a simple matter of wiring as per the schematic in the "other options" section of AMBs site? 




 now, assuming im relatively along the right lines here, would that reQUIRE me putting an input selector of some sorts? also, kind of a similar question regarding the outputs, would i need to incorporate an output selector, or would it just run all outputs simultaneously? if thats the case, using a quad pot would obviously change the volumes of all headphones plugged in , so the only issue would be differing impedences of the headphones? SORRY again i really hate asking questions like this


----------



## amb

That diagram assumes that you'll have the balanced and unbalanced inputs connected one at a time, not simultaneously. If you don't want to be pulling connectors then you'd need an input switch (4PDT minimum). A quad pot will adjust all channels simultaneously.

 You don't need to switch the outputs.


----------



## koike

buying the boards for the *x*22s end of the month when i get my salary! 
	

	
	
		
		

		
		
	


	



 may i ask for some suggestions on parts upgrades?
 Will be using blackgate caps non polarized versions if its possible and im torn between DACT stepped attenuator and twisted pear joshua tree or just buy the black beauty?
 and 1 more question...
 in the sigma22 whats the main difference between 2x 2200uF and 1x 4700uF?


----------



## Clutz

amb suggests you use the default parts and not bother with expensive boutique caps, because they are unnecessary in this design.


----------



## el_matt0

as predicted, here we go as i begin to run into a massive SLEW of problems with my b22/s22 must undoubtedly at least partially due to my inexperience. instead of the "i told you so's" that im SURE are justified, im wondering if anyone can try to help to get me out of this hole that im in. relating to just my s22, ive got it wired with IEC, fuse, switch etc, and ive got my transfo wired up too. just went to do the initial power on checks and voila, nothing at all. absolutely squat, the fuse still isnt blown and ive checked that the cord is good so...obviously i went awry somewhere! ive inspected my board and all the joints look quite good, there are no obvious short circuits or solder bridges. im just seeing no signs of life once i turn it on plugged in (and when the switch is "off" for that matter so its not like i rigged it up backwards!!). also, i tried measuring DCV between the G and V+ of the output terminal block, and there is no visible readings at any point. im going to post up a few cell phone pics in a minute, this is very disheartening, as obviously this is NOT a good start 
	

	
	
		
		

		
			





! PLEASE let me know if you have any suggestions at ALL.


----------



## n_maher

It will be impossible to help without pictures. Take high-res, in focus pictures of the top and the bottom of the board with it wired as you currently have it, cell phone pictures probably aren't going to help at all. 

 If you're getting nothing and the fuse isn't blown I'm betting you've got the trafo wired wrong so I'd check that again, even if you think you've got it right. If pictures prove impossible try and described how you have it wired. Tell us what trafo it is (make, model) and what color wires you have connected to what.


----------



## el_matt0

just realized i cant post pics cuz i dont have hosting, i can email anyone that has the heart to offer me personal help 
	

	
	
		
		

		
		
	


	




! for references sake, i am using the identical transformer to fierce_freak, and i have it wired identically to as can be seen in his pic below.
http://www.lightmedark.com/p/mod/b22f.jpg
 i might not be using the exact same IEC and switch as him, but that really shouldnt make a difference like this obviously i assume?


----------



## n_maher

PM me your email address, I'll host them.


----------



## el_matt0

additional info. its an AvelLindberg Y236405. looking at the IEC from the back (like in fierce's pic above), i have the purple and blue wires twisted as a pair and soldered to the "top right" lug on the IEC (from the back view). the "top left" lug on the IEC is wired with 18 AWG to the top lug on my switch, the bottom lug of the switch being soldered to the twisted pair of grey/dark brown wires from my trafo. the 3rd "bottom right" lug on the IEC is simply wired to the chassis. in terms of secondaries, as seen in fierces above, my order from left to right (with the terminal block on the FAR side of the board from you) is yellow, orange, red, black.


----------



## el_matt0

incase the text description doesnt cut it for you guys 
	

	
	
		
		

		
		
	


	




 nate has been generous enough to offer to host a few pics for me so those will be up in the next hour or so hopefully, just gotta find a camera


----------



## n_maher

I don't think you've got the trafo wired correctly, try (from L to R) red, black, orange, yellow. See picture below.





*
 [edit]*I just reread your description, you've definitely got red and black flipped, switch those two and see what happens.


----------



## mb3k

Cool, matt, I'll take a second look at it also. I'm in the process of the ground channel, hopefully I can finish all the channels in a week or two.

 I'm in a small dilemma here. For the transistor matching - particularly the output mosfets:
Q21, Q22 - match these for Vgs within 0.3V
 Q23, Q24 - match these for Vgs within 0.3V
This question is aimed toward AMB... With the tested complementary pair IRFZ24N / IRF9Z34N, what do you specifically test for? I would assume no matching is done with those?


----------



## el_matt0

@ nate, THATS what jeff rossel said tOO! however, i was using fierce_freaks as a guide, and looking from him, the order is yellow orange red black i think!!! i sent jeff rossel back an email asking to clarify, and ti kan replied saying that fierce's order is correct.....so.....WHAT is the correct order??? heres his email sent last night: 
 "It should be yellow-orange-red-black (either left to right or right to left,
 it doesn't matter).

 -Ti"

 soooooooooo........should i try the swap or no


----------



## vvs_75

correct:from L to R: yellow, orange, red, black


----------



## el_matt0

k so i wont try swapping them then?, and...still lifeless


----------



## n_maher

Matt,

 I'm downloading your pictures now and I'll try to get them up as soon as I can. Bottom line, I don't think that either configuration is wrong, one may result in the two secondaries being out of phase with each other but as long as black and red are used as a pair and correspondingly yellow and orange the PS should work fine. 

 As a check take the wires out of the sigma22, apply power to the trafo and check the output across one of the pairs (black/red for example). You should read about 30VAC, probably a bit higher. Make sure that the other leads are kept separate, you don't want to short part of the trafo. Clearly if you don't get the right measurement here something upstream is wrong (IEC wiring, for example).


----------



## n_maher




----------



## thrice

Check to see if your transfo is wired right...you'll want to remove it and test it as n-Maher mentioned.

 If that's all good then you may need to check operating voltages on the board when powered up. AMB has schematics detailing the operating voltages:

 +/- 30V http://www.amb.org/audio/sigma22/s22_30v_voltages.pdf

 +/- 24V http://www.amb.org/audio/sigma22/s22_24v_voltages.pdf

 +/- 15V http://www.amb.org/audio/sigma22/s22_15v_voltages.pdf

 Probably some transistor somewhere is shot. Check Q1 and Q2 first and work your through the schematic.

 Oh yeah, don't shock yourself


----------



## thrice

On second glance...are your diodes on correctly...perhaps it's just the light playing tricks,but they may be reversed.


----------



## mb3k

Quote:


  Originally Posted by *thrice* /img/forum/go_quote.gif 
_On second glance...are your diodes on correctly...perhaps it's just the light playing tricks,but they may be reversed._

 

Yeah, it looks as though you have your diodes the wrong way. Looking from the front (side closest to the LED) the diodes should all be facing toward you (metal tabs facing the back where the AC comes in).

 EDIT:
 See AMB's post #*187*


----------



## amb

el_matt0, your four rectifier diodes do indeed look to be installed backwards. The front side (with the printed labels) should face the center of the board. Compare against the assembled board pic at the σ22 website.


----------



## n_maher

Yup, confirmed on the full sized pics, rectifiers are in bassakwards.


----------



## el_matt0

! GUYS thank you, silly me im going to fix that right away and hopefully things should actually work! out of curiousity, does a trafo make any perceptible noise when "working and on"? ill keep you all posted on results..thanks again everyone for all the help, knowing me im sure youll all get another opportunity to before this beast is actually up and working 
	

	
	
		
		

		
		
	


	




!


----------



## n_maher

The trafo might hum slightly, but it'll also hum pretty loudly (at least some have) if you hook it up incorrectly and short something that doesn't want to be shorted.


----------



## thrice

Quote:


  Originally Posted by *n_maher* /img/forum/go_quote.gif 
_The trafo might hum slightly, but it'll also hum pretty loudly (at least some have) if you hook it up incorrectly and short something that doesn't want to be shorted._

 

Something might blow up too...then you know something's wrong...caps popping is.....exciting.


----------



## amb

mb3k, for the Avel-Lindberg Y23 transformers, the secondary windings should be connected to the board in the following order:
 ~ G G ~ = yellow-orange-red-black (either left to right or right to left, it doesn't matter).


----------



## el_matt0

urgh, i absolutely dread unsoldering and resoldering thru hole components. i find desoldering braid to be for all intensive purposes, fairly useless, and often times accessing the top side with the iron so that you can place a desoldering pump on the underside is very difficult to do. tips/pointers/tricks?


----------



## thrice

Quote:


  Originally Posted by *el_matt0* /img/forum/go_quote.gif 
_urgh, i absolutely dread unsoldering and resoldering thru hole components. i find desoldering braid to be for all intensive purposes, fairly useless, and often times accessing the top side with the iron so that you can place a desoldering pump on the underside is very difficult to do. tips/pointers/tricks?_

 

You know I actually find desoldering braid easier than the pumps. Just get your iron a little hotter and lay a piece of the braid flat against the solder joint.

 You might want to pull up a littte as you heat the solder joint (not much might you, you don't want to rip off traces...but just a little once the solder has melted.

 Get some PCB board from Radioshack and practice....it helps.


----------



## amb

el_matt0, another comment -- your power transformer looms rather close to your amp boards on the left side. There has been plenty of discussion at the headwize β22 thread about how this causes hum and noise... Have you read them?


----------



## el_matt0

yea i was planning on installed a divider or something of the sort with some sort of insulating covering...that should help shouldnt it?


----------



## Clutz

THe problem with desoldering braid is that if your soldering iron is only minimally hot enough to get the job done, it'll have a hard time getting the solder braid hot (and keeping it hot - it's a pretty effective heatsink) enough to melt the solder. I have a crappy 40 watt soldering iron that I use when my 25 watt soldering iron isn't up to snuff for the desoldering.


----------



## amb

Quote:


  Originally Posted by *el_matt0* /img/forum/go_quote.gif 
_yea i was planning on installed a divider or something of the sort with some sort of insulating covering...that should help shouldnt it?_

 

A divider won't be good enough because the magnetic field from the transformer radiates and curves around. Again, please take the time to read the headwize thread (both part1 and part2), especially n_maher's posts which show what he had to do to tame the hum.


----------



## n_maher

Quote:


  Originally Posted by *el_matt0* /img/forum/go_quote.gif 
_yea i was planning on installed a divider or something of the sort with some sort of insulating covering...that should help shouldnt it?_

 

Help, maybe. Solve the issue, no.


----------



## thrice

Quote:


  Originally Posted by *el_matt0* /img/forum/go_quote.gif 
_yea i was planning on installed a divider or something of the sort with some sort of insulating covering...that should help shouldnt it?_

 

 Quote:


  Originally Posted by *amb* /img/forum/go_quote.gif 
_A divider won't be good enough because the magnetic field from the transformer radiates and curves around. Again, please take the time to read the headwize thread (both part1 and part2), especially n_maher's posts which show what he had to do to tame the hum._

 

 Quote:


  Originally Posted by *n_maher* /img/forum/go_quote.gif 
_Help, maybe. Solve the issue, no._

 

Perhaps if you put the transfo outside of the amp case in a smaller enclsure....you could then run an umbilical to the amp. The hum issue was well documented in the aforementioned Headwize threads...I would also encourage you to read them. Placing a transformer in the same case as the amp boards tends to yield humming issues.... it's best to separate the PS and the amp, or at the very least the amp and the transfo.


----------



## el_matt0

yea i read SOME of them i only had no idea there is like 60 pages in each of the threads. got thru most of nates posts last night...i think at this point my plan is, once i GET the thing running (assuming i manage that) ill take care of the hum at that point. ill probably start by trying various combinations of adding a smaller enclosure to suround the trafo and putting some kind of material on the inside of that. also repositionining and rotating the trafo like nate said sometimes helped. if all else fails, ill just move the trafo to an external enclosure like several have suggested. ill get back to you about my progress with the rectifier diodes, still working on unsoldering and repositioning them!


----------



## el_matt0

question, when heating up solder joints from underneath with desolderiing braid or whatnot, how long is "too long" to heat the component for? i realize they get very hot, very quickly, but have no real gauge of how much heat it would take to actually permanently damage any of the components? i know some say that when forming a solder joint, 5 seconds is the max you want to take, but to be honest, its definitely taking more than 5 seconds to even get the solder flowing on some of my old joints. im using a hakko936 on max setting too so maybe im just doing something wrong...


----------



## kklee

What size and type of braid are you using? How are you using it?

 I find that .075" braid that has rosin impregnated in it works well. Make sure your iron tip is tinned since you have to have good heat transfer to the braid (and to the solder).

 I set my Weller station to its max setting when desoldering with braid and the braid will absorb solder in a couple of seconds. It usually takes several passes (with cooling time in between each pass) since the small braid will saturate quite quickly.


----------



## el_matt0

hmm, i have 0.050 and 0.10 " desoldering braids. ive mainly been trying the 0.1, maybe the thinner would be better. it doesnt mention anything about impregnated rosin though! i just got the 936 for my birthday, so i doubt thats the issue whatsoever. the braid im using now however seems to soak up virtually none of the solder however, or at least in such small amounts i feel like ill next actually get it OUT of the joint!!


----------



## el_matt0

based on my knowledge of soldering principles...maybe my lack of rosin in the soldering braid could explain the problem..what seems to be the issue for me is that it often takes quite a few seconds (or longer) for the stubborn joint to reflow...often it only really starts going once a bit of flux has visibly melted around the perimeter first. getting the solder to melt THRU my desoldering braid is another story altogether..doesnt seem to be workign the way it should. i didnt really know there was diff grades of desoldering braid, this is juts cheap stuff from a local store, maybe i should try something else?


----------



## kklee

I use this:
http://www.mgchemicals.com/products/400braid.html


----------



## n_maher

Despite repeated attempts I've never been able to clear a hole using only braid. I find it much easier to use a pump. The one exception is small ground plane holes where sometimes regardless of what I do solder seems to get trapped in between the two ground planes and never comes out. In those cases I just use the heat and stick method.


----------



## el_matt0

heat & stick?


----------



## el_matt0

@ kklee. HMM, same stuff as ive got! i just have smaller spools, but ive got yellow (0.05") and blue (0.1"). i was trying with my VERY fine chisel tip on last night and the 0.1 " braid. maybe ill have better luck with a slightly larger iron tip along with the thinner braid!


----------



## thrice

put the braid on the joint, then the soldering iron and flow just a little bit of solder onto the braid from your spool, just to get things flowing...sometimes that helps.

 But seriously, get some breadboard and practice..it took me a little while, but once you get it, it can be easier than solder pumps.


----------



## koike

hey matt try using a sucker?


----------



## n_maher

Quote:


  Originally Posted by *el_matt0* /img/forum/go_quote.gif 
_heat & stick?_

 

Yeah, heat the joint and stick whatever you want to go in there, in there. Not recommended but it can be done, even with multi-leg/hole arrangements. Most of the time I find a way to clear the hole but sometimes there's just no getting the solder out of there unless your name is Stephen. 
	

	
	
		
		

		
			





 [size=xx-small]ok, ok, i'll get some breadboard and work on my braid technique[/size]


----------



## el_matt0

argh okay so being realistic with myself i think its going to be more hassle than anything else trying to minimize trafo hum with it this close. took the plunge and reordered a fresh back panel from parmetal today, im gunna keep the 5 boards in the main chassis, and have my trafo in a separate enclosure. couple questions regarding this, so now, all i will have going between the chassis are 4 wires (secondaries) right? for connectors, i remember having trouble finding a place to order these before, just looking through the redco site, will any of these work? http://www.redco.com/shopdisplayprod...con+Connectors

 also, anyone have suggestions on a place i might look to order an appropriately sized case for trafo, just realized par metal doesnt make anything that small in a 20 series. so long as its anodized black it should match just fine.


----------



## el_matt0

after more careful reading, the powercon series is only 3 pole i believe, obviously i need 4 pole so would something like the speakon work? 
http://www.redco.com/shopexd.asp?id=229


----------



## n_maher

Matt,

 There are 4-pole versions of the Speakon series, IIRC, and they should be fine for carrying the AC voltage and current you're dealing with. I personally tend to avoid right angle connectors whenever possible, they've always caused me more grief than good.

 For cable you might try your local hardware store or Home Depot/Lowes, the bulk cable section usually has pretty reasonably priced stuff ($1/ft).


----------



## el_matt0

any 4 conductor cable should work though? gauge doesnt need to be too big im guessing by the fact that the secondaries are probably only about 24 or so themselves?


----------



## n_maher

The secondaries are quite 24ga, but I'd still go with a larger wire for the umbilical cord. It certainly doesn't need to be huge but I wouldn't use something like starquad or mic cable either. I believe there are some tips given on amb's site about this stuff.


----------



## el_matt0

yea there are, its specifically with regards to setting up the s22 in the separate enclosure as well, and it says 18AWG minimum, i figured since thats not exactly what ill be doing, id still be better off going with something around 20 or 22. ill look into powercables online, we have terrible local selection around here as its just a tiny university town! 

 anyone know of good places to order small enclosures? im not too picky, but something with a removable front/back panel would be the best as im planning on probably just sending a whack of stuff to FPE to get done due to my lack of equipment. i know the hammond 14 series could be a serious option....


----------



## thrice

Quote:


  Originally Posted by *n_maher* /img/forum/go_quote.gif 
_Most of the time I find a way to clear the hole but sometimes there's just no getting the solder out of there unless your name is Stephen. 
	

	
	
		
		

		
			





 [size=xx-small]ok, ok, i'll get some breadboard and work on my braid technique[/size]_

 

Damn straight skippy! i might not be so good at it if I hadn't made so many soldering errors though 
	

	
	
		
		

		
		
	


	




  Quote:


  Originally Posted by *el_matt0* /img/forum/go_quote.gif 
_yea there are, its specifically with regards to setting up the s22 in the separate enclosure as well, and it says 18AWG minimum, i figured since thats not exactly what ill be doing, id still be better off going with something around 20 or 22. ill look into powercables online, we have terrible local selection around here as its just a tiny university town! 

 anyone know of good places to order small enclosures? im not too picky, but something with a removable front/back panel would be the best as im planning on probably just sending a whack of stuff to FPE to get done due to my lack of equipment. i know the hammond 14 series could be a serious option...._

 

How about Hammond cases...pretty cheap and ready to go from Digi-key or Mouser. They come in black as well.

 AMB has some multi-pole connectors listed on the Sigma 11 parts lists I think.

http://dkc3.digikey.com/PDF/C071/0320.pdf


----------



## Clutz

Quote:


  Originally Posted by *el_matt0* /img/forum/go_quote.gif 
_yea there are, its specifically with regards to setting up the s22 in the separate enclosure as well, and it says 18AWG minimum, i figured since thats not exactly what ill be doing, id still be better off going with something around 20 or 22. ill look into powercables online, we have terrible local selection around here as its just a tiny university town! 

 anyone know of good places to order small enclosures? im not too picky, but something with a removable front/back panel would be the best as im planning on probably just sending a whack of stuff to FPE to get done due to my lack of equipment. i know the hammond 14 series could be a serious option...._

 

I fit the S22 in to the case supplied by Jeff Rossel for the S22 in the S22 kit. It took a bit of manouvering and some work with a dremel, but it got done.


----------



## bperboy

Does anyone have a relatively inexpensive source for a quad stepped attenuator kit? As in less that $100? Or should I just go for the quad Alps from the german ebay site?


----------



## n_maher

I don't think that cheap and quad stepped attenuator belong in the same sentence. 
	

	
	
		
		

		
		
	


	




 FWIW I've never seen a kit for a quad, only preassembled bits.


----------



## amb

Re: replacing the diodes

 Since these are two-pin devices with relatively good sized pins, it shouldn't be too difficult to remove, but you need to heat the two pins simultaneously (or nearly so) after getting rid of most of the solder around the joint (either with braid or desoldering pump), at the same time gently pulling the diode away from the board (with needle nose pliers).

 Once removed, the holes may still be plugged with solder, but the heat-and-stick procedure that Nate described is doable. You could also try to clear the hole by heating it and then plunging it quickly with a thin wire.

 One thing to avoid is to heat any pad for too long, which could cause the pad to come off the board. If you use a desoldering braid you have to take extra care not to heat things for a long time. If you have a flux pen, you might find that applying some flux would help the solder to flow.

 Just be glad you aren't doing this to a device with many pins (think OPA541AP on the Dynahi PSU)...


----------



## bperboy

Quote:


  Originally Posted by *n_maher* /img/forum/go_quote.gif 
_I don't think that cheap and quad stepped attenuator belong in the same sentence. 
	

	
	
		
		

		
		
	


	




 FWIW I've never seen a kit for a quad, only preassembled bits._

 

Thats a bummer 
	

	
	
		
		

		
		
	


	




 I thought I remembered seeing some cheap kit with a switch and resistor pack, but I suppose it must have been a dual one. Have you used the Alps quad pot? Any problems with quality?


----------



## holland

When using a braid, it sometimes helps to apply more solder, especially if it's plugged in a hole. Fill the pad, then use a clean section of braid that is still soft. Braids are flux infused, so once it's melted it's really not good anymore unless it's just a lump of solder you need to remove. The solder will come out quick. The trick is getting it to flow into the braid first, which is what filling the pad does, and being in liquid form, solder follows the flow, once the flow begins (surface tension and fluid dynamics mumbo jumbo). Sometimes more is less, as opposed to less is more. It'll be much faster than trying to heat the braid and get a section of it into a through hole.

 I don't know if it's recommended for the case being discussed, but you can make a solder bridge and pull out the diode quickly. If you don't want a solder bridge you can build up the solder on the underside so that it's nice and tall, and stick a diode leg or a few resistor legs between the pads (elevated from the board), shorting out the component. Then heat the legs in the middle, and it should melt both pads simultaneously.

 I'd prefer to just cut it, and remove a pin at a time, unless there's some reason you need to keep the diode functional. Diodes are thicker than resistors, so it should be fairly easy to get a snipper in there and cut out the diode.

 Another possible suggestion is to get some thin bare metal wire, like used for picture hanging, etc. Loop it around one leg of the component. Heat the pad from the under side and then yank the wire. I've never known a component to be completely rigid and the component will bend on the leg that's still soldered down, pulling the heated leg up.

 The wire trick is used, sometimes, for surface mount components (QFN), but instead of pulling up, you pull outward to get a slight gap between the pads and the component.


----------



## n_maher

Quote:


  Originally Posted by *bperboy* /img/forum/go_quote.gif 
_Thats a bummer 
	

	
	
		
		

		
		
	


	




 I thought I remembered seeing some cheap kit with a switch and resistor pack, but I suppose it must have been a dual one._

 

You were probably thinking of DIY Fidelity's kit, which is a dual stepper. However, if you've got room you could always use 2.

  Quote:


 Have you used the Alps quad pot? Any problems with quality? 
 

I've got one, but haven't used it yet. And I can't imaging quality being a big issue, this is what Headroom uses in their balanced desktop.


----------



## bperboy

Quote:


  Originally Posted by *n_maher* /img/forum/go_quote.gif 
_I've got one, but haven't used it yet. And I can't imaging quality being a big issue, this is what Headroom uses in their balanced desktop._

 

I think this will probably be the best way to go then.


----------



## el_matt0

yea ive got one and thats what im planning to use for now, i might go to stepped attens later. ive still never REAAALLY fully understood why stepped attenuators are so much more high end and expensive than a potentiometer. is having the "steps" really that helpful, in remembering exactly where you like it set etc? or is it a higher "quality" way to alter the amount of volume, by increasing the resistance?


----------



## thrice

Quote:


  Originally Posted by *el_matt0* /img/forum/go_quote.gif 
_yea ive got one and thats what im planning to use for now, i might go to stepped attens later. ive still never REAAALLY fully understood why stepped attenuators are so much more high end and expensive than a potentiometer. is having the "steps" really that helpful, in remembering exactly where you like it set etc? or is it a higher "quality" way to alter the amount of volume, by increasing the resistance?_

 

A good article:

http://tangentsoft.net/audio/atten.html


----------



## swt61

Another choice is the Twisted Pear Audio Joshua Tree logarithmic stepped attenuator. That's the way I chose to go, and will comment on it once I receive my finished β22. The Joshua Tree balanced kit is $133.00, much less than some high end steppers. Luvdunhill says he likes it better than the Single Power stepper.

 Nate have you used one yet?


----------



## thrice

I'm working on getting a JT up and running...another day or so.


----------



## swt61

I know Nate has a few, but I'm not sure if he's implemented one into an amp yet?
 The only feedback I've seen thus far is from luvdunhill, and it was very possitive. 

 Let us know what you think Steve.


----------



## thrice

Quote:


  Originally Posted by *swt61* /img/forum/go_quote.gif 
_I know Nate has a few, but I'm not sure if he's implemented one into an amp yet?
 The only feedback I've seen thus far is from luvdunhill, and it was very possitive. 

 Let us know what you think Steve._

 

Actually Nate's are about to be implemented by me


----------



## Ferrari

Quote:


  Originally Posted by *bperboy* /img/forum/go_quote.gif 
_Thats a bummer 
	

	
	
		
		

		
		
	


	




 I thought I remembered seeing some cheap kit with a switch and resistor pack, but I suppose it must have been a dual one. Have you used the Alps quad pot? Any problems with quality?_

 

About the quality of the Alps quad potentiometer, it's actually the same as the well known stereo Blue Velvet but with 4 channels. I'm using this one on my build... typical Alps, very good for the price 
	

	
	
		
		

		
		
	


	




 .


----------



## n_maher

Quote:


  Originally Posted by *thrice* /img/forum/go_quote.gif 
_Actually Nate's are about to be implemented by me 
	

	
	
		
		

		
		
	


	


_

 

Shhhh, you're supposed to keep our back room parts exchanges private! Geez, I guess you can't trust a penguin, can you?


----------



## swt61

He can't help it Nate! The name Steve means blabbermouth in some early Saxon tongue. I'm living proof!


----------



## luvdunhill

Quote:


  Originally Posted by *thrice* /img/forum/go_quote.gif 
_I'm working on getting a JT up and running...another day or so._

 

yeah, that's about right... I was surprised how long it took to build. Don't forget to put the 1n914 diodes on the back of the board after the relays 
	

	
	
		
		

		
		
	


	




 Looks like I'm going to be able to get those KOA for audio SMD resistors as well (well, I ordered the first 10 values I needed already... maxed out the sample form... in a bit I'll need to place an order for the rest!), so I'll have a a Dale TH and KOA SMD version to compare =) I'm betting you won't go back after listening to it


----------



## thrice

Quote:


  Originally Posted by *n_maher* /img/forum/go_quote.gif 
_Shhhh, you're supposed to keep our back room parts exchanges private! Geez, I guess you can't trust a penguin, can you? 
	

	
	
		
		

		
		
	


	


_

 

D'oh, I guess I shouldn't mention the ****** ****** DIY ******* you ****** the other day.

  Quote:


  Originally Posted by *luvdunhill* /img/forum/go_quote.gif 
_yeah, that's about right... I was surprised how long it took to build. Don't forget to put the 1n914 diodes on the back of the board after the relays 
	

	
	
		
		

		
		
	


	




 Looks like I'm going to be able to get those KOA for audio SMD resistors as well (well, I ordered the first 10 values I needed already... maxed out the sample form... in a bit I'll need to place an order for the rest!), so I'll have a a Dale TH and KOA SMD version to compare =) I'm betting you won't go back after listening to it 
	

	
	
		
		

		
		
	


	


_

 

These were prebuilt...just got tired last night and couldn't finish the casing up part.


----------



## n_maher

Quote:


  Originally Posted by *swt61* /img/forum/go_quote.gif 
_He can't help it Nate! The name Steve means blabbermouth in some early Saxon tongue. I'm living proof! 
	

	
	
		
		

		
		
	


	


_

 

Wait till he blabs about the other little thing that he picked up the other day...

 And I'm still considering using the JT's on my beta. That project has been back-burnered until I can get a bunch of other things done. Hopefully this winter.


----------



## MrMajestic2

While waiting for my 4-channel kit to arrive, Im having plenty of ideas on the construction 
	

	
	
		
		

		
		
	


	




 So here is one question:
 Is anyone building the 4-channel version with some kind of converter from SE to Balanced input? Would be nice to be able to just plug in an SE source and get balanced out. I know it can be wired to accept SE input as two separate SE amps, but thats not what Im after.


----------



## amb

Quote:


  Originally Posted by *MrMajestic2* /img/forum/go_quote.gif 
_...
 Would be nice to be able to just plug in an SE source and get balanced out. I know it can be wired to accept SE input as two separate SE amps, but thats not what Im after._

 

Look at the DRV134 chip from TI, and the example circuit in the datasheet.


----------



## MrMajestic2

Quote:


  Originally Posted by *amb* /img/forum/go_quote.gif 
_Look at the DRV134 chip from TI, and the example circuit in the datasheet._

 

Since I currently suck at Eagle, I found this board instead:
http://assemblycraft.com/bld.htm


----------



## n_maher

Quote:


  Originally Posted by *MrMajestic2* /img/forum/go_quote.gif 
_Since I currently suck at Eagle, I found this board instead:
http://assemblycraft.com/bld.htm_

 

You know what I'm pretty sure I have a couple of those boards, guess it's time to dig through parts box. They might come in handy for my balanced beta.


----------



## grawk

Just say no to chip balancing. If you're spending time and money building a great amp, do you really want to cripple the unbalanced inputs? Check out cinemag balancing transformers. You should be able to get a pair for under $150 shipped, and you'll be MUCH happier with the results.


----------



## MrMajestic2

Quote:


  Originally Posted by *grawk* /img/forum/go_quote.gif 
_Just say no to chip balancing. If you're spending time and money building a great amp, do you really want to cripple the unbalanced inputs? Check out cinemag balancing transformers. You should be able to get a pair for under $150 shipped, and you'll be MUCH happier with the results._

 

I will be running my amp mostly from balanced inputs, but would like a fairly cheap option of unbalanced input and balanced output. $150 for a pair just isnt an option at the moment.


----------



## el_matt0

k more follow up bad news from me! i just put together a totally new S22 i had that i was planning to use for a separate project down the line and swapped that in to my b22. STILL no signs of life!! no led light, no noise, no warmth, nothing 
	

	
	
		
		

		
			





! ive attached some photos, ive inspected the underside of the board carefully for cold joints and cross bridges, it looks fine. could it be a problem with my IEC entry module or with the fuse or switch im using? the fuse hasnt blown at all in trying to get it going. the switch im using is just a basic 2 pole switch i picked up from a local electronics shop. i know the power cable im using is fine, and i ASSUMe that there wouldnt be anythign wrong wtih my trafo...so...suggestions? ive attached some photos (taken on a cell phone so sorry if the quality isnt up to par). but yea, similar scenario to my problems i was having a few weeks ago, clearly its not due to the reversed rectifiers this time 
	

	
	
		
		

		
		
	


	




! anyways, lemme know guys, obviously any help would be VERY much appreciated!


----------



## el_matt0

i dont need to tin the wires before screwing them down in terminal blocks do i? it would be nice if its something REALLY obvious like that, but sadly i doubt it


----------



## amb

Quote:


  Originally Posted by *el_matt0* /img/forum/go_quote.gif 
_i dont need to tin the wires before screwing them down in terminal blocks do i? it would be nice if its something REALLY obvious like that, but sadly i doubt it_

 

No, that shouldn't be necessary.

 Looks like you are using an IEC with an integral fuse holder. you do have a fuse installed in there, right?

 With your DMM in AC Volts mode, measure across ~ and G, and then the other ~ and G. What do you read? Switch the probes to across the two ~ terminals. What do you get now?


----------



## el_matt0

yea i do have a fuse in there. while the secondaries are screwed into the terminal blocks, measuring across the pads you suggested all read 0 VAC. even with them unscrewed, measuring across black-red for example with the power on and plugged in there is still 0 reading. clearly it looks to be something with the IEC wiring or my fuse or switch...but im a little perplexed as to which to be honest!


----------



## amb

Remove the fuse and measure with your DMM ohms mode. Should read close to zero ohms. If not, it's blown. Measure the AC voltage across the neutral and hot tabs of the IEC, do you get the full AC mains voltage? Also, what kind of switch is it? I hope it's not momentary contact. Measure the AC voltage across the switch contacts with the switch in the off position. You should also get the full AC mains voltage.


----------



## el_matt0

k, measuring across the fuse itself does show 0 ohms, and i can still see the filament is intact not burnt out. however, i seem unable to register any AC voltage across any of the tabs of the IEC or between the two poles of the switch! my switch isnt momentary i dont believe (those are moreso push button ones etc right). its just a basic 2 pole rocker switch. i guess its starting to seem like it might be a problem with the IEC? i did notice one thing, that when soldering to one of the tabs on the IEC, the hot one i believe, the metal did heat to the point that it moved slightly by melting some of the plastic. i was able to move it back into place by just reheating it, and it was only off by a few MM in the first place, and nothing is visibly melted or damaged now, so i assumed no permanent damage resulted....any more suggestions on how i can narrow this down, or does it look like its the IEC? bummer if it is because im absolutely beat on a good place to order or find one in my general whereabouts!!


----------



## n_maher

You sure you have the fuse installed correctly? Most IEC's have a spot for a "spare" fuse in addition to the primary fuse. Most of the time they're in the same drawer. Just a thought of something simple that could go wrong and would produce the results that you're seeing (no AC at the IEC). You should be able measure the resistance from the hot (non fused) tab to the tab that you're using (fused) and see 0 ohm there. If you don't then you know something about the fuse setup is hosed.


----------



## el_matt0

nate man i love you! 
	

	
	
		
		

		
		
	


	




 always being able to pinpoint my silly mistakes so darn well! i had NO idea that the top spot in the fuse "drawer" was a spare slot, i thought from that position it would reach the contacts - oh so wrong lol! anyways, fuse in the right spot = life. everything seems fine. now to tweak the other 4 boards so i can hopefully get sound from this beast! thanks as always


----------



## el_matt0

oh one quick question that i was kind of unable to determine from ambs site. if im keeping my trafo and iec in a separate enclosure, but all 5 b22 and s22 boards in the other enclosure, do i still need to use a ground loop breaker for connecting the IEC ground to the chassis? im currently assuming no...


----------



## thrice

Quote:


  Originally Posted by *el_matt0* /img/forum/go_quote.gif 
_oh one quick question that i was kind of unable to determine from ambs site. if im keeping my trafo and iec in a separate enclosure, but all 5 b22 and s22 boards in the other enclosure, do i still need to use a ground loop breaker for connecting the IEC ground to the chassis? im currently assuming no..._

 


 No you don't. Check out the picture marked option 2 under Wiring and Ground on amb's site...it also lets you know which panel components need to be isolated from the chassis.


----------



## el_matt0

yea i was going to ask about that, so im using a 4 pole speakon connector for my umbilical. it has a tiny rubber o-ring, but that doesnt count as being "isolated" does it? whats the proper technique for isolating these larger components, ive never used isolating washers or anythign so im not sure exactly what id need to order. same thing applies for my panel mount XLRs...! is it possible to use teflon tape or something of the like, or is a proper washer the standard?


----------



## thrice

Well the speakeron connectors are plastic yes? so they should be fine as long as none of the contacts that are used for the power connections are connected to something that connects it to the case.


----------



## el_matt0

what would be the case for XLR connectors?
http://www.takefiveaudio.com/mall/shopexd.asp?id=368
 those are the ones im planning to use. i cant seem to digup info on whether the signal is isolated or not in those


----------



## Alick

I'm just about to start building a four board fully balanced beta22. My only dilemma (currently) is finding a nice enclosure which won't cost an arm and a leg to ship to the UK. Best I can come up with locally is a 2U rack box which is a bit too big (wide) for my preferred location. Ideally, I'd like something less than 15.5" wide but I can go to 16.75" at a push. It only needs to take the four boards, pot and connectors. The PSU will be housed separately. Any ideas?


----------



## MrMajestic2

Im going for the Hifi2000 Slimline cases for my 4-channel build. I think you can fit the 4 boards in a Galaxy case also, the widest being 310mm inside. They are available from www.modushop.biz and www.audiokit.it.
  Quote:


  Originally Posted by *Alick* /img/forum/go_quote.gif 
_I'm just about to start building a four board fully balanced beta22. My only dilemma (currently) is finding a nice enclosure which won't cost an arm and a leg to ship to the UK. Best I can come up with locally is a 2U rack box which is a bit too big (wide) for my preferred location. Ideally, I'd like something less than 15.5" wide but I can go to 16.75" at a push. It only needs to take the four boards, pot and connectors. The PSU will be housed separately. Any ideas?_


----------



## Alick

Nice cases and even nicer prices. Thanks.


----------



## n_maher

Quote:


  Originally Posted by *el_matt0* /img/forum/go_quote.gif 
_what would be the case for XLR connectors?
http://www.takefiveaudio.com/mall/shopexd.asp?id=368
 those are the ones im planning to use. i cant seem to digup info on whether the signal is isolated or not in those_

 

If you don't have the XLR's already I can't see any way of telling you with 100% certainty that they don't carry ground on their casing, but usually XLR's don't. Most often they have tab that can be used to ground the jack to the case if that's what you want to do. The Vampires that you linked to appear to have some sort of ground tab (the silver tab on the right connector) so it would be my _guess_ that the 3 other contacts are isolated. 

 And I'm glad that the fuse position was the answer.

 MrMajestic2, I guess you're somewhat lucky that your shipping for the cases will only be € 30,00, for those of us in the US we're looking at more than double that amount. It makes using those chassis simply not an option which is a shame.


----------



## MrMajestic2

Quote:


  Originally Posted by *n_maher* /img/forum/go_quote.gif 
_MrMajestic2, I guess you're somewhat lucky that your shipping for the cases will only be € 30,00, for those of us in the US we're looking at more than double that amount. It makes using those chassis simply not an option which is a shame._

 

Yeah, for once we in europe are better off 
	

	
	
		
		

		
		
	


	




 Im fortunate enough to have a few friends who also buys the same cases so we can share shipping. Its almost like stealing 
	

	
	
		
		

		
		
	


	




 I have 8 Galaxy cases already and more on the way.


----------



## el_matt0

well, everything seems OK so far. ive got everything wired and was just running through some of the final tests when i ran into a bit of a problem. on all 4 boards, i can get R9 (and co) to rest at about 4.5V after heating up. i can also keep R34 and 35 at a pretty constant 75mV, all consistently staying within the range of 74-76mV. now, on 3 of my boards (L+,L-,R-) i can get the dc offset to just about 0.0mV, maybe 0.2 at max on either side of 0. however the 3rd board, my R+ board has a way higher offset than the others. with VR3 all the way counterclockwise it still only drops my offset to about 31mV. all the way the other way brings it way up to about 150 or so. is this a scenario where i would want to try swapping Q1 and Q2? or is there something else i should try first!


----------



## amb

el_matt0, at the β22 website, on the Initial setup page, under the Troubleshooting heading, are all the answers you need.


----------



## Edwood

I've been out of the DIY game for some time now, but I've been lurking and eyeing the Beta22 project with great interest.

 I must say that of all the project's features, the ε22 backplane board is the single simple feature that really makes the Beta22 stand out. Such a neat package.

 Bravo.

 -Ed


----------



## MisterX

Does that mean you are going to build one Ed?


----------



## el_matt0

ALRIGHT, in BUSINESS! swapped Q1 and Q2 on my "problem board", and bingo, 0 mV dc offset. i can get it down to a steady +/-0.2-0.3mV for all 4 boards, is that within acceptable limits? what is considered "dangerous"? sounds DAMN great on my balanced 650s so fAR!!! one problem, it seems i wired my potentiometer backwards! im using an alps quad pot and i wired it as shown on AMBs site, with the axle facing towards you, all 12 lugs upwards, i have my grounds on the left, middle is going TO the boards, and the right is coming from the inputs. problem is counterclockwise all the way is MAX, and clockwise all the way is off or minimum! obviously ive just gotten something totally backwards, which do i need to swap?? leave the ground and swap the other two so that the "right" side lugs are all going to my boards?


----------



## thrice

Quote:


  Originally Posted by *el_matt0* /img/forum/go_quote.gif 
_ALRIGHT, in BUSINESS! swapped Q1 and Q2 on my "problem board", and bingo, 0 mV dc offset. i can get it down to a steady +/-0.2-0.3mV for all 4 boards, is that within acceptable limits? what is considered "dangerous"? sounds DAMN great on my balanced 650s so fAR!!! one problem, it seems i wired my potentiometer backwards! im using an alps quad pot and i wired it as shown on AMBs site, with the axle facing towards you, all 12 lugs upwards, i have my grounds on the left, middle is going TO the boards, and the right is coming from the inputs. problem is counterclockwise all the way is MAX, and clockwise all the way is off or minimum! obviously ive just gotten something totally backwards, which do i need to swap?? leave the ground and swap the other two so that the "right" side lugs are all going to my boards?_

 


 Actually that diagram is a bird's eye view showing you the pins "through" the potentiometer....you've just got the wires reversed.

 Hold the pot with the pins down and rewire according to the picture and you'll be fine.


----------



## el_matt0

ah ok, so my middle ones are fine, but my ground and wires coming from inputs need to be flipped?


----------



## thrice

Quote:


  Originally Posted by *el_matt0* /img/forum/go_quote.gif 
_ah ok, so my middle ones are fine, but my ground and wires coming from inputs need to be flipped?_

 

edit: oops, NM Yes you're right.


----------



## MrMajestic2

Yay, got my kits from JRossel and the cases from modushop today. I have some serious construction ahead of me, but it will be worth it I hope.


----------



## el_matt0

@ mr majestic. took me longer than expected to get mine going, but maaaan it was worth it!! 
	

	
	
		
		

		
		
	


	







 sounds GREAT


----------



## MrMajestic2

Quote:


  Originally Posted by *el_matt0* /img/forum/go_quote.gif 
_@ mr majestic. took me longer than expected to get mine going, but maaaan it was worth it!! 
	

	
	
		
		

		
		
	


	







 sounds GREAT_

 


 Yeah, its a lot of pcbs and components, but I like the challenge


----------



## Edwood

Quote:


  Originally Posted by *MisterX* /img/forum/go_quote.gif 
_Does that mean you are going to build one Ed? 
	

	
	
		
		

		
		
	


	


_

 

Since I have not finished my DynaMid, that would be a "no" until I finish that one.

 I may have enough spare time during the holidays to do so.... 
	

	
	
		
		

		
		
	


	




 -Ed


----------



## Edwood

Just out of curiosity, has anyone measured how many watts the B22 sucks out of the wall when in use?

 Also wondering how many watts a balanced B22 uses. (probably pretty close to x2.)

 Also, how hot does it get? We're not talking DynaHi hot, here, right?

 -Ed


----------



## el_matt0

when starting up my b22, after its cooled down etc, i sometimes get VERY "unstable" dc offset readings. i believe i was registering almost 60mV on two of my boards for about 5 minutes. all the measurements seemed a bit wonky and then after about 10 minutes without touching anything, all the dc offset drops back to within 1mV of 0. how much dc offset is OK? what is dangerous, and should this initial unsteadiness be a worry? is there danger of having cans plugged in @ that point? surely this must be a common thing and not just my poor b22....


----------



## amb

el_matt0,
http://headwize.com/ubb/showpost.php...6923&pid=63445


----------



## gates_2

I've been quite stressed recently over my relay-based attenuator from dantimax.dk ... When its in the circuit, I get a noise in the background, almost like the grounding isn't fully working(read: when no pot plugged into the backpane, I get the white noise, when the stepped attenuator plugged in, it works, but the noise remains the same(varies with each step)... plug in an Alps pot... no noise..

 Could it be due to the fact that the attenuator board runs on a different supply/ground from the amp?


----------



## el_matt0

Quote:


  Originally Posted by *amb* /img/forum/go_quote.gif 
_el_matt0,
http://headwize.com/ubb/showpost.php...6923&pid=63445_

 

thats pretty much what i figured, however is there any potential danger having the headphones plugged in? or each time i "cold" start it should i wait 15 mins before plugging in cans and turning up volume? or is it safe to just have the pot at 0 till its warmed up, with the cans in.


----------



## cotdt

I'm glad you got it working, el_matt0. And I'm glad I talked you into building this wonderful amp. See, that wasn't so hard was it?


----------



## amb

Quote:


  Originally Posted by *gates_2* /img/forum/go_quote.gif 
_I've been quite stressed recently over my relay-based attenuator from dantimax.dk ... When its in the circuit, I get a noise in the background, almost like the grounding isn't fully working(read: when no pot plugged into the backpane, I get the white noise, when the stepped attenuator plugged in, it works, but the noise remains the same(varies with each step)... plug in an Alps pot... no noise..

 Could it be due to the fact that the attenuator board runs on a different supply/ground from the amp?_

 

I can't find a full schematic or documentation for your stepped attenuator on their site, but its analog "ground" must be connected to the amp's IG.

  Quote:


  Originally Posted by *el_matt0* 
_should i wait 15 mins before plugging in cans and turning up volume? or is it safe to just have the pot at 0 till its warmed up, with the cans in._

 

60mV DC offset is high, but shouldn't yet be damaging to most headphones (particularly high-Z phones). If you want peace of mind, then don't plug in headphones until the amp is warmed up, or add a ε12 muting/delay/protection circuit and set a long-ish delay time.


----------



## el_matt0

haha no it wasnt too much of a nightmare! it did take me awhile, as i had to move across country to university etc etc. i definitely had a few "bumps" along the way but it was a great learning experience and im stoked to build my next amp (a MHMAX thats sitting in front of me). man tho...it REALLY was worth it, this is an amazing sounding amp, it makes my hd650s sound like a new pair of headphones (in a good way 
	

	
	
		
		

		
			





)! im VERY glad you talked me into it! 
	

	
	
		
		

		
		
	


	




 Quote:


  Originally Posted by *cotdt* /img/forum/go_quote.gif 
_I'm glad you got it working, el_matt0. And I'm glad I talked you into building this wonderful amp. See, that wasn't so hard was it?_


----------



## cotdt

Quote:


  Originally Posted by *el_matt0* /img/forum/go_quote.gif 
_haha no it wasnt too much of a nightmare! it did take me awhile, as i had to move across country to university etc etc. i definitely had a few "bumps" along the way but it was a great learning experience and im stoked to build my next amp (a MHMAX thats sitting in front of me). man tho...it REALLY was worth it, this is an amazing sounding amp, it makes my hd650s sound like a new pair of headphones (in a good way 
	

	
	
		
		

		
		
	


	




)! im VERY glad you talked me into it! 
	

	
	
		
		

		
		
	


	


_

 

Great! Now it's time to upgrade/mod your DAC!


----------



## el_matt0

i know! ive had my eyes on the benchmark..but well... $$$ lol. i know the other obvious suggestion is the opus but i dont know anything about the difficulty of that build.


----------



## cotdt

Quote:


  Originally Posted by *el_matt0* /img/forum/go_quote.gif 
_i know! ive had my eyes on the benchmark..but well... $$$ lol. i know the other obvious suggestion is the opus but i dont know anything about the difficulty of that build._

 

LOL considering that the OPUS boards are already stuffed, and the fact that everything comes in a kit, it's far easier than the Beta22 build. 90% is just casework. Now that you accomplished the Beta22, you can feel confident about other projects (which tend to be less involved).


----------



## thrice

Quote:


  Originally Posted by *el_matt0* /img/forum/go_quote.gif 
_i know! ive had my eyes on the benchmark..but well... $$$ lol. i know the other obvious suggestion is the opus but i dont know anything about the difficulty of that build._

 

Congrats on your build! It's the best feeling in the world when you turn on your first amp.... it works, and you start listening to it. For me that was 4 years ago with a CMOY!

 Enjoy your amp!

 PS...Yeah the Opus is easy, you're pretty much casing it up.


----------



## el_matt0

got a friend whose interested in putting togetehr a b22 as a speaker amp. what are going to be the upsides/merits to using 3 boards and 3 s22, vs using 2 boards and 2 s22? how important is an active ground for running bookshelf speakers? the pair he is interested in powering are Royd bookshelves. theyre pretty easy to drive, but need a "good" amp to sound up to their full potential. a b22 came to mind seeing that ive seen people build em as speaker amps and i know its possible etc etc. suggestions? at this point im kind of thinking 2 b22 boards and 2 s22 would do the trick?


----------



## VncentValntine

From what I've read, yes two boards and two PSUs (both with big heat sinks and good ventilation) is the recommended config for dedicated speaker power amp.


----------



## el_matt0

cool, thats just what i thought. cant remember if its explicitly mentioned on AMB's site, but how strong of a trafo would i want for each s22?


----------



## VncentValntine

Quote:


  Originally Posted by *el_matt0* /img/forum/go_quote.gif 
_cool, thats just what i thought. cant remember if its explicitly mentioned on AMB's site, but how strong of a trafo would i want for each s22?_

 

A 100VA trafo should be used for each psu for this kind of application.


----------



## n_maher

Quote:


  Originally Posted by *el_matt0* /img/forum/go_quote.gif 
_cool, thats just what i thought. cant remember if its explicitly mentioned on AMB's site, but how strong of a trafo would i want for each s22?_

 

More than anything you'll want to take a close look at the heatsinking for both the power supply and amp boards. If you're building a dedicated speaker amp you really should go with something other than the stock, board mounted sinks.


----------



## el_matt0

ya thats what i was thinking as well. what case companies make nice outboard sinks down the sides that could be worked with?


----------



## thrice

Quote:


  Originally Posted by *el_matt0* /img/forum/go_quote.gif 
_ya thats what i was thinking as well. what case companies make nice outboard sinks down the sides that could be worked with?_

 

ATI Reseach might have something, but shipping is going to be expensive.

 You might look at DIY Enclosures... a couple of their cases feature side heatsinks.


----------



## luvdunhill

Quote:


  Originally Posted by *el_matt0* /img/forum/go_quote.gif 
_ya thats what i was thinking as well. what case companies make nice outboard sinks down the sides that could be worked with?_

 

hifi2000 does











 The second largest has two heatsinks that have a Rt°C/W of 0.23. The smallest have a Rt°C/W of 0.62, just to give you an idea.


----------



## cotdt

as a speaker amp, you want to turn up the gain to around 20x or so. for most speakers lower is OK, but it should be higher than 8x. it's easiest to get higher gain by using balanced, since the stock build for the balanced is already 16x gain. for 2/3-channel higher gain would mean tighter transistor matching. I would also turn up the Class A bias a little, and use larger heatsinks. I don't hear any difference with Class AB and Class A on this amp, but if you're using very efficient speakers it's not too hard to acheive pure Class A.

 also beef up the heatsinks on the S22. the math says that one is enough for 2-channel Beta22 speaker amp, and two is enough for 4-channel Beta22 speaker amp. But using more S22 spreads the load and it doesn't have to handle as much heat. You don't really need a big transformer since even the recommended Beta22 build is all about overkill and going over that is overkill of the overkill. Transformers are heavy.

 the 2-channel and 3-channel Beta22 has around 20W of continuous output and the 4-channel version 3 to 4x that. but don't be too obsessed with power output, 20W is pretty loud already. most speakers that advertise 300W of output will actually melt if you give it a 10W sine wave (the tweeters will melt). Besides that, for music the peak output is more important, and the amp can deliver very high peak power.


----------



## el_matt0

thanks cotdt, very helpful post. on a different note, back to my own 4 channel b22. listening on balanced senn 650s, i can hear a very faint fuzz when my pot is in the off position and at VERY low volumes (lower than any volumes i listen at reastically so its not a huge concern for that reason). it disappears altogether giving a clean black background as i get close to my listening volume range. however, at the upper end of the pots range, i get a significantly louder intermittent humming and other weird loud buzzes, and again with that same faint fuzz as before underneath it all as before. again its not a huge issue as this is in the very upper range of the pot only, and at a level far above what i listen to. should this be something of concern for me? it doesnt affect me persay but id like to know my amp is in tip top shape anyways...! what can symptoms like this usually be attributed to?


----------



## amb

el_matt0, does your build have the output Zobel network? If not, try installing it across the outputs of both channels and see if it fixes the fuzz.


----------



## el_matt0

Quote:


  Originally Posted by *amb* /img/forum/go_quote.gif 
_el_matt0, does your build have the output Zobel network? If not, try installing it across the outputs of both channels and see if it fixes the fuzz._

 

no it doesnt, i could do it fairly easily i guess. if the hum doesn't bother me enough to do it (at this point at least), is there any potential harm in any of what ive described, or is everything "fine" to use normally?


----------



## el_matt0

Another quick question im a little confused about. if i want to additionally add in a couple of single ended 1/4" outputs for using SE cans with. can i just wire as shown but without the RCA inputs? i dont really want to have to install rca inputs as well, i have no need for them and dont wanna hafta hassle with an input selector. 




 if i just keep my inputs AS is, and add in the additional two 1/4 outputs as shown wired, is that all there is to it? if thats the case my pot will simply just control everything at once? (balanced headphone outs, and both SE outputs?) obviously listening on all wouldnt be that doable because of impedence etc, but theoretically doable right


----------



## amb

el_matt0, yes, you don't have to install the RCA inputs. The two unbalanced amps in each channel will each amplify the non-inverting and the inverting signals, respectively. You can listen to either one relative to ground.

 -Ti


----------



## gates_2

Quick update on my attenuator woes...

 there is definitely something weird going on. I have the Input ground from the amp connected to the signal ground of the attenuator board. What I don't understand is why there is a varying level of "white noise" depending on what step you are on.. with 2 steps in the middle and one at the very top being silent(black background)

 I have attached a schematic


----------



## amb

gates_2, do you have a completely separate PSU powering the attenuator? If so, the attenuator board has an inductor L1 connecting its digital ground to the analog ground and it should be ok to remove it. Try and see if that makes the noise go away. The attenuator portion is comprised of only resistors being switched by relays, there is no reason the digital control section's ground has to be connected to the analog ground if the PSUs are separate.


----------



## gates_2

Quote:


  Originally Posted by *amb* /img/forum/go_quote.gif 
_gates_2, do you have a completely separate PSU powering the attenuator? If so, the attenuator board has an inductor L1 connecting its digital ground to the analog ground and it should be ok to remove it. Try and see if that makes the noise go away. The attenuator portion is comprised of only resistors being switched by relays, there is no reason the digital control section's ground has to be connected to the analog ground if the PSUs are separate._

 

Hi Ti,

 I have a completely separate PS powering it(trafo + little 7805 I put together). clipping the L1 inductor just induced a large hum in to the circuit.. When I touch the leads of the severed inductor back together, the hum goes away...

 Just to clarify, imagine having a 3 channel B22 build with the stock gain on the E22 backpane. Now, disconnect the L/R volume from the front... That hiss is what I'm still getting(although less so) with the attenuator in...

 Oddly enough, with my source(comp. soundcard) turned up high, I can hear my music faintly through the B22...normal?


----------



## amb

Quote:


  Originally Posted by *gates_2* /img/forum/go_quote.gif 
_I have a completely separate PS powering it(trafo + little 7805 I put together). clipping the L1 inductor just induced a large hum in to the circuit.. When I touch the leads of the severed inductor back together, the hum goes away..._

 

Hmm, ok.

  Quote:


 Just to clarify, imagine having a 3 channel B22 build with the stock gain on the E22 backpane. Now, disconnect the L/R volume from the front... That hiss is what I'm still getting(although less so) with the attenuator in... 
 

When you unplug the pot/attentuator from the ε22 backplane, the amp will have an open input except for 1M resistors (R2) going to ground. This is going to pick up noise, and is the hiss that you hear. When a pot is plugged in, at low volume positions the amp board's input is shunted to ground through a low resistance in the pot. Near the maximum position the input is shunted to the equivalent of "ground" (the low output impedance of the source). At middle position the input "sees" the paralleled value of the two pot sections to ground, and it also keeps the noise low.

 Now, with your stepped attenuator, the situation is similar, except that it's six cascaded stages of resistor dividers switched by the relays. I don't know what state each relay is in for any given position of the control, but if there is any circumstance that the amp board's input would "see" an open circuit or high impedance, then you'll hear noise.

  Quote:


 Oddly enough, with my source(comp. soundcard) turned up high, I can hear my music faintly through the B22...normal? 
 

With the attenuator set to minimum? Looking at its schematic, it would appear that there is no relay position that correspond to "fully off". In other words, its lowest volume position would still allows a little bit of signal through...


----------



## gates_2

Quote:


  Originally Posted by *amb* /img/forum/go_quote.gif 
_

 When you unplug the pot/attentuator from the ε22 backplane, the amp will have an open input except for 1M resistors (R2) going to ground. This is going to pick up noise, and is the hiss that you hear. When a pot is plugged in, at low volume positions the amp board's input is shunted to ground through a low resistance in the pot. Near the maximum position the input is shunted to the equivalent of "ground" (the low output impedance of the source). At middle position the input "sees" the paralleled value of the two pot sections to ground, and it also keeps the noise low.


 Now, with your stepped attenuator, the situation is similar, except that it's six cascaded stages of resistor dividers switched by the relays. I don't know what state each relay is in for any given position of the control, but if there is any circumstance that the amp board's input would "see" an open circuit or high impedance, then you'll hear noise._

 

Hmm... interesting...Perhaps this attenuator is just not a great fit for this amp(high impedance? hmm) I'm 95% sure there isn't an issue with assembly of the actual attenuator, like a bad solder join or something like that.

  Quote:


  Originally Posted by *amb* /img/forum/go_quote.gif 
_With the attenuator set to minimum? Looking at its schematic, it would appear that there is no relay position that correspond to "fully off". In other words, its lowest volume position would still allows a little bit of signal through..._

 

Yea, I know the attenuator doesn't have an "off" position. Actually, i'm hearing this with no attenuator plugged in at all...


----------



## amb

Quote:


  Originally Posted by *gates_2* /img/forum/go_quote.gif 
_Hmm... interesting...Perhaps this attenuator is just not a great fit for this amp(high impedance? hmm) I'm 95% sure there isn't an issue with assembly of the actual attenuator, like a bad solder join or something like that._

 

FWIW, β22 isn't much different than most other amps as far as compatibility with stepped attenuators is concerned.

  Quote:


 Yea, I know the attenuator doesn't have an "off" position. Actually, i'm hearing this with no attenuator plugged in at all... 
 

Again, if you don't have a pot or attenuator plugged in to the backplane, the amp board input traces on the backplane are essentially "floating", high impedance nodes, and could pick up crosstalk from adjacent traces. That is simply not a valid mode of operation.


----------



## gates_2

hmm... I guess I'm kinda stuck then...Perhaps its just the high(ish) gain with sensitive phones... Tried my K1000's and it sounds great

 Thanks for your suggestions/help Ti


----------



## MrMajestic2

Sitting here staring at my massive component pile from JRossel, I have a few questions 
	

	
	
		
		

		
			





 Its a 4-channel kit with dual S22's by the way.

 1. Im thinking about using a Joshua Tree attenuator for it. Do I need a separate transformer for this or is it ok to tap power from one of the S22's without adverse effect? It runs on lower voltage than the B22 so I will have to stick a TREAD or something in between of course.

 2. When mounting speaker outputs do you guys use a switch between headphone and speaker outs?

 3. When using speaker outputs do I or tap it before or after the E12 relay?

 4. I want to have single ended inputs that convert to balanced. Whats the best way to do this? I have looked at some DRV134 boards but they seem hard to find. I think I can easily get my hands on Lundahl transformers since they are manufactured here, but I have no idea how to wire them.


----------



## SoapSeller

MrMajestic2, We on the same way.
 I'm ordering parts from JRossel and have the Jouhua Tree on the way.

 1. I've choose to use a separate trafo, But I don't know if it's really needed.

 4. You can get DRV134 from assemblycraft, I'm going to build it with some THAT1646 that I've got from ebay

 Cheers

 Btw, For what do you need the E12 for?


----------



## MrMajestic2

Quote:


  Originally Posted by *SoapSeller* /img/forum/go_quote.gif 
_MrMajestic2, We on the same way.
 I'm ordering parts from JRossel and have the Jouhua Tree on the way.

 1. I've choose to use a separate trafo, But I don't know if it's really needed.

 4. You can get DRV134 from assemblycraft, I'm going to build it with some THAT1646 that I've got from ebay

 Cheers

 Btw, For what do you need the E12 for?_

 

I e-mailed assemblycraft about the DRV134 some time ago but he doesnt reply.

 The E12 is for headphone protection.


----------



## amb

Quote:


  Originally Posted by *MrMajestic2* /img/forum/go_quote.gif 
_1. Im thinking about using a Joshua Tree attenuator for it. Do I need a separate transformer for this or is it ok to tap power from one of the S22's without adverse effect? It runs on lower voltage than the B22 so I will have to stick a TREAD or something in between of course._

 

Looks like Joshua Tree has its own onboard rectifers and voltage regulator, and wants a 9V-15VAC single secondary transformer, not a DC power supply. Tapping off the σ22 won't be feasible. The Joshua Tree's current consumption is (200mA + (n * 150mA)) where n is the number of relay boards used (2 for balanced), so it's 0.5A in your case. Giving some headroom says you should use at least a 10VA transformer. As in any power transformer, you should place it well away from the β22 boards and the Joshua Tree relay boards to minimize magnetic field interference.

  Quote:


 2. When mounting speaker outputs do you guys use a switch between headphone and speaker outs? 
 

If you want to be able to enable/disable either output then yes, otherwise you could always unplug headphones and speakers. If you use a switch, it should be heavy duty (I recommend at least 8A contact rating, preferably more).

  Quote:


 3. When using speaker outputs do I or tap it before or after the E12 relay? 
 

Before. The small relay on ε12 is not rated for high enough current for speaker use.

  Quote:


 4. I want to have single ended inputs that convert to balanced. Whats the best way to do this? I have looked at some DRV134 boards but they seem hard to find. 
 

It comes in DIP-8 package and requires very few external components, so you could either build one on a perfboard, or etch your own PCB for something a bit better. The circuit is simple enough that a single-sided board should suffice. You could tap off the σ22 and use 78L15 and 79L15 TO-92 voltage regulators to drop the voltage down to +/-15V locally on this board.

  Quote:


 I think I can easily get my hands on Lundahl transformers since they are manufactured here, but I have no idea how to wire them. 
 

When you see the transformer it should be fairly obvious.

 Both the DRV134 solution and the transformer solutions have their advantages and disadvantages. DRV134 will be more linear, have wider bandwidth, less phase shift, etc., but it's an active circuit and requires DC power, and may add a little bit to the noise floor. Transformer is passive, so no DC power necessary, but it's much more expensive, has intrinsic inductance which restricts bandwidth, reduces slew rate and introduce phase shifts. Depending on the particular model it may have magnetic nonlinearities.

 Either way (DRV134 or transformer), you need to have a switch to select between balanced and unbalanced operation (in other words, switch the converter out of the balanced input path when you use balanced mode). This is so that your balanced source won't "see" the output of the converter which will have low impedance to ground.


----------



## MrMajestic2

Thanks for taking the time to write such an exhaustive reply.

 Didnt realise that the JT needed AC input, guess Im back to the drawing board on that one. I could put another transformer in my S22 case, there is plenty of room 
	

	
	
		
		

		
		
	


	




 But at this point I already have two umbilicals so I think I have to redesign that part. Maybe an 8-pole Speakon, hmm. 

 Switching to speakers will then have to be done with big-a** relays then. Omron has the G2R at 16A, which should be sufficient.

 Tapping before the E12, got it 
	

	
	
		
		

		
		
	


	




 Just checked the price for 2 Lundahl tranformers and I will now look harder for the DRV134 boards 
	

	
	
		
		

		
		
	


	




 Dang, those things are expensive.


----------



## dbfreak

*"Roll Call: Who's building, built, or thinking of building a beta22?"*

 I am thinking (if I may), if they let me come up for air.


----------



## koike

ground channel has problems and the volume pot seems to pan left and right without attenuating any volume. 
	

	
	
		
		

		
		
	


	




 and i thought i could enjoy my weekend with my new hd600 and b22...


----------



## MrMajestic2

Quote:


  Originally Posted by *koike* /img/forum/go_quote.gif 
_ground channel has problems and the volume pot seems to pan left and right without attenuating any volume. 
	

	
	
		
		

		
		
	


	




 and i thought i could enjoy my weekend with my new hd600 and b22..._

 

What volume pot are you using? Are you sure its not a balance control?


----------



## devin_mm

Well I'm in the process of building my 6 channel b22 and I am thinking about volume control at the moment. Now to me the JT attenuator seems like a good way to go but I was wondering (for anyone with some experience with it) if I could have some sort of switch that combines two boards for balanced then when I want unbalanced it separates them into two independent controls?


----------



## koike

Quote:


  Originally Posted by *MrMajestic2* /img/forum/go_quote.gif 
_What volume pot are you using? Are you sure its not a balance control?_

 

its a 50KAX2 i ordered from glassjar...


----------



## MrMajestic2

Quote:


  Originally Posted by *koike* /img/forum/go_quote.gif 
_its a 50KAX2 i ordered from glassjar..._

 


 Is that the famous "fake" Alps pot? The behaviour does sound like its a balance control, but Im not sure how to check to make sure. Maybe it is broken.


----------



## koike

aw crap.
 nah its a real alps pot.
 might be broken.
 i wired it correctly though.


----------



## MrMajestic2

Just found out from Twisted Pear that the JT does take DC if its less than 35V. Although the heatsink will get very hot when running that high. They recommend 5-12V. I will probably go external transformer anyway though.

  Quote:


  Originally Posted by *amb* /img/forum/go_quote.gif 
_Looks like Joshua Tree has its own onboard rectifers and voltage regulator, and wants a 9V-15VAC single secondary transformer, not a DC power supply. Tapping off the σ22 won't be feasible. The Joshua Tree's current consumption is (200mA + (n * 150mA)) where n is the number of relay boards used (2 for balanced), so it's 0.5A in your case. Giving some headroom says you should use at least a 10VA transformer. As in any power transformer, you should place it well away from the β22 boards and the Joshua Tree relay boards to minimize magnetic field interference._


----------



## SoapSeller

MrMajestic2, We are on the same road.
 I'm ordering parts from JRossel and have the Jouhua Tree on the way.

 You can get DRV134 based BLD boards from assemblycraft, I'm going to build it with some THAT1646 that I've got from ebay

 For what do you need the E12 for?


----------



## Alick

I've decided to go with the 330mm wide HiFi2000 Galaxy Max case(s) for my 4 channel beta22. I just have to decide which one(s) of the following four options to go for:

 1. Everything (including PSU and transformer) in a 280mm deep enclosure. (I'd screen the transformer in an interior metal box).

 2. Amp in a 280mm deep Galaxy Max and the PSU in a 230mm Galaxy Max sitting on top (the shorter case avoiding covering the amp's rear ventilation slots).

 3. Amp and PSU in a 280mm deep case with the transformer in a separate cheap 'n' cheerful box not on show (but perhaps awkward to switch on and off).

 4. As 3. but transformer and psu in the separate 'out of sight' box. 

 I plan to locate the amp (and possibly PSU) in a glass fronted cabinet which has reasonable ventilation via wide cable slots at the rear. I'm wondering how warm the amp gets, how much ventilation is required and which of the four options makes most sense. Thoughts?


----------



## luvdunhill

Quote:


  Originally Posted by *amb* /img/forum/go_quote.gif 
_FWIW, β22 isn't much different than most other amps as far as compatibility with stepped attenuators is concerned.


 Again, if you don't have a pot or attenuator plugged in to the backplane, the amp board input traces on the backplane are essentially "floating", high impedance nodes, and could pick up crosstalk from adjacent traces. That is simply not a valid mode of operation._

 

amb:

 what about putting a 1k resistor in series with a 680pF capacitor to ground after the attenuator to form a RF filter?


----------



## luvdunhill

Quote:


  Originally Posted by *amb* /img/forum/go_quote.gif 
_Looks like Joshua Tree has its own onboard rectifers and voltage regulator, and wants a 9V-15VAC single secondary transformer, not a DC power supply. Tapping off the σ22 won't be feasible. The Joshua Tree's current consumption is (200mA + (n * 150mA)) where n is the number of relay boards used (2 for balanced), so it's 0.5A in your case. Giving some headroom says you should use at least a 10VA transformer. As in any power transformer, you should place it well away from the β22 boards and the Joshua Tree relay boards to minimize magnetic field interference._

 

according to TPA, for the Joshua Tree attenuator:

 "Input impedance ranges from approximately 2.2K to 10K (pretty easy load for a source like the Opus).

 The output impedance is 750R."

 If using the Joshua Tree with an amplifier like a Dynamight or β22, would a buffer be required to deal with the high source impedance? What are the effects of changing the 1M resistor to say 100K to counteract this?


----------



## MrMajestic2

Quote:


  Originally Posted by *SoapSeller* /img/forum/go_quote.gif 
_MrMajestic2, We are on the same road.
 I'm ordering parts from JRossel and have the Jouhua Tree on the way.

 You can get DRV134 based BLD boards from assemblycraft, I'm going to build it with some THAT1646 that I've got from ebay

 For what do you need the E12 for?_

 

Didnt you post the same reply already?
http://www.head-fi.org/forums/showpo...&postcount=305







 But I will answer again:

 Assemblycraft doesnt reply to my emails, so Im guessing there is no interest in selling boards.

 The E12 board is for headphone protection. its available from Amb's site.


----------



## amb

Quote:


  Originally Posted by *luvdunhill* /img/forum/go_quote.gif 
_according to TPA, for the Joshua Tree attenuator:

 "Input impedance ranges from approximately 2.2K to 10K (pretty easy load for a source like the Opus).

 The output impedance is 750R."

 If using the Joshua Tree with an amplifier like a Dynamight or β22, would a buffer be required to deal with the high source impedance? What are the effects of changing the 1M resistor to say 100K to counteract this?_

 

The JT's output impedance is not high, and no changes to the amp is necessary. However, an input impedance of 2.2K is fairly low and may be a problem with some sources. For example, if the source has an output impedance of 600 ohms (not unusual), then that 600 ohms will form a voltage divider with the 2.2K input impedance to cause a 2.1dB signal loss. If the source output impedance is not linear across the audio band, then the frequency response will be affected. For example, most sources have an output coupling capacitor, which causes its output impedance to rise at low frequencies. When driving a low-ish input impedance like the JT, the result is a low-pass filter. Whether the rolloff occurs within the audio band depends on the coupling capacitor's value. If the source's output coupling cap is 1uF, then the -3dB corner frequency would occur at 72Hz -- which would be very audible! Not to mention that phase shifts would affect the signal well into the lower midrange region.


----------



## SoapSeller

Opps, I've used the "quick reply" option when going to work, and when I've come back and seen it with my message still in post it again 
	

	
	
		
		

		
		
	


	




 He seems to have some malfunction with the mail in his site, you can reach him in: vcgft at yahoo.com.cn.
 (I've told him about that, but seems that he didn't fixed it yet)


 About the E12, I must say that I like my headphones, and I starting to think that it might be a good idea to is it in my build.


----------



## koike

i am listening to my b22 now.
 its perfect sounding but i am getting about 60~100+mV dc offset in my left channel only. i dont think that is normal right?


----------



## Ferrari

Quote:


  Originally Posted by *koike* /img/forum/go_quote.gif 
_i am listening to my b22 now.
 its perfect sounding but i am getting about 60~100+mV dc offset in my left channel only. i dont think that is normal right?_

 

Is this DC off-set number is measured under load (with your headphone connected)? And is the DC off-set is ~0 (zero) mV without load? If this is the case, it seems to be that your left channel is unstable under load, in one or other way. You might try a Zobel network on your backplane board.
 Take a look at ε22 website, AMB has pointed out how to construct a Zobel network. Good luck !


----------



## el_matt0

hey guys, good to be back on headfi, ive had a bunch of questions!! so ive been looking at a pair of Onix Signature Rocket 750 loudspeakers, im sure you guys are familiar with them. im TOTALLY new to the speaker world (and the world of b22 as a speaker amp for that matter), and im wondering at all if my b22 would be capable of driving such speakers? would it be a "suitable" pairing of amp and speakers, or is the b22 as a speaker amp mainly intended for bookshelves? assuming it is very possible to run the onix speakers from my b22, what changes would i need to implement to my b22 other than the addition of 4 speaker outputs with zobel networks across them? there is no need for any output selector right, my quad pot would simply control all headphone and speakers connected simultaneously? is this going to be possible to run off just one s22 and trafo, or am i going to need to purch at least one more s22/trafo to be able to amply power such speakers? im currently using a 100VA trafo. thanks for bearing with me guys if any of these questions were painfully obvious to any of you 
	

	
	
		
		

		
		
	


	




! 
 *added note, my front panel was shipped out to me today from FPE so hopefully i should have a schnazzy b22 all cased up within the next few weeks!


----------



## n_maher

Matt,

 A ton of what you're asking about is covered on amb's site, don't make me start hammering you again...

 And no, I have no idea what the speakers are or what type of design they are. Again, amb gives some guidelines on his site about what parameters to look for if you're thinking about using the beta as a speaker amp.

 Long story short, RTFM man.


----------



## el_matt0

finally arriveD! just a few cruddy quality photos with my unsteady hand on a cell phone camera, proper photos to come once ive cased it up nicely! one question i have, on my first wiring of the b22 i used the same navships wire that fierce freak used in his b22. im however wondering, is there something that is a little more flexible that would be just as suitable to use for the internal wiring? my only "beef" with the navships wire is that it is so resilient to bending it is quite hard to do a "neat" job wiring without wires going all over the place. stranded copper would be perfectly suitable right? what would be a good brand (id hate to end up using something "cheapy" that might bring down my amp!)! thanks guys


----------



## el_matt0

guys, any suggestions on a good choice for some more flexible wiring for my internal hookup wire (excluding the PSU wiring as that needs to be higher gauge i realize)? i just find the navships wire to be too resilient to bending to it appears uber messy! would just some standard stranded copper from parts connexion be fully acceptable? recommendations on gauge that would be ideal?


----------



## amb

Standard 22-24 AWG stranded hookup wire is perfectly fine for most internal signal wiring. Keep input wiring as short as possible to minimize interference and capacitive crosstalk. If they must run more than a few inches, consider shielded cables.


----------



## MrMajestic2

Quote:


  Originally Posted by *el_matt0* /img/forum/go_quote.gif 
_http://i221.photobucket.com/albums/d...6/DSC00092.jpg
http://i221.photobucket.com/albums/d...6/DSC00087.jpg
http://i221.photobucket.com/albums/d...6/DSC00088.jpg

 finally arriveD! just a few cruddy quality photos with my unsteady hand on a cell phone camera, proper photos to come once ive cased it up nicely! one question i have, on my first wiring of the b22 i used the same navships wire that fierce freak used in his b22. im however wondering, is there something that is a little more flexible that would be just as suitable to use for the internal wiring? my only "beef" with the navships wire is that it is so resilient to bending it is quite hard to do a "neat" job wiring without wires going all over the place. stranded copper would be perfectly suitable right? what would be a good brand (id hate to end up using something "cheapy" that might bring down my amp!)! thanks guys_

 

Very nice panel. I especially like the headphone logo


----------



## el_matt0

Quote:


  Originally Posted by *MrMajestic2* /img/forum/go_quote.gif 
_Very nice panel. I especially like the headphone logo 
	

	
	
		
		

		
		
	


	


_

 

yes, to give credit where credit is due, thanks a ton mrmajestic2 for the brilliant headphone logo you came up with! the second time around looked a lot better than the initial ones u came up with 
	

	
	
		
		

		
		
	


	




 heh! looks groovy though


----------



## gates_2

um... problem

 I was working on a completely unrelated part (stepped attenuator)... things were fine.. all of the sudden, smoke out of the right channel board... the 75 ohm resistor right below Q23

 I'm curious as to why this occured at this time, when all was working fine before

 i chekced the back... there was a tiny fiber that looked like it was contacting q19, althouh would that be conductive enough to cause the resistor to smoke?

 Should I just replace it and try again?(and 100 ohm won't work here, will it?(don't have another 75 ohm)
 PIC:




 Regards,

 Michael


----------



## Ferrari

Quote:


  Originally Posted by *gates_2* /img/forum/go_quote.gif 
_um... problem

 I was working on a completely unrelated part (stepped attenuator)... things were fine.. all of the sudden, smoke out of the right channel board... the 75 ohm resistor right below Q23

 I'm curious as to why this occured at this time, when all was working fine before

 i chekced the back... there was a tiny fiber that looked like it was contacting q19, althouh would that be conductive enough to cause the resistor to smoke?

 Should I just replace it and try again?(and 100 ohm won't work here, will it?(don't have another 75 ohm)

 Regards,

 Michael_

 

That looks really nasty. Have you tried to measure the value of R32? If it's toasted, you should have to replace it with 75Ω.
 I also notice that the MOSFET legs look quite smokey (or is that just the smoke from the toasted R32?).

 After replacing R32 (if necessary), you might check the voltage on this board against the values as depicted on the PDF file showing the β22 schematic diagram and the operating points available at the β22 website. This can help you to determine if there are more parts toasted or not. (Hopefully not! )


----------



## amb

gates_2, R32 smoking is a sign that Q23 is shorted. Normally there should be negligible current into the gate of R32 (see schematic). Whatever caused it, there be be other damage, so check for shorts between all pins of each output MOSFET (they should all read very high resistance on your DMM), and also R34, R35.

 While 100 ohms will "work" as a replacement for R32, 75 ohms is a "tuned" value for best performance.


----------



## joneeboi

.


----------



## akione

Hi All,

 First Post , so be gentle 
	

	
	
		
		

		
		
	


	




  Quote:


  Originally Posted by *gates_2* /img/forum/go_quote.gif 
_um... problem

 I was working on a completely unrelated part (stepped attenuator)... things were fine..
 ... all of the sudden, smoke out of the right channel board... the 75 ohm resistor right below Q23

 I'm curious as to why this occured at this time, when all was working fine before

 Regards,

 Michael_

 

 I had to join up when I saw this. I had exactly the same thing happen to mine.

 Working fine and then R32 suddenly burst into flames ! 
 When I stripped the board down and tested the parts I found 1 dead BC550 (not sure which one, unfortunately), 
 a damaged diode (D9 or 10) and of course R32. 

 I've not tested the Mosfets yet, but I will.

 Colin


----------



## gates_2

indeed...pins 1 and 3 of q23 are shorted

 is this a failure of the mosfet itself?

 none of the other mosfet pins are showing direct shorts


----------



## amb

Quote:


  Originally Posted by *gates_2* /img/forum/go_quote.gif 
_indeed...pins 1 and 3 of q23 are shorted

 is this a failure of the mosfet itself?_

 

The MOSFET failure is probably a result of another cause, such as overheating due to lack of ventilation or a shorted output, etc.


----------



## Tedro

Quote:


  Originally Posted by *gates_2* /img/forum/go_quote.gif 
_um... problem

 I was working on a completely unrelated part (stepped attenuator)... things were fine.. all of the sudden, smoke out of the right channel board... the 75 ohm resistor right below Q23

 I'm curious as to why this occured at this time, when all was working fine before

 i chekced the back... there was a tiny fiber that looked like it was contacting q19, althouh would that be conductive enough to cause the resistor to smoke?

 Should I just replace it and try again?(and 100 ohm won't work here, will it?(don't have another 75 ohm)
 PIC:




 Regards,

 Michael_

 

I had the exact same thing happen to me, just out of the blue when I was listening to it. I ended up replacing all the mosfets, D9, and D10, Q17,Q18,Q19 and of course R32 to be functional again.


----------



## Tedro

Quote:


  Originally Posted by *akione* /img/forum/go_quote.gif 
_Hi All,

 First Post , so be gentle 
	

	
	
		
		

		
		
	


	






 I had to join up when I saw this. I had exactly the same thing happen to mine.

 Working fine and then R32 suddenly burst into flames ! 
 When I stripped the board down and tested the parts I found 1 dead BC550 (not sure which one, unfortunately), 
 a damaged diode (D9 or 10) and of course R32. 

 I've not tested the Mosfets yet, but I will.

 Colin_

 

Thanks for Posting, a documented third person with the smoking R32 makes me feel a little better and that im not the only person having problems with their B22. Not that the B22 is a bad amp or anything, Ti is a great guy and I much respect for him. He was able to help me out on several occasions including this minor issue, now I am just trying to figure out that one last issue I have with one of the output resistors on one of my boards


----------



## gates_2

Quote:


  Originally Posted by *Tedro* /img/forum/go_quote.gif 
_I had the exact same thing happen to me, just out of the blue when I was listening to it. I ended up replacing all the mosfets, D9, and D10, Q17,Q18,Q19 and of course R32 to be functional again._

 

do you think replacing all of the mosfets was necessary? Or jsut the one that failed?

 -michael


----------



## Tedro

Quote:


  Originally Posted by *gates_2* /img/forum/go_quote.gif 
_do you think replacing all of the mosfets was necessary? Or jsut the one that failed?

 -michael_

 


 I think I first replaced the the Mosfets on that side and Q19 and of course the resistor but that did not work. I replaced all of then, again and D9,D10 for the second round. After the second round the Mosfets went thirmal and the output resistors started to smoke 
	

	
	
		
		

		
		
	


	




 The third time around I replaced Q19,Q17 and Q18 and the board fired right back up. Not sure what exactly happened and or what gave out but I think it was a chain reaction each time I replaced parts.


----------



## akione

Quote:


  Originally Posted by *Tedro* /img/forum/go_quote.gif 
_I think I first replaced the the Mosfets on that side and Q19 and of course the resistor but that did not work. I replaced all of then, again and D9,D10 for the second round. After the second round the Mosfets went thirmal and the output resistors started to smoke 
	

	
	
		
		

		
		
	


	




 The third time around I replaced Q19,Q17 and Q18 and the board fired right back up. Not sure what exactly happened and or what gave out but I think it was a chain reaction each time I replaced parts._

 

 Hmmm, this is interesting. I followed AMB's advice from earlier about testing the mosfets' resistances.
 I found that all 4 had very low resistances, so it does look like it took them all out. 
	

	
	
		
		

		
		
	


	



 It's nice to know I'm not alone


----------



## amb

Replace only those parts that measured bad. If any MOSFET doesn't show up as shorted on the DMM, then keep it there.


----------



## gates_2

oh- i need to change my order with you then Ti ....:-/


----------



## swt61

Well I got back from a 6 week out of town job today, and my β22 was waiting for me, along with my new Opus DAC .

 This β22 is a four channel balanced unit with dual σ22 power supplies in a seperate chassis. It also has speaker binding posts installed for efficient speakers. The stepper is Twisted Pear Audio's Joshua Tree logarythmic stepped attenuator, and it's fully programmable. 

 No real impressions until I've had a few days to spend with it, but I have a big, stupid grin on my face that won't go away. 
	

	
	
		
		

		
			




























 These were built by fierce_freak, and his workmanship is incredible!


----------



## utilisateur

I'm planning on building a β22 aswell ; I was just having a look at the heatsinking for use as a speaker amp and tried to calculate the needs 
 BUT assuming 3/4 of max output current i get an output power of 13,5W with 30V supply , with a minimum load of 6 Ω and a maximum ambient temperature of 40°C amb's equation shows the need for a thermal resistance way below 2°C/W
 to stay below 100° , which would be impossible with the mosfets thermal resistance !?

 I'd be pleased to get some help/hints here

here the equation

*TIA!*

  Quote:


  Originally Posted by *swt61* 
_ Well I got back from a 6 week out of town job today, and my β22 was waiting for me, along with my new Opus DAC .

 This β22 is a four channel balanced unit with dual σ22 power supplies in a seperate chassis. It also has speaker binding posts installed for efficient speakers. The stepper is Twisted Pear Audio's Joshua Tree logarythmic stepped attenuator, and it's fully programmable.

 No real impressions until I've had a few days to spend with it, but I have a big, stupid grin on my face that won't go away._

 

sweet

 looking forward to further impressions


----------



## amb

You should assume a much lower average output power (e.g., 1/10 of maximum) for the purpose of this calculation because music is not sine waves. You'll get much more reasonable heatsink demands. See a similar discussion in the β22 thread at headwize starting at post #502 and a few posts onwards.


----------



## utilisateur

Aah thanks alot amb thats wonderful

 so 1/10 would be a safe assumption? 
 sweet thats 5°C/W alot more practical
 i have to add up the heat dissipation of every transistor that attaches to one heatsink though eh?

 compliments for your work and helpfulness 
	

	
	
		
		

		
		
	


	



 regards

 EDIT. thank you for the specific link , your answers over there help alot


----------



## amb

Quote:


  Originally Posted by *utilisateur* /img/forum/go_quote.gif 
_so 1/10 would be a safe assumption? 
 sweet thats 5°C/W alot more practical_

 

Yes, it's safe as long as you don't use the amp to run a disco.

  Quote:


 i have to add up the heat dissipation of every transistor that attaches to one heatsink though eh? 
 

Makes sense, doesn't it?


----------



## swt61

Quote:


  Originally Posted by *amb* /img/forum/go_quote.gif 
_Yes, it's safe as long as you don't use the amp to run a disco._

 

Crap! Well I guess I'll put that mirrored ball in the for sale forum.


----------



## el_matt0

hey all, ive got a question about what exact wiring scheme i should use for my beta22 setup. i plan to have one set of balanced outputs, 2 single ended 1/4 outputs, and speaker outputs (not all for simultaneous use hehe). i know there are several diagrams on the AMB site that are very close to this, but the one thing that im unsure of is, i dont want to necessarily have any single ended inputs, id be much happier with just one set of balanced inputs. can i make this work is basically what im asking 
	

	
	
		
		

		
		
	


	




? any help or advice = greatly appreciated as always. thanks all


----------



## n_maher

Matt,

 Yes, it's perfectly possible to do this. How? I'm going to let you stew on that one a bit and see if you can't figure it out. Ask yourself, what is a balanced signal really and how is it different from a single ended signal? And the answer is in amb's beta22 web pages.


----------



## swt61

And I have only balanced inputs on mine, with a SE 1/4" output, as well as balanced and speaker outputs.


----------



## el_matt0

do i just wire them all up together? ie, for the speaker outputs i just run L+, L-, R+, R- each to a binding post right? i connect the XLR balanced outputs as before, but with grounds as shown in many of the diagrams on AMBs site. and then for the SE outputs, do i just run my L+ to the L signal, the R+ to the right signal, and what for the ground, both L- and R-? do these outputs not connect to the ground pins of the pot?


----------



## strangedaze39

Wow do I need one of these. Very cool guys.


----------



## naamanf

Quote:


  Originally Posted by *el_matt0* /img/forum/go_quote.gif 
_do i just wire them all up together? ie, for the speaker outputs i just run L+, L-, R+, R- each to a binding post right? i connect the XLR balanced outputs as before, but with grounds as shown in many of the diagrams on AMBs site. and then for the SE outputs, do i just run my L+ to the L signal, the R+ to the right signal, and what for the ground, both L- and R-? do these outputs not connect to the ground pins of the pot?_

 

Look at the last picture in the "Wiring & Ground" section on the B22 site. Just like that. With the SE jack wire the ground to PSU ground.

 Edited.


----------



## n_maher

It would also be wise to peruse the "Other Options" section of the site.


----------



## el_matt0

thanks guys i think ill manage to figure it out, ill be sure to have more questions if not! 
	

	
	
		
		

		
		
	


	




 on a bit of a different note, i figure this is the appropriate place to place the question, what speakers would you guys say pair best with something like the b22? i think im looking for a moderately affordable (definitely <$1000) pair of bookshelves (as bookshelves are pretty much all it is intended to drive right?). any advice would be appreciated. for those of you that do already use a b22 for speakers, do you just use speakers with woofers in em, or do you use a separate sub (if you do use a separate sub how do u hook it up since i believe ive only seen most ppl incororate 2 pairs of speaker outputs from the b22)


----------



## naamanf

You do not want to run a sub off the B22. If you get a pair of bookshelves and want more bass look into getting a powered sub. As far as speakers go you are going to want to look for ones that have high efficiency. I also suggest you go back and read about using the B22 as a speaker amp and the power supply and cooling requirements.


----------



## swt61

Agreed. 
 I'm not running any speakers off of my β22 yet, but if I do I'll make certain they're extremely efficient, as I don't have the proper larger heatsinks for anything else. 
 I have two powered subs that have XLR inputs, and I run them from the second XLR outputs of my preamp. Most powered subs have line level RCA inputs, and you can do the same thing with single ended RCA outputs of your preamp.


----------



## el_matt0

ok so high efficiency bookshelves would be the way to go? yea i was planning to add on a second s22/trafo. was planning to however try it with just the stock heatsinks at first unless im strongly advised against doing that. im new to the speaker world anyone mind throwing out a few names or brands of some quality high efficiency bookshelf speakers i could possibly look into purchasing?


----------



## liwei

Hey all, could I get an estimate on how much a balanced B22 (4 board implementation) costs?

 I need a new rig and I'm thinking about going the diy route this time to have some fun and save a little bit of money.

 Opus dac > Balanced B22 > Balanced AKG701 is what I'm thinking about right now.

 Thanks


----------



## swt61

Quote:


  Originally Posted by *el_matt0* /img/forum/go_quote.gif 
_ok so high efficiency bookshelves would be the way to go? yea i was planning to add on a second s22/trafo. was planning to however try it with just the stock heatsinks at first unless im strongly advised against doing that. im new to the speaker world anyone mind throwing out a few names or brands of some quality high efficiency bookshelf speakers i could possibly look into purchasing?_

 

I have no idea what your budget is, but here are a few choices.

CBM-170 SE High Performance Bookshelf Loudspeaker

DECWARE / High Fidelity Engineering Co.

 The Decware are particularly nice, the MODEL MG944 are 94 db., and would probably negate the need for an additional subwoofer.


----------



## naamanf

Quote:


  Originally Posted by *liwei* /img/forum/go_quote.gif 
_Hey all, could I get an estimate on how much a balanced B22 (4 board implementation) costs?

 I need a new rig and I'm thinking about going the diy route this time to have some fun and save a little bit of money.

 Opus dac > Balanced B22 > Balanced AKG701 is what I'm thinking about right now.

 Thanks_

 

You are looking at about $1200 as a base price. Price can rapidly increase from there depending on the components used.


----------



## el_matt0

in the case of the b22, if using an alps quad-pot as the potentiometer, is there any need to consider unscrewing one of the "back" screws on the potentiometer housing and wiring that to one of the signal grounds (as I've done in my Millet Max)?


----------



## amb

Quote:


  Originally Posted by *el_matt0* /img/forum/go_quote.gif 
_in the case of the b22, if using an alps quad-pot as the potentiometer, is there any need to consider unscrewing one of the "back" screws on the potentiometer housing and wiring that to one of the signal grounds (as I've done in my Millet Max)?_

 

You would only need to do that if your front panel where the pot is mounted to is not connected to ground (i.e., a non-conductive panel).


----------



## el_matt0

will i truly be out of luck if my plan is currently to use 2 sigma 22s with a 100VA trafo for each to power my 4 b22 boards in order to run a pair of small high-efficiency bookshelf speakers as well as headphones? would i "be able" to get away with this just using 2 s22s or is it a STRICT requirement / recommendation that i use one s22 board per b22 board (so in my case 4 s22s). just seems like a LOT just to power a pair of bookshelves, and i was pretty sure that i thought i had seen ppl do it with just 2 s22's before - but i could easily be wrong, wouldnt be the first time either!


----------



## amb

el_matt0, it's not a _strict_ requirement. It's just a recommendation for more serious speaker driving duty. Ultimately the amount of current that the σ22 could safely deliver without burning itself up depends on the amount of heat that could be dissipated. There is a limit on how much two TO-220 MOSFETs per rail could do, even with very large, off-board heatsinks. By using four instead of two σ22 boards, then the current each one has to deliver is halved, which will result in half the amount of heat each MOSFET has to handle.

 If you have efficient speakers, your room is not very large, and you won't be listening at high power levels for sustained periods of time, then one σ22 per two β22 boards is probably ok.


----------



## el_matt0

thanks ti. it is just for a tiny room in fact so i definitely wouldnt be thumping on the speakers too hard by any means. since this is the case and hopefully ill be able to get away with just 2 sigma22s, what about the heatsinks. should those definitely be upgraded to something bigger or off-board, or could i try and see what the results are like using the stock ones?


----------



## amb

You can try using the stock heatsinks first if you like. It would be good if you have some way to actually measure their temperatures. There are DMM thermocouple adapters and handheld IR thermometers.


----------



## el_matt0

K GUYS I NEED HELP! i had taken my b22 completely apart to re-wire neatly etc. i didnt change any of the components on the boards themselves. the only thing i really changed about the wiring from how i had it before (and working) is that I included 2 pairs of speaker binding posts through which i have wired my outputs so that I can down the line use speakers. I havent yet included my second sigma22 or the zobel networks - figuring that since im not going to be using speakers, it should be fine just "having" the speaker binding posts there right? 

 anyways, on to where the trouble began. after getting it all re-wired, i began biasing, the s22 looked good, 28V across V+ and G on all the terminals. I spent most of the morning in the slow process of trying to adjust r34 to 75mV on all the boards. after a good number of hours i managed to get it all level at 75mV, as well as getting the DC offset to within 0.5mV of 0. everything looked good, so i went ahead and plugged in headphones for the first time with audio, and initially everything sounded OK - a tad blurry, but OK. then i noticed in my left channel it seemed to be cutting out almost and had a faint buzz at times, the right channel seems fine. however im not sure if its a problem with JUST my left channel, seeing as it "sounds" the same on a SE pair of headphones out of one of either of the two single ended jacks (left side blurry etc). 

 unplugged the load and now my s22 is only giving out about 18V across V+ to G (on all the terminals), when it was at 28V a few hours ago! my DC offset readings look fine without a load plugged in, but now i cant even get a reading across R34 on the mV scale, i think its in the realm of 0.5V or so. HELP! where should i start - im in a bit of a panic so anything is appreciated. ill snap some pics in a bit. sorry for the long post guys


----------



## el_matt0

k BIT of an update prior to posting photos. just started it up again and the s22 is pumping out 28V again fine, biased again, everything looked ok so i tried running it under load with headphones again. everything seems fine at first (sounds good, nothing audibly wrong). checking mV across R34 while listening, some boards stray from 75, to around 90 or so, but thast it. after a number of songs i decided to turn up the volume, near to the max end of the range i heard the left channel suddenly buzz somewhat noticeably, and then began alternating between a quieter and a louder volume every second or so. now the reading across the R34 is ranging from 180-250mV or so and even with the volume reduced again, the left channel is audibly "impaired". i believe the problems are once again rectified upon startup. what could i be looking at here - is this specifically a direct result of my lack of zobel networks (unstable under load)? the only reason this strikes me as odd is that this exact b22 setup without any components changed, just the addition of speaker posts and single ended outputs, worked FINE about 2 weeks ago before i took it apart! any help from you b22 gurus would be, as always, much needed / appreciated


----------



## naamanf

Zobel network won't be needed till speakers are connected. If everything worked before you rewired it that means you did something wrong on rewiring. Look everything over with a fine tooth comb. Triple check to make sure everything is going where it is supposed to. Check all your solder joints and look far any solder/wire.


----------



## el_matt0

yea i have done that! i may have missed something of course, but like i said, none of the components were changed so i doubt its a cold-solder on one of the boards. and i was pretty anal with the wiring this time around! ive narrowed down the symptoms of the problem a bit. so again, like i said earlier, once the problems kick up, if i turn it off, wait a few minutes, then power up, the biasing was a bit off across R34, so i adjusted it as close as i could get em all to 75mV. plug my headphones back in and start listening, sounds GOOD, everything sounds like its working, no obvious problems at all, and i can listen indefinitely at these lower volumes. the measurement across R34 wobbles around a bit ranging from 60-90 mV or so (dont know if thats normal or not). and when i plug in a pair of S.E. headphones to one of the single ended jacks powered by the L+ and L- (for L and R respectively) , the R34 value on my L+ and L- boards jumps up to around 120 mV or so. it returns back to 75ish once the S.E headphones are removed, so i assume this is normal! 

 so basically, when i increase the volume to higher listening levels on my balanced cans, i hear buzzing start at some point and then the left channel basically cuts in and out even once the volume is reduced (and it OBVIOUSLY doesnt sound good). problems gone upon power down, and quick re-bias. explanations / solutions?


----------



## el_matt0

im no electronics whiz by any means, so im kind of wondering - is something with symptoms like this possibly related to a biasing problem? my basic intuition would tell me it couldnt be a wiring or solder problem (cold joint, short, etc) because the problem clearly only happens at higher volume levels, could i be wrong though? and to clarify, the issue definitely only occurs past a certain volume, its not just that its only noticeable at the higher levels. "SOMETHING" clearly starts going wrong at aobut 3/4 turn on my pot. :S


----------



## el_matt0

is 75mV supposed to be the reading across R34 without a load connected? because it definitely changes once a headphone load is connected and volume is applied - is that expected (goes up above 75)?


----------



## amb

Quote:


  Originally Posted by *el_matt0* /img/forum/go_quote.gif 
_is 75mV supposed to be the reading across R34 without a load connected? because it definitely changes once a headphone load is connected and volume is applied - is that expected (goes up above 75)?_

 

The initial setup for quiescent current should be done without a load, and the input shorted (or volume turned all the way down). That said, if the DC offset is 0, and the amp isn't oscillating, then a load shouldn't affect the readings. Measuring the quiescent current with the volume up and playing music is meaningless -- the amp is no longer "quiescent".


----------



## el_matt0

ok...so what course of action should i take for trying to figure out what is wrong? it doesnt sound like something "major" is wrong necessarily, but compared to how it sounded before, id say something definitely IS wrong. like i said, it seems fine listening for extended durations at low levels, but upon increasing the volume, after awhile, something kind of goes audibly awry, and upon powering it down, unplugging load, and powering back up, all of my biasing is quite significantly off. (not having moved my trimpots from when they were all roughly 75mV across R34, my L+ and L- boards read roughly 125mV or so and my R+ and R- boards read around 50-60mV until I re-adjust them.

 totally bewildered as to where exactly i should begin trying to fix this....


----------



## amb

I suggest checking the voltages at various points in the circuit against the operating points PDF diagram at the β22 website (in the Initial Setup section, under "Troubleshooting").


----------



## el_matt0

so i should be doing all this testing with no load connected right (volume at zero, etc)?


----------



## amb

Yes. Those are all bias point voltages, which assume quiescent conditions.


----------



## utilisateur

Could anyone please
	

	
	
		
		

		
			





 confirm i'm not going to get a significant difference between using
Avel Lindberg Transformers and Feickert R-Cores or O-Cores  assuming they have the same rating !?

 I was planning to go with Feickert Transformers but as i cant seem to reach them
 i thought i should just go with Avel Lindberg as they'll most probably be cheaper ...


----------



## amb

There won't be a sound quality difference, if that's what you mean. Whatever you use, keep the transformer mounted far away from the amp boards, preferably in a separate chassis.


----------



## utilisateur

Thanks =)

 I was quite persuaded the magnetic field emission wouldn't have that much of an impact if put the PS in a different chassis anyway 

 Time to fill that definite order than


----------



## el_matt0

hey guys, still having a bit of instability problems with my b22. as aforementioned, i didnt change any of the components on the boards since it was last setup and working succesfully, all i did was re-do my input/output and PSU wiring, as well as adding in the speaker binding posts and single ended outputs. i have yet to add the zobel networks across the speaker outputs, but since i am not using speakers yet, this should not affect the headphone out usage right! can any of you experts see anything obviously wrong with my wiring etc that might be causing me the troubles? incase the pics are unclear, basically the outputs of the boards are running to the speaker binding posts, then from there to the balanced XLR outputs. from those balanced xlr outputs basically the 2 pin is a L and the 3 pin is an R, the left XLR feeding S.E. output 1, and the right XLR feeding s.e. output 2, with the ground running to one of the empty G terminals on my psu. other than that i cant really see anything ive done wrong, no obvious shorts or anything, all my boards are cleaned, everything is heatshrunk etc to a decent degree i think. again just to reiterate the problems that ive been having are that i seem to hear a little fuzz etc in my left channel after listening at louder volumes, and once the buzz becomes apparent, the biasing is all out of whack, despite that it was all in check just minutes before! anyway, heres pics, sorry for the long post but any help will be greatly appreciated! im yet to check with the operating voltages against AMBs chart but ill try to get on that.


----------



## akione

Hi el_matto,

 I'm not sure I can be of much help, but if it happened to me, I'd start by wiring the L & R channels as a single-ended amp and see if it still happens. That way you'd know if it was the amp module or the wiring.

 edit: Another thing you might try is swapping the ground channels to see if it changes to the other side.


----------



## el_matt0

mmm, well heres the thing, after biasing the amp properly, it maintains stability and does in fact sound decent listening at low volumes (ie. its not blatantly obvious theres anything awry). usually only after increasing the volume significantly, i begin to hear a faint buzz in the left year, and the sound just loses its quality, not painfully obvious perse, but noticeable without a doubt! the odd thing is, it seems like the buzzing is audible in the left channel of even single ended headphones (out of either output), as well as on the balanced ones, which is why im not inclined to think its a problem with my L+orL- boards, since one of the S.E outputs is driven entirely by the R+ and R- boards, yet stll the problem persists. must be something with my input wiring or pot? but why would it cause this instabliity in this fashion....hmmmm. still seeking advice


----------



## akione

Hi,

 ..... yeah, I see what you mean. I should've checked the wiring plan first.
	

	
	
		
		

		
		
	


	




 ...... if it's happening when the volume increases, maybe the pot's not tracking properly ? 
 or an input stage is going unstable ? overheating maybe ?


----------



## el_matt0

hmm yea i dont really know, thats the problem, im no electronics whiz so troubleshooting like this is definitely by far my weakest link. im inclined to think it isnt related to any of the components/boards, or potentiometer even, since i had it wired up in a very simple fashion (without speaker binding posts or single ended outputs), and it was working fine for a good number of months, running very stable. i havent changed a single component, just rewired it in a different fashion and re-biased it, so logic implies it MUST be something related to that - oh if only it were so simple


----------



## el_matt0

how would a balanced pair of v3 darth beyers sound paired with a balanced b22? what about cable choice, i find i feel my setup sounds a little bit too cold at times, would black copper perhaps be a superior choice to black max for me in that case, or would i still be better off to stick with the common choice of black max?


----------



## ferds

Hi Guys,

 I'm building a 3channel Beta22 amp for a friend. I received the kit from Jeff yesterday.. As always top notch service from Jeff. thanks 

 I started building this morning and manage to stuff all the boards with almost 6hours of soldering.. Will test the amp tomorrow or on Saturday..












 Thanks also to AMB for sharing this wonderful amp.. 

 Regards


----------



## el_matt0

hey man, looks good! hope to see that baby up and running soon! 
	

	
	
		
		

		
		
	


	




 i had to put my 4 channel b22 on hold for awhile because of exams etc coming up as well as moving back home for the summer. im kinda mid-process adding on a second sigma22 and recasing up the PSU, should look and sound good hopefully for the summer though!


----------



## vvs_75

Quote:


  Originally Posted by *ferds* /img/forum/go_quote.gif 
_
 I started building this morning and manage to stuff all the boards with almost 6hours of soldering.._

 

You are really fast man! 
	

	
	
		
		

		
		
	


	




 Good luck!

 It took me almost a year to put everything together. Hopefully few more days to finish the amp. I am perfectionist plus very meticulous person; I think that is my problem.


----------



## naamanf

Wowser! Looking great. Looks like B22s are going to be coming out in full force in the next couple of weeks.


----------



## el_matt0

hey guys, got a question. so as you all know, my rig is a 4 channel b22, im currently kind of in the process of re-wiring it. im wondering if hypothetically i was to use one e22 board, could i simply put 3 of the boards on the e22, and have the 4th just to the side. im just thinking it might neaten up the internal wiring somewhat - thoughts? I dont have room to put 2 full e22s with 2 boards on each in my case, just room for the one (or none). if i was to put one in, it would neaten up the hookup wiring for those 3 boards, and just the 4th would need to be air wired right? other than that, are there any other factors i need to take into account, or is this straightforward and more than possible to do?


----------



## vixr

so far so good...


----------



## el_matt0

anyone have an answer to my question from a few posts back? about using a single e22 to neaten up a 4 board balanced b22 (no room for 2 e22s), or will this just add too much unecessary confusion, if im air wiring one board, might as well do all 4 tpye thing?


----------



## naamanf

I say don't use one. Save it for a three channel B22. If you spend a little time with the wiring you can make it neat.


----------



## el_matt0

yea thats what i think as well after really thinking into the matter. that aside, kind of an off question, but how hard is it to wire up something like a DACT rotary balanced attenuator? where might i best research to findout or start learning about something like that, because im interested in moving up from the 50 dollar alps quad pot ive got now.


----------



## FallenAngel

A quick question, I'm not sure if it was answered, or perhaps it wasn't asked because it's so obvious, but either way; I I was to wire the same transformer to more than one Sigma22 board, how would I wire it? Would it simply be a matter of wiring one, then running jumpers to another Sigma22 board to make them run in parallel?


----------



## fierce_freak

Quote:


  Originally Posted by *vvs_75* /img/forum/go_quote.gif 
_You are really fast man! 
	

	
	
		
		

		
		
	


	




 Good luck!_

 

Haha, that's about the time it takes me, too (just under 2 hours per b22 board). Of course, it's the rest of the work that takes so much longer (casework, testing, etc.).

 vvs, your amp looks like it's coming along very very well! Can't wait to see it finished


----------



## amb

Quote:


  Originally Posted by *FallenAngel* /img/forum/go_quote.gif 
_A quick question, I'm not sure if it was answered, or perhaps it wasn't asked because it's so obvious, but either way; I I was to wire the same transformer to more than one Sigma22 board, how would I wire it? Would it simply be a matter of wiring one, then running jumpers to another Sigma22 board to make them run in parallel?_

 

Yes, you can drive multiple σ22 boards from a single transformer. Whether you daisy-chain it like you describe, or simply make Y-splices in the transformer secondary leads and run to each board, the effect is the same.

 Don't short the σ22 boards' outputs together, though.


----------



## FallenAngel

Quote:


  Originally Posted by *amb* /img/forum/go_quote.gif 
_Yes, you can drive multiple σ22 boards from a single transformer. Whether you daisy-chain it like you describe, or simply make Y-splices in the transformer secondary leads and run to each board, the effect is the same.

 Don't short the σ22 boards' outputs together, though._

 

Thanks _amb_, another quick question: aside from the Beta24, is there any reason NOT to use a balanced Beta22 for speakers as a 50 Watt amp?


----------



## amb

Quote:


  Originally Posted by *FallenAngel* /img/forum/go_quote.gif 
_is there any reason NOT to use a balanced Beta22 for speakers as a 50 Watt amp? 
	

	
	
		
		

		
			



_

 

A balanced β22 will comfortably give you 50W+ of power into 8Ω (provided that the PSU is sized appropriately), but it wasn't designed to do so in a sustained manner. The TO-220 MOSFETs' thermal resistance is not low enough, even if you use big heatsinks, to run at high output continuously without risk of overheating (and this applies to both the amp and the σ22 PSU). Obviously, what defines "high output" vary depending on the efficiency of the speakers and the size and acoustics of the room. For most moderately-sized rooms and relatively efficient speakers, and with enough heatsinking, and reasonable playback volumes with occasional high peaks, it should be fine. Just don't have any expectations that this amp would be able to serve as a pro-grade PA or concert amp!

 The β24 on the other hand, is designed from the outset to be a speaker power amp, with larger TO-247 output MOSFETs and large heatsinks. Also, in the β24, the σ22 PSU provides power to everything _except_ the output stage, so it's relieved of the high-current and high power dissipation burden that's present in the β22. Thus, β24 would be much more adept at high sustained outputs.


----------



## FallenAngel

Thanks again amb, a beautiful distinction.

 I have been holding off building a Beta22 because ever since I saw it released in design over a year ago on HeadWize, I've been seeing it as the King of headphone amps. Therefore I wanted to build the other headphone amps before I reach this level.

 After reading it can drive speakers in balanced mode to 50Watts, lets say it's very hard to resist. Your post about the 630VA 2x30V transformer for $75 pretty much sealed my fate into wanting to build it for my speakers as well.

 Well, that is definitely if I can sell off my latest experience with an over-the-top maxed out all-in-one with 4-input switchbox with 3x RCA and USB AlienDAC source, CKK-III preamp/headphone amp with custom PSU and LM3886 Gainclones amp for hopefully most of the parts cost, oh and very much THANK YOU for your help in the ground wiring scheme, it reduced the transformer hum to non-existent!

 My speakers at the moment are 6Ohm Wharfedale 9.2 and I like them, but as with all great things, they don't last and I will likely upgrade sooner or later, which means they will be floor-standers and will likely want more power than the 50Watts the Beta22 can produce in balanced mode.

 Having said that, it's just so hard to decide between a speaker-enabled Beta22 and Beta22 + Beta24. Oooh, here comes the little devil on the shoulder saying build both 
	

	
	
		
		

		
		
	


	




 and I think I'm going to listen.

 Any recommendations on a cheap yet good transformer to drive a balanced Beta22 headphone amp? The $75 for 630VA knocked my socks off!


----------



## amb

Quote:


  Originally Posted by *FallenAngel* 
_Any recommendations on a cheap yet good transformer to drive a balanced Beta22 headphone amp? The $75 for 630VA knocked my socks off!_

 

In terms of VA per dollar it's hard to beat that transformer, and it's shielded to boot. But, it is BIG and a bit overkill for four β22 boards, but if you've got the space... why not. Use it to drive four σ22 PSUs and you'll have quite a monster. It's even got a couple extra secondary windings that might be useful for other gizmos.

 For those who are wondering what we're talking about, it's this one.

 Other than that, Parts Express carries some Avel-Lindberg transformers at excellent prices (cheaper than you could buy them directly from A-V for at single-quantities).


----------



## FallenAngel

Quote:


  Originally Posted by *amb* /img/forum/go_quote.gif 
_In terms of VA per dollar it's hard to beat that transformer, and it's shielded to boot. But, it is BIG and a bit overkill for four β22 boards, but if you've got the space... why not. Use it to drive four σ22 PSUs and you'll have quite a monster. It's even got a couple extra secondary windings that might be useful for other gizmos.

 For those who are wondering what we're talking about, it's this one.

 Other than that, Parts Express carries some Avel-Lindberg transformers at excellent prices (cheaper than you could buy them directly from A-V for at single-quantities)._

 

Oh completely, I was thinking of an OPUS and receiver off the 1A 16V-0V 1A secondary running off a TREAD, it's a fantastic find, thank you.

 Now I just have to find a new Programmer Analyst job in the next 10 days to get a TN-1 Visa and stay in the country so I can continue this hobby.


----------



## el_matt0

could i use that big ol 630VA trafo to power both my sigma22s for my 4 channel balanced b22, or would i be better off just buying another 100VA avel-lindberg for the 2nd s22 to match the one I currently have? I'm terrible with this kind of stuff so any advice you guys can offer would be much appreciated - will the 630VA one just be overkill, no harm done though? will i be losing anything perse going this route as opposed to getting two separate 100VA trafos, or is the 630VA single trafo still going to far overpower the 2 individual ones?


----------



## amb

el_matt0, you can use the 630VA transformer for both σ22s and it will be way overkill but no harm done (provided that you have room for a 6.5" diameter lump). Otherwise, using a second 100VA transformer is probably a more sensible solution.


----------



## el_matt0

ok, i THINK thats what im seeing in the pictures of that 630VA trafo, but is that a second set of secondaries (ie for hooking up a second sigma 22 board without needing to splice) or am i a bit off base in my labelling of the wires....?


----------



## amb

el_matt0, look at the transformer label. There is only one 30V-0-30V secondary so you must splice the wires. The other secondaries are 13V-0-13V and 0-16V.


----------



## vixr

WOO HOO!!!


----------



## el_matt0

niiiiiiice vixr!


----------



## fault151

Whats the main difference in the 3 channel option over the 4 channel version of the b22, apart from the obvious?

 Do they sound similar?


----------



## el_matt0

single ended with active ground (3 board) versus fully balanced configuration (4 boards)


----------



## fault151

Quote:


  Originally Posted by *el_matt0* /img/forum/go_quote.gif 
_single ended with active ground (3 board) versus fully balanced configuration (4 boards)_

 

You mean the input being single ended and balanced out put? 

 Is one better than the other or is it just preference depending on your set up?


----------



## amb

Quote:


  Originally Posted by *fault151* /img/forum/go_quote.gif 
_You mean the input being single ended and balanced out put?_

 

Sort of, but not really. In a 3-channel active-ground amp, the output ground is actively driven by an amplifier just like the stereo channels, but the ground amp does not swing voltage (only source/sink return load current). It allows you to get most of the benefits of balanced output without the need to modify the 3-wire headphone. It also does not require a balanced source to make full-use of its capabilities. See the "tech highlights" section at the β22 website for more detailed info.


----------



## el_matt0

yea, to clarify my earlier post, 3 channel board = single ended inputs and single ended outputs. its a 3 channel single ended amp. if you go with the 4 board version, youd need (ideally) balanced dual XLR inputs and likewise for the outputs, although you can set a 4 board up to also run single ended outputs in addition to the balanced ones (just using 2 boards instead of 4).


----------



## amb

Btw, I prefer to call it "unbalanced" vs. "balanced". The term "single-ended" is overloaded and means different things depending on context. For example, "single-ended" also refers to an output stage topology within an amp channel (the opposite would be "push-pull"). You could build a balanced amp with amplifier channels having SE output stages. Confusing? Yup.


----------



## Nebby

I like "balanced" vs. "unbalanced" makes it somewhat clearer than mud


----------



## fault151

Right thanks for that, i understand it but better now. Well its just a case of which to go with? Part of me wants to try the full 4 channel version but that would mean i would need a balanced dac (which i haven't got, yet). The other means i could use it with my existing gear no problem. 

 I know this must be a very commonly asked question, but is there really a great deal of difference in the 4 channel and 3 channel sound? 


  Quote:


  Originally Posted by *amb* /img/forum/go_quote.gif 
_Sort of, but not really. In a 3-channel active-ground amp, the output ground is actively driven by an amplifier just like the stereo channels, but the ground amp does not swing voltage (only source/sink return load current). It allows you to get most of the benefits of balanced output without the need to modify the 3-wire headphone. It also does not require a balanced source to make full-use of its capabilities. See the "tech highlights" section at the β22 website for more detailed info._


----------



## amb

Quote:


  Originally Posted by *fault151* /img/forum/go_quote.gif 
_I know this must be a very commonly asked question, but is there really a great deal of difference in the 4 channel and 3 channel sound?_

 

You're going to get different answers from different people. Some might hear a big difference while others might hear a small difference, or none at all. I know this is a big hand-wave answer, but such is the nature of audiophilia. You just have to decide what's right for yourself.


----------



## fault151

Ha ha i thought that would be the respone. I wish i could hear the two before deciding one one option. I suppose for me its easier to make the 3channel as i dont need to mod other bits. Hmmm..... It's a tough one.


  Quote:


  Originally Posted by *amb* /img/forum/go_quote.gif 
_You're going to get different answers from different people. Some might hear a big difference while others might hear a small difference, or none at all. I know this is a big hand-wave answer, but such is the nature of audiophilia. You just have to decide what's right for yourself._


----------



## el_matt0

where do you live? if your in any sort of major city i wouldnt be surprised if theres DIYers local to you who might have a 3 or 4 channel b22 to try. im in vancouver BC if it ever suits your fancy lol


----------



## fault151

Im in the UK. Thanks for the offer anyway. I think im just going to take the plunge and buy a kit and see how it goes. I'll practice making my cmoy first, then maybe attemp it when im a bit more confident.

  Quote:


  Originally Posted by *el_matt0* /img/forum/go_quote.gif 
_where do you live? if your in any sort of major city i wouldnt be surprised if theres DIYers local to you who might have a 3 or 4 channel b22 to try. im in vancouver BC if it ever suits your fancy lol_


----------



## vixr

most of the wiring done...


----------



## n_maher

Ooooohhhhh, I bet that stepper sounds sweet.


----------



## el_matt0

bit of a balanced/SE conceptual problem i was having troubles wrapping my head around this morning. am im correct in thinking that, on a b22, you can run solely balanced inputs (2x XLR in), and from that, can run a balanced headphone output (using 4 boards) and a single ended headphone output (using 2 boards). dont know why i asked..lol thats how mine is setup, havent gotten it 100% working yet as im working on the casework at the moment, but to say the least - i HOPE thats a possible configuration. basically my "trip up" is that howcome no balanced to single ended conversion is needed in this case to drive the SE outputs? whereas if I was to run a set of single ended INPUTS into my b22 in addition to the balanced inputs, in order to drive a balanced pair of headphones from the single ended input, THEN id need some kind of converter inside the b22 right (SE to balanced)? are all my assumptions correct so far? ....basically in that you need a converter to go from SE to balanced, but in some senses, one isnt needed to go from balanced to SE (as i intend for mine to be setup)?


----------



## naamanf

When using balanced you have both a + and - for each channel(L/R). When using unbalanced(SE) you only need the + (or -) of each channel and ground. You don't need to do any conversion because you already have two boards that are amplifying the + (or -)signal. 

 You need to do conversion when using unbalanced on the input side because there is only + and ground.


----------



## el_matt0

lol, yea thanks thats all i needed, the obvious to be pointed out. 
	

	
	
		
		

		
		
	


	




 its early in the morning where i am- cut me slack. hehehe!


----------



## el_matt0

if im planning to place 2 sigma 22s and trafos in a separate enclosure, powering 4 beta 22 boards, do i need to run 12 conductors through my umbilical (3 for each board), or can i simply just run a 6 conductor umbilical, 3 from each of the s22s, and then use terminal strips or something to then "split" each of those 6 conductors in order to feed 4 b22 boards once in the amplifier board chassis. does that make sense/work?


----------



## el_matt0

just as a reminder, im running a 4 channel beta 22 with 1 set of balanced outputs on the front, and 2 1/4" single ended outputs (each driven by 2 boards). My question is, would it be possible to create one essentially "higher gain" S.E. output, ie so I could hypothetically say use IEMs on that output? would this be just a simple matter of putting a resistor in line with the L and R channels of that output? if so, any recommendations on what a good value/brand of resistor would be appropriate here? this is where I want to use something like a kiwame etc right?


----------



## amb

el_matt0, surely you meant "lower gain" for IEMs, right?

 Resistors inline with the headphones are a way to reduce the effective gain, but it's got its share of problems.

 First, the resistor forms a voltage divider with the headphone load, which is what causes the gain drop. But the headphone impedance is not perfectly flat, so the attenuation will not be uniform over the audio band, causing frequency response aberrations. Such aberrations are not a good thing if you want the amp to remain faithful to the input signal, but in some cases the frequency response change may "complement" a weakness in the headphones. It is my opinion that the amplifier is not the proper place to put such "fixes" for headphone deficiencies.

 Second, placing series resistance with the headphone raises the amplifier's effective output impedance, as "seen" by the headphone. This results in a loss of damping factor. The β22 has extraordinarily low output impedance which gives it such commanding control over the headphone diaphragm, and such resistors will be detrimental to that quality. Some headphones that lack bass may actually sound "better" with high output impedance (the looser control imparts a false sense of increased bass), but again I question this as an appropriate thing to do.


----------



## el_matt0

Ok, thanks for the info AMB, very helpful. I kind of suspected that might be the case (oh btw yes I meant low gain 
	

	
	
		
		

		
			





 my mistake). So what you would recommend instead would be to simply just use an adapter of sorts with resistance built in, on the odd time one might want to use IEMs rather than have it actually built into one of the outputs of the amp.


----------



## amb

Quote:


  Originally Posted by *el_matt0* /img/forum/go_quote.gif 
_So what you would recommend instead would be to simply just use an adapter of sorts with resistance built in, on the odd time one might want to use IEMs rather than have it actually built into one of the outputs of the amp._

 

Yes, with such an adapter the resistors can be easily removed, so you can have the attenuation (and its associated foibles) if you need it without making it a permanent part of the amp.


----------



## el_matt0

Cool thanks a ton, and for the PM. 
	

	
	
		
		

		
		
	


	




 Hopefully I will have my baby back up and running in a couple weeks, with some more decent photos to come.


----------



## dreamwhisper

Is there any improvement in sound quality with running a two Sigma 22s as opposed to one when amping Senn HD650s?

 Also, why the Joshua Tree attenuator?


----------



## el_matt0

with hd650s I dont believe so. adding a second sigma22 will only really benefit you if your driving EXTREMELY power hungry cans, basically speakers for all intensive purposes. the only ones that come to mind - AKG K1000. And if you intend to use speakers a lot , in addition to just adding a second s22, offboard heatsinks should definitely be considered, as the stock sinks aren't specd to handle speaker heat loads. 

 With respect to the stepped attenuators, its kind of an ongoing debate somewhat on the forums. Most people prefer a stepped attenuator in higher-end amps, but some people swear by just a potentiometer, as they dont like the "click-click-click" feel of a stepper, and some claim they can never adjust it to the right position with a stepped attenuator. There are technical advantages I believe, but I'm not tech savvy enough to explain that fully, I'm sure you could look it up or someone else could explain better. Ultimately its really just preference, I dont think its going to hugely change how your amp sounds. If you want just an alps quad potentiometer instead of a stepper, I think by all means thats a perfectly suitable option, many people go that route on balanced amps. Why the Jtree over other steppers, I couldnt tell you specifically, as I havent tried them to compare, but price is a big factor. For a good rotary balanced stepped attenuator like a DACT one, I think you are looking at a minimum of $300. The fact that the Jtree is less than half that cost, and can be adjusted both in terms of the total number of steps and the level of attenuation per step is a big motivating factor for alot of people. Bottom line is a lot of people have used it and report very good things about it, so for its price I dont think you can really go wrong. That said however, if you arent totally convinced on your want or need for a stepped attenuator, I'd say you might be almost just as well off opting for an Alps Quad Potentiometer and save $80 bucks or so. My 2 cents.


----------



## vvs_75

Quote:


  Originally Posted by *el_matt0* /img/forum/go_quote.gif 
_with hd650s I dont believe so. adding a second sigma22 will only really benefit you if your driving EXTREMELY power hungry cans, basically speakers for all intensive purposes. the only ones that come to mind - AKG K1000. And if you intend to use speakers a lot , in addition to just adding a second s22, offboard heatsinks should definitely be considered, as the stock sinks aren't specd to handle speaker heat loads. 

 With respect to the stepped attenuators, its kind of an ongoing debate somewhat on the forums. Most people prefer a stepped attenuator in higher-end amps, but some people swear by just a potentiometer, as they dont like the "click-click-click" feel of a stepper, and some claim they can never adjust it to the right position with a stepped attenuator. There are technical advantages I believe, but I'm not tech savvy enough to explain that fully, I'm sure you could look it up or someone else could explain better.* Ultimately its really just preference, I dont think its going to hugely change how your amp sounds.* If you want just an alps quad potentiometer instead of a stepper, I think by all means thats a perfectly suitable option, many people go that route on balanced amps. Why the Jtree over other steppers, I couldnt tell you specifically, as I havent tried them to compare, but price is a big factor. For a good rotary balanced stepped attenuator like a DACT one, I think you are looking at a minimum of $300. The fact that the Jtree is less than half that cost, and can be adjusted both in terms of the total number of steps and the level of attenuation per step is a big motivating factor for alot of people. Bottom line is a lot of people have used it and report very good things about it, so for its price I dont think you can really go wrong. That said however, if you arent totally convinced on your want or need for a stepped attenuator, I'd say you might be almost just as well off opting for an Alps Quad Potentiometer and save $80 bucks or so. My 2 cents._

 

I think steps vs. pots not just matter of preference but big sonic advantage. Why would anybody pay $350 vs. $50, if it was just preference? Quality Metal film resistor doesn't have competitors on today’s market and always will be sonically ahead of carbon or any other materials used in pot controls.
 Just my 2c.


----------



## grawk

Well, it boils down to sound quality vs control. So it IS preference...


----------



## el_matt0

yea grawk got at what i was kinda moreso referring to. obviously there ARE more than just sonic differences between the two, as i referred to a technical advantage to the steppers, i just cannot elaborate cuz im a tech nitwit. lol. but basically yes as he said, tradeoff between control versus SQ, although honestly having used a quad pot its not like it makes your amp sound bad or anything by any means lol


----------



## dreamwhisper

Quote:


  Originally Posted by *grawk* /img/forum/go_quote.gif 
_Well, it boils down to sound quality vs control. So it IS preference..._

 

Are you saying that one has more sound quality and the other more control. Is it that simple? Which is which?

 i thought the Jtree just had more of both?


----------



## grawk

A stepper is better quality than any reasonable potentiometer. The pot is going to have more flexibility, because it's not limited to specific steps.


----------



## el_matt0

some people simply prefer the potentiometer in the sense that it allows for infinite amount of control over the volume. perhaps you may not be exactly clear on the difference, a potentiometer is going to just be smooth turning all the way around as you turn the knob, a stepped attenuator has a preset number of "steps", with a specific amount of volume attenuation per step, so basically as you turn the volume up, instead of just a smooth turn of the knob, you would feel click, click, click. i believe the jtree has 128 steps, although im not 100% on that, id hafta check. some people just dont like the having to go through a set number of clicks, as a pot would allow you to theoreticaly put it at a volume "inbetween" 2 of the clicks. if that makes any sense lol...hope im not just blabbin!


----------



## akione

Quote:


  Originally Posted by *el_matt0* /img/forum/go_quote.gif 
_some people simply prefer the potentiometer in the sense that it allows for infinite amount of control over the volume. perhaps you may not be exactly clear on the difference, a potentiometer is going to just be smooth turning all the way around as you turn the knob, a stepped attenuator has a preset number of "steps", with a specific amount of volume attenuation per step, so basically as you turn the volume up, instead of just a smooth turn of the knob, you would feel click, click, click. i believe the jtree has 128 steps, although im not 100% on that, id hafta check. some people just dont like the having to go through a set number of clicks, as a pot would allow you to theoreticaly put it at a volume "inbetween" 2 of the clicks. if that makes any sense lol...hope im not just blabbin!_

 

Just to clarify. It's the relays that click, not the pot, in the JT. The pot's smooth. 
	

	
	
		
		

		
		
	


	




 Also, 128 steps is excellent for a stepped attenuator, most of them are around 24 steps.


----------



## el_matt0

@ akione, yes thats better said 
	

	
	
		
		

		
		
	


	




, thanks for the clarification!


----------



## dreamwhisper

so it has better control (128 steps) as well as better sound quality (quality metal resistors)?


----------



## el_matt0

a normal potentiometer has no steps at all, it is smooth turning all the way from no volume to the max volume. this is why sometimes people refer to the basic potentiometer as having more control in some ways. but the jtree, FOR a stepped attenuator, yes has very good control, because it has 128 steps


----------



## MrMajestic2

Still slowly finishing my b22 build. Managed to finish my power supply today. The backpanel is from cardboard panel express 
	

	
	
		
		

		
			





 Will order the real one when I got everything running.






 Yes, I like sleeving 
	

	
	
		
		

		
		
	


	




 The small transformer feeds a TREAD at 5v for some relay switches and there is also an unregulated secondary for the Joshua Tree attenuator.


----------



## wquiles

Quote:


  Originally Posted by *MrMajestic2* /img/forum/go_quote.gif 
_The backpanel is from cardboard panel express 
	

	
	
		
		

		
		
	


	




 Will order the real one when I got everything running._

 

You certainly have spared no cost 
	

	
	
		
		

		
		
	


	




 Those panels by cardboard express are some of the most expensive in the DIY industry 
	

	
	
		
		

		
		
	


	




 By the way, nice progress - thanks for the photos 
	

	
	
		
		

		
		
	


	




 Will


----------



## Covenant

/raises hand

 In the planning stages for a build now, which will be a combined work of me and a skilled DIY friend of mine who will be doing the assembly and testing. I initially had thought to build a 4-channel balanced version, but i've since changed my mind in favour of a 3-channel active ground config.. fed by 3 sigma22's 
	

	
	
		
		

		
		
	


	




 The amp will be a dual purpose unbalanced headphone amp/speaker amp, using mostly reccomended parts (Kermet ceramics, Wima polystylene, Panasonic FM/FC eletrolytic, Dale Vishay 1% tol resistors, Alps 'black beauty' pot), with the exception of using triple sigmas, with a 330V +30v+30v Toroidal, both in an external enclosure.

 No parts have been ordered yet, we're still trying to find a good source for hookup wire - we'd prefer to have multiple colours to help keep track of which wire's which, and I'd personally like to do all the internal wiring with silver plated copper, but we've so far only been able to find 100ft+ reels of the stuff which would be ridiculously expensive to buy multiples of.

 Will keep people posted on the progress


----------



## wnmnkh

Another one (single-ended) here....


----------



## Ech0

Just got started by ordering part's for a single ended 3 channel B22 from amb's webiste. 
	

	
	
		
		

		
		
	


	




 I have some vacation time coming up and I needed something to do! This DIY stuff is pulling me in.....

 I'm sure I'll be posting questions sooner or later. 

 Ech0


----------



## fault151

A bit of advice needed, i'm not sure whether to go for a balanced option or the 3 channel version, has anyone made both who can give me a comparison in sound? I don't have any other balanced gear so if i went fully balanced id need to make a dac and wire my headphones.


----------



## akione

Quote:


  Originally Posted by *fault151* /img/forum/go_quote.gif 
_A bit of advice needed, i'm not sure whether to go for a balanced option or the 3 channel version, has anyone made both who can give me a comparison in sound? I don't have any other balanced gear so if i went fully balanced id need to make a dac and wire my headphones._

 

Well ....... I built a 3 channel Beta22 ........

 .... then I decided to build a DAC. It eventually ended up being a fully-balanced DAC and pre-amplifier. 
	

	
	
		
		

		
		
	


	




 Now I wish I'd built the balanced Beta22, so I could make full use of the pre-amp. 
	

	
	
		
		

		
		
	


	




 If you intend to go balanced later ...... at least make sure your case is big enough to expand it.


----------



## swt61

Very nice MrMajestic2! Looks very similar to mine as far as parts and layout.


 Covenant I haven't seen you on here in ages! Good to see you!


----------



## fault151

Yeh the only thing thats putting me off full balanced is th fact id need a dac fully balanced to even try it out. What dac did you make? 

  Quote:


  Originally Posted by *akione* /img/forum/go_quote.gif 
_Well ....... I built a 3 channel Beta22 ........

 .... then I decided to build a DAC. It eventually ended up being a fully-balanced DAC and pre-amplifier. 
	

	
	
		
		

		
		
	


	




 Now I wish I'd built the balanced Beta22, so I could make full use of the pre-amp. 
	

	
	
		
		

		
		
	


	




 If you intend to go balanced later ...... at least make sure your case is big enough to expand it. 
	

	
	
		
		

		
		
	


	


_


----------



## grawk

Grab a pair of balancing transformers from cinemag and you can use an unbalanced source with pretty good results. a simple box iwth rcas on one side and xlrs on the other works wonders. It won't give you the double source voltage swing, but gives most of the other benefits.


----------



## fault151

Whats the best gain set up to use on the balanced amp? Would an 8 gain be too high to for use on the balanced amp with hd600's?


----------



## Covenant

For HD600's i'd reccomend a gain of 5, since that'd effectively be doubled and give you 10.

 One option you might want to persue is to build a 5 or 6-channel design so that you can have simultaneous balanced and unbalanced with active ground. Also keep in mind that the standard 4-channel balanced setup can be used with unbalanced headphones too, you just switch to a 2-channel passive ground configuration when doing so.


----------



## MrMajestic2

Quote:


  Originally Posted by *swt61* /img/forum/go_quote.gif 
_Very nice MrMajestic2! Looks very similar to mine as far as parts and layout._

 

Thanks mate. Yeah, didnt realize it was that similiar until you said it 
	

	
	
		
		

		
		
	


	




 Hopefully Ill get it done within a week or so.


----------



## akione

Quote:


  Originally Posted by *fault151* /img/forum/go_quote.gif 
_Yeh the only thing thats putting me off full balanced is th fact id need a dac fully balanced to even try it out. What dac did you make?_

 

Twisted Pear Opus - Dual-mono with Metronome, USB and SP/Dif integrated into the pre-amp.


----------



## synaesthetic

I'm planning on building probably a 2-channel beta-22 and stuffing it in a Hifi2000 case. Not sure if I'll use the o22 power supply or another solution yet. Desk space is at a premium and I can always upgrade to an o22 PSU later on if I so desire.

 I've been looking over the details of the design and what's involved in building it, I'm pretty sure I can handle it once I get some tools; I think it'd just be good to build something that will have some longevity. =)

 Won't be soon, maybe three months from now while I assemble a better workspace to handle something this involved. I'd also like to get some worthy headphones to pair with such an amplifier!


----------



## fault151

Well i have the 4 channel kit on order so i think i'll get it and see how i get on with it. Just hope i can put the bloody thing together! 

  Quote:


  Originally Posted by *Covenant* /img/forum/go_quote.gif 
_For HD600's i'd reccomend a gain of 5, since that'd effectively be doubled and give you 10.

 One option you might want to persue is to build a 5 or 6-channel design so that you can have simultaneous balanced and unbalanced with active ground. Also keep in mind that the standard 4-channel balanced setup can be used with unbalanced headphones too, you just switch to a 2-channel passive ground configuration when doing so._


----------



## fordgtlover

I'll build a 3 channel as soon as I figure out a case. (I have too many uncased amps already)


----------



## m11a1

i'm building a balanced/unbalanced combo, i just got my order from AMB today...waiting for my order from mouser to start soldering..i'm gonna design my own case with heatsinks on the side of it...


----------



## fault151

Quote:


  Originally Posted by *m11a1* /img/forum/go_quote.gif 
_i'm building a balanced/unbalanced combo, i just got my order from AMB today...waiting for my order from mouser to start soldering..i'm gonna design my own case with heatsinks on the side of it..._

 

Would the amp be selectable as too which sound you want? Balanced or un balanced? Is it possible to do that? Id love to be able to have that option.


----------



## naamanf

Quote:


  Originally Posted by *fault151* /img/forum/go_quote.gif 
_Would the amp be selectable as too which sound you want? Balanced or un balanced? Is it possible to do that? Id love to be able to have that option._

 

Take a look at the other options portion of the B22 website


----------



## el_matt0

yep, lots of people have that option, its easy to do! i have it and it was absolutely no extra trouble when doing the build, although i rarely find myself using it SE


----------



## fault151

Quote:


  Originally Posted by *el_matt0* /img/forum/go_quote.gif 
_yep, lots of people have that option, its easy to do! i have it and it was absolutely no extra trouble when doing the build, although i rarely find myself using it SE 
	

	
	
		
		

		
		
	


	


_

 

Sounds like it's worth wile adding in to the build. Guess it means you wouldn't have to mess with re wiring your headphones too.


----------



## fault151

naamanf= Hows your b22 sounding? Am i right in thinking you have a 3 channel version and now a 4 channel? Would you be able to shed some light on the differences between the two? If there are many?


----------



## naamanf

So far the four channel version sounds really good, but I don't have any other comparable amps to evaluate it against. 

 Also have not had a chance to compare the three channel to the four because they are in two separate places. Not much help I know.


----------



## fault151

Quote:


  Originally Posted by *naamanf* /img/forum/go_quote.gif 
_So far the four channel version sounds really good, but I don't have any other comparable amps to evaluate it against. 

 Also have not had a chance to compare the three channel to the four because they are in two separate places. Not much help I know._

 

What set up did you build in the end? Do you use the Joshua tree and opus dac in the case? 

 Overall is it worth the money and build? 
	

	
	
		
		

		
		
	


	




 The pic you sent me of it looked great, i liked the case design.


----------



## swt61

Quote:


  Originally Posted by *fault151* /img/forum/go_quote.gif 
_What set up did you build in the end? Do you use the Joshua tree and opus dac in the case? 

 Overall is it worth the money and build? 
	

	
	
		
		

		
		
	


	




 The pic you sent me of it looked great, i liked the case design._

 

I'm gonna jump in and give my two cents worth.

 Firstly the JT is an excellent attenuator, I absolutely love it.

 Secondly I'm not so sure I'd want to include the Opus in with the amp. My β22 is going to keep me happy for a very long time, but DAC technology changes much faster, and I'd like to be able to easily move onto another DAC when that happens.
 I love my Opus, but I doubt it's time in my system will be nearly as long lived as the β22.


----------



## fault151

Yeh i know what you mean. How do you find it sounds then? Im just trying to get a general idea. Did you get the 4 channel balanced version?


----------



## utilisateur

I just started my build yesterday after alot of hesitation and all went well =)
 I basically finished 2 sigmas yesterday (except for the mosfets as i still need the heatsinks). 
 The first one took me hours but the second was done within an hour.

 Started with the first β22 board this morning and i just finished matching the VAS transistors.
 Again everything a bit slow as i had to find the correct parts and understand the board...
 but i guess it'll be easier know that i know which part is which =)

 Most helpful thing i learned was fixing small caps and transistor with yellow tack to hold them in place while soldering
	

	
	
		
		

		
		
	


	




_Now if only there was a way to use the standart Avid heatsinks with the transistors mounted on the underside of the board..._


----------



## fault151

where do you get the bits needed to hold the heat sinks down? Im getting a kit from glass jar audio.


----------



## naamanf

You could use a 6-32 tap and 6-32 x 1/4" screws. In the US Mcmaster-Carr is the place I get all my hardware. Not sure about the UK.


----------



## fault151

Quote:


  Originally Posted by *naamanf* /img/forum/go_quote.gif 
_You could use a 6-32 tap and 6-32 x 1/4" screws. In the US Mcmaster-Carr is the place I get all my hardware. Not sure about the UK._

 

Thanks, i'll have to see what i can find. Did you use one power supply or two? One per channel? Do i even need two. The site says it can cope with one.


----------



## utilisateur

If you only intend to use it for headphones one σ22 should be sufficient,you may need to use offboard heatsinks though.



_I just discovered how many heatsinks i'd have to buy and remembered theirprice :S ...._

 Would it be detrimal to the FETs to desolder them, bend them and resolder them under the board once i find enough time and money? (_Besides the major pain .....***_)

 I'd love to put the amp to use but i just cant afford those >100€ for external Heatsinks atm


----------



## fault151

Yeh at the minute i would but it may be nice for use with speakers.


----------



## swt61

Quote:


  Originally Posted by *fault151* /img/forum/go_quote.gif 
_Yeh i know what you mean. How do you find it sounds then? Im just trying to get a general idea. Did you get the 4 channel balanced version?_

 

Yes mine is the Four Channel balanced version with two sigma 22s in a separate case.
 As for SQ, I've heard a lot of nice amps, and the β22 has surpassed them all. I feel that this amp is about as good an amp as can be found today, and I won't let mine get away from me.
 It's very refined, and the detail is incredible. It's a neutral amp with very little flavor of it's own. Bass slam is fantastic. I own some very different headphones (see my profile) and the β22 is phenomenal with all of them, high and low impedance.
 One thing is for sure, with the level of this amp you'll want to make sure your source is up to par.

 It also drives my Omega Grande Six speakers beautifully.


----------



## utilisateur

For Speaker use one σ22 will definately NOT be enough.
 I dont know whether or not it could be able to supply enough power to a β22 driving speakers. but your main concern would be the heat generated!
 Theres an explanation on how to calculate how much heat is generated in the last third of the Board+heatsinking section of amb[size=xx-small]s[/size] website


----------



## fault151

Quote:


  Originally Posted by *swt61* /img/forum/go_quote.gif 
_Yes mine is the Four Channel balanced version with two sigma 22s in a separate case.
 As for SQ, I've heard a lot of nice amps, and the β22 has surpassed them all. I feel that this amp is about as good an amp as can be found today, and I won't let mine get away from me.
 It's very refined, and the detail is incredible. It's a neutral amp with very little flavor of it's own. Bass slam is fantastic. I own some very different headphones (see my profile) and the β22 is phenomenal with all of them, high and low impedance.
 One thing is for sure, with the level of this amp you'll want to make sure your source is up to par.

 It also drives my Omega Grande Six speakers beautifully._

 

Thanks for that, i found it useful. I have a kit on order so hope i can build it ok.


----------



## amb

Quote:


  Originally Posted by *fault151* /img/forum/go_quote.gif 
_where do you get the bits needed to hold the heat sinks down? Im getting a kit from glass jar audio._

 

Read the "instructions" section of the β22 and σ22 websites. You should be able to find #4-40 machine screws and tap at your local hardware store.


----------



## MrMajestic2

Quote:


  Originally Posted by *amb* /img/forum/go_quote.gif 
_Read the "instructions" section of the β22 and σ22 websites. You should be able to find #4-40 machine screws and tap at your local hardware store._

 

Or M3 screws and taps work fine too which are more common in europe.


----------



## utilisateur

I'm still in the above described "dilemma" ... Am i right assuming it's safer to
 mount the Mosfets in their standart position and not cut the legs [size=xx-small]_(and later desoldering bending and replacement under the board)_[/size] than

 mounting them under the board without bending them so i can use the avid heatsinks until i get bigger ofboard heatsinks [size=xx-small]_(and then bending the Mosfet legs without desoldering)_[/size]


----------



## cotdt

It's time for a Beta24 =)


----------



## utilisateur

Could anyone comment on the correct wiring of an Avel Lindberg Y23xxs primaries for 230V operation ???
 I'm not sure i get their sheet right

 + I think i'm in trouble the blue wire must have been cut by customs or crushed in the package, there's just a little stub sticking out :S

 TIA!


----------



## Pars

Quote:


  Originally Posted by *utilisateur* /img/forum/go_quote.gif 
_Could anyone comment on the correct wiring of an Avel Lindberg Y23xxs primaries for 230V operation ???
 I'm not sure i get their sheet right

 + I think i'm in trouble the blue wire must have been cut by customs or crushed in the package, there's just a little stub sticking out :S

 TIA!_

 

You are thinking correctly, as you do need that blue wire, irregardless of primary voltage. I'd send it back.


----------



## Pars

.


----------



## utilisateur

Sending it back and forth will dig deeper in my wallet than getting a new one.
 I'm in Germany and got a kit from Jeff(GlassjarAudio)

 Looking at the transformer you can see how the leads continue across the side to the opposite face of the transformer..
 I 'm considering cutting a little slit in the outermost insulation so as to get a little more length to work with in order to reattach the cut lead.. 
 Wouldn't be very long but i'm not sure how much insulation there'd be left underneath.

 In the end i'm planing to get a new transformer anyways as to match it to the three others,but thats only once i can afford the outboard heatsinks+4new trafos....

 EDIT:

 to be sure:
Live
Neutral
Ground

*?*
 What happens if Live and Neutral are reversed? (Schuko plugs here..)

 Looks like i'd be fine with the tranny!?
 There's only one layer to cut that is the white surrounding strip ,the vertical insulation layers leave out this passage so it looks like it's no real problem!?


----------



## utilisateur

I think i solved the problem with the blue lead for the moment
 As said above the outermost insulation layer on the Transformer is the only thing covering these primary leads until halfway down the windings were another layer is superimposed, so imho no technical problem cutting a little slit in that spot for a simple repair





 As soon as anyone confirms my wiring i'll finally be able to power it up for the first time
	

	
	
		
		

		
		
	


	





 voila


----------



## amb

utilisateur, I can't see your IEC's solder tabs very well, but the transformer primary doesn't seem to be wired correctly. Your local AC mains is 230V, correct? If so, then the two primary windings should be wired in series, like the second diagram in post #492 above.

 The blue wire should go to AC live, brown wire should go to AC neutral, and the grey and violet wires should be connected to each other, but to nowhere else. Looks like your grey/violet wires are also erroneously connected to AC ground.

 By the way, to answer your question, it doesn't matter if you reverse the live or neutral connections, as AC has no polarity.


----------



## luvdunhill

Quote:


  Originally Posted by *amb* /img/forum/go_quote.gif 
_By the way, to answer your question, it doesn't matter if you reverse the live or neutral connections, as AC has no polarity._

 

I do however try and respect phase markings on the primaries and secondaries.


----------



## utilisateur

Ah i see
 Of course ! BAD MISTAKE! I had it connected to Ground ! Thats what i meant when i said i dont totally understand their sheet.Seems like a pretty clear thing now that you point it out

 Sounds like it should fit now

 Thank you !

_And i was just going to ask why i'm measuring a short between Blue(Brown) and Grey(Violet) . yuck I should make myself aware of what part i'm looking at 
	

	
	
		
		

		
			



_


----------



## amb

Quote:


  Originally Posted by *luvdunhill* /img/forum/go_quote.gif 
_I do however try and respect phase markings on the primaries and secondaries._

 

Yes, that is very important.


----------



## amb

Quote:


  Originally Posted by *utilisateur* /img/forum/go_quote.gif 
_And i was just going to ask why i'm measuring a short between Blue(Brown) and Grey(Violet) . yuck I should make myself aware of what part i'm looking at 
	

	
	
		
		

		
		
	


	


_

 

You will measure a "short" (or some low amount of resistance) there anyway, because a transformer winding is just a long coil of wire. When it's powered up, the transformer's magnetic field does its magic so that it no longer "looks" like a short to your house AC wiring.


----------



## utilisateur

That`s what i meant
 I must have been thinking, _ouhh , two shorted wires .. something is wrong_
 Instead of switching even my basic physics knowledge back into the processing chain
	

	
	
		
		

		
		
	


	




 I updated the pictures so nobody is mislead

 It's up and running(was)
 But measuring around 1VAC on -VDCOUT
 Went to check to operating points everything was a little higher guess thats normal though, i get ~33VAC from the Transformer.

 NOW i ****ed up, probe slipped and shorted D5s output to either R3 or Q7s Emitter giving me a _nice_ blue spark
 Taking it from the positive side, once i figured out what that did and what will most probably be gone i'll understand the schematic to a far wider extend ....

AC problem is fixed, meter was just not up par, inverting the probes gave a correct measurement.
 So i blew the transistors for nothing


----------



## utilisateur

Quote:


  Originally Posted by *utilisateur* 
_[size=xx-small]Now i realy dont get the problem, especially as the spark and the traces really look like i had shorted D5s Cathode to R3 wich is nonsense as they are connected anyways !!? 

[size=xx-small]Unless it was not my hand slipping but the other probe slipping from the Ground tab to V-Out(nonsense)[/size]








 Q3,7,8 measure around 18M Ω from C to E ...[/size]_

 

Guess i'll fix the sigma i'm quite sure i just blew those transistors around D5 and maybe the zener ? ..

 Now trying to setup the b22 modules with the other S22


----------



## indikator

from what I understand from wiring section
 4 board amp have all common ground to chassis, is it right?


----------



## amb

Quote:


  Originally Posted by *indikator* /img/forum/go_quote.gif 
_from what I understand from wiring section
 4 board amp have all common ground to chassis, is it right?_

 

All four boards should share the same signal/power ground, but whether that signal ground is directly connected to the chassis (or via a ground loop breaker) depends on your choice of casing configuration. The box containing the IEC inlet, mains wiring and power transformer should have its chassis tied to the AC ground for safety. If you have a single-box amp then a ground loop breaker should be used to isolate signal/power ground from AC ground, in order to prevent a ground loop. If you're building a two-box amp, then the amp chassis can be tied directly to signal/power ground while the PSU chassis would be tied to AC ground without a ground loop breaker. The two chassis are not otherwise linked.

 See the "Wiring & ground" section of the β22 website for details.


----------



## diego

Hello,

 I just finished my B22 and everything looks good except one thing. I can adjust everything to the required parameters on all boards but on the ground chanel I can't get current to flow through the mosfets. Even if I open VR3 it reads 1.5mv on one side and 0 on the other. I'd appreciate if anyone can give an idea of what's wrong. Thanks in advance!

 Diego


----------



## diego

Well, I couldn't wait and connected the amp and it appears to work well. In fact, it sounds great. I am assuming it's working as a 2 channel amp though, without using the active ground.

 Any input would be appreciated though.


----------



## amb

diego, why not read through the headwize β22 thread? I recall helping someone with a similar issue there.


----------



## diego

I found that part of the thread late last night. There are a lot of helpful pointers in it that I'm going to work with.

 Thanks for your quick response.

 Diego


----------



## diego

I tested the voltage at both sides of R14 and R15 and they are ok so the VAS stage appears to be fine. R29, 28 32 and 33 are fine too. Power from the PS is fine too and voltage across all zeners is 12v.

 The area that is not good is around VR2, both sides of R26 are wrong at 0.3v and -1.8v and both sides of R25 are slightly off at 3.03v and 1.01v. Voltage across C7 remains constant around 3.7v while adjust VR2 and voltage across R34 and 35 is 1.5mv and 0.

 I reflowed VR2 and checked resistance on all other joints to make sure they were connected to what they should and weren't shorted to others. I also replaced Q17 and 18 and nothing improved so I'm guessing VR2 is defective. Is that right? Also, to make sure I get everything I need in one shipment to Costa Rica, what extra parts do you recommend me to order just in case?

 Regards,
 Diego


----------



## n_maher

Diego,

 Have you tried to verify that VR2 is working in circuit? You should be able to do so by measuring the appropriate pins while adjusting the pot (or taking incremental measurements).


----------



## ziplock

I'm going to build one of these this year.

 I think it will pair well with my Pioneer PD-91!


----------



## vixr

if anyone is looking to add the switch driver and transformer boards to the beta22 build, it is absolutely worth it. I added it to mine and its just awesome


----------



## TheRobbStory

I just received four of each board. I'm using one on both my B24 and my (yet to be built) B22. I think they'll lend a nice touch of class as opposed to a big toggle on the rear panel.

 I'll also be using the Bulgin style illuminated pushbuttons.

 I actually had a dream last night that influenced my casework for this diabolical pair. 

 No details yet, but know that it's going to be red and black and hotter than sizzlin' fajita meat.


----------



## diego

n_maher,

 Not directly, but I thought that the voltage on one side of R26 is the one that comes from VR2 modified by R27, so it should change with the adjustments in VR2 unless R27 is damaged which I thought was unlikely. However, since I'm just learning this I could be totally wrong 
	

	
	
		
		

		
			





 .


----------



## amb

diego, to test VR2, power off and let all capacitors discharge. Then, use your DMM in ohms mode to measure the resistance across the two outer pins of that trimpot. As you turn the trimpot screw the resistance should change. When it's at fully-clockwise position it should read 0 ohms or close to it, and increase in resistance as you turn it counter-clockwise. It will not quite reach the full 500 ohms because there are other resistors in the circuit "in parallel" with it.

 NOTE: Be sure to reset VR2 back to the fully-counterclockwise position before turning the power on again. If you don't do that, you could potentially over-bias the MOSFETs and damage them (and the output resistors too).


----------



## diego

It turns out VR2 appears to be good (it measures 2.5 -456.7 ohms). So, what could be wrong then?


----------



## amb

Quote:


  Originally Posted by *diego* /img/forum/go_quote.gif 
_It turns out VR2 appears to be good (it measures 2.5 -456.7 ohms). So, what could be wrong then?_

 

OK, reset VR2 to the fully-counterclockwise position, then turn on the power. Measure the DC voltage _across_ the R30 and R31 wire jumpers. Watch the voltage as you slowly turn VR2 clockwise. After some turns the voltage should begin to rise. Keep turning until you see about 7V. Be very careful not to let the meter probes slip and short something out.

 If you could achieve 7V, then the Vbe multiplier section (Q17, Q18) is working properly. Proceed to step 7 of the initial setup procedure to set the output quiescent current. If you still cannot get 75mV across R34 and R35, then check to make sure D9 and D10 are installed in the correct orientation, and have approximately 12V DC across each of them. If that still doesn't reveal a problem, then one or more of the output MOSFETs is probably blown.

 If you could not achieve 7V across the R30/R31 jumpers even if you reached VR2's full clockwise position, then something is wrong with Q17, Q18 or maybe one or more of the resistors (R25, R26, R27) is the wrong value.


----------



## diego

The max I got was 4v across r30,31. Both of my other boards had 7.2v. D9 and D10 are ok, good orientation and flowing 12v. I changed Q17 and Q18 so I would be very unlucky if they are also bad 
	

	
	
		
		

		
		
	


	




 (although perfectly possible). R25 and 26 read 2211f and R27 reads 5620f. I don't know if it's possible that I fried one of them or C7 while I soldered them but I don't remember having trouble when I did.

 Tomorrow night I'll check all the operating points to see if there is something wrong in the other areas.

 Thanks a lot for your help.

 Diego


----------



## vixr

FWIW, I had a hard time getting some of the components on the ground plane to solder good. The places where the solder didn't take hold looked kinda funny, with the solder wanting to creep up the lead more than stick to the pad...I ended up cranking up my Hakko to max temp and reflowing some places. Its worth a try.


----------



## n_maher

Just to second what vixr said, soldering to the ground plane on these boards takes a very hot iron. While working on my beta I just set my Hakko to max and went for it. Still felt like I could have used more heat for some of the ground connections.


----------



## akione

Sometimes a heat gun (not too hot ! ) or hair dryer can help. 

 Just warm the pcb up a bit before you start.


----------



## diego

Thanks for your input guys, I'm gonna try that too.


----------



## amb

http://www.head-fi.org/forums/f5/hea...s-sing-330775/


----------



## diego

That's an awesome B22 and even though I've only heard mine with 2 channels for 20 minutes, its detail and resolution were the first things that caught my attention. I'm really looking forward to get the 3 channels working to compare against my SP Extreme.

 Back to my debugging work, I redid every suspect joint and checked with my DMM the rest. All of them have at most 0.4 ohms of resistance with parts they should be connected to and different but much higher resistances with parts they shouldn't. So, I think I should rule that out.

 I checked all the operating points and the other that I would think are also bad are between Q13 and R20 ( 6.5v) and between Q15 and R21 (-7.8v ). Also between Q22 and Q24 (-10v) and between Q23 and Q21 (9.39v), although these two point seem close enough.

 Based on that I was thinking on replacing: Q9-16, Q21-24, R25-27, VR2 and C7 just in case. Would that be enough or should I replace some other parts to be sure?


----------



## amb

diego, if you have a spare set of 2SK170/2SJ74 matched quads, replace that first before anything else. Re-do the initial setup after doing this (reset all trimpots and start over). I have a suspicion that the fault lies at the input stage.


----------



## Namrac

I'm playing around with the idea of it... damn this hobby.


----------



## diego

Quote:


  Originally Posted by *amb* /img/forum/go_quote.gif 
_diego, if you have a spare set of 2SK170/2SJ74 matched quads, replace that first before anything else. Re-do the initial setup after doing this (reset all trimpots and start over). I have a suspicion that the fault lies at the input stage._

 

That was it, I changed them and now the amp is working perfectly. So, after 4 months of work here it is:

 It's built in 2 Par Metal 12123 cases, it has a Goldpoint stepped attenuator, Nichikon Muse caps on the amp, Cardas RCAs, Amphenol Tuchel connectors for the umbilical and the rest are standard parts.

















 The amp is dead silent, if I turn the volume all the way up with the source off I can't hear a thing, and as many of you know it sounds great. Thanks a lot for all the help.


----------



## MasiveMunkey

Quote:


  Originally Posted by *diego* /img/forum/go_quote.gif 
_That was it, I changed them and now the amp is working perfectly. So, after 4 months of work here it is:

 It's built in 2 Par Metal 12123 cases, it has a Goldpoint stepped attenuator, Nichikon Muse caps on the amp, Cardas RCAs, Amphenol Tuchel connectors for the umbilical and the rest are standard parts.

















 The amp is dead silent, if I turn the volume all the way up with the source off I can't hear a thing, and as many of you know it sounds great. Thanks a lot for all the help._

 

Which case is that? Is it the painted par-metal case or the anodized one? Looks great!


----------



## amb

Quote:


  Originally Posted by *diego* 
_That was it, I changed them and now the amp is working perfectly.
 ...
 The amp is dead silent, if I turn the volume all the way up with the source off I can't hear a thing, and as many of you know it sounds great._

 

Terrific!


----------



## diego

It's anodized. Thanks!

 PS. I have to paint the scratch I made drilling the back of the power supply, but for now I'm just going to enjoy it.


----------



## Beefy

Quote:


  Originally Posted by *diego* /img/forum/go_quote.gif 
_It's anodized. Thanks!

 PS. I have to paint the scratch I made drilling the back of the power supply, but for now I'm just going to enjoy it._

 

diego man..... posts like this aren't helping me resist the urge to build on of these things! 
	

	
	
		
		

		
		
	


	




 I just wish it was easier to get nice cases in Australia, without paying a fortune for shipping. Maybe I should post something in the DIY cases thread......?

 [EDIT] Oh, one *very mild* criticism. With the layout of your umbilical, you will have live wires at a plug on the amp side. Now I know you'll probably never have the PSU turned on without the umbilical connected, but it is very easy to remedy for future builds. Just go with a socket on the amp-end of the umbilical instead like I did with my MMM/σ11; look at the third photo here for an example: http://www.head-fi.org/forums/f6/pos...ml#post4255177


----------



## Ech0

@diego, very very nice and clean build. I like it alot...I'm doing something similiar once I get past a bump in the road in my build.

 @Beefy, I did the same thing as Diego on my build. I would have never thought to do otherwise. That's a good tip. 

 Matt


----------



## diego

Thanks for your kind words guys. 
	

	
	
		
		

		
		
	


	




 @Beefy, thanks for the tip, I'll do it that way for my next project.


----------



## fault151

When it comes to heat sinks for the b22, is it best to use off board heatsinks? Is this mainly for the use with running speakers? Do the size of the heatsinks make a big difference?


----------



## n_maher

Quote:


  Originally Posted by *fault151* /img/forum/go_quote.gif 
_When it comes to heat sinks for the b22, is it best to use off board heatsinks? Is this mainly for the use with running speakers? Do the size of the heatsinks make a big difference?_

 

If the amp is 100% for speaker duty it would be wise to use off-board heat sinks, specifically for the power supply but you can achieve quite a bit of power with the stock on-board bits. And of course it is completely dependent on the speakers that you want to drive. I've been using a 2-ch, single power supply beta for driving some efficient bookshelf speakers (~90db/W) for months now without issue and even with a gain of 4 it drives them well for my near field setup.


----------



## fault151

I see, so it's only the power supply thats really an issue with the heatsinks. Id like to use it to power speakers but it will be mostly headphones. I might just do it anyway with off boards. Do you think that's the best idea? Is it important to use two power supplies or just the one? IO know you said you have the one powering speakers, but id like to power my floorstanders.


----------



## n_maher

Quote:


  Originally Posted by *fault151* /img/forum/go_quote.gif 
_I see, so it's only the power supply thats really an issue with the heatsinks. Id like to use it to power speakers but it will be mostly headphones. I might just do it anyway with off boards. Do you think that's the best idea? Is it important to use two power supplies or just the one? IO know you said you have the one powering speakers, but id like to power my floorstanders._

 

As I said, before real meaningful advice can be given we probably need a bit more information about the speakers you want to drive and what your expectations are for how loud you want it to go. Generally speaking if you're going to use the beta22 with floor standing (assumed to be less efficient) speakers I would use one power supply per channel and use off-board mounted (large) heat sinks for both the power supplies and the amplification channels. That turns this into quite the complicated build though.


----------



## fault151

Yeh it will do. I'll have a think and see if it's worth doing it or not. I want it mainly as a headphone amp, but it would be cool to use for both.

 I'm still not sure what to use as a balanced source. So far i'm thinking of going with an opus dac.


----------



## n_maher

Just make sure you understand how expensive things are going to get when you go balanced.


----------



## indikator

what about 12 watt small nearfield, will a single sigma22 suffice to power it?

 If I have an active sub, can I at the same time drive the speaker from the amp and tapping the signal for that active sub from volume control? will it effect the sound?

 and also in parts recommendation in amb site, is it 'grab which one you encounter' or 'the upper in the list the better', I'm not kinda familiar with parts quality


----------



## fault151

Quote:


  Originally Posted by *n_maher* /img/forum/go_quote.gif 
_Just make sure you understand how expensive things are going to get when you go balanced._

 

Yeh i know it's going to be an expensive build, I won't be doing something like this again in a hurry. I just need to make sure if i start it, i manage to get it finished.


----------



## el_matt0

@ fault151. try out a balanced rig and be 100% sure u want to go balanced before you commit. When I built my first beta22 I ended up kind of blindly deciding that I wanted to go balanced as well. At the time i thought I had set out and ample budget for the amp ($1500 believe it or not), which over the proceeding months was very very quickly eaten up. The one thing that is hard to see before actually being there, is that its not simply just the additional parts cost of the amp that makes balanced drive so expensive, its the additional cost for a balanced source, balanced headphones, XLR interconnects. Let me just say from personal experience, that unless you really 100% feel that there's a black and white difference for you between balanced and single ended, you'd better be darned sure that the audible difference between the two is enough to merit the massive differences in price between single ended and balanced as a whole.


----------



## fault151

Yeh i know what you mean. The problem is I'm not sure where i could go to listen to a b22 before i decided to buy. I'm in the UK. So would you say your b22 is worth it in terms of sound? I guess if i decide to get one, i will be making it over a long period of time and spend money on it when i can.

 Cheers for your help.


*
 For those who have heard a b22 BALANCED amp, was it much better than a single ended amp?*





  Quote:


  Originally Posted by *el_matt0* /img/forum/go_quote.gif 
_@ fault151. try out a balanced rig and be 100% sure u want to go balanced before you commit. When I built my first beta22 I ended up kind of blindly deciding that I wanted to go balanced as well. At the time i thought I had set out and ample budget for the amp ($1500 believe it or not), which over the proceeding months was very very quickly eaten up. The one thing that is hard to see before actually being there, is that its not simply just the additional parts cost of the amp that makes balanced drive so expensive, its the additional cost for a balanced source, balanced headphones, XLR interconnects. Let me just say from personal experience, that unless you really 100% feel that there's a black and white difference for you between balanced and single ended, you'd better be darned sure that the audible difference between the two is enough to merit the massive differences in price between single ended and balanced as a whole._


----------



## el_matt0

It was definitely fantastic and by no means do I have any regrets of building a balanced one - it was a great experience in a ton of ways. Really I just wish I had realized all of the additional costs that tend to stack up with balanced drive though, as I outlined briefly above (which in reality probably doesn't even begin to cover the half of it). To be honest, the b22 is an incredible amp and I'd be pretty hard pressed to say you wouldn't be utterly impressed with a single ended one either. Really I'd say simply base whether you want to go single ended or balanced based on A) preferably if you've had a chance to A/B compare balanced versus single ended setups, and B) how much you are willing to spend elsewhere in your rig on a good source, and balanced headphones etc. What I'd say is, unless you have a ton of money floating around to throw into audio, and by that I mean once finished your balanced b22, the ability to purchase a good quality balanced source (probably in the realm of $1000-2000 realistically), and of course balanced phones etc, then I'd say go for balanced, as I did notice *minor improvements with respect to some slight clarity and soundstage widening*. For me however as a student earning my own living, it was too small to justify the huge price difference, and I'm still extremely happy with the sound from my single ended rig. I'd almost say its just a bit of a "different" sound rather than a better or worse sound (rarely unfortunately in audio are things that black and white). However, if you are on any kind of budget at all, I'd probably much more strongly recommend going with a 3 channel beta22 build and investing in a good quality single ended source. That also opens up your options a lot if you aren't looking to use a CD player and were more so set on a DAC of some sort. There are a lot more options in terms of reasonably priced single ended DACs than balanced ones, where you are limited to things like the DAC-1 and Opus, among a couple of others in that similar price bracket. Added bonus to the 3 channel is the ability to use an e22 backplane board, which could really help to neaten up the wiring job inside, especially if this is one of your first builds. Its really hard to speak enough of how helpful that is until you've actually built a b22 at which point you'd appreciate the headache which the internal wiring CAN potentially result in if messy!


----------



## fault151

What do you use to supply your b22? An opus dac? I already have a set of hd600's which i can convert for balanced. I know it's going to be expensive project but i hope it would be worth it. Have you still got your balanced dac then? I think for me it's a kind of thing i'll enjoy doing, i have saved a bit of cash already. Hopefully i can pace out the price over a few months.
*Have you got any pics of yours? Id love to see some!!!*


----------



## el_matt0

I had a number of sources that I tried out with the beta22. I tried out a cambridge audio azur 840c which i was quite happy with. I did have a zhaolu at one point which I was terribly UNhappy with, sounded like crud from the beta22 to be honest. I've heard good things about the opus dac, but I suspect amps in something like an 840c or a meridian g08 or 508.24 would be of slightly better quality (although dont quote me on that, as i know the opus IS sworn by by several members). converting the headphones for balanced isnt the issue really, as thats like a $30 dollar chop and solder job. Its really just the additional costs of balanced source, interconnects etc, it just adds up and its hard to realize that. Really just makes you think about whether you'd rather have a balanced rig OR a single ended rig and have more money to spend on better headphones and sources, or just cash in the pocket 
	

	
	
		
		

		
		
	


	




 which is always nice (but rare in this hobby).


----------



## fault151

cheers, the pic looks great. Yeh i think i will give it a go. I don't have money to burn, but i can save up for it. It is one of my main hobbies. 

 What option did you go for with wiring? 

 Can you run speakers of it? Is it dual power supply?

 You got any pics of the inside?


----------



## drc73rp

Single ended (unbalanced) works out perfectly for me. I think balanced is superior but takes some commitment and cost (balanced source, amp and cans). I say take it one step at a time and enjoy the journey. 




 Im using Stello DA-100 DAC as source from PC via Foobar. While i haven't finished with the casing (wood face plate still in the works) im trying out different headphones which would match my setup and music. The amp is very capable and transparent i've had to reconfigure and re-tune my setup.
	

	
	
		
		

		
		
	


	




 So it makes sense to leave some cash for when you have to try out and possibly upgrade your source and headphone(s).

 This is 3-channel with pre-out and speaker amp capabilities. I was able to try it with 8" Fostex Sigma speakers in a folded Voight cabinet and was very pleased with the results. The beta22 was capable of driving them without overheating even with just a single S22 power supply and standard heat sinks. I like it that i can use it as an amp now and upgrade to pre-power (Beta24?) later with it still in the chain.


----------



## fault151

Quote:


  Originally Posted by *AnaKinDV8* /img/forum/go_quote.gif 
_Single ended (unbalanced) works out perfectly for me. I think balanced is superior but takes some commitment and cost (balanced source, amp and cans). I say take it one step at a time and enjoy the journey. 




 Im using Stello DA-100 DAC as source from PC via Foobar. While i haven't finished with the casing (wood face plate still in the works) im trying out different headphones which would match my setup and music. The amp is very capable and transparent i've had to reconfigure and re-tune my setup.
	

	
	
		
		

		
		
	


	


_

 


 Yeh i like the look of the amp! I can't wait to have a go at the b22. Was it fairly easy to build?


----------



## drc73rp

Quote:


  Originally Posted by *fault151* /img/forum/go_quote.gif 
_Yeh i like the look of the amp! I can't wait to have a go at the b22. Was it fairly easy to build?_

 

I had a friend build the amp and power supply while i took care of the casing. As he is skilled to do this i imagine it was fairly easy for him to build (took him about a day or two without any problems). Fitting it into the case is not as simple as it may seem. Also the process of designing how the amp would come out finished is something you seriously have to consider. I had to build my own casing from aluminum sections to get the dimension and look that i wanted without costing an arm an a leg. But it took a lot of effort and time (sourcing, fabricating, powder coating, etc.) The wood face plate is taking some time as i'm doing it myself and while its something i like doing, im not that skilled and well-equipped. I like how i've progressed with it so far though...




 Using recycled hardwood from an old furniture.


----------



## fault151

Yeh its a cool idea, hope it works out! So is the plan to build the whole case in metal with wooden faceplate. Im after making the 4channel amp if i go for it. I think it will just be time consuming, Yeh i know what you mean about transferring a built amp in to a case. I transfered a millet max amp in a custom box i made with face plate from FPE. Took me a lot longer than i realised!


----------



## amb

Some people stuff the boards and get things working before even thinking about the case, but the really standout builds are usually those that have thought through the casing from the ground-up. This includes panel component placement, internal organization, including wiring and heatsinking, if applicable.

 You visualize the final result in your head, in 3-D, drawing sketches, making measurements of boards, parts and case parts with not just a ruler, but a caliper where accuracy counts. Not only must everything fit, the form and function must be equally considered, such as minimum internal wiring lengths and routing, as well as ergonomics and aesthetics.

 For a 3-channel active ground β22, the ε22 backplane board goes a long way to help make a tidy, functionally-correct build.


----------



## fc911c

Quote:


  Originally Posted by *amb* /img/forum/go_quote.gif 
_
 For a 3-channel active ground β22, the ε22 backplane board goes a long way to help make a tidy, functionally-correct build._

 


 Yes it does.
 A Ballanced backplane would be very nice any intrist in making one AMB?

 Thanks
 Frank


----------



## amb

Quote:


  Originally Posted by *fc911c* /img/forum/go_quote.gif 
_A Ballanced backplane would be very nice any intrist in making one AMB?_

 

The vast majority of β22 builds are 3-channel active-ground. Balanced configuration is "glamorous" but the number is low. At such numbers a 4-channel backplane board would be prohibitively expensive, because it is also going to be large.


----------



## fc911c

Quote:


  Originally Posted by *amb* /img/forum/go_quote.gif 
_The vast majority of β22 builds are 3-channel active-ground. Balanced configuration is "glamorous" but the number is low. At such numbers a 4-channel backplane board would be prohibitively expensive, because it is also going to be large._

 

I see, well what ever the cost might be I would consider it worth it. Maybe an intrist check might be in order. You count me in it it ever happens.

 thanks
 Frank


----------



## bperboy

Quote:


  Originally Posted by *fc911c* /img/forum/go_quote.gif 
_A Ballanced backplane would be very nice any intrist in making one AMB?_

 

Just go all out and use 2 backplane boards for a 6-channel build!


----------



## fc911c

Quote:


  Originally Posted by *bperboy* /img/forum/go_quote.gif 
_Just go all out and use 2 backplane boards for a 6-channel build!_

 


 now were talking BIG


----------



## bperboy

Quote:


  Originally Posted by *fc911c* /img/forum/go_quote.gif 
_now were talking BIG 
	

	
	
		
		

		
		
	


	


_

 

_Real_ big! I saw a 6-channel at CanJam.. I think it was Voltron's.


----------



## srserl

I liked that 4 ch B22 at the Norcal Summer meet where there were 2 boards on the bottom with the heat sinks to the outside of the case, then the other 2 boards were on top with their heat sinks towards the middle of the case.




 Looked really compact. This is the only picture I see of it (stolen from the meet impressions thread).

 Scott


----------



## Beefy

Quote:


  Originally Posted by *srserl* /img/forum/go_quote.gif 
_Looked really compact. This is the only picture I see of it (stolen from the meet impressions thread)._

 

I believe that is one of naamanf's B22's.

 Read more about it here: http://www.head-fi.org/forums/f5/hea...-tales-330775/


----------



## fault151

Yeh his amps look sweet! I love seeing them with off board heatsinks. Yeh i think the b22 balanced board would be great! I know what you mean about the expense. I'm going to wait till i get all my bits through and then plan the case.


----------



## fault151

By the way is this the amp your referring to?


----------



## amb

You can find photos of naamanf's build (and many others) at the β22 website gallery.


----------



## fault151

amb= where did you get your case for your new b24 from? Was it Hifi 2000? What size is the box? It looks great! Do you think it would be suitable for a b22?


----------



## n_maher

Quote:


  Originally Posted by *fault151* /img/forum/go_quote.gif 
_amb= where did you get your case for your new b24 from? Was it Hifi 2000? What size is the box? It looks great! Do you think it would be suitable for a b22?_

 

All of the details you seek are clearly laid out in the beta24 thread. Go, now, read.

 Also, your comment about asking if the beta was a "fairly easy" build scares me. Regardless of incarnation (2ch, 3ch, 4ch, 6ch) it's not an easy build. Simply stuffing the boards is straightforward enough (although easy to screw up) but the chassis work can be a monumental task for even experienced builders.


----------



## fault151

Quote:


  Originally Posted by *n_maher* /img/forum/go_quote.gif 
_All of the details you seek are clearly laid out in the beta24 thread. Go, now, read.

 Also, your comment about asking if the beta was a "fairly easy" build scares me. Regardless of incarnation (2ch, 3ch, 4ch, 6ch) it's not an easy build. Simply stuffing the boards is straightforward enough (although easy to screw up) but the chassis work can be a monumental task for even experienced builders._

 

I take it the b24 thread can be found on here? Ill have a search in a minute. 

 I think i should be OK with it once i get started. Iv made a millet max custom panel design and whilst it isnt no where near as big as the b22, i learnt a lot in the process. Hopefully i should pull it off.


----------



## MrMajestic2

Quote:


  Originally Posted by *n_maher* /img/forum/go_quote.gif 
_All of the details you seek are clearly laid out in the beta24 thread. Go, now, read.

 Also, your comment about asking if the beta was a "fairly easy" build scares me. Regardless of incarnation (2ch, 3ch, 4ch, 6ch) it's not an easy build. Simply stuffing the boards is straightforward enough (although easy to screw up) but the chassis work can be a monumental task for even experienced builders._

 

Yeah, its not too bad to stuff, just a lot of components. But due to the cheer amount of components its very easy to put something the wrong way or in the wrong spot. And when that is done and you have to troubleshoot it, then it gets really complicated. I was fortunate enough to have very little problems with my build compared to some others. I chalked that down too luck and not skillz 
	

	
	
		
		

		
		
	


	




 Case work can be a handful too, Im not done yet and Ive been at it since November last year


----------



## amb

All my "official" project threads are at headwize.

 To answer your question about my β24, yes it's based on a Hifi2000 Pesante Dissipante case but the size I used is needlessly large for a β22. They do have shorter ones but I am not sure how you're going to attach four boards to two heatsinks unless you do it like vvs_75, but then you'd end up with a big void in the center of the case. For β22 serving as a headphone amp, I do not recommend putting the transformer(s) there. Too close to the amp boards and you'd hear hum/buzz.


----------



## fault151

Yeh i know what you mean. It just looks so nice the case you used. I will probably go for something from par metal. I'm not planning on this being a quick project at all, i just want to build one and I'm determined to make it work. Im sure you guys on here will help out with any problems i may have 
	

	
	
		
		

		
		
	


	




 I'm more worried about the dac to be honest. 


  Quote:


  Originally Posted by *amb* /img/forum/go_quote.gif 
_All my "official" project threads are at headwize.

 To answer your question about my β24, yes it's based on a Hifi2000 Pesante Dissipante case but the size I used is needlessly large for a β22. They do have shorter ones but I am not sure how you're going to attach four boards to two heatsinks unless you do it like vvs_75, but then you'd end up with a big void in the center of the case. For β22 serving as a headphone amp, I do not recommend putting the transformer(s) there. Too close to the amp boards and you'd hear hum/buzz._


----------



## MrMajestic2

Quote:


  Originally Posted by *amb* /img/forum/go_quote.gif 
_All my "official" project threads are at headwize.

 To answer your question about my β24, yes it's based on a Hifi2000 Pesante Dissipante case but the size I used is needlessly large for a β22. They do have shorter ones but I am not sure how you're going to attach four boards to two heatsinks unless you do it like vvs_75, but then you'd end up with a big void in the center of the case. For β22 serving as a headphone amp, I do not recommend putting the transformer(s) there. Too close to the amp boards and you'd hear hum/buzz._

 

Would a 2U Dissipante case have enough heatsink for a balanced 4-board b22?


----------



## MrMajestic2

Just got my new HD650s and I just had to balance them right away. Listening now on my B22 and it sounds fantastic 
	

	
	
		
		

		
			





 Can you spell synergy, amazing.


----------



## fault151

Id love to hear that! I have some hd600's and i bet they would sound very nice balanced. I cant wait to make mine!!!


----------



## MrMajestic2

Quote:


  Originally Posted by *fault151* /img/forum/go_quote.gif 
_Id love to hear that! I have some hd600's and i bet they would sound very nice balanced. I cant wait to make mine!!!_

 

Come over to Stockholm and have a listen


----------



## el_matt0

@ fault, just out of curiosity what amps / etc DIY stuff have you built in past, just for a point of reference? I'd just like to know so I can give you my own advice, because about a year or so ago I was in exactly the same position as you, fairly new to DIY, and that was the stage that I had contemplated building my balanced b22. However I had at that stage already built at least 4 or 5 cmoys, 1 millet max, and a soha with jisbos, along with an alien dac. Even with those earlier builds, I still ran into some troubleshooting issues with my beta22 that took an extremely long time to work out due to my inexperience, and that was even WITH the help of all these fantastic forum members. With the 4 board b22, the inability to use e22's really adds to the wiring mess/complication, and especially if your fairly inexperienced, this could lead to some major headaches and confusion. As others have stated earlier, theres really a lot more to building one of these than simply following step by step instructions and stuffing components into a PCB (which a trained monkey could do). I'm just really interested to know what DIY you've got under your belt before taking up such a major project, it would be nice to know!


----------



## bperboy

Quote:


  Originally Posted by *amb* /img/forum/go_quote.gif 
_For β22 serving as a headphone amp, I do not recommend putting the transformer(s) there. Too close to the amp boards and you'd hear hum/buzz._

 

A little off topic, but is having a transformer in the same case as amp boards not such a huge deal with hum in the case of a speaker amp as opposed to a headphone amp? And if so, why, and if not, why not?


----------



## amb

Quote:


  Originally Posted by *bperboy* /img/forum/go_quote.gif 
_A little off topic, but is having a transformer in the same case as amp boards not such a huge deal with hum in the case of a speaker amp as opposed to a headphone amp? And if so, why, and if not, why not?_

 

Headphones are much, much more efficient than speakers. Grados, for example, are said to be 98dB SPL at 1mW, which corresponds to about 178mV into 32 ohms. Contrast that with a fairly efficient speaker at 90dB SPL at 1W and 1 meter distance, which is 2.83V into 8 ohms. To get to the equivalent of 98dB SPL, you'd have to drive that speaker with a bit over 7V of voltage. 7V vs. 178mV is almost 40x difference, so given these two examples, a hum problem in a speaker amp will have to be 40x stronger in voltage amplitude than that in a headphone amp to be perceived as equal in loudness.

 Headphone transducers sit right next to your ears. Even a small amount of hum will be easily audible. The same small magnitude of hum will be difficult to hear even if you put your head up next to the speaker, and will certainly be inaudible at normal listening distances (which is usually much farther than 1 meter). Add to this the fact that headphone earcups tend to isolate ambient noise to some degree (even open air types), but there is no such effect with speaker listening. So a small amount of hum through speakers will likely be masked while it would be quite distinct in a headphone.


----------



## bperboy

Quote:


  Originally Posted by *amb* /img/forum/go_quote.gif 
_Headphones are much, much more efficient than speakers. Grados, for example, are said to be 98dB SPL at 1mW, which corresponds to about 178mV into 32 ohms. Contrast that with a fairly efficient speaker at 90dB SPL at 1W and 1 meter distance, which is 2.83V into 8 ohms. To get to the equivalent of 98dB SPL, you'd have to drive that speaker with a bit over 7V of voltage. 7V vs. 178mV is almost 40x difference, so given these two examples, a hum problem in a speaker amp will have to be 40x stronger in voltage amplitude than that in a headphone amp to be perceived as equal in loudness.

 Headphone transducers sit right next to your ears. Even a small amount of hum will be easily audible. The same small magnitude of hum will be difficult to hear even if you put your head up next to the speaker, and will certainly be inaudible at normal listening distances (which is usually much farther than 1 meter). Add to this the fact that headphone earcups tend to isolate ambient noise to some degree (even open air types), but there is no such effect with speaker listening. So a small amount of hum through speakers will likely be masked while it would be quite distinct in a headphone._

 

Thanks, that helps a bunch!


----------



## fault151

Quote:


  Originally Posted by *MrMajestic2* /img/forum/go_quote.gif 
_Come over to Stockholm and have a listen 
	

	
	
		
		

		
		
	


	


_

 

I would if i could


----------



## fault151

Well iv built a grado amp (very similar to a cmoy), i bought a millet max and changed a load of parts and designed a custom panel at FPE, i upgraded my x-can v3 with all capacitors and resistors and with the help of a friend i built a John Broskie, Aikido valve amp. the valve amp was a fairly difficult build as it involved a lot of calculating what resistors + capacitors i needed and making sure the valves and heaters ran at the correct voltages.It uses 4 valves and a rectifier valve. By no means am i an expert, but I'm learning all the time and I'm bloody determined to make a b22. 
	

	
	
		
		

		
		
	


	




  Quote:


  Originally Posted by *el_matt0* /img/forum/go_quote.gif 
_@ fault, just out of curiosity what amps / etc DIY stuff have you built in past, just for a point of reference? I'd just like to know so I can give you my own advice, because about a year or so ago I was in exactly the same position as you, fairly new to DIY, and that was the stage that I had contemplated building my balanced b22. However I had at that stage already built at least 4 or 5 cmoys, 1 millet max, and a soha with jisbos, along with an alien dac. Even with those earlier builds, I still ran into some troubleshooting issues with my beta22 that took an extremely long time to work out due to my inexperience, and that was even WITH the help of all these fantastic forum members. With the 4 board b22, the inability to use e22's really adds to the wiring mess/complication, and especially if your fairly inexperienced, this could lead to some major headaches and confusion. As others have stated earlier, theres really a lot more to building one of these than simply following step by step instructions and stuffing components into a PCB (which a trained monkey could do). I'm just really interested to know what DIY you've got under your belt before taking up such a major project, it would be nice to know! 
	

	
	
		
		

		
		
	


	


_


----------



## el_matt0

@ fault, dont get me wrong, i mean either way its DEFINITELY a fantastic learning experience, just if you are leaning towards the side of inexperience, keep your fingers crossed you dont run into any major troubleshooting issues! 
	

	
	
		
		

		
		
	


	




 best of luck, im sure ull be fine


----------



## fault151

Quote:


  Originally Posted by *el_matt0* /img/forum/go_quote.gif 
_@ fault, dont get me wrong, i mean either way its DEFINITELY a fantastic learning experience, just if you are leaning towards the side of inexperience, keep your fingers crossed you dont run into any major troubleshooting issues! 
	

	
	
		
		

		
		
	


	




 best of luck, im sure ull be fine_

 

Cheers, I think the wiring will definitely be the hardest bit. I could almost do with a wiring diagram to follow.


----------



## drc73rp

From our experience it is better to have separate casing for amp section and power supply. Its always nice not to have to worry about hum or any noise due to proximity to the torroidal transformer, and the umbilical with neutrik power connectors look cool too. 




 With extra space in the PSU casing, i have an option to upgrade to dual Sigma 22 for whatever reason( O yeah.
	

	
	
		
		

		
		
	


	




)




 Just make sure to provide enough space at the front for the switches and vol control esp when using stepped attenuators or Joshua tree types. Same case at the back for the rca, speaker and power connectors. I modelled the layout in CAD with the actual board footprint and i still missed out on the extra space for the stepped atten. We almost had to settle for an Alps to keep the knob at the middle center of the fascia, but i couldnt take not having the stepped atten so i settled for slightly offset position.

 Im definitely hearing the effect of burn in with the amp at almost 200 hours. The AKG 601's are definitely singing now. Mahler symphonies have become wider and the sound has more weight. There is also better extension in the highs. Whether this is indeed burn in or some other factor, the amp is definitely living up to its reputation now. Now stop reading and build your own.


----------



## fault151

My kit arrived today, can't wait to put the boards together. Hope i can do it!!!!!


----------



## fc911c

Just take your time and don't rush it, I know it's hard not too. Make sure all the right parts are in the right places double check everything, you will be happy you did later on. Also check the polairities and read the instructions a couple of times before you even start.

 good luck with the build


  Quote:


  Originally Posted by *fault151* /img/forum/go_quote.gif 
_My kit arrived today, can't wait to put the boards together. Hope i can do it!!!!!_


----------



## fault151

Quote:


  Originally Posted by *fc911c* /img/forum/go_quote.gif 
_Just take your time and don't rush it, I know it's hard not too. Make sure all the right parts are in the right places double check everything, you will be happy you did later on. Also check the polairities and read the instructions a couple of times before you even start.

 good luck with the build_

 

Cheers, i will do. I'm a bit nervous. I think im going to have a trial run with all the parts first, place them on the board, check them, then solder them after.


----------



## fc911c

I wouldnt put parts on the board only to take them off again. Just take it one step at a time, do one board at a time. I'd start with the power supply, its the easyer of the two. Do your resistors first and all your low parts then move up to the taller parts. Also when you place the resistors on the board bend the leads so the value of the part can be read when it's on the board. This will save you a headache later on if you have to trouble shoot a problem. If you have any more questions PM me I will help you if I can. I am no expert on how these amps work exactly but thats not important for now. What is very important is to follow the instructions to the letter. Also your best place for help is the Headwize B22 forum I'm told.

 Frank

 Edit: I forgot to ask, how are your soldering skills, good I hope. This is not a good board to learn on.



  Quote:


  Originally Posted by *fault151* /img/forum/go_quote.gif 
_Cheers, i will do. I'm a bit nervous. I think im going to have a trial run with all the parts first, place them on the board, check them, then solder them after._


----------



## Beefy

Quote:


  Originally Posted by *fc911c* /img/forum/go_quote.gif 
_Just take it one step at a time, do one board at a time._

 

Many people put the same part in all channels at the same time. At least make your errors consistent....


----------



## fc911c

Quote:


  Originally Posted by *Beefy* /img/forum/go_quote.gif 
_Many people put the same part in all channels at the same time. At least make your errors consistent.... 
	

	
	
		
		

		
		
	


	


_

 

or you could build one board complete and test it and not make the same mistake 3 times.


----------



## Beefy

Quote:


  Originally Posted by *fc911c* /img/forum/go_quote.gif 
_or you could build one board complete and test it and not make the same mistake 3 times. 
	

	
	
		
		

		
		
	


	


_

 

Three to four times the potential number of errors 
	

	
	
		
		

		
		
	


	




 (I wonder how many time we could back and forward this if we wanted to? 
	

	
	
		
		

		
		
	


	




 )


----------



## bperboy

Quote:


  Originally Posted by *Beefy* /img/forum/go_quote.gif 
_Three to four times the potential number of errors 
	

	
	
		
		

		
		
	


	




 (I wonder how many time we could back and forward this if we wanted to? 
	

	
	
		
		

		
		
	


	




 )_

 

Just solder the whole damn project in 2 hours, plug it in, and see what happens!


----------



## akione

Quote:


  Originally Posted by *bperboy* /img/forum/go_quote.gif 
_Just solder the whole damn project in 2 hours, plug it in, and see what happens! 
	

	
	
		
		

		
		
	


	





_

 

....... and remember to take plenty of pics for us


----------



## fault151

cheer, yeh i'll do the power supply first, then the rest. 

 Yeh i think will do all the same parts on the 4 boards at the same time, it seems to make more sense.


----------



## MrMajestic2

Quote:


  Originally Posted by *fault151* /img/forum/go_quote.gif 
_cheer, yeh i'll do the power supply first, then the rest. 

 Yeh i think will do all the same parts on the 4 boards at the same time, it seems to make more sense._

 

I did mine 2 boards at a time and I wish I did all 4 afterwards. And it a good idea to do the PSU first, you're going to need it when the boards are finished anyway.


----------



## fc911c

Quote:


  Originally Posted by *bperboy* /img/forum/go_quote.gif 
_Just solder the whole damn project in 2 hours, plug it in, and see what happens! 
	

	
	
		
		

		
		
	


	





_

 

Lots of smoke


----------



## MrMajestic2

Quote:


  Originally Posted by *fc911c* /img/forum/go_quote.gif 
_Lots of smoke 
	

	
	
		
		

		
		
	


	


_

 

That might happen anyway


----------



## krmathis

I really wish I had the skills to build myself a balanced β22. 
	

	
	
		
		

		
		
	


	



 Sadly I don't...


----------



## bperboy

Quote:


  Originally Posted by *MrMajestic2* /img/forum/go_quote.gif 
_And it a good idea to do the PSU first, you're going to need it when the boards are finished anyway._

 

Although I've not built a B22, I think this is a pretty good idea. The way I think about it, building the power supply first is like building the foundation of a building.. the amp isn't going to work without it, and you might as well get it built and working before you even try to work on the amp!


----------



## MrMajestic2

Quote:


  Originally Posted by *krmathis* /img/forum/go_quote.gif 
_I really wish I had the skills to build myself a balanced β22. 
	

	
	
		
		

		
		
	


	



 Sadly I don't..._

 

You know where to get one


----------



## krmathis

Quote:


  Originally Posted by *MrMajestic2* /img/forum/go_quote.gif 
_You know where to get one 
	

	
	
		
		

		
		
	


	


_

 

So do I! 
	

	
	
		
		

		
		
	


	



 For now I have settled on the Signature 30.2. But would be nice to audition a β22 some day.


----------



## amphead

I could build you 1/2 pro bono for labour, but the shipping would kill.  Edit: someone else would have to volunteer to build the other half. We would need to start a new thread though "Let's build Krmathis a Beta22."


----------



## fault151

Am i right in thinking, when addint the heatsinks to the board, you use the sticky pads and a screw and bolt to secure the sinks? I have read the amb site about installing them, i just want to make sue i interpreted it correctly. 

 I take it, its the same process for installing off board sinks too?


----------



## akione

Quote:


  Originally Posted by *fault151* /img/forum/go_quote.gif 
_Am i right in thinking, when addint the heatsinks to the board, you use the sticky pads and a screw and bolt to secure the sinks? I have read the amb site about installing them, i just want to make sue i interpreted it correctly. 

 I take it, its the same process for installing off board sinks too?_

 

The sticky pads are for mounting the mosfets to the heatsinks. they're required to isolate the mosfets electrically from the heatsinks. 

 The heatsinks fasten to the board with 2 screws at the bottom. They will need to be tapped to take whatever screws you use. 
 There is also a variation of the heatsinks, which have two pegs at the bottom, which can be soldered to the pcb, but most 
 people use the screw fix ones, I think. 

 For off-board sinks you're on your own really, as it all depends on what sinks/case etc you use.


----------



## fault151

ok so in the case of the b22 i need to use screw taps to mount them to the boards. When you stick the mosfets to the heatsinks, do you need to put a screw through them?


----------



## Pars

You should be using some TO-220 mounting kits such as Standard Products - Mounting Kits. The important part besides the insulator pad is the nylon shoulder washer, which insulates the screw from the device tab. The pictorial on the link I gave you should help as well. Mount the device to the heatsink, then put the heatsink on the board, before you solder the part in. This will help ensure that you get nice flat contact between the device and the heatsink. Ratshack sella a similar kit BTW.


----------



## akione

Quote:


  Originally Posted by *fault151* /img/forum/go_quote.gif 
_ok so in the case of the b22 i need to use screw taps to mount them to the boards. When you stick the mosfets to the heatsinks, do you need to put a screw through them?_

 

Hi fault151,

 Sorry, I couldn't reply earlier ....... different time zones 
	

	
	
		
		

		
			





 I think Pars has sorted you out, though.

 Thanks Pars.


----------



## amb

If you're using the default board-mount heatsinks, it's optional to isolate the MOSFETs from the heatsinks because the 'sinks are individual. You just need to take care not to allow the heatsinks to touch each other or to the case. When mounted directly without isolation pads (smear some heatsink compound to the mating surface), you get slightly better heat transfer.


----------



## fault151

Cheers guys, i have a better understanding now. The diagram in the link really helped. I think i'll use the isolating pads and do it as shown in the diagram. 

 Id like to use the big heatsinks like naaman used in his power supply for mine. I guess that would need insulating with the pads as it is one large unit. How do you support the weight of the off board heatsinks if it can't touch the case? Would it not put stress on the joint and board?


----------



## amb

If you isolate the MOSFETs then a common, shared offboard heatsink can, and should be mounted to the case.


----------



## fault151

Right i see. So if i used something like these, how would i isolate it to the case? 

heat sinks


----------



## amb

If you isolated the MOSFETs from the heatsink, then you don't need to isolate the heatsink from the case. Just fabricate your own mounting brackets or drill and tap holes to the bottom of the heatsink for mounting to the case.


----------



## fault151

Quote:


  Originally Posted by *amb* /img/forum/go_quote.gif 
_If you isolated the MOSFETs from the heatsink, then you don't need to isolate the heatsink from the case. Just fabricate your own mounting brackets or drill and tap holes to the bottom of the heatsink for mounting to the case._

 

Ok thank you for that. I'll isolate them and mount them on brackets.

 Thanks for your help, that cleared a lot of confusion!


----------



## MrMajestic2

I finally finished building my headphone/speaker switch that I ordered from Olimex. Its not yet tested in my B22, but at least it switches 
	

	
	
		
		

		
		
	


	




 It has four Omron G2R-1-DC5 that can handle 10A each. It also has integrated Zobel network for the speaker outputs. 

 Dont ask me about a schematic, because I dont have one. This is all done by hand.


----------



## fault151

Quote:


  Originally Posted by *MrMajestic2* /img/forum/go_quote.gif 
_I finally finished building my headphone/speaker switch that I ordered from Olimex. Its not yet tested in my B22, but at least it switches 
	

	
	
		
		

		
		
	


	




 It has four Omron G2R-1-DC5 that can handle 10A each. It also has integrated Zobel network for the speaker outputs. 

 Dont ask me about a schematic, because I dont have one. This is all done by hand.
_

 

Nice one mate, looks cool! Hope it works all ok with your b22. Did you create the board design yourself? Or is it a kit?


----------



## MrMajestic2

Quote:


  Originally Posted by *fault151* /img/forum/go_quote.gif 
_Nice one mate, looks cool! Hope it works all ok with your b22. Did you create the board design yourself? Or is it a kit?_

 


 Thanks 
	

	
	
		
		

		
		
	


	




 Its my own design, but the board was manufactured by Olimex.


----------



## fault151

Does anyone know which way the led goes on the power supply board? Theres no markings.


----------



## amb

Quote:


  Originally Posted by *fault151* /img/forum/go_quote.gif 
_Does anyone know which way the led goes on the power supply board? Theres no markings._

 

The LED cathode points toward the V- side of the board.


----------



## fault151

Quote:


  Originally Posted by *amb* /img/forum/go_quote.gif 
_The LED cathode points toward the V- side of the board._

 

I don't understand what you mean by that? Is the cathode the longer leg?


----------



## MrMajestic2

Quote:


  Originally Posted by *fault151* /img/forum/go_quote.gif 
_I don't understand what you mean by that? Is the cathode the longer leg?_

 

Light Emitting Diodes (LEDs)


----------



## Pars

led cathode - Google Search


----------



## amb

fault151, as others have linked, you could have done a little homework and answered these for yourself. The board orientation for the LED could be easily determined by looking at the schematic diagram and the PCB layout, and a look at the LED datasheet (or any generic site that describes a diode) will tell you which is the cathode pin.


----------



## swt61

Quote:


  Originally Posted by *MrMajestic2* /img/forum/go_quote.gif 
_I finally finished building my headphone/speaker switch that I ordered from Olimex. Its not yet tested in my B22, but at least it switches 
	

	
	
		
		

		
			





 It has four Omron G2R-1-DC5 that can handle 10A each. It also has integrated Zobel network for the speaker outputs. 

 Dont ask me about a schematic, because I dont have one. This is all done by hand._

 

Very impressive. Keep us posted on this. A+


----------



## MrMajestic2

Quote:


  Originally Posted by *swt61* /img/forum/go_quote.gif 
_Very impressive. Keep us posted on this. A+_

 

Thank you, I will. Now I just need some speaker I can switch to


----------



## n_maher

Quote:


  Originally Posted by *fault151* /img/forum/go_quote.gif 
_I don't understand what you mean by that? Is the cathode the longer leg?_

 

By giving this answer I feel I should give the following advice - you need to take a step back and realize something. Several of us tried to caution you before you started this build but you insisted on proceeding. The types of questions that you are raising so far point to big problems down the road. There are lots of other components that if installed backwards are not going to simply not light up. In fact they might light up with disastrous results.


----------



## fault151

Cheers to those who posted the links. So i now have established which is the cathode. I looked at the board layout and schematic. I really struggle with reading the schematics. So all i now need to do is align it to the way the schematic shows?


----------



## fault151

Quote:


  Originally Posted by *n_maher* /img/forum/go_quote.gif 
_By giving this answer I feel I should give the following advice - you need to take a step back and realize something. Several of us tried to caution you before you started this build but you insisted on proceeding. The types of questions that you are raising so far point to big problems down the road. There are lots of other components that if installed backwards are not going to simply not light up. In fact they might light up with disastrous results._

 

It was just the led that was throwing me. I'm ok with the other bits so far. As far as I'm concerned, i am learning as i progress. Most of the bits i can identify and match to the board layout providing they are marked. I struggle with schematics. Most of the parts on the amps are marked anyway. I have all the parts i need now so i am going to finish the build no matter what. Id rather ask the question on here than make stupid mistakes with disastrous results (as you keep mentioning). Sorry to the rest of you if the questions seem so basic. I just have the mosfets and heatsinks left to put on the power supply.

 I have also been chatting with Mr Majestic on the b22 for the past few months, so he has helped me with a hell of a lot! A *Big* thank you to him!


----------



## amb

The schematic shows LED+ and LED-. Since an LED is supposed to work in a forward-bias condition with current flowing from anode to cathode (positive to negative), you can deduce which way things go.


----------



## fault151

Quote:


  Originally Posted by *amb* /img/forum/go_quote.gif 
_The schematic shows LED+ and LED-. Since an LED is supposed to work in a forward-bias condition with current flowing from anode to cathode (positive to negative), you can deduce which way things go._

 

Yeh i got it, cheers. 
	

	
	
		
		

		
		
	


	




 Thanks for your help. I'm on to the b22 boards next. Oh that should be fun. 

 I bet *n_maher* is cringing at the thought!


----------



## fault151

Well i have my power supply now built up and i'm half way through my b22 boards. So far its going OK. I'm still not sure whether to use the big off board heat sinks. I'm intending this amp to be for my speakers and headphones. Does anyone else use the standard heat sinks to run speakers off?


----------



## swt61

^^^

 Yes. I have a four channel with standard heatsinks, and while it's not my main amp for my speakers, I've used it on several occasions. It sounds fantastic, and better yet it does not get overly hot while driving them.

 That being said however, I should point out that my speakers are super efficient single driver Omegas that are commonly driven by flea amps, and I listen at moderate levels.


----------



## fault151

Quote:


  Originally Posted by *swt61* /img/forum/go_quote.gif 
_^^^

 Yes. I have a four channel with standard heatsinks, and while it's not my main amp for my speakers, I've used it on several occasions. It sounds fantastic, and better yet it does not get overly hot while driving them.

 That being said however, I should point out that my speakers are super efficient single driver Omegas that are commonly driven by flea amps, and I listen at moderate levels._

 


 Well i made the decision this morning and bought the bigger heatisnks. I guess it just future proofs the amp a little bit. 
 Thanks for getting back to me.


----------



## tenorsaxophone

Hello to all of you!
 Can anyone say to me if it is possible to connect an unbalanced headphone to the Beta22 amplifier when it is in fully Balanceed configuration?
 In the AMB's website, I've seen that, when he connect an Unbalaced headphone, he changes the input configuration from Balanced to Unbalanced.
 Is it possible to arrange an adapter cable to avoid to change the input configuration everytime I want to use a different headphone?
 Many thanks. Best regards.
 Davide.


----------



## naamanf

Quote:


  Originally Posted by *tenorsaxophone* /img/forum/go_quote.gif 
_Hello to all of you!
 Can anyone say to me if it is possible to connect an unbalanced headphone to the Beta22 amplifier when it is in fully Balanceed configuration?
 In the AMB's website, I've seen that, when he connect an Unbalaced headphone, he changes the input configuration from Balanced to Unbalanced.
 Is it possible to arrange an adapter cable to avoid to change the input configuration everytime I want to use a different headphone?
 Many thanks. Best regards.
 Davide._

 

The amp can be wired so that it can be used both balanced and unbalanced.


----------



## tenorsaxophone

Quote:


  Originally Posted by *naamanf* /img/forum/go_quote.gif 
_The amp can be wired so that it can be used both balanced and unbalanced._

 

Hello naamanf!
 Many thanks for your soon answer.
 Escuse me, but I have not a Beta22 amp, and I have not any Balanced electronics, so I have no experience.
 Do you mean that I could connect a unbalanced hearphone directly to the R+, L+ and GND outputs of Beta22 wiring them?
 Many thanks again. Best regards.
 Davide.


----------



## FallenAngel

Quote:


  Originally Posted by *tenorsaxophone* /img/forum/go_quote.gif 
_Hello naamanf!
 Many thanks for your soon answer.
 Escuse me, but I have not a Beta22 amp, and I have not any Balanced electronics, so I have no experience.
 Do you mean that I could connect a unbalanced hearphone directly to the R+, L+ and GND outputs of Beta22 wiring them?
 Many thanks again. Best regards.
 Davide._

 

That's the idea, but you cannot convert an unbalanced (single-ended) input signal into balanced, so you'll actually be using only 2 Beta22 boards for amplification and using the PSU ground.


----------



## amb

If you don't have any balanced sources, unless you add extra circuitry (an unbalanced to balanced convertor or transformers), you won't have the four active signals (L+, L-, R+ and R-) to feed a fully-balanced 4-channel β22 amp. Therefore you won't be able to take advantage of your balanced headphones.

 However, if you do have a balanced source, then you can use either balanced or unbalanced headphones. The latter will need to be referenced to ground. If you build a 4-channel β22 then it will be passive-ground whereas a 5 or 6-channel could be active-ground.


----------



## fault151

Does anyone have a the B22 logo and 022 logo as a vector file? I could do with it when making my front panel design. 

 Thank you.


----------



## MrMajestic2

Quote:


  Originally Posted by *fault151* /img/forum/go_quote.gif 
_Does anyone have a the B22 logo and 022 logo as a vector file? I could do with it when making my front panel design. 

 Thank you._

 


 I do


----------



## fault151

Quote:


  Originally Posted by *MrMajestic2* /img/forum/go_quote.gif 
_I do 
	

	
	
		
		

		
		
	


	


_

 

Could you send me them please?


----------



## MrMajestic2

Quote:


  Originally Posted by *fault151* /img/forum/go_quote.gif 
_Could you send me them please? 
	

	
	
		
		

		
		
	


	


_

 


 You've got mail


----------



## fault151

Quote:


  Originally Posted by *MrMajestic2* /img/forum/go_quote.gif 
_You've got mail_

 

Got them, thank you!


----------



## rhester

Could I get the files also, PLEASE?


----------



## MrMajestic2

Quote:


  Originally Posted by *rhester* /img/forum/go_quote.gif 
_Could I get the files also, PLEASE?_

 

Sure, PM me you email address.


----------



## fault151

My new heatsinks from conrad arrived today. Can i drill straight through them and bolt through them or do they need to be tapped? My heatsinks have a flat edge bracket. See pic


----------



## naamanf

I recommend drilling and tapping. Make sure you using tapping oil for the drilling and tapping. I also suggest a quality spiral tap.


----------



## fault151

Right looks like im doing that then. Cheers.


----------



## TheRobbStory

Quote:


  Originally Posted by *naamanf* /img/forum/go_quote.gif 
_I recommend drilling and tapping. Make sure you using tapping oil for the drilling and tapping. I also suggest a quality spiral tap._

 

Can you elaborate on this? I've snapped a few taps while tapping mosfet sinks. I thought they were just cheap taps.


----------



## naamanf

You want to use a lubricant when drill the hole and tapping it. Helps to keep the tap from binding. Also using a spiral fluted tap will do a better job of cutting and removing material, especially on soft aluminum. I get my bits from McMaster-Carr.


----------



## fault151

Quote:


  Originally Posted by *naamanf* /img/forum/go_quote.gif 
_You want to use a lubricant when drill the hole and tapping it. Helps to keep the tap from binding. Also using a spiral fluted tap will do a better job of cutting and removing material, especially on soft aluminum. I get my bits from McMaster-Carr._

 


 Would it be disasterous if i were to just simplly drill the sinmks and bolt them through? I guess the tapping will just ensure better a joint. Is that the only reason for doing it? 


 I'll be tapping them anyway. Just wondered.


----------



## naamanf

It's really just personal preference. I like doing it because it's a lot easier to remove and install the screws. Also one less piece of hardware required. You could pretty much use any method as long as it securely mounts the part and isolates it electrically.

 Edit: Also keep in mind those a large heavy sinks and they should also be secured to the chassis, especially if you ever think the amp will be shipped or moved.


----------



## fault151

Quote:


  Originally Posted by *naamanf* /img/forum/go_quote.gif 
_It's really just personal preference. I like doing it because it's a lot easier to remove and install the screws. Also one less piece of hardware required. You could pretty much use any method as long as it securely mounts the part and isolates it electrically.

 Edit: Also keep in mind those a large heavy sinks and they should also be secured to the chassis, especially if you ever think the amp will be shipped or moved._

 

How did you end up secruing them to the chassis? Could you put some sort of board munt unter the sink and bolt though the mosfet-throught the sink-through the board mount- to the chassis underneath? Would that be OK?


----------



## naamanf

I just tapped the underside on both ends.


----------



## fault151

What and then just put a stand off underneath it and screwed in to it?


----------



## naamanf

I have the heat sinks against the bottom of the case. So I just use a screw from the bottom of the case to hold the heat sink to the case.


----------



## MoodySteve

I just completed my ß22 last night. The electronics have been up and running for months but it was housed in a discarded video card box. I decided that I wanted to DIY the chassis and also to use gold-plated hardware to go for that 'Hi Fi' (expensive) look. I still have some finishing and touch-up to do, but I'm already very happy with how it came out.


----------



## fault151

MoodySteve;4577041 said:
			
		

> I just completed my ß22 last night. The electronics have been up and running for months but it was housed in a discarded video card box. I decided that I wanted to DIY the chassis and also to use gold-plated hardware to go for that 'Hi Fi' (expensive) look. I still have some finishing and touch-up to do, but I'm already very happy with how it came out.
> Cool, id like to see some other pics of the front, etc...


----------



## fault151

Quote:


  Originally Posted by *naamanf* /img/forum/go_quote.gif 
_I have the heat sinks against the bottom of the case. So I just use a screw from the bottom of the case to hold the heat sink to the case._

 

Ok fair enough. Oh does it matter which side is facing upwards? Theres two sides, one shiny one rough. Which does the mosfet go against, or does it not matter?


----------



## MoodySteve

Thanks for your feedback! I don't have what I consider to be a good picture of the front or of the unit with the cover on; I'll take those when I'm done with the front panel (I want a mirror finish). But for a good idea....


----------



## JamesL

I love the black/gold scheme. Very nice! Would you mind telling me what push-button that is? I've seen it used in a couple other builds here, but I'm trying to find one for my ppa build.


----------



## MoodySteve

Thanks!!! The push-button was definitely the hardest part to source. After searching high and low and subsequently discovering that nobody makes a general gold push-button, I had to resort to looking at doorbells. I ended up getting that doorbell from Ace Hardware online. An alternative that I found but didn't buy was a 'french gold' air switch for an Insinkerator at BuyPlumbing.net. It uses AMB's ε24 circuit since the doorbell is momentary.


----------



## jantze

So, I'm getting a balanced β22 with dual σ22 & ε12.

 What would be the best gain for me? 5? I'm including speaker outputs and my headphones are HD650 and D2000.

 I'm also getting a balanced/unbalanced switch. Initial idea is to use TPA IVY and OTTO. Is this a good way to implement it?

 My main source will be Buffalo DAC once I get it finished.


----------



## amphead

MoodySteve, nice look! Congrats from the Krmathis build team!


----------



## amb

Quote:


  Originally Posted by *jantze* /img/forum/go_quote.gif 
_What would be the best gain for me? 5? I'm including speaker outputs and my headphones are HD650 and D2000._

 

I don't know about the D2000, but for HD650 a gain of 4 to 10 is good. What this means for a balanced configuration is that the actual gain per amp board should be 2 to 5. The β22's website lists resistor/capacitor values for gains of 2, 5, 8 and 11.

 Note that for speakers, you'll typically want higher gains (depending on sensitivity of your speakers and output level of your source), so you'll need to compromise and find a happy medium.


----------



## Crow

Has anyone heard from or received a kit from Jeff Rossel lately? His last log on here was 7/31/08 and I can't seem to get him on email. Maybe he's on a much-needed holiday.


----------



## MoodySteve

Crow, I've been waiting to hear from him for a while too, so I think he may indeed be out of town for a while.


----------



## fault151

Yeh i heard from him 2 days a go. I ordered a power supply. He has just been on holiday and just very recently got back. I guess he's a busy guy and his kits are in demand!


----------



## ferds

Jeff replied to my email/inquiries last 17hrs ago. i think he's busy preparing the SOHA II kits..


----------



## Crow

If the b22 amp boards are in a separate, signal-grounded case, is it really such a bad idea to run about 12 inches of (unshielded!) cat5 as signal wiring to the pot--or must there be shielding?

 These b22 chasses can get large and this is the problem I'm facing. Pot extension shafts would be nice if only they were widely available!

 Thanks folks


----------



## Ferrari

Quote:


  Originally Posted by *Crow* /img/forum/go_quote.gif 
_If the b22 amp boards are in a separate, signal-grounded case, is it really such a bad idea to run about 12 inches of (unshielded!) cat5 as signal wiring to the pot--or must there be shielding?
 ..._

 

It's definitely not a good idea to use unshielded cables for the sensitive input signal to the volume pot at such a long distance. 
 If the wiring is over a few inches long, you should consider using shielded cables.


----------



## digger945

naamanf, did you ever listen to the Beta using the 0404usb as source(balanced)? Is it ok compared to Buffalo(I dont know if your Buffalo is balanced)?
 Thanks.


----------



## naamanf

I only used the Buffalo. I have not listened to the 0404 in over a year but I would say the Buffalo is superior.


----------



## jantze

My initial idea is to use 2 X Hi-Fi 2000 Slim Line 2U case with the optional aluminium covers for my balanced b22 and dual power supply's. Will there be enough cooling or should I go for vented covers?

 Aluminium cover:


----------



## naamanf

Go for the vented cover. Even when the amp is idle it gets very hot.


----------



## MrMajestic2

Quote:


  Originally Posted by *naamanf* /img/forum/go_quote.gif 
_Go for the vented cover. Even when the amp is idle it gets very hot._

 

X2 on that. Might even be recommended for both tops and bottoms.


----------



## jantze

Damn. Those aluminium covers look so much nicer comparend to the vented covers and I'm using that aluminum cover in my Buffalo DAC. Which one runs hotter, the psu or the amp?


----------



## MrMajestic2

Quote:


  Originally Posted by *jantze* /img/forum/go_quote.gif 
_Damn. Those aluminium covers look so much nicer comparend to the vented covers and I'm using that aluminum cover in my Buffalo DAC. Which one runs hotter, the psu or the amp?_

 

The amp runs hotter than the psu. You could always send the alumium cover to FPE to make holes in it, but it will get expensive I think.


----------



## Beefy

Quote:


  Originally Posted by *MrMajestic2* /img/forum/go_quote.gif 
_The amp runs hotter than the amp._

 

I'm curious as to how that works


----------



## MrMajestic2

Quote:


  Originally Posted by *Beefy* /img/forum/go_quote.gif 
_I'm curious as to how that works 
	

	
	
		
		

		
		
	


	







_

 

I meant the amp runs hotter than the psu. Im tired, give me a break


----------



## krmathis

Some great β22 builds in here!
 Keep them coming, and make me jealous (until I get my own)...


----------



## luvdunhill

Quote:


  Originally Posted by *jantze* /img/forum/go_quote.gif 
_My initial idea is to use 2 X Hi-Fi 2000 Slim Line 2U case with the optional aluminium covers for my balanced b22 and dual power supply's. Will there be enough cooling or should I go for vented covers?

 Aluminium cover:



_

 

there's some nice perforated aluminum for sale on Ebay that is reasonably cheap. I'd recommend trying that.


----------



## kklee

My revised Beta22. I pulled the power supply out of the main chassis due to a hum issue. AMB's remote power circuit got thrown in as well as a Joshua Tree attenuator.

 Power supply internals, everything barely fits:





 Power supply with umbilical:





 Rebuilt Beta22 with Joshua Tree attenuator:


----------



## amb

Very nice!


----------



## stevenkelby

Hi All, I'm considering the balanced b22 FS here at the moment and figure this as good a place as any to ask:

 Is it possible to just mount a pair of RCAs in the back panel, wire them to the XLRs internally, and bingo bango, I've got SE inputs?

 This would be the same result as just using RCA to XLR cables.

 Something tells me there's more to it than that, involving transformers and such shenanigans.

 If I do end up with a b22 I will certainly read every word at headwize, but don't have the spare month at the moment (slow reader too) 
	

	
	
		
		

		
		
	


	




 I did search and google, but came up empty.

 Thanks and regards,

 Steve


----------



## Ferrari

Take a look at the β22 website, other options, it's only a couple of minutes reading (and definitely NOT one month!!!).


----------



## stevenkelby

Thanks Ferrari, I have read that bit and the other ones there, but wasn't sure if I can use RCA inputs to drive balanced headphones. Still not. 

 I know, I know, look harder! 

 I know I should but it's 2:30 am and this is the first chance I've had to even ask the question, never mind look for the answer! 

 I promise to set aside time to read more before asking more stupid questions, I know how irritating that is.

 I'll be back with some intelligent ones hopefully! 
	

	
	
		
		

		
		
	


	




 Thanks anyway,

 Steve


----------



## n_maher

Short answer, no it's not that simple. The balanced inputs contain three separate connections each, the single-ended inputs have only 2 of the 3. There is no way, without circuitry, to convert that single-ended signal to balanced.


----------



## n_maher

Quote:


  Originally Posted by *kklee* /img/forum/go_quote.gif 
_Power supply internals, everything barely fits:_

 

If I may make a suggestion, I would find a way to add some sort of strain relief to your umbilical cord. Right now it appears as if all the force would be directly applied to the connection at the sigma22. Otherwise, nice clean build you got there.


----------



## stevenkelby

Quote:


  Originally Posted by *n_maher* /img/forum/go_quote.gif 
_Short answer, no it's not that simple. The balanced inputs contain three separate connections each, the single-ended inputs have only 2 of the 3. There is no way, without circuitry, to convert that single-ended signal to balanced._

 

Thank you Nate, that's perfect. 

 I assumed that the 3rd pin on an XLR was just for shielding and the + and - were the same as in SE apart from the shared - for SE, and the - for balanced being the inverse of the + instead of just ground.

 Clearly I need far more education.

 I shall look into this circuitry of which you speak next week and reconsider buying that amp FS.

 Thanks,

 Steve


----------



## naamanf

Quote:


  Originally Posted by *stevenkelby* /img/forum/go_quote.gif 
_
 I assumed that the 3rd pin on an XLR was just for shielding and the + and - were the same as in SE apart from the shared - for SE, and the - for balanced being the inverse of the + instead of just ground.
_

 

In SE there is the + and a ground. Balanced is + and - with most usually having a ground for shielding.

 Why not just purchase a balanced source?


----------



## kklee

Quote:


  Originally Posted by *n_maher* /img/forum/go_quote.gif 
_If I may make a suggestion, I would find a way to add some sort of strain relief to your umbilical cord. Right now it appears as if all the force would be directly applied to the connection at the sigma22. Otherwise, nice clean build you got there. 
	

	
	
		
		

		
		
	


	


_

 

I couldn't find a suitable strain relief of the right size (I spent several hours hunting online), so I have to settle for just a rubber grommet. Since the power supply will rarely ever get moved, it'll have to do.


----------



## stevenkelby

Quote:


  Originally Posted by *naamanf* /img/forum/go_quote.gif 
_In SE there is the + and a ground. Balanced is + and - with most usually having a ground for shielding.

 Why not just purchase a balanced source?_

 

Hi Naamanf,

 The way I understood it was that SE just has teh signal on the + side and - is all referenced to ground, but with balanced if you have a signal of +1V on the positive, there is the same signal but -1V on the negative? 

 I want to use my turntable as source mainly and did google balanced phono stages but $$$... 

 Also would be nice to use my imod or even laptop and Pico as a source. I plan on an RWA Isabella as my next source, from a laptop, and that's not balanced either. 

 Id there much sonic advantage to sorting out the transformers to turn an SE source into balanced, thus using all 4 boards? I suspect it might be better just to do a 2 board b22?

 Clearly I'm not ready to build anything although I can solder well. If I took the time to read enough I know I can build one but I just don't have time. Shouldn't be here now.

 Thanks again,

 Steve


----------



## stevenkelby

Quote:


  Originally Posted by *kklee* /img/forum/go_quote.gif 
_I couldn't find a suitable strain relief of the right size (I spent several hours hunting online), so I have to settle for just a rubber grommet. Since the power supply will rarely ever get moved, it'll have to do._

 

You've probably seen them but I've used these for things and they are great:

Farnell Export

 Up to 21mm but of course there are others on the site.


----------



## kklee

That link doesn't work for me, it just takes me to some kind of gateway page.

 I tried a couple of different cable strain reliefs, but I wasn't happy with them. Some of the more suitable looking ones were too expensive to order just to see if they'd work.


----------



## amb

stevenkelby, unbalanced (I really dislike the term "single-ended" because it's overloaded and ambiguous) has only a signal and a ground. Balanced has a hot signal (+), a cold signal (-) and a ground. To drive balanced headphones on a balanced amp from an unbalanced source requires either additional circuitry or a transformer to derive the "missing" cold signal.

 That said, wiring just an RCA to the hot signal and ground on 4-channel balanced amps "works", because the headphone at the output of the amp "sees" the swinging signal from the hot side amplifier on one end, and no signal from the cold side amp on the other. It's not truly balanced, and if the cold amp doesn't get an input signal, its input should be grounded to minimize noise.


----------



## FallenAngel

Quote:


  Originally Posted by *stevenkelby* /img/forum/go_quote.gif 
_Hi Naamanf,

 The way I understood it was that SE just has teh signal on the + side and - is all referenced to ground, but with balanced if you have a signal of +1V on the positive, there is the same signal but -1V on the negative? 

 I want to use my turntable as source mainly and did google balanced phono stages but $$$... 

 Also would be nice to use my imod or even laptop and Pico as a source. I plan on an RWA Isabella as my next source, from a laptop, and that's not balanced either. 

 Id there much sonic advantage to sorting out the transformers to turn an SE source into balanced, thus using all 4 boards? I suspect it might be better just to do a 2 board b22?

 Clearly I'm not ready to build anything although I can solder well. If I took the time to read enough I know I can build one but I just don't have time. Shouldn't be here now.

 Thanks again,

 Steve_

 

Not exactly.

 Single-Ended (actually, "unbalanced" is preferred since "single-ended" means something else as well): There is the signal (+) and there is ground. The signal (+) basically pushes the signal through the device and the ground absorbs it.

 Balanced: There is a signal (+), signal (-) and ground. The signal (+) pushes the signal through the device with the signal (-) pulling the other end. Ground is used to establish an actual "ground" and is generally used to connect to the PSU ground to provide a standard 0V between devices; it is not used for the headphones.

 Look into active-ground 3-channel Beta22; unless you're using a balanced source, just use an unbalanced amp.

 EDIT: _amb_ beat me to it


----------



## MrMajestic2

Quote:


  Originally Posted by *kklee* /img/forum/go_quote.gif 
_That link doesn't work for me, it just takes me to some kind of gateway page.

 I tried a couple of different cable strain reliefs, but I wasn't happy with them. Some of the more suitable looking ones were too expensive to order just to see if they'd work._

 

A cable tie on the inside would go a long way, and its cheap


----------



## kklee

Quote:


  Originally Posted by *MrMajestic2* /img/forum/go_quote.gif 
_A cable tie on the inside would go a long way, and its cheap 
	

	
	
		
		

		
		
	


	


_

 

That's exactly what I did.


----------



## MrMajestic2

Quote:


  Originally Posted by *kklee* /img/forum/go_quote.gif 
_That's exactly what I did._

 

Ah, I see. It usually work well for me, at least to keep the cable from pulling at the connectors on the inside.


----------



## stevenkelby

Quote:


  Originally Posted by *kklee* /img/forum/go_quote.gif 
_That link doesn't work for me, it just takes me to some kind of gateway page.

 I tried a couple of different cable strain reliefs, but I wasn't happy with them. Some of the more suitable looking ones were too expensive to order just to see if they'd work._

 

Sorry, still works for me. Cookies or something I guess. It's item number 1554654 if you want to search it.

 Cable tie sounds perfect though


----------



## stevenkelby

amb and FallenAngel, thank you, I understand now!


----------



## stevenkelby

Do these actually convert an unbalanced signal to balanced I wonder?

Browse for Products | CPC


----------



## amb

Quote:


  Originally Posted by *stevenkelby* /img/forum/go_quote.gif 
_Do these actually convert an unbalanced signal to balanced I wonder?

Browse for Products | CPC_

 

There is no link to any datasheets or technical info, but I would guess that they contain a transformer inside. The question is whether these provide any gain (transformer ratio), if they are optimized for microphone or line-level use, or for input or output. Also, no specifications are given such as frequency response, phase, square wave step response, etc.


----------



## jantze

Quote:


  Originally Posted by *jantze* /img/forum/go_quote.gif 
_I'm also getting a balanced/unbalanced switch. Initial idea is to use TPA IVY and OTTO. Is this a good way to implement it?

 My main source will be Buffalo DAC once I get it finished._

 

Any opinions to this idea? Should I consider something else?

 And I'm still looking for confirmation to what gain I should use (balanced b22). I have MD2000's that I'm a bit worried, but I might just use them with my WA6. In the future I might go for D7000, W5000 or even DX1000, so low impedance support is definitely needed.

 Any D2000 or D5000 users with a balanced b22?


----------



## amb

jantze, someone else had asked me essentially the same question, so I'll answer here.

 As far as I could tell, the TPA Ivy is an I/V converter for the Opus DAC (converts the DAC's balanced current outputs to balanced and unbalanced voltage outputs). It is not a general-purpose balanced/unbalanced conversion device.

 If you build a balanced β22, then you could just use the Ivy's balanced outputs to feed the β22. There is no need to use the Ivy's unbalanced outputs.

 You may want to use a source that _only_ has unbalanced outputs (e.g., a CD player, tape deck or whatever) with the balanced β22. This is where an unbalanced/balanced switch comes into play. But since the balanced β22 will accept only balanced inputs, before you could switch anything, you need to convert the unbalanced source' signal to balanced. This is because the inverted "cold" signal for each channel is missing. An unbalanced-to-balanced line driver circuit (which the Ivy isn't), or a special transformer made for this purpose must be used in order to derive that signal. That will then allow the balanced headphones to remain "balanced" (i.e., hot and cold signals of oposite phase at each end of its drivers).

 An example of an active unbalanced-to-balanced line driver is a circuit built around the DRV134 chip. Lundahl, Jensen, Cinemax and others make passive conversion transformers, but they are very pricey. Both methods have their benefits and drawbacks.

 If you don't have all balanced sources, then you should consider building the 3-channel active ground β22 instead. It gives you virtually all the benefits of balanced (except the doubled voltage swing), and you don't have to deal with unbalanced-to-balanced converters which would degrade the signal.

 As for amplifier gain, I am not familiar enough with the D2000 or D5000 to make a comment about it.


----------



## amb

A follow up to my post above...

 Here's a quick and easy way to add switchable balanced/unbalanced inputs to a 4-ch balanced β22 amp. It adds just a 4PDT switch (or two DPDTs) and some wiring. No extra circuitry or transformer necessary.

 This scheme could also be used on almost any 4-ch balanced amps.

 Note that when switched to unbalanced inputs, the - amps have their inputs grounded, so that they become active ground buffers similar to a 3-channel active ground amp (except in this case there is a separate ground amp per channel). In this mode, the "balanced" headphones are actually driven with unbalanced signals, only the + terminals of the headphone transducers "see" a varying signal. The - terminal is held to zero volts.


----------



## TimmyMac

Quick question. If I want to cool all the MOSFETs for two boards with a single, large heatsink, what thermal resistance am I going to want? This is for a balanced B22 with possible speaker duty and likely 2 PSU boards.


----------



## amb

TimmyMac, see the "Board and heatsinks" section of both the β22 and σ22 websites, which goes into how to calculate the junction temperature of the MOSFETs based on the heatsink thermal resistance and other variables.

 For headphone use, the default onboard heatsinks will be more than adequate. But for speaker driving duty I would recommend going through the exercise of calculating the MOSFET junction temperatures in order to select an appropriate heatsink.

 Note that the text was written assuming one device per heatsink. When you have multiple devices on a common heatsink, then the thermal resistances between the devices and the heatsink are in parallel (and you calculate them just like parallel electrical resistances), and you use the sum of the power dissipation of all devices.

 Note that there are some fairly loose assumptions about average output power, which in reality is heavily influenced by the efficiency of your speakers, size and acoustics of your listening space, type of program material, typical listening volume, etc.

 Also, as you do the calculations, you'll find that as you increase the heatsink size, at some point the thermal resistance of the MOSFETs' TO-220 package becomes a limitation.


----------



## TimmyMac

So I guess that means I can't just pick a heatsink with 8-fold greater thermal resistance than the individual TO-220 sinks? I was hoping to create a case using something like this - Conrad Heatsinks - Products - for the sides and mounting all the MOSFETs down to the flange on the sink. Also, I'm assuming the efficiency of the sinks would be higher since they're in open air rather than in a case with a few slots cut into it.


----------



## amb

Quote:


  Originally Posted by *TimmyMac* /img/forum/go_quote.gif 
_So I guess that means I can't just pick a heatsink with 8-fold greater thermal resistance than the individual TO-220 sinks?_

 

The bigger and more efficient the heatsink is, the lower the thermal resistance. So what you really mean here is 1/8 the thermal resistance, not 8x.

  Quote:


 I was hoping to create a case using something like this - Conrad Heatsinks - Products - for the sides and mounting all the MOSFETs down to the flange on the sink. Also, I'm assuming the efficiency of the sinks would be higher since they're in open air rather than in a case with a few slots cut into it. 
 

Of course you could use such heatsinks, and having the fins outside does improve convection, but just because one heatsink has 1/8 the thermal resistance as another, doesn't mean that the MOSFET's junction temperature will also drop to 1/8. The total thermal resistance is the sum of the thermal resistances of the device case, any isolating pads/thermal grease used, and the heatsink itself (see the formula posted at the website). As you go to larger and larger heatsinks, the heatsink's thermal resistance drops, but the device package and isolation pad/thermal grease thermal resistances stay the same, and may become dominant.

 One comment about that particular Conrad heatsink -- the mounting flange is in the center, which then puts the board mid-way up in the case, creating a large, unused space below, and depending on the height of the heatsink you choose, may limit the board components' height. The Conrad heatsinks with two flanges may be better for space utilization, or you could fabricate your own angle brackets and use plain, unflanged heatsinks. The latter would allow you to set the board to exactly where you want with minimum wasted space.


----------



## TimmyMac

Quote:


  Originally Posted by *amb* /img/forum/go_quote.gif 
_As you go to larger and larger heatsinks, the heatsink's thermal resistance drops, but the device package and isolation pad/thermal grease thermal resistances stay the same, and may become dominant._

 

But there are 8 of the thermal contacts and 8 device packages dumping heat into the sink, which should transmit 8 times the heat given the same temperature difference between device and sink, correct? The way I saw it is 2 heat sinks each with a thermal resistance of 4C/W should be replaceable with a single sink with 2 mounting points and a resistance of 2C/W.

  Quote:


  Originally Posted by *amb* /img/forum/go_quote.gif 
_One comment about that particular Conrad heatsink -- the mounting flange is in the center, which then puts the board mid-way up in the case, creating a large, unused space below._

 

I had planned on mounting one board above and one below the flange upside down, and mounting all the MOSFETs on the side of the board opposite the tall stuff. It'd be a tight fit but would make a nice compact amp. I haven't decided on anything yet; I'm just scoping out options.


----------



## Russ White

Hey Folks,

 I am only posting here because someone asked me to. 
	

	
	
		
		

		
			





 IVY certainly can be used as a SE to Balanced converter.

 You would just omit the BAL/SE part of the cct, and tie -IN to GND. The setup would be similar to the Opus setup, in fact you could use that setup sans the BAL/SE part.

 You might adjust the input impedance to 2K.

 Its a pretty simple mod. 
	

	
	
		
		

		
		
	


	




 The output will be a nice clean balanced signal.

 Cheers!
 Russ


----------



## amb

Thanks Russ for the info.

 TimmyMac, just do the math to compute the device junction temps and see what happens. As I said, if you're trying to dissipate a large amount of power (which might be the case when driving speakers), the thermal resistance of the TO-220 devices themselves eventually become the dominating limitation, even as you increase the heatsink size.


----------



## vvs_75

Quote:


  Originally Posted by *TimmyMac* /img/forum/go_quote.gif 
_So I guess that means I can't just pick a heatsink with 8-fold greater thermal resistance than the individual TO-220 sinks? I was hoping to create a case using something like this - Conrad Heatsinks - Products - for the sides and mounting all the MOSFETs down to the flange on the sink. Also, I'm assuming the efficiency of the sinks would be higher since they're in open air rather than in a case with a few slots cut into it._

 


 I mounted eight MOSFETs on one 250x100mm Conrad heat sink (MF25-100). 
 The whole amp gets really hot to the max point in about an hour. I can still hold my hand if I want, but it’s really not comfortable level. But the temperature stays at that level and don't go up even if you drive it for days. Ones I was running non stop my B22 for ten days and the amp was fine. I don't know if it helps but that's my experience. (Using just as headphone amp with gain of 8.)


----------



## fault151

Have you got any more pics of you completed amp? I'm using the bigger conrad sinks on my amp too. Hopefully it will help with the heat. I want to use a perspex lid on the case, but im not sure how hot the amp gets and whether the perspex will be ok?


----------



## vvs_75

Sorry that all pictures I have. When I finished it, I was so exited that I didn't take any pictures. Now my B22 disassembled due to one b22 board issue.
 My completed amp have FPE custom top, bottom, front and back panels. (not in the picture). So it helps with heat too. I don't think that it get hot enough to melt the perspex. But I think perspex is not tough enough to use it as a top or bottom. The amp is really heavy.


----------



## TimmyMac

Whoa, that death cube looks pretty sweet. That's pretty much exactly what I was planning on doing except I was going for a two-case design.


----------



## fault151

Quote:


  Originally Posted by *vvs_75* /img/forum/go_quote.gif 
_Sorry that all pictures I have. When I finished it, I was so exited that I didn't take any pictures. Now my B22 disassembled due to one b22 board issue.
 My completed amp have FPE custom top, bottom, front and back panels. (not in the picture). So it helps with heat too. I don't think that it get hot enough to melt the perspex. But I think perspex is not tough enough to use it as a top or bottom. The amp is really heavy._

 

Cool very nice and original! Is that a goldpoint attenuator? How do you find it? Good?


----------



## n_maher

Quote:


  Originally Posted by *fault151* /img/forum/go_quote.gif 
_Is that a goldpoint attenuator? How do you find it? Good?_

 

http://www.goldpt.com/

 And I think they sell them on Ebay.


----------



## fault151

Quote:


  Originally Posted by *n_maher* /img/forum/go_quote.gif 
_Goldpoint Level Controls

 And I think they sell them on Ebay._

 


 HI cheers for your reply. I actually meant, how do you find it? as in, does it work well with the b22 and do you like it?

 Cheers anyway


----------



## vvs_75

Quote:


  Originally Posted by *TimmyMac* /img/forum/go_quote.gif 
_Whoa, that death cube looks pretty sweet. That's pretty much exactly what I was planning on doing except I was going for a two-case design._

 

Well I was planning to do the same thing but last minute I changed my design. Why? First because two box design require two extra panels (one bottom and one top - each cost around $45-50). Also two power plugs and two receptacles and power cord which all add easily $50. So I skipped all the above and wired directly my B22 boards to S22 boards


----------



## vvs_75

Quote:


  Originally Posted by *fault151* /img/forum/go_quote.gif 
_HI cheers for your reply. I actually meant, how do you find it? as in, does it work well with the b22 and do you like it?

 Cheers anyway 
	

	
	
		
		

		
		
	


	


_

 


 here is also picture of my front and back panels when I just got them:








 At that time I was looking for the cheapest option. DACT quoted me $350 plus 5weeks of wait. The goldpoint was $250 next day shipping. I ask few questions and the guy from Goldpoint gave me 10% off the price to close the deal. The quality itself good. The attenuator shifts very smooth and nice. But due to the design it doesn't lock in each position very well, so if you turn it fast you can miss the point easy. Can't comment on the sound or what it does to it because I never compare to anything else. But the guy at Goldpoint said that their SDM resistors are the second best after the CADDOCK ones on today’s market.The Caddock not the very best resistors but good enough for me.

 Happy DIYing!


----------



## MrMajestic2

Quote:


  Originally Posted by *Russ White* /img/forum/go_quote.gif 
_Hey Folks,

 I am only posting here because someone asked me to. 
	

	
	
		
		

		
			





 IVY certainly can be used as a SE to Balanced converter.

 You would just omit the BAL/SE part of the cct, and tie -IN to GND. The setup would be similar to the Opus setup, in fact you could use that setup sans the BAL/SE part.

 You might adjust the input impedance to 2K.

 Its a pretty simple mod. 
	

	
	
		
		

		
		
	


	




 The output will be a nice clean balanced signal.

 Cheers!
 Russ_

 

Hi Russ,
 Could you be more specific about this mod? Exactly what parts should I omit and change? Would be really helpful as Im planning on using the IVY in a b22 build.


----------



## tenorsaxophone

Hello!
 To those who they have already built β22 amplifier:
 Is it better (or more easy to work on PCB) to use 1/8 or 1/4 watt resistors?
 Many thanks.
 Davide.


----------



## Ferrari

Except for the 0.47Ω power resistors, all resistors on my β22 amps are Vishay-Dale RN55D 1/8W.
 Resistors from other manufacturers like Xicon, BC, Panasonic... (1/4W) with the same dimensions as Vishay-Dale RN55D 1/8W will work fine but not necessarily better.


----------



## MrMajestic2

Quote:


  Originally Posted by *tenorsaxophone* /img/forum/go_quote.gif 
_Hello!
 To those who they have already built β22 amplifier:
 Is it better (or more easy to work on PCB) to use 1/8 or 1/4 watt resistors?
 Many thanks.
 Davide._

 

I though the recommended 1/8W was easy enough to work with. I dont see any benefits in going 1/4W unless you have trouble finding the 1/8W. There is space for slightly larger resistors on the boards though.


----------



## Crow

Hi amb (or anyone who knows for sure):

 I will have a Dantimax relay attenuator between the input and my 3 B22 boards (AG config.)

 Should I connect the ground channel to the RCA jacks (at the signal grounded case) or to the output of the attenuator?

 What type of cable is best to use for the ground channel's input--shielded (shield connected to what?!), or would simple hookup work for this (~7")?

 Thanks for your support. My build is going quite well thanks to all the posts here and elsewhere.

 Scott


----------



## amb

Crow, see the β22 website's "Parts list" and "Wiring and ground" sections. You'll note that the active ground channel board's input is already grounded via its own R2 resistor. The diagram shows a ground wire only, connected to the input ground (same place as the left and right channel board's input ground -- at the volume pot). Since it's only one wire, there is nothing to shield.


----------



## Crow

Got another one for you guys. On my B22 Left channel, both 2sj74 jfets measure a short across D-S. Indeed, my input is short circuited; my 170's are both ok (4.5v across R9), and during the initial setup all the procedures went ok--the board still powers up and biases (output at least) correctly. 

 So my 74's are blown. I don't know how this happened, but I have a couple guesses:

 1) As I recall, I did not have my inputs shorted while adjusting the bias of the input transistors (dumb mistake), but did so right after, and the setup still went as expected.

 2) Heat: Should I have used alligator clips on the transistors to keep heat down? I did not have the (40w) iron in contact for more than a second though, and I already have built one healthy board w/o clips...

 What else could have caused this?

 Thanks...


----------



## amb

Testbench accident (whether you were aware of it or not)? DMM probes and other objects, useful tools as they are, could also cause damage in the most inopportune moments.


----------



## Crow

Quote:


  Originally Posted by *amb* /img/forum/go_quote.gif 
_Testbench accident (whether you were aware of it or not)? DMM probes and other objects, useful tools as they are, could also cause damage in the most inopportune moments._

 

Hmm.. my voltmeter thought 30 ohms was a short across S-D of the 74's. It turns out that _all _input jfets have sane G-D and G-S resistances. Inspection of the board seems not to reveal any solder bridges/etc. Still operates normally.

 In light of this, would you think that there must be some bridged connection hidden somewhere between the input jumpers and the transistors? If not, what other components could cause a short between input and ground? Or are my jfets still dead?

 Just wanted to double check before I really start ripping stuff apart to check for shorts...

 Thanks so much


----------



## amb

Crow, how about a careful visual examination of all solder joints and traces (under magnifying glass)?


----------



## Crow

Quote:


  Originally Posted by *amb* /img/forum/go_quote.gif 
_Crow, how about a careful visual examination of all solder joints and traces (under magnifying glass)?_

 

Progress. The short is between the input pad and R1. I have connected a wire to the input side of R1 and disconnected it from the board there. I now have sound. Inspected all around the jumpers, and elsewhere--can't find the short. I'm thinking it may be inside the board, wish I'd checked it before I populated it.

 Thanks for your patience!


----------



## amb

It's possible the short is on the board, but not _inside_ the board as these are two-layer boards. Sometimes a manufacturing defect (under-etched spot) could cause such a short. You should look very carefully at the trace between the input pad and R1 (under magnification) to see if you could locate it. Then, it's a simple matter of scraping/cutting the short away with an X-acto blade.


----------



## Crow

So I found the short. Connected the dmm to the input and put it in continuity/beep mode. Started slicing around the input trace with an x-acto blade, and when the beep stopped, problem solved.

 Ti, this short escaped a 16x loupe and a bright flashlight. There was no reasonable way to visually find it. The moral of the story for prospective builders out there: check for shorts before you build.

 I know that having the manufacturer not do this step makes these boards affordable, etc, but this point is still important.

 Another B22 is born, and it's sounding fantastic. It has a spacious and mature sound that I won't soon grow tired of. I'll post some photos eventually.

 One quick Q amb, as I am plugging in the 'phones (volume at minimum), there is a quick, semi-loud squeal until the plug is fully seated. Hopefully this is harmless oscillation caused by a temporary short condition? Otherwise, the amp is behaving as spec'd (offset, bias, etc) and sounds excellent.

 I appreciate your support and may not have started this project without your presence here and elsewhere. Thanks for bringing so much perfection into DIY audio.

 Cheers,
 Scott


----------



## amb

Crow, do you have a 3-channel active ground configuration? Check that you used the correct C2-C5, R2, R3 and R4 values on the ground channel (they're different than the left and right).

 If those are correct you might want to try adding the zobel network to the output as described at the β22 website.


----------



## fault151

Hi guys, im thinking of getting an alps rk27 balanced control for my balanced b22 until the joshua tree becomes available again.

 Which should i go for, the 10k or 100k?

 What difference would it make to the amp?

 Cheers


----------



## Pars

10K. High values such as 100K are more prone to noise.


----------



## fault151

ok thanks for your reply. :0)


----------



## fault151

Hi guys, im having a bit of trouble with my baLanced b22. I have it powered up and the voltages are all running as they are meant to. The sounds isn't right. I'm getting a very weird high pitched noise in my ears. When itry adjust the volume the high signal noise pops lightly. I can hear sound coming through if i turn the volume up but it sounds like i am listening to music in an echo tunnel.If i unplug one of the input xlr jacks i get sound in both channels via the 1 input? 


 Any ideas where to start?


----------



## cotdt

Are you confusing the inputs and outputs? That tends to create the sound-out-of-tunnel effect.


----------



## fault151

Quote:


  Originally Posted by *cotdt* /img/forum/go_quote.gif 
_Are you confusing the inputs and outputs? That tends to create the sound-out-of-tunnel effect._

 

No I don't think so. I'm getting sound via both ears with only one headphone xlr plugged in. Thats weird?


----------



## fault151

Ok i now have sound but im still getting hissing and signal noises when the music is not playing and also when i turn the volume control.

 I can hear hissing when the volume is turned right down.


----------



## cotdt

You have a ground loop problem. How is everything connected? Pics?


----------



## fault151

Is there a quick way i can check that? I had the same problem with my dac that i'm using with the b22 at the minute.I had to put a ground breaker in it.It worked.


----------



## fault151

I could send pics but its too messy for you to be able to see anything. Im trying to get it running first before i tidy the wiring.


----------



## millwood

a few ways to debug it.

 1) are t he hissing / noises present when the input is grounded? 
 2) are the DC working points right for the amp?
 3) if all of the above is true, you have oscillation. the miller caps used by the amp (c2-c5, 33pf) are on the small end of the range, and the gate stoppers (R30-R31, 0ohm) are too small.

 I would use 47-110ohm for R30/R31 to see if that stops the oscilation. if that doesn't work, dial up C2/C5 (to about 110pf and then go down from there).

 but you will need to go through steps 1) and 2) first to rule out any parts / soldering problems first.


----------



## fault151

I can only hear the hissing slightly, its more when i turn the volume knob that i can hear sounds change and signal noises. The music is playing fine, its just got low hissing in the background. 

 All my caps should be ok, i bought the amps as a kit. I assume they are fine as i know other people have built the b22 balanced version with the exact kit as me from the same person.


----------



## fault151

I have a feeling it could be to do with the volume pot. I get a squeaky sound when i adjust the volume,its like interference. Its annoying because otherwise i have the music playing like it should.


----------



## Beefy

Quote:


  Originally Posted by *fault151* /img/forum/go_quote.gif 
_I have a feeling it could be to do with the volume pot. I get a squeaky sound when i adjust the volume,its like interference. Its annoying because otherwise i have the music playing like it should._

 

Is the volume pot grounded? The casing for the volume pot needs to be connected to input grounded - but isolated from output ground of course.


----------



## Pars

Quote:


  Originally Posted by *fault151* /img/forum/go_quote.gif 
_I have a feeling it could be to do with the volume pot. I get a squeaky sound when i adjust the volume,its like interference. Its annoying because otherwise i have the music playing like it should._

 

Sounds like you might have DC on the pot, which will cause noise when rotating it.


----------



## MrMajestic2

Quote:


  Originally Posted by *fault151* /img/forum/go_quote.gif 
_No I don't think so. I'm getting sound via both ears with only one headphone xlr plugged in. Thats weird?_

 

If you get sound in both ears when only one xlr is plugged in then your headphones are not wired correctly. It shouldn't be possible otherwise.


----------



## amb

Or an input or output wiring error within the amp.


----------



## fault151

Quote:


  Originally Posted by *MrMajestic2* /img/forum/go_quote.gif 
_If you get sound in both ears when only one xlr is plugged in then your headphones are not wired correctly. It shouldn't be possible otherwise._

 

I solved this problem,i had two of the pins on the volume pot the wrong way. The sounds is ok now.Its just the volume pot i need to look at.I decided to leave it and sleep on it before i did some damage.

 Just getting back in to it now.


----------



## fault151

Quote:


  Originally Posted by *Beefy* /img/forum/go_quote.gif 
_Is the volume pot grounded? The casing for the volume pot needs to be connected to input grounded - but isolated from output ground of course._

 

Ok i tried this, its still there. It seems to have helped a little but i still get interference from somewhere? Im just going to have a look through all my wires again and see if i can spot anything with fresh eyes.


----------



## fault151

The situation seems to have got a bit worse. I checked my readings and i can get an accurate reading on the left channel from the output pad and the gnd signal. It just keeps changing and doesnt settle.


----------



## millwood

Quote:


 It just keeps changing and doesnt settle. 
 

there is a good chance it is oscillating.

 do you have a scope? or you can make a high frequency probe and use your multimeter to see if you have oscillation.


----------



## fault151

I don't have one. Its only on the left - channel that i cant get a reading.The connection is ok. I tried plugging in my headphone and got a wierd loud noise so i very quickly unplugged it. Again the sound was only in the left ear. The right channel is fine. All my wiring one the amp seems ok.


----------



## millwood

I assume the reading was done with the input grounded, right?

 you may want to see what the dc working points are right: on the output, on Q25/Q26's emitters, to ground.

 then voltage drop on R34/R35, Q23/Q25's gate to output, R16 through R19, R14/R15, R9 through R12, and the base of Q1/Q3, and the base of Q2/Q4.

 the approach is to make sure that the amp is working properly DC-wise. and then you can narrow down the a/c problem.

 attached is an example for a probe. it is a half wave RF rectification, typical in an AM radio. the 1n4148's orientation doesn't really matter, nor does the values for the r/c filter. with the left side attached to the output of your amp (when its input is grounded), if you read something on the capacitor, you have oscillation.

 but you will need to make sure that the amp is working dc-wise first.


----------



## fault151

Im now wondering if i have a dodgy joint or the trim pot is faulty? It only happened since i tried to adjust it.


----------



## TimmyMac

Sorry to turn this into a troubleshooting thread, but I'm having problems with one of my sigma22 boards. Output is 0mV. The MOSFETs aren't internally shorted. Voltage across D5 is 600mV or so. Q2 gives a few tens of ohms across all pins, Q1 gives open circuit across all except 10k across collector and base (as it should).

 My guess is Q2 is blown - my other (working) sigma22 board gives more normal readings across it. Thoughts?


----------



## amb

TimmyMac, did you install D5 in the wrong way?
 Q2 is definitely blown if it's shorted like that.


----------



## TimmyMac

D5 is in the right way, and I replaced it just to make sure. I also reflowed pretty much every solder joint on the board - not that I expect it to help with a blown Q2. One of the joints on Q14 looked pretty questionable - would that cause Q2 to die? Also are there any other transistors I should be checking before placing an order? I suppose I could steal Q2 off the working board and test if that helps, but then I could pretty easily end up with 2 unworking boards.


----------



## amb

The most likely cause of Q1 and Q2 dying on these boards is an accidental short circuit somewhere downstream. It could be just that -- an accident, or a solder bridge, or some sort of overload. Why not read through the σ22 and σ11 thread (and its previous one) at headwize and get some ideas?


----------



## TimmyMac

I got the idea to check all the transistors from headwize, but there's over 50 pages of stuff there and I haven't had time to read it all yet. I tried swapping in Q2 from the working board - no luck. Same readings as before, except after power up Q2 is still giving normal ohm readings (and my other board works fine when I moved Q2 back to it). D5 is still giving ~0.5-0.7V across it, and has been replaced with no improvement.

 The reservoir caps are charging, so the rectifier and snubbers are fine. Resistance across the outputs is the same for both boards - ~17k from positive rail to ground and ~37k for the negative rail. I'm using the same transformer wired in the same phase to the inputs to test both boards; inputs are also not shorted on either board (unless the trafo is attached of course).


----------



## amb

What is the voltage at Q1 emitter? (hint: see the troubleshooting PDFs at the σ22 website, under "Initial check") If that's not what it should be then Q1 is dead too.


----------



## TimmyMac

Ok, after more reflowing and playing around, I managed to get +/-37V output. Board is configured for +/-30V using a dual 28.4V 150VA transformer.

 Output at the emitter of Q1 is 38.9V - 2 volts under the specced 40.9V, but my trafo is a couple volts under +/-30V that is usually used. Voltage across D5 is now 11.92V - also good. Things go a little wonky at the emitter of Q3 - 14.4V there, instead of 11.34. The base of Q4 (measured at R10, the non-grounded end) is 15.1V, instead of the expected 11.98. The voltages on all pins of Q7 and Q8 are 2V low, roughly.


----------



## TimmyMac

Oh, and I checked R10 just in case - 6.74kohm


----------



## amb

Check your MOSFETs to make sure you have the correct ones installed in each location:

 Q13, Q14: IRFZ24N
 Q15, Q16: IRF9Z34N


----------



## TimmyMac

MOSFETs are all installed ok. The high voltage at the emitters of Q3/4 concerns me, since its proportional to the increase in voltage I've got at output.

 Would I be correct in thinking that the bottom half of the regulator is probably working OK since it's tracking the positive rail (although, Q2 is likely fried...)? Or is it more likely that I'm just getting the unregulated output on both rails? I'm not too sharp on the topology of this circuit... my understanding ends at stuff like STEPS and single ended or simple pushpull tube circuits...


----------



## amb

Quote:


  Originally Posted by *TimmyMac* /img/forum/go_quote.gif 
_MOSFETs are all installed ok. The high voltage at the emitters of Q3/4 concerns me, since its proportional to the increase in voltage I've got at output._

 

Are all your CRDs mounted in the proper orientation? You said you were checking your transistors (I assume using the diode check function), do they all check out ok? The only exception to the 0.6-0.7V junction is Q8 and Q10, which, if you look at the schematic, has the B-C junctions intentionally shorted to each other.

  Quote:


 Would I be correct in thinking that the bottom half of the regulator is probably working OK since it's tracking the positive rail (although, Q2 is likely fried...)? Or is it more likely that I'm just getting the unregulated output on both rails? I'm not too sharp on the topology of this circuit... my understanding ends at stuff like STEPS and single ended or simple pushpull tube circuits... 
 

Not necessarily. While the negative rail is supposed to track the positive rail, that would happen only if everything is working properly. It could indeed be pegged against the unregulated rail like the positive rail is.


----------



## TimmyMac

Seems all I had done to 'fix' this thing is make a solder bridge from the unregulated supply to the output on one of the MOSFET pads. I think there may be several transistors blown on this board, and I'm thinking about just replacing all the silicon, minus diodes and CRDs, rather than fiddling with it for too much longer. Is there anything else that can blow up easily on the board?

 Also, Mouser no longer carries the MOSFETs. Is HUFA76419P3 and HUF75309P3 a suitable substitute?


----------



## amb

Mouser never carried both the IRFZ24N and IRF9Z34N. I don't recommend substitutions because the compensation cap values were tuned specifically for the specified IR parts.

 Btw, you could get all the MOSFETs and transistors for the σ22 from you know who.


----------



## TimmyMac

You make a good point...
 I'm going to assume the MOSFETs are fine, since they aren't shorted and haven't shot flames at me. Which just leaves a handful of transistors. I'll save you the trip to the post office and shipping $2 of parts to Canada and just place a Mouser order - I'll let you know how it turns out.


----------



## TimmyMac

So, while waiting for those transistors to arrive, I went about testing all my other boards with the single working PSU board and a single 160VA transformer. 3 boards checked out ok. Fourth board is fine except R9-12 don't give exactly the same voltage (they're off by a few tenths of a volt) when I set input bias and DC offset is ~150mV. This is with no load on the board. I tried doubling up D3/4, tried switching Q1/2 and 3/4 in succession, the lowest I can get is about 130mV with the trimpot. I checked a few voltages and they seemed ok +/- a few fractions of a volt.

 Oddly, when I switch the unit to speaker outputs (I have a DPDT switch on the outputs, one half goes to XLR on the front, the other goes speaker posts on the back, which are zobel'd as recommended) I can set DC offset to 0 no problem. 

 At about 150mA MOSFET bias, my heatsink is just warm, not hot by any means, so I don't think heat is the issue. Are my JFETs off?


----------



## amb

TimmyMac, maybe the "DC offset" you experience isn't actually DC. Perhaps it's high frequency oscillation. The fact that switching to speaker position (and the zobel) "fixes" the problem is a clue. Try reflowing the solder joints of all your compensation capacitors (C1-C5), and make sure they are installed in the right pads. All of them have 3 pads, if you're using 2.5mm pitch caps then you must install them across the 2 pads with the capacitor schematic symbol between them.


----------



## TimmyMac

I suspected that last night after I posted and checked AC on the output - 450mV. But I didn't know what to do about it. Sure enough, C5 was on the wrong pads. Thanks amb.


----------



## fault151

Hi guys i'm having a few problems with the trim pots on my balanced b22. I cant get the v3 pot on 1 of the boards to read 0mv. The lowest i get is 88mv which is way to high.

 Any ideas where to begin fault finding? Other than that i think the rest of the boards are operating as they should and the reading are ok. I'm totally stuck on this.


----------



## FallenAngel

Quote:


  Originally Posted by *fault151* /img/forum/go_quote.gif 
_Hi guys i'm having a few problems with the trim pots on my balanced b22. I cant get the v3 pot on 1 of the boards to read 0mv. The lowest i get is 88mv which is way to high.

 Any ideas where to begin fault finding? Other than that i think the rest of the boards are operating as they should and the reading are ok. I'm totally stuck on this._

 

Double check that you didn't switch VR2 and VR3


----------



## fault151

Hi guys i am building the b22 with the e24 board and its accompanying transformer,Im having a little trouble getting my head round how to wire it. I have attached a diagram of how i think it should be wired. Could someone let me know if it is correct please. Also how are you meant to connect the led part on the switch. My switch has 4 terminals and only two are labeled + and -. Im assuming these are for power? How and where do the other two terminals connect?

View my diagram here!


----------



## amb

Answered at headwize ε24 thread.


----------



## fault151

Well after along time of worrying and messing about trying to find faults,i finally have it working! The b22 i mean. Have a guess what it was?

 I have the capacitors on one of the boards in the wrong position. C2 + c3 on the board wasn't mounted over the (-||-) markings on the board, causing it to oscillate. It now works perfectly and i get the correct readings everywhere. Thank god for that! I can now listen to the amp for the first time.

 Wahoo!

 Thank you to TI and Mr Majestic who have been helping all along and anyone else who helped with problem solving.

 I just need to get the panels made and tidy things up.


----------



## utilisateur

I'm resurrecting my β22 boards and have some setup problems
 I bet the answers are already somewhere in the headwize thread but headwize is down
	

	
	
		
		

		
			






 So when i try to do the initial setup i cant adjust the Voltage across R9, VR1 makes minimal changes i have 1,3V across R9 with VR1 turned fully ccw and 1,8V with VR1 fully CW





 maybe someone has a clue or plain knows what is wrong or what i should check to find out
 I'd really appreciate your help !


----------



## MrMajestic2

Quote:


  Originally Posted by *utilisateur* /img/forum/go_quote.gif 
_I'm resurrecting my β22 boards and have some setup problems
 I bet the answers are already somewhere in the headwize thread but headwize is down
	

	
	
		
		

		
		
	


	





 So when i try to do the initial setup i cant adjust the Voltage across R9, VR1 makes minimal changes i have 1,3V across R9 with VR1 turned fully ccw and 1,8V with VR1 fully CW





 maybe someone has a clue or plain knows what is wrong or what i should check to find out
 I'd really appreciate your help !_

 

Are you sure you have the right VR in the right location? I remember I mixed mine up the first time since they are not in order on the board.


----------



## utilisateur

Thanks
 I quadruple checked as that had happened twice before, _and just rechecked_ , they are definitely in the right order and connections are good


----------



## Bojamijams

bought most parts.. waiting for them to arrive...


----------



## paaj

Just ordered the GJA kit (I'm not really into the whole DIY gathering stuff thing 
	

	
	
		
		

		
		
	


	




) and see how far I can get without blowing all up.


----------



## utilisateur

Quote:


  Originally Posted by *paaj* 
_Just ordered the GJA kit (I'm not really into the whole DIY gathering stuff thing ) and see how far I can get without blowing all up._

 

Jeffs Kit really is very convenient!

  Quote:


  Originally Posted by *utilisateur* 
_[size=xx-small]So when i try to do the initial setup i cant adjust the Voltage across R9, VR1 makes minimal changes i have 1,3V across R9 with VR1 turned fully ccw and 1,8V with VR1 fully CW



 maybe someone has a clue or plain knows what is wrong or what i should check to find out
 I'd really appreciate your help ![/size]_

 

On another board VR1 works fine and i pass that step but i have a discrepancy between R34 and R35
 Only 5mV to ground from R34/Q21source _OpPoints PDF says 80,52mV_
 And 1,4V to ground from R35/Q22source _-80,58mV_

 maybe something around Q17/18?
 the meter reads
*-*430mV to ground from the Q17/18 emitter junction _175,4mV_
 -1,1V at Q18 Base _-601,7mV_
 238mV at Q17 Base _900,3mV_

 Ideas?


----------



## Gatsu

Not long ago finished putting together my two Sigma22's.

 First one worked first time, second one I discovered I had gotten the 4 of the transistors swapped around. Only to blow up another transistor fixing those. /facepalm

 Once I sorted that out all worked. Haven't started on assembling the Beta boards yet. I've been working on the controller boards.
 My build is heavily influenced by naamanf's infamous build 
	

	
	
		
		

		
		
	


	




 2 picaxe microcontrollers (one in each case) control power and power status indication (S22 case) as well as input/output selection and indication (B22 case), as well as a Joshua Tree attenuator.

 Its certainly been a learning experience so far


----------



## FallenAngel

Quote:


  Originally Posted by *utilisateur* /img/forum/go_quote.gif 
_Jeffs Kit really is very convenient!_

 

And makes it that much easier for people to take on projects they don't know how to debug. 
	

	
	
		
		

		
		
	


	




  Quote:


  Originally Posted by *utilisateur* /img/forum/go_quote.gif 
_Ideas?_

 

Double and triple check that you did not swap the 5K and 500R trimpots.
 Take high quality photos of the top/bottom of the board and post.


----------



## utilisateur

Quote:


  Originally Posted by *FallenAngel* 
_Quote:
 Originally Posted by utilisateur View Post
 Jeffs Kit really is very convenient!
 And makes it that much easier for people to take on projects they don't know how to debug._

 






 Quite true ..
 Personally i only attempted seeing it as a great learning opportunity and counting on the enormous knowledge available trough the internet and especially forums like headwize (and this thread). 
 Assuming this wasn't available i would have tried to find knowledgeable people willing to share and teach around the place i live but the net makes such knowedge available far more easily and maybe makes it harder to find it locally (?) as people dont form clubs or whatever but go talk and exchange experience trough the web.



_[size=xx-small]Photos to follow in an [/size]_edit! = )

 board 1 where VR1 works but R34/R35 doesnt behave




 board 2 where VR1 had no effect





 more


----------



## amb

Check the voltage (relative to ground) at the outer pin of R9. If you don't have around 27-20V or so, then your Q25 is blown. Ditto at the outer pin of R11, you should get -27-29V. If not, then Q26 is blown.

 Make sure your Q1-Q4 are mounted according to the "instructions" section of the β22 website (not according to the silkscreen).


----------



## utilisateur

I measure 28,2V/-28,2V on both boards and Q1-4 are soldered according to the information on your website!

 Can i check the small signal transistors in circuit, except checking for shorts(there are none)? 

 Can you read anything explicit from the measurements?
 These were those that were the most suspicious to me
  Quote:


 On another board VR1 works fine and i pass that step but i have a discrepancy between R34 and R35
 Only 5mV to ground from R34/Q21source OpPoints PDF says 80,52mV
 And 1,4V to ground from R35/Q22source -80,58mV

 maybe something around Q17/18?
 the meter reads
 -430mV to ground from the Q17/18 emitter junction 175,4mV
 -1,1V at Q18 Base -601,7mV
 238mV at Q17 Base 900,3mV


----------



## amb

Yes, you can test the BJTs. Power off and let all caps discharge fully. Then, set your DMM to the diode check mode. For NPN transistors (BC550C), put the red probe on the B pin and the black probe on the C and E pins. You should read about 0.6V on both. Reverse the probes and you should read infinity (depending on your DMM it would display either "OL" or "1"). For PNP transistors (BC560C), it's just the opposite. Black probe on B and red probe on C or E = 0.6V, reverse probes and you should get infinity.

 Any transistor that fails this test on the β22 board is most assuredly blown.

 Note that this test does not apply to JFETs or MOSFETs.

 For your other board, the initial setup procedure is to measure the voltage _across_ R34 and R35, not relative to ground. Your observed discrepancy simply means that the output DC offset has not been nulled yet.


----------



## utilisateur

Quote:


  Originally Posted by *amb* 
_Yes, you can test the BJTs._

 

Thanks i will test them
 Now a substantial amount of the BJTs measures around 1,5 or 1,8 in the reverse direction and some fluctuate slightly before my meter settles above the range..
 [size=xx-small]_In diode check mode my meter reads 1 when the forward voltage is higher than 2V_[/size]
 Assuming they are dead, what could have caused this ? I don`t think i was this heedless when soldering them but always trying not to heat them too long


  Quote:


 For your other board, the initial setup procedure is to measure the voltage across R34 and R35, not relative to ground. Your observed discrepancy simply means that the output DC offset has not been nulled yet. 
 

I think i did measure across the resistors but the change across R34 was not large enough, just posted the values relative to ground in case this could hint to a fault!
 I hope my mind doesn't fool me on this or better i hope it did, anyhow i go and check again!
 thank you!
 So i just checked and i cannot adjust the voltage across R34 at all it sits quietly at 0,0V
 When i measure R35 on the other hand with the pot fully closed i get 1,13V across it and it climbs when VR2 is changed
 I did not turn VR2 fully clockwise as i didnt want to raise the voltage across R35 further , four turns it it's at 1,5V and R34 still at 0,0V


----------



## utilisateur

_I cant see how most of the BJT on both my boards could be dead

 To make sure the replacements do well, what else can i check ,considering they are not dead short but fail the reverse test as described above ?_

 Wow, after trying to get a better understanding of the schematic i went ahead to check some points on the board and checked R34 R35 while doing so and
 R35 measured 51*k*Ω
 It' marked with a 0,47Ω color code !
 Weird stuff
*
 HEUREKA*

 I got both boards through the initial setup procedure =)

 I still wonder what i should do with the BJTs measuring slightly lower than amb recommended,
 in what way are they detrimental to the circuits properties ?

 Also on the board i had the wrong/damaged resistor in position R35 the voltage across r35 is 20mV lower than across r34 ,has this happened to anyone or does someone know what could cause this? 


 Having to look for the solution myself I definitely learned more, and i'm happy i now have a better understanding about what's happening on this green miracle that makes sound mo' big and transducers sing .)


----------



## utilisateur

What consequences are there from the 20mV difference between R34 and R35?
 And what could cause this behaviour? 

_Q17/18 are not the culprit i replaced them and it did not change anything_

 As said there are no immediate audible effects.. i would like to know whats going on there as the amp is changing hands and i dont want to hand down this issue


----------



## amb

A small difference between R34 and R35 is ok, but 20mV seems excessive. Try measuring the resistance these two resistors (power off) to see if there is a discrepancy between them. If not, power up and check the voltage across R28, R29, D9 and D10. What do you get for these?


----------



## utilisateur

Quote:


  Originally Posted by *amb* /img/forum/go_quote.gif 
_A small difference between R34 and R35 is ok, but 20mV seems excessive. Try measuring the resistance these two resistors (power off) to see if there is a discrepancy between them. If not, power up and check the voltage across R28, R29, D9 and D10. What do you get for these?_

 

1,31V across R28
 1,36V across R29
 12,0V across D9
 12,45V across D10

 and R34 and R35 seem to be fine, my meter is not capable to measure them accurately but they both measure the same and around 1,2Ohm or something

 no clue...


----------



## amb

Well, those measurements are all fine, I can't think of another reason that might cause a 20mV discrepancy between R34 and R35. As long as the output DC offset is nulled closed to zero and does not drift excessively, and the quiescent current settles to something reasonable, then I say not to worry about it.


----------



## utilisateur

Good news! I hope it stays this way 
	

	
	
		
		

		
			






*Thank you! *


----------



## qkizz

Hi,
 I'm considering going from 3-channel active ground configuration(with ε22) to balanced. I would like to keep active ground(1 board only) and ε22 and just add 2 more boards. What would be potential problems associated with this kind of configuration? Assuming all parts are the same, the same gain on 4 boards. Should I pair the boards new-old per channel to minimize burn-in effect?
 Thanks


----------



## amb

qkizz, yes you can build a 5-channel config to add balanced capability. I wouldn't worry about pairing the boards for "burn-in effect".


----------



## qkizz

Thanks AMB


----------



## alwayshungry

I've finally gotten around to powering up my boards and I'm running in to issues. Both of my S22s test fine and I followed the initial setup instructions and I don't have any issues with them (~+30V between +V and G, ~-30 between -V and G). 

 I hooked up 1 beta 22 board to setup and adjust. I'm using a JT so I'm using one balanced output not connected to an input load. I hooked up a b22 board and the LED lights up but before I could test any points, I cooked my Q23 and R32 and had a little fireworks show 
	

	
	
		
		

		
		
	


	




 I double checked all my connections and retested all the outputs from the S22 and connected another board and this time blew a fuse (1.6A slow blow). Any ideas?


----------



## johnwmclean

alwayshungry, if are you using an Avel Lindberg transformer your wires are not connected correctly to the Sigma.

 black, red, orange, yellow

 It doesn’t matter whether it’s left to right or vice versa.

 Only if it is an Avel Lindberg though, otherwise ignore this post and refer to the manufacturers specs.


----------



## alwayshungry

Hi John,
 I'm not sure if you got my PM but thanks for the help.

 I have 2 of my b22 boards biased and working. I'm running into issues with my remaining 2 though.

 (1) Every time I hook this board up to the power supply and turn it on, I get the LEDs lit on the S22 and B22 for about 2 seconds and then it blows the fuse (I'm using a 1.6A slo blo). I checked the V+, G and V- on the board for a short between them and got nothing.

 (2) I am performing the biasing on this board and I'm able to bias VR1 to get 4.5V across R9. However when I try to adjust VR2 to set the bias across VR34, the voltage doesn't change. I checked to make sure that turning the trimpot changes the resistance and from earlier posts in this thread I'm thinking that I have some possible blown BJTs. 

 Thanks in advanced for the help.


----------



## El_Doug

Just ordered some boards and transistors from AMB! 


 ...and god help me, if I didnt do so just 1 hour after completing my first cmoy


----------



## naamanf

Quote:


  Originally Posted by *El_Doug* /img/forum/go_quote.gif 
_Just ordered some boards and transistors from AMB! 


 ...and god help me, if I didnt do so just 1 hour after completing my first cmoy_

 

Good luck. It's either going to end in audio bliss or total failure


----------



## johnwmclean

Quote:


  Originally Posted by *alwayshungry* /img/forum/go_quote.gif 
_Hi John,
 I'm not sure if you got my PM but thanks for the help._

 

Thanks alwayshungry I got it 
	

	
	
		
		

		
		
	


	




 In regards to point 2, double check the trimpots are in their correct positions.


----------



## alwayshungry

Quote:


  Originally Posted by *johnwmclean* /img/forum/go_quote.gif 
_Thanks alwayshungry I got it 
	

	
	
		
		

		
		
	


	




 In regards to point 2, double check the trimpots are in their correct positions._

 

Hey John, I double checked all my parts and the trimpots are in the right positions.


----------



## amb

alwayshungry, there is an incongruence between your two points. If the fuse blows within 2 seconds after power-up, how do you even get to do the biasing at all?


----------



## johnwmclean

Quote:


  Originally Posted by *amb* /img/forum/go_quote.gif 
_alwayshungry, there is an incongruence between your two points. If the fuse blows within 2 seconds after power-up, how do you even get to do the biasing at all?_

 


 I read it as this...

 He has two boards biased and working. Point 1 an 2 are his two remaining boards.


----------



## amb

Yes, that's what I was asking. If powering up causes the fuse to blow within 2 seconds, then how does he even have time to check the voltage across R9, adjust it to 4.5V, and then proceed to measuring the voltage across R34 (which he reports as having no effect when turning VR2)?


----------



## alwayshungry

Quote:


  Originally Posted by *amb* /img/forum/go_quote.gif 
_alwayshungry, there is an incongruence between your two points. If the fuse blows within 2 seconds after power-up, how do you even get to do the biasing at all?_

 

Hi Ti,
 I should have clarified but each of my points refers to a different b22 board.


----------



## amb

OK, for the board that causes the fuse to blow, check to make sure your VR2 is installed in the proper orientation and that it's pre-set to fully-counterclockwise position before initial power-up. Also, make sure you didn't mix up the MOSFETs (Q21/Q23= IRFZ24N, Q22/Q24 = IRF9Z34N). Check the MOSFETs for shorts.

 For the board that doesn't respond to VR2 adjustments, after setting VR1 to get 4.5V across R9, did you also measure the voltage across R10, R11 and R12? Check the voltage across D11 and D12. They should be no more than a couple of volts. If you get more, than the corresponding Q25 or Q26 might be blown.


----------



## MrMajestic2

Never mind, forgot to refresh


----------



## nkd

I just finished my Sigma22 a few days ago. Worked first time! Considering my only other amp was a cmoy a about five years ago I was more than a little shocked! 
	

	
	
		
		

		
		
	


	




 Now to order the rest of the components for the beta22 boards!


----------



## dbfreak

Did you spec it out with a load on it?


----------



## alwayshungry

Quote:


  Originally Posted by *amb* /img/forum/go_quote.gif 
_OK, for the board that causes the fuse to blow, check to make sure your VR2 is installed in the proper orientation and that it's pre-set to fully-counterclockwise position before initial power-up. Also, make sure you didn't mix up the MOSFETs (Q21/Q23= IRFZ24N, Q22/Q24 = IRF9Z34N). Check the MOSFETs for shorts.

 For the board that doesn't respond to VR2 adjustments, after setting VR1 to get 4.5V across R9, did you also measure the voltage across R10, R11 and R12? Check the voltage across D11 and D12. They should be no more than a couple of volts. If you get more, than the corresponding Q25 or Q26 might be blown._

 

Hi amb
 For the board with the blown fuse the MOSFETs are correctly installed but I found shorts between various pins (resistance measures between 0.8 and 130 ohms between different pins on each MOSFET). I checked the resistances of R28, R29, R30, R32, R33, R34 and R35 and they look correct. Do I just need to replace the MOSFETs?

 For the board with VR2 adjustments, it is not responding to VR1 adjustments now 
	

	
	
		
		

		
		
	


	




 I getting the following readings:
 R9 = 0.74V
 R10 = 0.78V
 R11 = 0V
 R12 = 1.50V
 D11 = 30.7V
 D12 = 0.8V
 When it did bias at VR1 before, I remember the voltages at R10, R11 and R12 being slightly higher (4.5-4.6V).

 Thanks for your help John and Ti.


----------



## amb

Quote:


  Originally Posted by *alwayshungry* /img/forum/go_quote.gif 
_Hi amb
 For the board with the blown fuse the MOSFETs are correctly installed but I found shorts between various pins (resistance measures between 0.8 and 130 ohms between different pins on each MOSFET). I checked the resistances of R28, R29, R30, R32, R33, R34 and R35 and they look correct. Do I just need to replace the MOSFETs?_

 

Yes, you should not get such low ohms between any MOSFET pins. Now, they blew out for a reason, so make sure you check the rest of the board carefully. I previously posted using the diode check function of the DMM to veryfy the small signal BJTs. You should do this on all the BC550C and BC560C transistors. This method will not work on JFETs, though. Also check for bad solder joints, particularly around R25-R27, VR2, Q17 and Q18.

  Quote:


 For the board with VR2 adjustments, it is not responding to VR1 adjustments now 
	

	
	
		
		

		
		
	


	




 I getting the following readings:
 R9 = 0.74V
 R10 = 0.78V
 R11 = 0V
 R12 = 1.50V
 D11 = 30.7V
 D12 = 0.8V
 When it did bias at VR1 before, I remember the voltages at R10, R11 and R12 being slightly higher (4.5-4.6V). 
 

Looks like your Q25 is blown.


----------



## Gatsu

Just finished putting together the PSU for my Beta22 last night.
 Fully assembled




 Initial testing of the Sigma's, using an Ardiuno and LCD to track all four rails at once.





 Yes its heavily based on Naamanf's build


----------



## johnwmclean

Quote:


  Originally Posted by *Gatsu* /img/forum/go_quote.gif 
_Just finished putting together the PSU for my Beta22 last night.
 Fully assembled




 Initial testing of the Sigma's, using an Ardiuno and LCD to track all four rails at once.





 Yes its heavily based on Naamanf's build 
	

	
	
		
		

		
		
	


	


_

 

Whooo sounds nice, but those images are not viewing for me


----------



## Gatsu

Hmm... lets try that again...


----------



## johnwmclean

Nice Gatsu, a real beast! Was this a Glass jar kit? You’ve got great tolerances with those specs. Congratulations looks absolutely awesome!


----------



## luvdunhill

gatsu:

 Can you post a close-up of one of the mosfets on the PSU? It's hard to tell how it's mounted. What's the board in the back for again?


----------



## Gatsu

Yup, thats the glass jar kit, makes things so much easier 
	

	
	
		
		

		
		
	


	




 (Thanks Jeff!)

 I have cut notches into the heatsink so I could have them mounted closer together. The vents in the bottom of the case now line up with the heatsink fins. I figure the way Perth summers get I need it to handle as much heat as it can 
 I'll grab a couple of close up shots when I get home tonight.

 The board in the middle is the power controller. Its a picaxe microprocessor as well as a 5V PSU (for the amp controller as well). The picaxe senses the supply rails through 4 opto-couplers and if one drops out it flashes an error code on the power switch LED.


----------



## sachu

simply beautiful gatsu...

 did you write the picaxe code yourself?...Very cool..


----------



## johnwmclean

Quote:


  Originally Posted by *Gatsu* /img/forum/go_quote.gif 
_I figure the way Perth summers get I need it to handle as much heat as it can _

 

Is a headphone/speaker design?

  Quote:


  Originally Posted by *Gatsu* /img/forum/go_quote.gif 
_I'll grab a couple of close up shots when I get home tonight._

 

Keep em coming 
	

	
	
		
		

		
			





  Quote:


  Originally Posted by *Gatsu* /img/forum/go_quote.gif 
_The board in the middle is the power controller. Its a picaxe microprocessor as well as a 5V PSU (for the amp controller as well). The picaxe senses the supply rails through 4 opto-couplers and if one drops out it flashes an error code on the power switch LED._

 

Never heard of this, like to hear more about the pros and cons regarding this feature - never seen any on other builds.


----------



## Gatsu

Quote:


  Originally Posted by *johnwmclean* /img/forum/go_quote.gif 
_Is a headphone/speaker design?

 Keep em coming 
	

	
	
		
		

		
		
	


	




 Never heard of this, like to hear more about the pros and cons regarding this feature - never seen any on other builds._

 

Primarily headphone, but I like to leave my options open 
	

	
	
		
		

		
		
	


	




 The is definitely a case of me making something more complicated than it needed to be 

 I wanted the front panel of the PSU case to just have a single button with the power indicator, however it was to be a dual PSU so I really needed to be able to show what state each PSU was in.
 My original idea was to use the LED into an optocoupler and that told the microcontroller the sigma was working.

 But! During the build, I messed up. One rail had 40V and the other 0V, but the LED was still lit, ok so that idea wasn't going to work the way I wanted, and it evolved into what it is now. Who says I don't learn from my mistakes 

 As you guessed yes there are pros and cons to this. The main downside is that you can't tell what the actual voltage is, just that there is voltage and its over the threshold for the optocoupler and picaxe logic to trigger. You could fine tune the threshold with some experimentation however, so it would be a known value.

 The Arduino rig on the breadboard is a much better way of doing this (the Arduino has 6 analog inputs while the picaxe08M has 3, the picaxe20 has 6). I can sense 6 analog lines and give accurate values, so the four voltage rails as well as temperature in each case, not to mention output to an LCD. That's getting close to information overload though 

 As it is, the power LED will flash a different code depending which sigma22 is giving problems or if both are down.

 All because I just wanted a single power indicator on the front of the case 

 I was a bit hesitant about the picaxe at first but I had a little help from someone at work to get started (Thanks Egon!) and it turned out easier than I initially thought.


----------



## johnwmclean

^ WOW my LEDS are purely cosmetic then LOL. Thankyou so much for the info, I'm really looking forward to those pics.

 If this turns out to be a purely headphone psu, you get my vote for over the top OVERKILL. Please keep us posted with your amp developments!


----------



## Gatsu

As requested, a closeup of the FETS mounted on the heatsink 




 As you can see I cut away a section of the heatsink. This helps the fins of the heatsink line up with the vents in the bottom of the case.

 And also a closeup of the picaxe controller





 The four six pin chips near the front are the optocouplers - one for each rail.
 Behind the heatsink for the regulator you can see the solid state relay mounted to the back panel.


----------



## fault151

Just looking at your pics, what does the picaxe controller do? Its a fiddly job mounting them mosfets to the conrad sinks isn't it? I know i did it on mine. Your pics are looking really good!


----------



## Gatsu

Primarily the picaxe handles the power switching with some added bells and whistles.
 In its simplest form it allows you to use a momentary push button to toggle the power on and off. But because of the additional inputs and logic also allows you to do some more interesting stuff.

 If you didn't want to get fancy you could trim it down to just a handful of components to switch the power.

 The Conrad (well I think its a Conrad - I bought them from my local Jaycar, no brand is mentioned on them) wasn't too bad to work with. It was just fiddly lining up everything at once.

 Hopefully I'll get time to start casing up the amp this weekend.


----------



## fault151

So it is a bit like the AMB LABS e24 board in a way. That is what i am using with my illuminated bulgin switch and power relay.

 Can't wait to see your finished amp.


----------



## El_Doug

Quote:


  Originally Posted by *fault151* /img/forum/go_quote.gif 
_So it is a bit like the AMB LABS e24 board in a way. That is what i am using with my illuminated bulgin switch and power relay.

 Can't wait to see your finished amp._

 

im in the middle of soldering my e24, myself! my bulgin switch has a red LED - what about yours?


----------



## fault151

Quote:


  Originally Posted by *El_Doug* /img/forum/go_quote.gif 
_im in the middle of soldering my e24, myself! my bulgin switch has a red LED - what about yours?_

 

I went for the blue type as my leds on the psu and amp are also blue.

 Here's my blog which i post quite a bit about my b22 build on there.


----------



## Nebby

Quote:


  Originally Posted by *fault151* /img/forum/go_quote.gif 
_I went for the blue type as my leds on the psu and amp are also blue.

 Here's my blog which i post quite a bit about my b22 build on there._

 

Very cool blog, any more info on that relay board by MrMajestic?


----------



## fault151

Quote:


  Originally Posted by *Nebby* /img/forum/go_quote.gif 
_Very cool blog, any more info on that relay board by MrMajestic?_

 

In terms of trying it out i haven't had chance yet. I'll post a blog wehen i do get it hooked up.

 If you need info on the actual design, PM him, im sure he will be happy to help. 

 He also designed another version which switches for a prer amp. I would have had that but was struggling for space in my amp.


----------



## El_Doug

space is certainly at a premium in my setup - im cutting every corner imaginable to get the amp section (all 4 boards, plus attenuator) into a 310mm x 230mm 1U enclosure. should look AMAZING... should I succeed...


----------



## n_maher

Quote:


  Originally Posted by *El_Doug* /img/forum/go_quote.gif 
_space is certainly at a premium in my setup - im cutting every corner imaginable to get the amp section (all 4 boards, plus attenuator) into a 310mm x 230mm 1U enclosure. should look AMAZING... should I succeed..._

 

I hope you've accounted for ventilation. The more I work on beta22's the more I think you can never have too much.


----------



## smeggy

I have partial success with mine now. The Sigma 22 is fixed but only one of the three boards is making sound. One seems to be blown blown and the third measures properly and the LED is lit but nothing is coming out so I have to see what's going on tomorrow. Hopefully it's something simple. If not I'll be running a single board mono Beta 11


----------



## ting.mike

Building a 3 channel here. Still waiting for parts to arrive from Glassjar.. Saw a small black hammond case the other day, and I think I'll go that route for my beta22.


----------



## naamanf

Quote:


  Originally Posted by *ting.mike* /img/forum/go_quote.gif 
_Building a 3 channel here. Still waiting for parts to arrive from Glassjar.. Saw a small black hammond case the other day, and I think I'll go that route for my beta22.





_

 

When I think small Hammond case I think it might be good for a Mini3. How small are we talking?


----------



## oneplustwo

Quote:


  Originally Posted by *naamanf* /img/forum/go_quote.gif 
_When I think small Hammond case I think it might be good for a Mini3. How small are we talking?_

 

Yah... I thought the biggest Hammond cases were the ones I used for my M3 (8x6x2 I think) which I can't see being anywhere near big enough for a 3 channel beta. Maybe I missed some of the bigger ones?

 I guess you could put one board in one case and wire them together?


----------



## yuk228

dear AMB,

 I would like to ask 2 questions.

 1. Can u recommend some choices for power switch of the sigma 22?I just want a toggle one which is connected in series with the IEC, but there are too much choices, and I want to choose one which is no harm for the sound quality. U may recommend some brands or even the model name.

 2. Install the mosfet chips in contact with the case or install the mosfet in contact with the heatsink, which one is better?

 Thanks a lot!


----------



## TimmyMac

I'll eat my hat if anyone on this board can distinguish between two power switches in a blind listening test.


----------



## El_Doug

Quote:


  Originally Posted by *yuk228* /img/forum/go_quote.gif 
_dear AMB,

 I would like to ask 2 questions.

 1. Can u recommend some choices for power switch of the sigma 22?I just want a toggle one which is connected in series with the IEC, but there are too much choices, and I want to choose one which is no harm for the sound quality. U may recommend some brands or even the model name.

 2. Install the mosfet chips in contact with the case or install the mosfet in contact with the heatsink, which one is better?

 Thanks a lot!_

 

1) It is impossible to tell the difference. Unless youre of the "Judge power cable"-persuasion, in which case youll probably be happy just buying the most expensive button you can find 
	

	
	
		
		

		
		
	


	




 2) That depends on your case. If its a thin steel case, then the heatsinks will be better. If it's a thick, flanged, aluminum case, then case mounting will be better. Of course, if this is simply a headphone amp and not going to be used as a speaker amp, then the heatsinks will provide adequate cooling regardless.


----------



## alwayshungry

I got my balanced beta22 up and running this weekend.
 Big thanks to amb, johnwmclean, fierce_freak, fault151 and Russ and Brian at TPA for their help along the way. I still need to get the front/rear plates for the case made but so far it sounds fantastic. This was my 2nd amp build (1st being the MH MiniMAX) and despite the difficulty and amount of work needed, it was well worth it. I will post pictures of the final product when everything is finished.


----------



## johnwmclean

Congrats Justin, can’t wait to see the pics. Glad you got through it relatively unscathed. It’s an awesome feeling listening to those first few tracks, I’m still coming down from it.


----------



## Bojamijams

congrats!


----------



## fault151

Quote:


  Originally Posted by *alwayshungry* /img/forum/go_quote.gif 
_I got my balanced beta22 up and running this weekend.
 Big thanks to amb, johnwmclean, fierce_freak, fault151 and Russ and Brian at TPA for their help along the way. I still need to get the front/rear plates for the case made but so far it sounds fantastic. This was my 2nd amp build (1st being the MH MiniMAX) and despite the difficulty and amount of work needed, it was well worth it. I will post pictures of the final product when everything is finished.



_

 

Welldone mate, glad it's working! Can't wait to see the pics of the panels and everything.


----------



## fault151

Quote:


  Originally Posted by *yuk228* /img/forum/go_quote.gif 
_dear AMB,

 I would like to ask 2 questions.

 1. Can u recommend some choices for power switch of the sigma 22?I just want a toggle one which is connected in series with the IEC, but there are too much choices, and I want to choose one which is no harm for the sound quality. U may recommend some brands or even the model name.

 2. Install the mosfet chips in contact with the case or install the mosfet in contact with the heatsink, which one is better?

 Thanks a lot!_

 

Peraonally i went with the bulgin illuminated vandal switch. they look really cool and have a really nice feel to them when you click them. 

 For the mosfets i installed mine with the heatsinks.


----------



## alwayshungry

Thanks guys. Do any of you with a balanced b22 have an issue with it being too loud? I'm using the balanced outs from a PS Audio DLIII and a Twisted Pear JT2 attenuator and I can barely go 1/4 of a turn before it goes from mute to earblowing. Also there is too much volume difference between the steps around my preferred listening volume. My b22 boards have the gain at 2x (4x overall). I know I could modify the resistor values on the JT2 but perhaps there is a more elegant solution.


----------



## johnwmclean

Quote:


  Originally Posted by *alwayshungry* /img/forum/go_quote.gif 
_Thanks guys. Do any of you with a balanced b22 have an issue with it being too loud? I'm using the balanced outs from a PS Audio DLIII and a Twisted Pear JT2 attenuator and I can barely go 1/4 of a turn before it goes from mute to earblowing. Also there is too much volume difference between the steps around my preferred listening volume. My b22 boards have the gain at 2x (4x overall). I know I could modify the resistor values on the JT2 but perhaps there is a more elegant solution._

 

Well you can’t reduce the gain anymore over the β22 boards, don’t know much about the JT2. Once you get the gain right the ratio between the steps will be a lot more subtle.


----------



## naamanf

Quote:


  Originally Posted by *alwayshungry* /img/forum/go_quote.gif 
_Thanks guys. Do any of you with a balanced b22 have an issue with it being too loud? I'm using the balanced outs from a PS Audio DLIII and a Twisted Pear JT2 attenuator and I can barely go 1/4 of a turn before it goes from mute to earblowing. Also there is too much volume difference between the steps around my preferred listening volume. My b22 boards have the gain at 2x (4x overall). I know I could modify the resistor values on the JT2 but perhaps there is a more elegant solution._

 


 I have built both a 2x and 5x gain balanced B22 with JTs. I have not head any problems with to much gain or large differences in attenuator steps. I would say either something is wrong with the JT, you balanced IEMs, or you listen too quietly 
	

	
	
		
		

		
		
	


	




 What headphones are you using?


----------



## peanuthead

Quote:


  Originally Posted by *alwayshungry* /img/forum/go_quote.gif 
_Thanks guys. Do any of you with a balanced b22 have an issue with it being too loud? I'm using the balanced outs from a PS Audio DLIII and a Twisted Pear JT2 attenuator and I can barely go 1/4 of a turn before it goes from mute to earblowing. Also there is too much volume difference between the steps around my preferred listening volume. My b22 boards have the gain at 2x (4x overall). I know I could modify the resistor values on the JT2 but perhaps there is a more elegant solution._

 

It might be your DAC. I think DLIII has higher than average output voltage.


----------



## amb

If you're using a source that is "too hot", then you might want to add an input attenuator at the amp. Here is a schematic of a switchable attenuator. It is drawn for an unbalanced (2 or 3 channel) amp, for a 4-channel balanced amp you'll need to double everything for the negative signal, and use either a 4PDT switch, or two DPDT switches.







 If you use the same value for all the resistors, then the attenuator will drop the effective gain of the amp by one half (-6dB). A good value to use is anywhere from 10K to 47K.


----------



## johnwmclean

AMB, since on the subject of gain I have a question.
 I'm building a dac that outputs 4Vp-p in balanced, my Beta 22 is set to 2 total 4 in balanced, driving 650's.
 Do you think I'll have an issue with these gain settings?


----------



## amb

Quote:


  Originally Posted by *johnwmclean* /img/forum/go_quote.gif 
_AMB, since on the subject of gain I have a question.
 I'm building a dac that outputs 4Vp-p in balanced, my Beta 22 is set to 2 total 4 in balanced, driving 650's.
 Do you think I have an issue with these gain settings?_

 

4Vp-p is only 1.4Vrms and should not be excessive with the HD650 on a low gain amp.

 EDIT: I hope you really mean 4Vp-p, and not 4Vrms. If the latter, then the gain might be on the high side. Only way to know is to try it, I guess.


----------



## johnwmclean

Thanks AMB, for the quick reply. 4p-p is correct..


----------



## askforwhy

Hello guys,
 I am planning to build 6-channel Beta22 combining balanced and SE amp. I would use balanced K701 and maybe balanced HD600 in the future. With a 23-step attenuator, will the default 8x gain(which would be 16x balanced) be too loud or not so flexible?


----------



## johnwmclean

There is no clear answer as it depends on your source output, and all sources vary to a degree. Gain 8 in balanced configuration is generally way too high with the 600’s from what I’ve heard and read. Maybe for this type of build you might want to try the gain positions socketed. Could be tricky with a 6 board build to get right first time round.


----------



## askforwhy

thanks johnwmclean,
 I'll go for 5X first then.


----------



## TimmyMac

5x drives my sony SA5000 to uncomfortable levels at around one oclock, and still has plenty of juice to drive my 8-ohm speakers. Seems to be a good balance.


----------



## alwayshungry

Thanks for the input everyone. I'm using HD650s btw. Apparently the DLIII puts out 5.5 Vmax on it's balanced outputs. I was under the impression that 2.5-3.5V was normal. I contemplated replacing the resistors on my JT boards but it looks like the input attenuator is a better way to go. Thanks amb.


----------



## El_Doug

I just discovered that it is possible to stuff 4 B22 boards in a single day


----------



## johnwmclean

I averaged 10 hrs a board, 1 hr testing each. 40 hrs total.
 Betcha the debuggings going to average out with my 40hrs


----------



## aloksatoor

i averaged 2 hours per board with around an hour to debug each


----------



## askforwhy

Sorry for my stupid questions again
	

	
	
		
		

		
		
	


	



 But may I substitute the MLCC C1-C5 with silver mica caps?
 I've purchased some cheap MLCC but I don't really trust their quality.


----------



## amb

Yes, you can use silver mica in those positions, as long as the fit is good and the cap can be mounted tightly against the board without extra lead-length.


----------



## askforwhy

Thanks, Ti


----------



## Karu

Hi Everybody,

 I'm planning to use my K-701 with the β22 and have done some calculations. I have made some assumptions, the validity of which I have no idea. Can someone more knowleable check that they at least resemble the reality? 
	

	
	
		
		

		
			





K-701
 - Max. input power: 200mW
 - Impedance: 62Ω
 - Max current: √(200mW * 62Ω) = 56.8mA (I guess this is per can)

Balanced β22 board current draw (4 total)
 - From earlier post by AMB, I gather the there is an inherent ~40mA draw by each board.
 - Selected quiescent current: 120mA
 - Idle current draw per board: 40mA + 120mA = 160mA
 - Max current draw per board: 160mA + (56.8mA / 2) = 188.4mA

Power dissipation by β22 board (4 total)
 - per β22 amp MOSFET: 8V * (120mA + (56.8mA / 2)) = 1.2W
 - per β22 cascade MOSFET: (30V - 8V) * (120mA + (56.8mA / 2)) = 3.3W
 - per β22 board: 2 * 1.2W + 2 * 3.3W = 9W

Power dissipation by σ22 board (2 total)
 - per σ22 MOSFET: (42V - 30V) * ((2 * 188.4mA) / 2) = 2.26W
 - per σ22 rail: 2 * 2.26W = 4.5W
 - per σ22 board: 2 * 4.5W = 9W


----------



## johnwmclean

Karu, I can’t help you with the math, I’ll leave that to the more knowledgeable personages, but as for heat dissipation over dual sigma 22’s powering a 4 channel β22 driving K701’s. Wouldn’t even raise a sweat.


----------



## Karu

Thanks johnwmclean. That's my feeling too. 
	

	
	
		
		

		
		
	


	




 The reason I included it in the calculations is to see whether I understand correctly load's effect on the system. There may be a time later when I want to drive something more hungry.


----------



## amb

Karu, you don't need to add the 56.8mA load current to the quiescent current in order to get the total output stage current. This is because the amp operates in pure class A, the output current through the load comes from the quiescent current (which is much greater than the current through the headphone load).

 Other than that, your calculations are mostly correct. Deducting the 56.8mA from all your math causes all your power dissipation numbers to be a bit lower.


----------



## askforwhy

Sorry to bother you guys again.
	

	
	
		
		

		
		
	


	



 I am planning using two 2-ch attenuator for my balanced beta22, one for L+ R+, another for L- R-, so I can control the volume individually when listen to two unbalanced headphones with balanced input.
 My question is that will it damage the headphone if I don't turn up/down the L+ R+/L- R- attenuator simultaneously?
 I just want to make sure before I do something stupid.


----------



## digger945

One balanced 4 channel attenuator would work for both/either.


----------



## Karu

Thanks amb for checking the numbers and clarifying things a bit!

 Just out of curiosity. If I attach an efficient speaker to the output, wouldn't I most likely draw a peak current much greater than the quiescent? If I understand correctly, then the amplifier is no longer operating in class A. Where should I add those numbers to the calculations?

 A second question in the opposite vein: If I assume, on the other hand, that I will never drive anything more hungry than those K-701s. Shouldn't I be able to reduce the quiescent current to 56.8mA and still be able to enjoy the full range of my cans and stay in class A?


----------



## askforwhy

Quote:


  Originally Posted by *digger945* /img/forum/go_quote.gif 
_One balanced 4 channel attenuator would work for both/either._

 






Sure you can.
 But when using two different unbalanced headphones(different sensitivity) on beta22, I may want to adjust the volume individually.


----------



## amb

Quote:


  Originally Posted by *askforwhy* /img/forum/go_quote.gif 
_Sorry to bother you guys again.
	

	
	
		
		

		
		
	


	



 I am planning using two 2-ch attenuator for my balanced beta22, one for L+ R+, another for L- R-, so I can control the volume individually when listen to two unbalanced headphones with balanced input.
 My question is that will it damage the headphone if I don't turn up/down the L+ R+/L- R- attenuator simultaneously?
 I just want to make sure before I do something stupid.
	

	
	
		
		

		
		
	


	


_

 

Nothing would be damaged, but if you're going to use two pots, you should use one for L+ and L- and the other for R+ and R-. This is to ensure that each stereo channel's hot and cold signals are on the same pot for the best tracking. That said, it 's inconvenient to turn two knobs to change the volume, and if you use regular (especially undetented) pots, then it would be difficult to keep the two stereo sides level-matched.

 A 4-gang pot or stepped attenuator is a much better solution.


----------



## mattcalf

Just a quick, 99% hypothetical question that will hopefully become relevant a long way down the track.
 And it's probably a question best answered by Jeff at Glass Jar Audio but I'm sure there are many in this thread that can answer it for me.

 I have a plan (read: dream) in which I build a Beta22 passive config for a pre-amp as well as a fully balanced build with speaker and headphone out. 
 Glass Jar Audio only offer three and four board kits, are all the boards the same so in reality: Can I could just order 2x three board kits and build the two and four board amps?


----------



## Stevesebastianb

Have interest in building one, but need to read up on all the details first.


----------



## amb

Quote:


  Originally Posted by *Karu* /img/forum/go_quote.gif 
_Just out of curiosity. If I attach an efficient speaker to the output, wouldn't I most likely draw a peak current much greater than the quiescent? If I understand correctly, then the amplifier is no longer operating in class A. Where should I add those numbers to the calculations?_

 

With an 8Ω speaker load the peak output current could exceed the quiescent current when you turn up the volume, in which case the output stage will flow more than the quiescent current. You don't need to add the output current to the quiescent current, though. The current flowing through the output stage at that point is basically just the output current.

 For an amp with a push-pull output stage like the β22, the output stage will drop out of class A operation when the quiescent current is less than half of the peak output current.

  Quote:


 A second question in the opposite vein: If I assume, on the other hand, that I will never drive anything more hungry than those K-701s. Shouldn't I be able to reduce the quiescent current to 56.8mA and still be able to enjoy the full range of my cans and stay in class A? 
 

You could reduce the quiescent current, but the MOSFETs will be operating at a region of its transfer curve that's less linear. The β22 has a dynamically-cascoded output stage which linearizes the effective transfer curve, but the amp will still sound better when biased to the recommended operating points.

 By the way, the minimum quiescent current (Iq) for the amp to stay in class A is 40mA, assuming that you will not make the amp deliver more than 200mW into 62Ω (these are the limits you specified for the K701).

 The RMS output current into 62Ω (per channel) is:

 Prms = Irms² * R
 Irms = √(Prms / R) = √(200mW / 62Ω) = 56.8mA
 Ipeak = Irms * 1.4142 = 80mA

 The amp must quiesce at least half of Ipeak to remain in class A, therefore Iq should be at least 40mA.
 Of course, if you use different headphones, then the power and impedance conditions change and the class A threshold will also change. This is why the default recommended Iq is so high -- to make sure that the amp will run in pure class A for any conceivable headphone load even at very high output levels.


----------



## askforwhy

Quote:


  Originally Posted by *amb* /img/forum/go_quote.gif 
_Nothing would be damaged, but if you're going to use two pots, you should use one for L+ and L- and the other for R+ and R-. This is to ensure that each stereo channel's hot and cold signals are on the same pot for the best tracking. That said, it 's inconvenient to turn two knobs to change the volume, and if you use regular (especially undetented) pots, then it would be difficult to keep the two stereo sides level-matched.

 A 4-gang pot or stepped attenuator is a much better solution._

 

Thanks Ti,
 I have two pre-matched stepped attenuator, I hope it work fine.


----------



## johnwmclean

Quote:


  Originally Posted by *mattcalf* /img/forum/go_quote.gif 
_Just a quick, 99% hypothetical question that will hopefully become relevant a long way down the track.
 And it's probably a question best answered by Jeff at Glass Jar Audio but I'm sure there are many in this thread that can answer it for me.

 I have a plan (read: dream) in which I build a Beta22 passive config for a pre-amp as well as a fully balanced build with speaker and headphone out. 
 Glass Jar Audio only offer three and four board kits, are all the boards the same so in reality: Can I could just order 2x three board kits and build the two and four board amps?_

 

Don’t order the 2 x 3 channel Active Ground kit as one of the boards is used as a ground channel, the difference is a resistor on the ground board (R1) is not used.

 What you need to do is order a 2 board passive kit (choose the gain you need) even though Jeff doesn’t advertise this kit he’ll do it, no problems. And a balanced kit, again you will have to nominate your gain with this build also.


----------



## Karu

Thanks amb for a good explanation. I think I got it now. 
	

	
	
		
		

		
		
	


	




 This will make dimensioning decisions much easier.


----------



## Karu

My next question centers on gain. I assume the same K-701, a balanced β22 with the minimum gain of 2 and a typical 2Vrms source.

K-701
 Prms = 200mA

β22
 Vrms = 2 * 2 * 2Vrms = 8Vrms
 Prms = (8Vrms)²/62Ω = 1W

Difference in max. power
 dB = 10 * log (1W / 0.2W) = 7dB

 Does that mean that I can use only a bit less than half of the range of the typical attenuator?


----------



## oneplustwo

Anyone have any recommendations for an 8 conductor umbilical cable? I'm trying to keep things simple and run the 6 wires for two sigma 22's plus the wires for my joshua tree attentuator in one cable. The joshua tree wires will be AC though... should I run a separate cable for that one?


----------



## sachu

there are some russian connectors available on ebay. Suggest you cehck them out. mil spec.


----------



## linuxworks

you're in the bay area - go to halted (south bay) and get military multipin connectors.

 I did. I have some mating 'camo green' connectors that seem old but never used. they were $15 a set, I think. I be they costed the US more than 10x that


----------



## aloksatoor

thanks for the tip 
	

	
	
		
		

		
		
	


	




 i need to pickup some as well for a sigma for a gilmore lite 
  Quote:


  Originally Posted by *linuxworks* /img/forum/go_quote.gif 
_you're in the bay area - go to halted (south bay) and get military multipin connectors.

 I did. I have some mating 'camo green' connectors that seem old but never used. they were $15 a set, I think. I be they costed the US more than 10x that 
	

	
	
		
		

		
		
	


	


_


----------



## oneplustwo

thanks for the tips. how about the wire/cable itself?


----------



## oneplustwo

Ooo... found this on ebay.


----------



## digger945

I am pretty sure Speakon connectors only have two contacts. Notice the seller doesn't show the ends of the connectors.
 Another reasonable connector would be the Amphenol Ecomate line, available at Mouser.
 I think I paid something like about $25 per set.


----------



## alwayshungry

I'm using Amphenol Ecomate connectors from mouser and belden 16 ga spc from here. I'm looking forward to your balanced b22 build. Your 3 channel was great looking and such a bargain on the F/S forum.


----------



## yuk228

I would like to ask about wiring

 If I made the 4 boards B22 with balanced input only, after reading the guidelines of wiring section, it assumed that the input signal for unbalanced headphone is coming from the unbalanced input. 

 But if I want to connect both unbalanced and balanced headphone to B22 with balanced input signal only, do I need a switch to do so? Here is my idea.

 There are 4 boards of beta22, no. 1,2,3,4.

 unbalanced headphone 1:
 switich the terminal 2 of both left and right XLR input to no. 1,2 b22 boards.

 unbalanced headphone 2:
 switch the terminal 2 of both left and right XLR input to no. 3,4 b22 boards

 balanced headphone
 switch 1,2 terminal of both left and right XLR input to 1,2,3,4 board respectively.

 Is my idea correct?
 Also any other methods can be recommended?I doubt is there a switch can do what I want.


----------



## digger945

You really don't need a switch at all, for anything, if you don't want.
 You can listen to both Bal and Unbal source with both Bal and Unbal cans, without a switch for anything.
 You'll find complete schematics at the AMB.org website, and I believe the schematic for the switch that allows you to ground the inputs of the negative amps to enhance listening to a SE source with Balanced cans either there or maybe on this thread here, can't remember.


----------



## yuk228

Quote:


  Originally Posted by *digger945* /img/forum/go_quote.gif 
_You really don't need a switch at all, for anything, if you don't want.
 You can listen to both Bal and Unbal source with both Bal and Unbal cans, without a switch for anything._

 

So how is the wiring of the boards?
 do u mean the output signal from the boards which amplified the terminal 2 of both left and right XLR can be wired to unbalanced headphone??


----------



## digger945

Yes, exactly.
Have a look, directly from the designer and builder of the Beta22 himself, on his own website.
 All the information you'll ever need to know about the Beta 22 is found at AMB.org, plus lots more, 
 in addition to the wealth of information found here at Head-Fi.


----------



## smeggy

Ah, my replacement parts have arrived! 

 I'll know tonight whether it is just some blown MOSFETs on my board or not. Hopefully it's gonna work. *Fingers crossed*


----------



## amb

Quote:


  Originally Posted by *Karu* /img/forum/go_quote.gif 
_My next question centers on gain. I assume the same K-701, a balanced β22 with the minimum gain of 2 and a typical 2Vrms source.
 ...
 Does that mean that I can use only a bit less than half of the range of the typical attenuator?_

 

It only means that if you're listening to highly-compressed music that has an average recorded level near 0dBFS. Many recordings are very dynamic and averages much, much less than that. so you have to have extra gain to accommodate them.


----------



## oneplustwo

yuk - here's another way to wire up the boards. I'm actually going to try to implement this method. Just placed my order with mouser for all the bits and pieces that I didn't get from glass jar. The boards are all soldered up with the exception of the mosfets. (Waiting on pinned heatsinks... don't want to tap 24 heat sinks.)

 The speakon cable I bought from ebay is indeed 8 pin. It will carry the 6 wires from both sigmas and the 2 wires from the trafo for the joshua tree. I'm actually short one wire as the wiring diagram above has the signal ground going back to the sigma case via it's own wire. Can I share the ground wire from the 2 sigmas? Is that kosher? If so, then I have the signal ground wire I need. If not... I'll have to think of a different solution.


----------



## linuxworks

amb told me, pretty strongly, that if your psu board was 'remote' that the ground wire to the phones jack ALSO had to be in that 'remote' cord.

 grounding is VERY important on this amp. I'd take that seriously.


----------



## oneplustwo

linuxworks - no question there... just trying to understand if I can get away with using 5 wires for the PSUs (two V+, two V-, and one G). That way I'll have a wire available for the headphone ground wire.


----------



## amb

You should run the TRS headphone jack ground (sleeve) return to the σ22 G pad on its own wire. Don't pollute the signal reference G wire from the β22 boards with the headphone return current, even though it also connects to the σ22 G pad.

 Ideally, since you're also running two σ22 boards, the left and right β22 signal reference G wires should also be independent to each respective σ22 board, this is especially true if you're running separate transformers for each σ22. In that case the only point where the two channels' signal reference G connect together is at the input jacks.


----------



## oneplustwo

Hmm, I was afraid of that. Any problem running 9VAC through two of the wires in an 8 conductor cable?

 New question - Is there a good way of connecting the power and output wires to the Beta boards? I just soldered them directly in last time but thought it would be nice to have something similar to the molex connectors for the input wires.


----------



## amb

Avoid running AC wires (even if it's only 9V) along the length of V+/G/V- and signal wires. There is enough amplitude at 60Hz to induce noise into the other wires. It's best to run DC instead, and put all trafos in the PSU chassis.


----------



## oneplustwo

Yah... that's what I thought. Unfortunately, the joshua tree needs 7-24VAC so I'll probably just run a separate umbilical for it. Oh well... I have an amphenol ecomate cable set I was originally going to use for this project before I decided on going with 2 sigmas so I guess it will get used after all.


----------



## dbfreak

Quote:


  Originally Posted by *oneplustwo* /img/forum/go_quote.gif 
_Hmm, I was afraid of that. Any problem running 9VAC through two of the wires in an 8 conductor cable?

 New question - Is there a good way of connecting the power and output wires to the Beta boards? I just soldered them directly in last time but thought it would be nice to have something similar to the molex connectors for the input wires._

 

Presto!


----------



## oneplustwo

Nice! I didn't even bother trying those! Thanks! Are there single position versions?


----------



## KONAKONA

So, about how much does it cost for all the parts to build one of these? I did a little bit of searching on the site but I can't seem to bring anything up, and it's too late to look up all the parts so I thought I'd just ask.


----------



## oneplustwo

Glass Jar Audio : Home is the way to go in my opinion since a number of the parts need to be matched. I think the 4 channel kit plus 2 sigma 22's with the upgraded caps cost me $575 after the paypal fee and shipping. You can check out other permutations on the site. Of course, you still need jacks, enclosure, IEC, wire, etc.


----------



## johnwmclean

Quote:


  Originally Posted by *dbfreak* /img/forum/go_quote.gif 
_Presto!_

 

I found this method a godsend, the advantage of being able to unscrew the V+ G V- wiring from the boards was great, makes testing the boards very easy too. No wiring to be seen from above, and easy access to the boards if something should go wrong. Why solder?


----------



## FallenAngel

Nice post dbfreak, now where were you a week ago when I was running my power wiring. 
	

	
	
		
		

		
		
	


	




 Opening this baby up this weekend to install those instead.


----------



## Karu

Quote:


  Originally Posted by *amb* /img/forum/go_quote.gif 
_It only means that if you're listening to highly-compressed music that has an average recorded level near 0dBFS. Many recordings are very dynamic and averages much, much less than that. so you have to have extra gain to accommodate them._

 

Thanks amb. So, would you recommend a gain of 2 in my setup, or should I consider setting it higher?


----------



## FallenAngel

Gain of 4 is good for me


----------



## smeggy

Bah, my dead board is still dead.

 Replaced the mosfets but I'm not getting any results. The trimpots don't seem to be doing anything and I'm not getting any readings from R12 or R34. I'm getting a small reading from the output so something's going on but I can't figure out where the signal is going.34 R34 R34


----------



## johnwmclean

Quote:


  Originally Posted by *FallenAngel* /img/forum/go_quote.gif 
_Nice post dbfreak, now where were you a week ago when I was running my power wiring. 
	

	
	
		
		

		
			





 Opening this baby up this weekend to install those instead._

 

You'll be soldering between two very close heatsinks when you install these puppies. Check your iron has reach before desoldering your wiring


----------



## amb

Quote:


  Originally Posted by *smeggy* /img/forum/go_quote.gif 
_Replaced the mosfets but I'm not getting any results. The trimpots don't seem to be doing anything and I'm not getting any readings from R12 or R34. I'm getting a small reading from the output so something's going on but I can't figure out where the signal is going._

 

Turn all trimpots back to their initial setup positions (see website instructions) and start over. After applying power, first make sure that both supply rails have the correct voltage, then measure the voltage across D11 and D12 to make sure that neither is more than a couple of volts. If one or both of these have too much voltage across them, then the corresponding Q25 or Q26 is dead.

 Assuming you passed the above check, then proceed to the initial setup steps. When you're setting VR1, can you achieve 4.5V across R9, R10, R11 and R12?


----------



## mattcalf

Quote:


  Originally Posted by *johnwmclean* /img/forum/go_quote.gif 
_Don’t order the 2 x 3 channel Active Ground kit as one of the boards is used as a ground channel, the difference is a resistor on the ground board (R1) is not used.

 What you need to do is order a 2 board passive kit (choose the gain you need) even though Jeff doesn’t advertise this kit he’ll do it, no problems. And a balanced kit, again you will have to nominate your gain with this build also._

 

Cheers John, I'm very jealous of your build! Thanks for clearing that up and let me know if you ever want to send your B22 to another home.


----------



## oneplustwo

So it turns out I can feed the Joshua Tree board with DC so I was considering poaching one of the sigma 22 feeds to power the attenuator. It doesn't seem like it would draw so much current that it would adversely affect the two beta boards but thought I would check here and see what people thought.


----------



## dbfreak

Quote:


  Originally Posted by *oneplustwo* /img/forum/go_quote.gif 
_Nice! I didn't even bother trying those! Thanks! Are there single position versions?_

 

Not that I am aware. I used a two position and clipped one of the legs. Use the Press Fit type, they are stronger (especially for the signal out connection that must rely on a single solder pin/leg).


----------



## smeggy

Quote:


  Originally Posted by *amb* /img/forum/go_quote.gif 
_Turn all trimpots back to their initial setup positions (see website instructions) and start over. After applying power, first make sure that both supply rails have the correct voltage, then measure the voltage across D11 and D12 to make sure that neither is more than a couple of volts. If one or both of these have too much voltage across them, then the corresponding Q25 or Q26 is dead.

 Assuming you passed the above check, then proceed to the initial setup steps. When you're setting VR1, can you achieve 4.5V across R9, R10, R11 and R12?_

 

Thanks Ti

 I tested D11 and 12 and they have 0.45 and 0.76v across them so that seems ok, the working board values are a little higher. 

 I cannot get any voltage change from either VR1 or VR2. The LED is on, the mosfets are fine and cross checking with the working board I haven't found any great discrepancies in readings.

 I'm going to go through the whole PDF voltage checklist to see if I can find anything. Any other suggestions would be welcome


----------



## smeggy

so it looks like generally the left side resistors to ground read 0.5v and the right side we're getting 28.8v.

 The good board is more like 24.# on both sides. Hopefully this helps


----------



## amb

You need to be more descriptive and specfic, smeggy... I am not sure what you mean by "left side resistors", which resistors are we talking about? And which end of the resistors are you measuring?


----------



## naamanf

Quote:


  Originally Posted by *oneplustwo* /img/forum/go_quote.gif 
_So it turns out I can feed the Joshua Tree board with DC so I was considering poaching one of the sigma 22 feeds to power the attenuator. It doesn't seem like it would draw so much current that it would adversely affect the two beta boards but thought I would check here and see what people thought._

 

The only problem I could think you might run into is that regulator might get pretty hot with the stock heat sink.


----------



## El_Doug

"If your standoffs or spacers are short, you should glue an insulating plastic sheet beneath the board to prevent board flexture from causing short circuits. " 

 indeed, my B22 boards will be quite close to the bottom of the case: the longest remaining tail of a resistor is about 5mm from touching metal, once the spacers are installed. 

 what kind of plastic sheet should I be looking for? I know there are probably many "hacks," that I can probably get the appropriate material at Michaels, and not necessarily an electronics store. still, I have no ideas. anyone have a suggestion?


----------



## Nebby

perhaps teflon sheet?

Order Plastic Teflon Sheet in Small Quantities at OnlineMetals.com


----------



## amb

5mm is quite a bit of clearance, I wouldn't worry it if that is indeed the closest thing to the chassis (don't forget heatsink mounting screws, if applicable and if your MOSFETs are not isolated from the 'sinks).


----------



## smeggy

AMB, how easy is it to convert a ground board to a channel board and what parts would be needed for an 8x gain? I've given up on the dead board, I can't troubleshoot for crap.


----------



## amb

Quote:


  Originally Posted by *smeggy* /img/forum/go_quote.gif 
_AMB, how easy is it to convert a ground board to a channel board and what parts would be needed for an 8x gain? I've given up on the dead board, I can't troubleshoot for crap._

 

Given up so easily? tsk tsk.

 Anyway, the parts differences between L&R and the G board are listed on the β22 website, under "parts list". Same for gain setting parts.


----------



## smeggy

Yeah well, I'd much rather have a working amp than an everlasting DIY project. I've been trying to get a working Beta for months.


----------



## dbfreak

Quick question. What is the voltage before the RLED's on both the Beta22 boards and the backplane board (wasn't clear in the voltage schematic)? I'll be using 30V configured Sigma22.


----------



## rshuck

I am strongly considering building a 4 channel for use with both Headphones and Speakers. Interestingly, I haven't seen an implementation here with a sigma for each beta, which I seem AMB recommends on the site.

 Considering two 350mm*151.5mm Conrads for this, and basically doing the same as the "Death Cube" as seen in this thread, and just FPExpressing the front and back. I figure I can get the 4 Sigmas and that gigantic 640VA Trafo that I saw in the other B22 thread in this case with a modder's mesh top panel and and *very* slow moving 120mm fan or two on the bottom to speed up heat dissipation.

 The Beta boards would be in another, 350*100mm case to the right, with the option to have a Buffalo32 cased similarly on top.

 FYI - Took me 3 days to read all of this thread. No stone unturned, I tell you.


----------



## amb

Quote:


  Originally Posted by *dbfreak* /img/forum/go_quote.gif 
_Quick question. What is the voltage before the RLED's on both the Beta22 boards and the backplane board (wasn't clear in the voltage schematic)? I'll be using 30V configured Sigma22._

 

The LED resistors are run directly off the +/-30V rails.


----------



## amb

Quote:


  Originally Posted by *rshuck* /img/forum/go_quote.gif 
_I am strongly considering building a 4 channel for use with both Headphones and Speakers. Interestingly, I haven't seen an implementation here with a sigma for each beta, which I seem AMB recommends on the site._

 

There is at least one (built by oj) shown in the β22 website gallery, but that one is for headphones only -- massive overkill! 
	

	
	
		
		

		
			





  Quote:


 FYI - Took me 3 days to read all of this thread. No stone unturned, I tell you. 
 

There is A LOT more at headwize, but unfortunately it's still down.


----------



## Karu

I have noticed that the venerable internet has a distinct lack of easily accessible discussion about mounting multiple sources to one heatsink. The available models for heat dissipation seem quite heavy. The following format from amb's website seems to provide a good approximation with a small modification.

 For single source per heatsink:

 Tj = Ta + (Pd * (Rjc + Rcs + Rsa))

 For multiple sources per heatsink:

 Tj = Ta + (Pd * (Rjc + Rcs) + Pt * Rsa))

 Where,
Tj = junction termperature
Ta = ambient temperature
Pd = power to be dissipated by device
Pt = total power to be dissipated by all mounted devices
Rjc = thermal resistance of junction to device case
Rcs = thermal resistance of device case to heatsink
Rsa = thermal resistance of heatsink to ambient

 It looks like this is an easy way to dimension the heatsink. Just pick the hottest running MOSFET and have look that it runs in the safe zone with these figures, the rest of the MOSFETs should automatically be fine.

 What is the consensus, will this work?


----------



## yuk228

can anyone tell is there any difference between toroidal transformer and encapsulated one?
 Will the sound be clear, and the noise becomes smaller?

 I am struggling whether choose which one on my beta22,btw the sigma 22 and transformer are in separate case.


----------



## digger945

I don't think it would matter, and even less if your PS is in a seperate case.


----------



## oneplustwo

If they're in separate cases, you probably don't need the encapsulated (shielded) one. It could matter quite a bit if you have your transformer in the same case. With my first beta, I tried to put it all together and even though I kept the toroid on the opposite end of the input and output wires, I still got humming until I moved it into it's own "enclosure." (This was for my cookie tin beta.)


----------



## ShinyFalcon

I need some fuse recommendations, since I'm not sure what the σ２２ needs (seems like 1.6A slow blow is enough?; the transformer is 80VA). I plan on getting this IEC and switch from Mouser:

 - 103-R13-112A-02-EV (Mountain Switch)
 - 693-6200.4315 (Schurter)

 ...*wonders what everyone is using for their IEC and switch*

 Edit: 2A fuse it is!


----------



## FallenAngel

That switch would work, as will the IEC.

 Personally, I REALLY like the anti-vandal switches, like the MP0045/1E2BL012.


----------



## NoValidTitle

Still making my way through this entire thread but I have a question...

 AMB or anyone else who may know for sure...

 I did read what rshuck also read that if going fully balanced and you plan on using speakers you should use 1 S22 per B22. Does that still stand with high efficiency speakers? I'm thinking about building a balanced B22 to use on some 95db(24Wrms 32Wpeak) full range speakers. I was thinking 2 S22s for the 4 B22s would be sufficient seeing some cans like the K1000 are pretty inefficient and do fine on a 2S/4B setup.


----------



## linuxworks

Quote:


  Originally Posted by *digger945* /img/forum/go_quote.gif 
_I don't think it would matter, and even less if your PS is in a seperate case._

 

spend the extra for a FULLY shielded trafo.

 it does matter.

 big-time.

 in this amp more than any other I've ever seen.

 believe it.


----------



## linuxworks

I also thought I'd need 2 trafos and 2 s22's for my spkr driver.

 I was wrong. it doesn't hurt to try and see how it works for you.

 my sprkrs are tannoy pbm8 (pretty efficient, ported design) and I get enough bass and volume to fully fill a bedroom size room (12x12 or so).

 what I'm going to do is to mount some heat sensors (lm34 or something) near the heatsinks in the b22 and see how the temp varies between phones and spkrs. at that point, I'll have DATA rather than "I think...".

 but so far, nothing has blown up (lol) and I am continuing to use my 2ch b22 for spkr use, for music and movies.

 honestly, I was not sure the b22 was cost effective for me. now that it does double duty, its a much better value


----------



## MrMajestic2

Quote:


  Originally Posted by *linuxworks* /img/forum/go_quote.gif 
_spend the extra for a FULLY shielded trafo.

 it does matter.

 big-time.

 in this amp more than any other I've ever seen.

 believe it._

 

X2. In a single case solution I would say its almost a must.


----------



## smeggy

I finally ordered the resistors and caps to convert my ground to a channel board. Hopefully it'll work and I can put this thing to bed finally.


----------



## MoodySteve

Quote:


  Originally Posted by *linuxworks* /img/forum/go_quote.gif 
_spend the extra for a FULLY shielded trafo.

 it does matter.

 big-time.

 in this amp more than any other I've ever seen.

 believe it._

 

X3

 Upgrading to a fully shielded/encapsulated transformer from SumR cured a line-borne buzz that I was hearing in sensitive phones. The difference was not subtle.


----------



## aloksatoor

x4 I have the 80VA SumR too... The encapsulation works like a charm

  Quote:


  Originally Posted by *MoodySteve* /img/forum/go_quote.gif 
_X3

 Upgrading to a fully shielded/encapsulated transformer from SumR cured a line-borne buzz that I was hearing in sensitive phones. The difference was not subtle._


----------



## linuxworks

can you take some shots of that sumr?

 I keep wanting to order a custom one from him, but I haven't seen any good photos of them and I'm kind of curious..

 did you have any quant. a/b on how well the shielding worked?

 I do have the faintest hum on my setup and I'm very tempted to upgrade from the avel unshielded to a sumr shielded.

 I believe you can also request extra voltage windings. that might also make the deal, for me, as I need a few strong 5v lines and some -12/+12 lines. if he can add those in and not have to go to a 2nd physical core, that gives a cleaner install and saves a lot of space and weight.


----------



## linuxworks

for now, I've remoted my toroid in a small box WAY away from things, on the floor.

 but I really don't like that solution. not really. not long-term.


----------



## oneplustwo

I'm ordering one for a build. He quoted me $105 for a 100VA unit, +-30V, 115VAC out the door.


----------



## linuxworks

my toroid was for 30v but I am thinking, if I had to do again, I might opt for 25.

 less heat = goodness. I kind of believe that.


----------



## linuxworks

Quote:


  Originally Posted by *oneplustwo* /img/forum/go_quote.gif 
_I'm ordering one for a build. He quoted me $105 for a 100VA unit, +-30V, 115VAC out the door._

 

well, if you have not finalized it yet, do consider getting an extra 5v winding, for any control circuits and some dual rail set of windings for any 'analog things' (lol) you might also want to bundle into the box.

 that's my thinking, at least.


----------



## NoValidTitle

So I got a tad bored and started playing with sketchup haha...

 The board dimensions and heat sink height are to scale. I wasn't sure the board thickness so I guess on that. 0.09"


----------



## El_Doug

Quote:


  Originally Posted by *NoValidTitle* /img/forum/go_quote.gif 
_So I got a tad bored and started playing with sketchup haha...

 The board dimensions and heat sink height are to scale. I wasn't sure the board thickness so I guess on that. 0.09"

http://farm4.static.flickr.com/3607/...95d6edd4_b.jpg_

 

dont power up! you installed Q1-Q4 incorrectly!!!


----------



## ShinyFalcon

I bought some Context Engineering case from Fry's and am doubting that the σ２２ will be able to slide in smoothly due to the heatsinks. There is a 6" clearance slot edge to edge, and if I'm lucky there will be 1mm of clearance from the edge of the board to the heatsinks' edges. Otherwise I'll have to fit the transformer and the board in awkward positions and more than likely I'll have to move the transformer to a smaller case. I guess I'll find out when the kit arrives...


----------



## amb

The board thickness is 0.062" (plus a smidge more for the copper, plating and soldermask).


----------



## ShinyFalcon

The slots are approximately 2mm high, so I'm definitely hoping that it will slide in. What I was concerned about is the vertical distance from the edge of the σ２２ to the heatsinks' edge. The case's slots are about 2mm wide.

 Also, when I decide to add the ground channel, will the separate matching of the JFETs cause the ground channel to be "different" from the left/right channels?


----------



## amb

Quote:


  Originally Posted by *ShinyFalcon* /img/forum/go_quote.gif 
_Also, when I decide to add the ground channel, will the separate matching of the JFETs cause the ground channel to be "different" from the left/right channels?_

 

No.


----------



## TStewart422

Does saving up and looking for a builder count?


----------



## NoValidTitle

Quote:


  Originally Posted by *amb* /img/forum/go_quote.gif 
_The board thickness is 0.062" (plus a smidge more for the copper, plating and soldermask)._

 

Sweet, thanks. Time to edit my model.


----------



## dbfreak

What is/are the benifit/s of installing a loop out for the Beta22? In other words, what is it's purpose?


----------



## linuxworks

loop-out just saves you from swapping cables or installing switches to let a source signal pass thru or 'around' a device.

 if I have a line-out from a dac and I want to send it to my phones amp and ALSO my spkr amp, a pass-thru would be useful for that.


----------



## dbfreak

Quote:


  Originally Posted by *linuxworks* /img/forum/go_quote.gif 
_loop-out just saves you from swapping cables or installing switches to let a source signal pass thru or 'around' a device.

 if I have a line-out from a dac and I want to send it to my phones amp and ALSO my spkr amp, a pass-thru would be useful for that._

 

Thanks, makes sense!


----------



## jtostenr

Would this also work for passing the signal along to a powered subwoofer? Or should there be a different output for that?

 Jeff


----------



## linuxworks

I did exactly that - to parallel the input wires with some outputs that go to my sub.

 in fact, I go thru a 2nd vol control so that I can remotely control sub volume.

 you may want a LP filter or band split (hp/lp) or just use the one in the sub.

 but yes, a passthru has good use for subwoofers.

 passthru is just a y-cable, folks


----------



## Nebby

Quote:


  Originally Posted by *linuxworks* /img/forum/go_quote.gif 
_I did exactly that - to parallel the input wires with some outputs that go to my sub.

 in fact, I go thru a 2nd vol control so that I can remotely control sub volume.

 you may want a LP filter or band split (hp/lp) or just use the one in the sub.

 but yes, a passthru has good use for subwoofers.

 passthru is just a y-cable, folks 
	

	
	
		
		

		
		
	


	


_

 

Would that affect the sound? How about two sub-outs? Would that require a buffer of some sort?


----------



## linuxworks

you are dividing the 'drive' between 2 loads.

 in practice, loads on inputs are high-z so it should not hurt. but some voltage will get 'lost' in terms of slightly lower output.

 proper way is to buffer each output. benefit includes having gain controls on each buffer so you can 'trim'.


----------



## ShinyFalcon

Quote:


  Originally Posted by *ShinyFalcon* /img/forum/go_quote.gif 
_The slots are approximately 2mm high, so I'm definitely hoping that it will slide in. What I was concerned about is the vertical distance from the edge of the σ２２ to the heatsinks' edge. The case's slots are about 2mm wide._

 

The board slides in perfectly. However I'm unsure if it's safe for the bottom ground plane to have the potential to short into the case. I'm sure the σ２２ wasn't designed as a slide-in board, but this solution is the only way that the σ２２ and the transformer can fit into my particular case. Otherwise I'll have to separate them or go for the Hammond case. Or, what I could do is hack at it with a knife and remove the portion of the plane that is contacting the case.

 I do recall that someone attached a wire of some sort into the transformer's mounting kit, and that it was considered something bad (short something). I don't know if it's related to my situation, but it doesn't hurt to know.


----------



## amb

Quote:


  Originally Posted by *ShinyFalcon* /img/forum/go_quote.gif 
_I do recall that someone attached a wire of some sort into the transformer's mounting kit, and that it was considered something bad (short something). I don't know if it's related to my situation, but it doesn't hurt to know._

 

Just don't use the toroid's mounting bolt as a ground point for chassis grounding. For that matter, don't let the head of that bolt touch anything at all except the toroid's top-mounting washer/dish. It's ok for the bottom of the bolt to be electrically connected to the chassis.


----------



## oneplustwo

Man... I think my first beta and all the other projects I've done going so well is making me too comfortable with this stuff (ie, sloppy). I accidentally powered up my beta boards with V+ and V- switched this morning. Damnit. Nothing smoked, but I noticed the trafo getting pretty hot and when I checked the voltage coming out of the sigma it was low. After disconnecting the beta, the sigma seemed ok. First thing I checked on the beta was the V+ and V- and of course there you have it. Any guidance on trouble shooting steps before I power up again?


----------



## amb

oneplustwo, if your σ22 still puts out the correct voltage, then there is a good chance that all is well. The β22 should have survived, because its output MOSFETs have an internal reverse body diode that looks like a dead short to the power supply if the V+ and V- were swapped, which should protect the β22 from damage. Fix the wiring and power up again. After you successfully adjust the bias, check the σ22 to see if all four MOSFETs get warm. If any MOSFET stays cold, then maybe the 0.47 ohm resistor in series with that MOSFET is blown.


----------



## oneplustwo

Thanks Amb. That's exactly the direction I was looking for! Any similar guidance for the sigma 22 that I messed up by putting in CR2 backwards?


----------



## amb

I don't remember what your broken σ22's symptoms are. But the standard thing to do is to check MOSFETs for shorts, check 0.47 ohms resistors for open circuit, and check your BJTs using the DMM's diode check mode (I described this several times elsewhere, search for it). The CRD itself is probably ok, but if you have a spare, replace it anyway.


----------



## rshuck

Quote:


  Originally Posted by *NoValidTitle* /img/forum/go_quote.gif 
_Sweet, thanks. Time to edit my model._

 

Are you by chance going to make this model available for download?


----------



## El_Doug

I happened to accidentally get some bi-polar caps, of the same values, for C9,C10,C11,C12. (UEP1H101MPD)

 Though I have a suspicion that this is a terrible idea that will serve no purpose other than to demonstrate my total lack of understanding of how different capacitors work, I do wonder - can I use these in my B22?


----------



## oneplustwo

Quote:


  Originally Posted by *amb* /img/forum/go_quote.gif 
_I don't remember what your broken σ22's symptoms are. But the standard thing to do is to check MOSFETs for shorts, check 0.47 ohms resistors for open circuit, and check your BJTs using the DMM's diode check mode (I described this several times elsewhere, search for it). The CRD itself is probably ok, but if you have a spare, replace it anyway._

 

MOSFETs and resistors look fine so far. It's probably the BJT(s). I might just go ahead and replace them all anyway since I need an excuse to practice using my Hakko 808 desoldering gun anyway. That being said, I could probably use some practice checking them with my DMM as well so I guess I can take a crack at that first.

 BTW, three of my four beta boards passed the initial checks fine. The fourth board is getting 0 volts at R9 and is not responding to VR1 adjustment. The LED lights up fine though and the MOSFETs (no shorts) and 0.47 Ohm resistors (no opens) appear to be fine. Suggestions on next steps?

 Thanks!


----------



## amb

El_Doug, 
 bipolar electrolytics typicallly have higher ESR and do not perform as well as a good polarized cap on these boards.


----------



## amb

Quote:


  Originally Posted by *oneplustwo* /img/forum/go_quote.gif 
_MBTW, three of my four beta boards passed the initial checks fine. The fourth board is getting 0 volts at R9 and is not responding to VR1 adjustment. The LED lights up fine though and the MOSFETs (no shorts) and 0.47 Ohm resistors (no opens) appear to be fine. Suggestions on next steps?_

 

Search for my post about checking the voltage drop across D11 and D12.


----------



## El_Doug

Quote:


  Originally Posted by *amb* /img/forum/go_quote.gif 
_El_Doug, 
 bipolar electrolytics typicallly have higher ESR and do not perform as well as a good polarized cap on these boards._

 

thank you! 16 new caps ordered


----------



## oneplustwo

Well, D12 voltage was like 28 so I guess I know what to replace. Hopefully that's the last problem before I finish up the wiring and get a listen!


----------



## amb

Quote:


  Originally Posted by *oneplustwo* /img/forum/go_quote.gif 
_Well, D12 voltage was like 28 so I guess I know what to replace. Hopefully that's the last problem before I finish up the wiring and get a listen!_

 

Just to remind you that it's not D12 that you need to replace, it's Q26.


----------



## oneplustwo

Right. I actually got that believe it or not. Thanks for the reminder though!


----------



## linuxworks

hey, I finally got my 2ch b22 cased up well enough to show it. its probably the cheapest case-work in the whole lot but it is stable and functional.

 I re-used a 2U PC router chassis, as is apparent:











 I also use ABS plastic sheets that my local plastic store cuts to size and those become poor man's LW-panel-express, sans labels 
	

	
	
		
		

		
		
	


	




 nothing expensive on parts but I did want to pay attention to wiring, routing and layout internally. I believe I have a near silent B22, now.

 the case was $15, the plastic was $5. and it will get me by until something better comes along.


----------



## mattcalf

Very nice!
 Did you source the parts yourself?


----------



## oneplustwo

what's with the extra caps on the sigma?


----------



## sachu

Quote:


  Originally Posted by *oneplustwo* /img/forum/go_quote.gif 
_what's with the extra caps on the sigma? 
	

	
	
		
		

		
		
	


	


_

 

more reserve power for when driving speakers i suppose.


----------



## linuxworks

Quote:


  Originally Posted by *oneplustwo* /img/forum/go_quote.gif 
_what's with the extra caps on the sigma? 
	

	
	
		
		

		
		
	


	


_

 

ha! you saw that?

 that was one of the caps that I blew up by installing backwards.

 I swore to get revenge on those caps. so I buddied them up so they'd have someone to watch over them. 2 can't be trusted at a time, so I brought in a third.

 lol


----------



## linuxworks

Quote:


  Originally Posted by *mattcalf* /img/forum/go_quote.gif 
_Very nice!
 Did you source the parts yourself?_

 

oh, MORE than once.

 (don't ask.)


----------



## digger945

Very nice. I like the green led's for a change of pace. Neat wiring. You'll have to let us know whatcha think of the SQ now. I've looked high and low for something to route wires that is kinda like those retainers for spark plug wires. I saw them on some machinery when I worked in a hosiery mill once, a long time ago. The machines where Italian.
 I like the way you lined up the HS's also. Not a big surprise from you though, you seem to always have neat builds.
 Thanks for the pics.


----------



## smeggy

Very pretty inside, I like


----------



## Hayduke

Nice job Linuxworks!

 I think a Beta 22 is going to be my next project 
	

	
	
		
		

		
		
	


	




 Do you have pics of it cased up?


----------



## johnwmclean

Linuxworks, very nice build mate. Good to hear there are no noise problems, nice neat wiring. Congrats!


----------



## zare

Quote:


  Originally Posted by *linuxworks* /img/forum/go_quote.gif 
_can you take some shots of that sumr?

 I keep wanting to order a custom one from him, but I haven't seen any good photos of them and I'm kind of curious.._

 

from the buffalo build on works:






 It's a 30VA fully shielded and encapsulated. Very well build. Have to go this way due to close proximity with the rest of the TP modules.


----------



## n_maher

Quote:


  Originally Posted by *linuxworks* /img/forum/go_quote.gif 
_hey, I finally got my 2ch b22 cased up well enough to show it. its probably the cheapest case-work in the whole lot but it is stable and functional._

 

Nice work! But no volume control? If that is the case I'd suggest that you be EXTREMELY careful plugging and unplugging your headphones.


----------



## linuxworks

no *local* volume control.

 I have another box that does that. for now. (later on, I might have something inside the b22 box but for now, its purely an amp).

 not having a volume pot means I also get better performance (the amp will test better since there's no pot to smear the channel separation, which is typical of what a pot does on the rmaa graph).

 as for plugging phones in, I have that a/b switch up front and so if I did want to plug phones in, I'd switch to spkrs, then plug the phones in, then switch one more time. that ensures safety.


----------



## Beefy

Quote:


  Originally Posted by *zare* /img/forum/go_quote.gif 
_from the buffalo build on works:






 It's a 30VA fully shielded and encapsulated. Very well build. Have to go this way due to close proximity with the rest of the TP modules._

 

I was thinking of grabbing two of _exactly_ those transformers for when I re-case my Buffalo, and a third one for my MMM. Could you possibly tell me the physical size of those, and how much they cost you?

 Also, what configuration did you get for the primaries? And the rated supply frequency?

 Cheers!


----------



## digger945

I would also be interested to know the same about those transformers. I've seen these before here but can't seem to find them online.


----------



## Beefy

Quote:


  Originally Posted by *digger945* /img/forum/go_quote.gif 
_I would also be interested to know the same about those transformers. I've seen these before here but can't seem to find them online._

 

SumR - Richard Sumner Technology:: Custom

 I am trying to arm myself with as much info as possible before contacting Richard, just so that I'm not bugging him


----------



## TeraHz

To answer the thread: I will be building a b22+y1 dac in it all powered by sigma22. Will try to add some lcd/led monitors on the front panels as well. I am still debating over which configuration to make though. 

 I guess balanced b22 +y1 doesn't work?

 Will most likely start in July so I will need all the help I can get. Hopefully it will not be very hard to do. Good thing I have this community to help.

 Regards!


----------



## amb

Quote:


  Originally Posted by *TeraHz* /img/forum/go_quote.gif 
_I guess balanced b22 +y1 doesn't work?!_

 

γ1 has only unbalanced output, if your β22 is built to accept balanced and unbalanced sources, then it could work.


----------



## DoYouRight

I have started collecting parts for my B22 I would like it to have BALANCED and SINGLEENDED. 

 How many boards do I need. So far I have 3.

 I am going to use AMBs FPD files from the KRMATHIS build for mine with minor changes. Any help modifying those files is GREATLY appreciated.
 -Evan


----------



## DoYouRight

If I follow FallenAngels/KRMATHIS's do I just need a adapter for the SINGLEENDED cable like the K1K to 1/4?


----------



## DoYouRight

I want this to be upgrade proof. So in case I get K1Ks, Balanced Phones, or 1/4 SE will all work without mods. Thanks!


 EDIT: Also since the B22 balanced wont work with the Y1 as it is not, what is the good DIY DAC for this besides a Buffalo32 which is impossible to get parts for? Or is it easier now?


----------



## NoValidTitle

Quote:


  Originally Posted by *DoYouRight* /img/forum/go_quote.gif 
_I have started collecting parts for my B22 I would like it to have BALANCED and SINGLEENDED. 

 How many boards do I need. So far I have 3.

 I am going to use AMBs FPD files from the KRMATHIS build for mine with minor changes. Any help modifying those files is GREATLY appreciated.
 -Evan_

 

You need 4 B22 boards and you'll likely want at least 2 S22 boards. 

 Read this whole page like 5 times over so you don't miss anything and it answers most questions you'll have.

The &beta;22 Stereo Amplifier


----------



## FallenAngel

One post helps and even better, use the dedicated Beta22 build thread for this. 
	

	
	
		
		

		
			





 1) Balanced = 4 boards
 2) I can send you my modified FPE files if you want, but remember, you'll still need to make sure you get the holes cut for the connectors YOU intend to use (unless you want to duplicate mine 
	

	
	
		
		

		
		
	


	




)
 3) Output uses Neutrik 1/4" / 3-pin XLR combo jacks, have fun wiring, no adapter needed.
 4) Not too many balanced diy DACs (or DIY DACs in general), you can either buy commercial, look on ebay for kits or wait for next buffalo batch. If you want pre-built, I'll be selling my Buffalo24 DAC soon.


----------



## rds

Quote:


  Originally Posted by *DoYouRight* /img/forum/go_quote.gif 
_I want this to be upgrade proof._

 

Not possible


----------



## DoYouRight

for me it is for atleast a few years RDS as most consider this the best solidstate 
	

	
	
		
		

		
		
	


	




 and overkill for my current cans.

 Edit: Thanks FallenAngel


----------



## El_Doug

Quote:


  Originally Posted by *DoYouRight* /img/forum/go_quote.gif 
_I have started collecting parts for my B22 I would like it to have BALANCED and SINGLEENDED. 

 How many boards do I need. So far I have 3.
 -Evan_

 

 Quote:


  Originally Posted by *DoYouRight* /img/forum/go_quote.gif 
_If I follow FallenAngels/KRMATHIS's do I just need a adapter for the SINGLEENDED cable like the K1K to 1/4?_

 

 Quote:


  Originally Posted by *DoYouRight* /img/forum/go_quote.gif 
_I want this to be upgrade proof. So in case I get K1Ks, Balanced Phones, or 1/4 SE will all work without mods. Thanks!_

 

I woulda sworn I answered these questions for you in the krmathis build thread...


----------



## smeggy

So I just had another beta board die. 

 It doesn't register zip, the mosfets seem fine, the input voltage is fine, the LEDs light fine but nothing is happening on the board.. which was working until today. 

 I was doing some minor pot readjustments, tester leads on R9 to get 4.5V and I heard a tiny little pop while adjusting VR1. Don't know what or from where on the board but now it is dead.

 I really hate this damn thing.


----------



## nattonrice

Quote:


  Originally Posted by *smeggy* /img/forum/go_quote.gif 
_So I just had another beta board die. 

 It doesn't register zip, the mosfets seem fine, the input voltage is fine, the LEDs light fine but nothing is happening on the board.. which was working until today. 

 I was doing some minor pot readjustments, tester leads on R9 to get 4.5V and I heard a tiny little pop while adjusting VR1. Don't know what or from where on the board but now it is dead.

 I really hate this damn thing._

 

Ti may be able to guess who I am from this comment.... ^^

 But I had a tiny (~0.2mm across, couldn't see it when I initially inspected the board before starting the soldering) circular hole (like a popped bubble) in the solder mask under the left of R9. When I used my micro grabbers to get ready to adjust vr1 it shorted to the ground plane and pop... 

 I'd check the voltage across D11 cause I blew Q25 because of this.

 Now there are other problems but those I'm still working on! heheh 1 outta 4 boards ain't bad


----------



## krmathis

Quote:


  Originally Posted by *DoYouRight* /img/forum/go_quote.gif 
_If I follow FallenAngels/KRMATHIS's do I just need a adapter for the SINGLEENDED cable like the K1K to 1/4?_

 

No adapter needed at all.
 My β22 have 1x 4-pin XLR, 2x 3-pin XLR and 2x 1/4' TRS. As shown here.


----------



## smeggy

Thank you, thank you! 
	

	
	
		
		

		
		
	


	




 I replaced them both and it's working again. I really have to file those points down. Did not realize they poked through the pcb so easy.


  Quote:


  Originally Posted by *nattonrice* /img/forum/go_quote.gif 
_Ti may be able to guess who I am from this comment.... ^^

 But I had a tiny (~0.2mm across, couldn't see it when I initially inspected the board before starting the soldering) circular hole (like a popped bubble) in the solder mask under the left of R9. When I used my micro grabbers to get ready to adjust vr1 it shorted to the ground plane and pop... 

 I'd check the voltage across D11 cause I blew Q25 because of this.

 Now there are other problems but those I'm still working on! heheh 1 outta 4 boards ain't bad 
	

	
	
		
		

		
		
	


	


_


----------



## smeggy

Ok, partial success. I can get the boards reading perfect. 4.5V, 65mV, 0 DC offset. When I plug the source in and attach the phones, one side is playing fine, the other is just hissing. Measuring mV at the plug I get a couple of mV on the working side and about 1200 on the hissing side. If I unplug everything it's back to normal.

 Any clues?


----------



## digger945

I poked the tips of the probes through the solder mask about three times on the EHHA alone. After so many sparks I finally put those clip on leads on the ends to keep myself from damaging something.


----------



## amb

Quote:


  Originally Posted by *smeggy* /img/forum/go_quote.gif 
_Ok, partial success. I can get the boards reading perfect. 4.5V, 65mV, 0 DC offset. When I plug the source in and attach the phones, one side is playing fine, the other is just hissing. Measuring mV at the plug I get a couple of mV on the working side and about 1200 on the hissing side. If I unplug everything it's back to normal.

 Any clues?_

 

Try reversing the left and right cable hookups from your source. Does the problem stay on the same side or does it switch sides too? If the latter than the source or cable is the problem. If it stays on the same side, then inspect your wiring very carefully to make sure it's all correct.

 Is the hiss affected by the volume control? Does it hiss when the volume is turned full-off?


----------



## zare

Quote:


  Originally Posted by *Beefy* /img/forum/go_quote.gif 
_I was thinking of grabbing two of exactly those transformers for when I re-case my Buffalo, and a third one for my MMM. Could you possibly tell me the physical size of those, and how much they cost you?

 Also, what configuration did you get for the primaries? And the rated supply frequency?

 Cheers! 
	

	
	
		
		

		
		
	


	


_

 

They are 30VA($40CAD). Encapsulation and shielding adds $ 20. Shipping was ok for me as they are local. As for the size, they are quite big, 11.5cm by 11cm, but I'll check that for you. I have dual primaries. The frequency does not matter in my case as it is eventually rectified.


----------



## Beefy

Thanks zare. Confirmation on size would be brilliant 
	

	
	
		
		

		
		
	


	




 It is my understanding that frequency is important for ensuring that transformer headroom is acceptable, and that you don't over/under volt. In particular, you can have problems with 60Hz transformers if you use them at 50Hz. I'll check with Richard when I go to order.


----------



## zare

Quote:


  Originally Posted by *Beefy* /img/forum/go_quote.gif 
_Thanks zare. Confirmation on size would be brilliant 
	

	
	
		
		

		
		
	


	




 It is my understanding that frequency is important for ensuring that transformer headroom is acceptable, and that you don't over/under volt. In particular, you can have problems with 60Hz transformers if you use them at 50Hz. I'll check with Richard when I go to order._

 

That is true, but by also depends if you are using 50Hz equipment on 60Hz line or the other way. 60Hz transformer on 50Hz line will make 17-20% V increase. In some cases that can make transformer cores saturated in the no load scenario. Well, I'll check the papers that came with the transformers and get that clarified.


----------



## DoYouRight

So wait the Dual XLR center pin is just a 1/4?


----------



## NoValidTitle

Anyone able to provide the full height of the shielded/encapsulated SumR tranny?


----------



## smeggy

Hi amb,

 it suddenly occurred to me when I arrived at work today that the inputs might be reversed as the boards were constructed slightly differently regarding the input mounts, one above board and one below and in my foggy late night work session it never crossed my mind that hooking the connector in the same orientation on both boards would result in reversal on one. 
	

	
	
		
		

		
			





 Amazing what obvious stuff a tired mind misses.

 I won't be able to test until tonight when I get home but I think that is indeed the problem. If so I'll be ecstatic.

 In answer to your questions, the hiss is volume dependent, if the volume is all the way up you can faintly hear the signal coming through almost like crosstalk. Swapping inputs made no difference as I was still plugging the thing in the wrong way (plug mates to socket one way) so again, me being an idiot and missing the blatantly obvious. I'll let you know 
	

	
	
		
		

		
		
	


	





  Quote:


  Originally Posted by *amb* /img/forum/go_quote.gif 
_Try reversing the left and right cable hookups from your source. Does the problem stay on the same side or does it switch sides too? If the latter than the source or cable is the problem. If it stays on the same side, then inspect your wiring very carefully to make sure it's all correct.

 Is the hiss affected by the volume control? Does it hiss when the volume is turned full-off?_


----------



## Beefy

Quote:


  Originally Posted by *zare* /img/forum/go_quote.gif 
_That is true, but by also depends if you are using 50Hz equipment on 60Hz line or the other way. 60Hz transformer on 50Hz line will make 17-20% V increase. In some cases that can make transformer cores saturated in the no load scenario. Well, I'll check the papers that came with the transformers and get that clarified._

 

Awesome 
	

	
	
		
		

		
		
	


	




 For the benefit of others watching this, my dilemma is that I am in Canada now so would ideally have a transformer for 115V at 60Hz. But I will want to take my gear back to Australia with me in a couple of years time, so will want these transformers to also run at 230V 50Hz.

 It is my understanding that 2 x 115V primaries designed to run at 50Hz is the best semi-universal solution, without the transformer getting really huge and having a stupid number of taps on the primary. But for an investment like this, I want to get it right!


----------



## Hayduke

Quote:


  Originally Posted by *Beefy* /img/forum/go_quote.gif 
_Awesome 
	

	
	
		
		

		
		
	


	




 For the benefit of others watching this, my dilemma is that I am in Canada now so would ideally have a transformer for 115V at 60Hz. But I will want to take my gear back to Australia with me in a couple of years time, so will want these transformers to also run at 230V 50Hz.

 It is my understanding that 2 x 115V primaries designed to run at 50Hz is the best semi-universal solution, without the transformer getting really huge and having a stupid number of taps on the primary. But for an investment like this, I want to get it right! 
	

	
	
		
		

		
		
	


	


_

 

I don't know how much it would cost or if it's available, but can you get a single transformer that has multiple sets of wires coming out? ie you connect it to the boards for 115v here and switch it to 250v when you get down under.

 I'm still not an electronics expert by any means, so maybe you can't do that with a transformer. From what I recall studying how they worked, it seems like you should be able to do it.


----------



## Beefy

Quote:


  Originally Posted by *Hayduke* /img/forum/go_quote.gif 
_I don't know how much it would cost or if it's available, but can you get a single transformer that has multiple sets of wires coming out? ie you connect it to the boards for 115v here and switch it to 250v when you get down under._

 

Well yes, that is what the 2 x 115 primaries gives you. Connect them in parallel when you are on 115V supply, and in series when you are on 230V supply. This is pretty standard,

 But frequency complicates things, and I don't completely understand it yet.


----------



## smeggy

Ok, finally we have a working Beta 22!!!

 Thanks to everyone for their time, patience, generosity and knowledge, without all the help I received I would never have this working, and working gloriously I might add. Holy crap this is good.

 Thank you all.


----------



## boomana

Quote:


  Originally Posted by *smeggy* /img/forum/go_quote.gif 
_Ok, finally we have a working Beta 22!!!

 Thanks to everyone for their time, patience, generosity and knowledge, without all the help I received I would never have this working, and working gloriously I might add. Holy crap this is good.

 Thank you all._

 

Yay, Smeggy!


----------



## smeggy




----------



## mattcalf

Congratulations Smeggy, you give hope that hopefully one day I'll build myself one of these beasts! 
	

	
	
		
		

		
		
	


	




 Pics, pics, pics!!!!!!!!!!!!!!


----------



## FallenAngel

Gotta post pics buddy!


----------



## johnwmclean

Quote:


  Originally Posted by *smeggy* /img/forum/go_quote.gif 
_Ok, finally we have a working Beta 22!!!

 Thanks to everyone for their time, patience, generosity and knowledge, without all the help I received I would never have this working, and working gloriously I might add. Holy crap this is good.

 Thank you all._

 

Well done mate!


----------



## Pars

WTG Smeggy!


----------



## oneplustwo

I still remember the first time I heard my beta 22. Such a revelation. Hoping I get the same kind of reaction when my balanced version is done!


----------



## fishski13

smeggy,
 congrats, you needed and deserved this after the problems you've had. well deserved.


----------



## DoYouRight

awesome smeggy good job, and now you can rock those custom fostex with it 
	

	
	
		
		

		
		
	


	




 PLEASE post pics


----------



## smeggy

Thanks guys, I knew it was gonna be good, had no idea though.. it's *really* good

 Pics would show nothing special, just a few boards and some messy insides until I get it cleaned up and re-cased.

 This thing is like a bottomless pit of awesome. Such power and presence, warm and fast and no top end nastiness at all. As you might guess, this is my first ever hi-end phone amp and I like it a lot.


----------



## zkool448

smeggy, been anticipating the day to come when all is well -- CONGRATS!!


----------



## aloksatoor

good one smeggy 
	

	
	
		
		

		
			





 ..... i need all my setups (gilmore lite lisa 3) to sound like my beta 22 but alas my wallet lolz


----------



## zare

Quote:


  Originally Posted by *Beefy* /img/forum/go_quote.gif 
_Awesome 
	

	
	
		
		

		
		
	


	




 For the benefit of others watching this, my dilemma is that I am in Canada now so would ideally have a transformer for 115V at 60Hz. But I will want to take my gear back to Australia with me in a couple of years time, so will want these transformers to also run at 230V 50Hz.

 It is my understanding that 2 x 115V primaries designed to run at 50Hz is the best semi-universal solution, without the transformer getting really huge and having a stupid number of taps on the primary. But for an investment like this, I want to get it right! 
	

	
	
		
		

		
		
	


	


_

 

Well, most of stuff I build are dual voltage(hope one day to go back to Europe).
 Dimensions: 110mmX93xx51mm
 Paper that came with them does not mention frequency anywhere. Might be worth asking to be sure. I know Plitron specs says 50-60Hz.


----------



## Beefy

Quote:


  Originally Posted by *zare* /img/forum/go_quote.gif 
_Well, most of stuff I build are dual voltage(hope one day to go back to Europe).
 Dimensions: 110mmX93xx51mm
 Paper that came with them does not mention frequency anywhere. Might be worth asking to be sure. I know Plitron specs says 50-60Hz.
	

	
	
		
		

		
		
	


	


_

 

That is brilliant. Thanks again zare! 
	

	
	
		
		

		
		
	


	




 Seems I could fit a pair in my Buffalo when it finally makes it into its new home, but shoe-horning one into my MMM is a no-go......


----------



## n_maher

Quote:


  Originally Posted by *smeggy* /img/forum/go_quote.gif 
_Ok, finally we have a working Beta 22!!!

 Thanks to everyone for their time, patience, generosity and knowledge, without all the help I received I would never have this working, and working gloriously I might add. Holy crap this is good.

 Thank you all._

 

WUHOO!


----------



## krmathis

Quote:


  Originally Posted by *smeggy* /img/forum/go_quote.gif 
_Ok, finally we have a working Beta 22!!!

 Thanks to everyone for their time, patience, generosity and knowledge, without all the help I received I would never have this working, and working gloriously I might add. Holy crap this is good.

 Thank you all._

 

Well done!


----------



## smeggy

Thank you all.

 Really, I had no idea how much better a top tier amp amp was compared to what I thought sounded good. I don't know if it's a particularly good synergy with my orthos but the sheer clarity and ball-grabbing bass is quite phenomenal. Hooked to the Pico DAC it provides a level of performance I hadn't heard before. 

 Meet conditions are far from ideal so even great amps I'd heard there sounded no better than my old NAD/Hafler combo. In the quiet of my own space and time to suck it in is an eye opener. I know to a lot of you this is old hat and many of you have had amps in this league for a long time, me? Total awe!


----------



## ShinyFalcon

Darn, I somehow forgot 100uF caps for C9-12... It'll be another $10 or so from Mouser, but then again I also messed up with C2-C5 for different gains. I got lucky with 8x and 2x. I'll probably go to Radioshack and see if they have any 100uF caps. Later on I'll probably replace those. Hope it won't affect the performance too much.

 Edit: Hm probably won't work eh? They're low impedance caps.


----------



## smeggy

I'm always missing things on orders.. annoying!


----------



## ShinyFalcon

Yep, it scares me when I notice I'm short on something, and then realize that it's for another board... (the 3.3V and 5V regulators, same family) I even ordered 5 too many SMD caps!

 Great job on your β22 smeggy, it makes me even more excited!


----------



## smeggy

Speaking of disasters.. I'm about to order another S22 kit for another amp, anything I need to be aware of before I start on it? I don't want to go through this hell again.


----------



## digger945

I'm not good at giving other people advice, so can I just say what I do?

 A. I don't work at the bench if I don't feel some good chi happ'nin'(tired, hungry, mad, etc.)

 2. I don't even think about starting until I got everything I need to complete the whole board. Everything. If possible, I do sometimes have extra parts on hand just incase.

 III. I study the instructions(I've got some parts of Ti's website almost memorized), which will include proper orientation of components, including DIODES (lOl, I'm messin' witchya). More often than not, I'll print the instructions out and put in lots of pictures and diagrams, and have the computer tuned into the website or thread giving more info.

 Last: If I have a question, I ask someone for help or look online until I'm sure I got it. If I don't understand and the chi is running low, I stop 'till I got it down. If I had to guess, I would say sometimes, not always but sometimes, that for every minute at the bench I've probably got an hour doing research.


----------



## linuxworks

Quote:


  Originally Posted by *smeggy* /img/forum/go_quote.gif 
_I'm always missing things on orders.. annoying!_

 

<moe howard>"well, if we didn't forget *something*, we wouldn't be plumbers!"</moe>


----------



## smeggy

heh, yep

 Digger, thanks for the advice. At least I have a working one here to copy so should be easier than guessing


----------



## DoYouRight

Ya I can't wait for mine to be done. My uncle has decided all the parts and has begun, so very excited! Hopefully near my birthday Ill have it. Now I wonder if the y1 Gamma is good enough or a buffalo is going to be noticably different.


----------



## digger945

Quote:


  Originally Posted by *smeggy* /img/forum/go_quote.gif 
_heh, yep

 Digger, thanks for the advice. At least I have a working one here to copy so should be easier than guessing 
	

	
	
		
		

		
			



_

 

... and that puts you one step ahead of me 
	

	
	
		
		

		
		
	


	



 Maybe someday when all the other project get done, and nothing else pops up in the mean time.


----------



## nattonrice

Quote:


  Originally Posted by *nattonrice* /img/forum/go_quote.gif 
_Now there are other problems but those I'm still working on!_

 

... and now they are no more


----------



## saintalfonzo

If I decide on getting another ss amp I will be building one of these, or wussing out and paying someone else to do it for me. I've heard too many good things to NOT go with a beta22 if I stray from the tubes.


----------



## lynxkcg

For the sake of the thread, I'm planning on building a b22, after I get a y1. Seeing this thread bumped every day makes my wallet quiver in terror. I need a new multimeter, hopefully my 2 olds ones will get sold in this garage sale i'm about to have to pay for a new Fluke 179 to replace my 77 and 12b.


----------



## nattonrice

Quote:


  Originally Posted by *lynxkcg* /img/forum/go_quote.gif 
_Seeing this thread bumped every day makes my wallet quiver in terror._

 

It has been said many times before but...
 I have spent the same amount on caseing as almost all the components plus tooling combined~

 Looking back on it I should have just put it in a cookie tin hehe


----------



## Kenny12

hi guys, i'm deciding weither to build this or not, If i run a balanced setup, how much gain would i get from having 2 seperate power supplies? or even 4! 

 i noticed amb recommend 1 supply for each board??


----------



## digger945

Speaker amp or HP amp?


----------



## Kenny12

most likely headphone amp, 

 how well would they drive a pair of jbl monitors, 8ohms at 89dB sensitivity.


----------



## Bilavideo

Quote:


  Originally Posted by *Nebby* /img/forum/go_quote.gif 
_I've seen more than a few posts about the beta22 pop up recently, so I figure I'm not the only one getting ready to build one 
	

	
	
		
		

		
		
	


	




 Post here if you're thinking of building one, currently building one, or already built one! If you already built one, pics and specs would be handy!

 I'm planning on building one, but it seems my laundry list of wanted features will have to be pruned down a bit for practicality's sake. On a more positive note, I think I've figured out how to mount the six beta22 boards I have planned in a nice and efficient manner with bigger heatsinks 
	

	
	
		
		

		
		
	


	


_

 

HERE, SIR.


----------



## SemiAudiophile

sorry for my noobness, but is it possible to build a beta22 into a hybrid amp with balanced and unbalanced input/outputs?


----------



## MrMajestic2

Quote:


  Originally Posted by *SemiAudiophile* /img/forum/go_quote.gif 
_sorry for my noobness, but is it possible to build a beta22 into a hybrid amp with balanced and unbalanced input/outputs?_

 

Yes you can. Info about this is available on the forum and on amb.org


----------



## oneplustwo

Yes. See Amb's website. Also, here.


----------



## SemiAudiophile

awesome thanks. time to save some money and find someone to build it for me. 
	

	
	
		
		

		
		
	


	




 how much do you guys think it will cost to build btw? i wish i had the electronic/soldering skills to build it myself.


----------



## oneplustwo

There's a huge range. A basic two channel with minimal case work can be built for about $400. Then there's the other extreme of 4 or even 6 channels with fancy wiring/casework/etc. which can easily eclipse $2500.


----------



## Beefy

Quote:


  Originally Posted by *SemiAudiophile* /img/forum/go_quote.gif 
_how much do you guys think it will cost to build btw?_

 

If you even need to ask, you should consider cheaper projects!


----------



## sachu

Quote:


  Originally Posted by *SemiAudiophile* /img/forum/go_quote.gif 
_awesome thanks. time to save some money and find someone to build it for me. 
	

	
	
		
		

		
		
	


	




 how much do you guys think it will cost to build btw? i wish i had the electronic/soldering skills to build it myself. 
	

	
	
		
		

		
		
	


	


_

 

if you can be resourceful a passive ground 2 channel with case can be built for about 200$. Or at least that's what the estimation for my build has been..but then again don't think I will build it cause of time constraints.


----------



## Beefy

Quote:


  Originally Posted by *sachu* /img/forum/go_quote.gif 
_if you have connections..and be resourceful you can build a passive 2 channel with case for about 200$. Or at least that's what the estimation for my build has been..but then again don't think I will build it cause of time constraints._

 

Surely that is a typo. $200 is not even close.

 Using Glass Jar Audio's kit prices, the S22 power supply alone is $104, and extrapolating down from a 3-channel B22 kit, 2 channels will cost you at least $184.

 That is $288 with no volume control, no casework, no connectors, no wire, no labor......


----------



## ShinyFalcon

Just making sure my multimeter's not going crazy with the 1N5291...


----------



## sachu

Quote:


  Originally Posted by *Beefy* /img/forum/go_quote.gif 
_Surely that is a typo. $200 is not even close.

 Using Glass Jar Audio's kit prices, the S22 power supply alone is $104, and extrapolating down from a 3-channel B22 kit, 2 channels will cost you at least $184.

 That is $288 with no volume control, no casework, no connectors, no wire, no labor......_

 

No its not a typo..If you are resourceful you can build it for 200$ everything included. Well only way to convince everyone would be to build it..and since i just placed an order to replinish my solder supplies I might just as well.


----------



## Beefy

I'm sure it could be done, but I would NOT be happy with the corners that would have to cut.

 Saying that, I would love to see your BOM.


----------



## n_maher

It's clearly using surplus/free/leftover parts at that price which while neat is completely disingenuous. Just the pcb's, which if you're going to call it a beta22 you have to use, will cost you $50 shipped. Heck, I often feel that people quoting Jeff's kit prices are leaving themselves open to economic shock when they try to actually build the thing. 

 It has nothing to do with resourceful sachu, just reality. I have a drawer full of beta22 parts, boards, etc, should I claim I can build one for free?


----------



## sachu

Quote:


  Originally Posted by *n_maher* /img/forum/go_quote.gif 
_It's clearly using surplus/free/leftover parts at that price which while neat is completely disingenuous. Just the pcb's, which if you're going to call it a beta22 you have to use, will cost you $50 shipped. Heck, I often feel that people quoting Jeff's kit prices are leaving themselves open to economic shock when they try to actually build the thing. 

 It has nothing to do with resourceful sachu, just reality. I have a drawer full of beta22 parts, boards, etc, should I claim I can build one for free?_

 

Nate,

 While am using surplus parts for my transformer and case the rest all were bought. Maybe not bought here in the US but bought nonetheless specifically for the B22. It wasn't easy though., I have had to wait for 6 months for the parts to get to me which probably negates the whole idea of getting them cheaply.

 In any case already having the EHHA I don't feel like building the B22 all that much considering the labor that goes into it and also the fact that for me the EHHA outperforms the B22 quite handily.

 Edit: And I don't think calling it disingenuous is right. All I said was it can be built for that price.


----------



## n_maher

What I find disingenuous is that it was implied (at least the way I read your initial post) that all that was required was a little resourcefulness. If 99% of the population is not going to have access to the resources no amount of drive or desire is going to change that. So the fact remains that for most folks a two-channel build, even using some surplus and free parts, is going to run double (or more) than your estimate. 

 Don't get me wrong, it's great that you're able to do it so cheaply, but it's likely a feat that cannot be duplicated. I have a pretty extensive list of connections and I know I couldn't pull it off. You have to realize that people around here are simply going to look at that number and start parroting it around the various forums. Before you know it someone will ask "What's the best $200 amp" and someone will answer the beta22 and reference you as the source of the information.


----------



## sachu

Quote:


  Originally Posted by *n_maher* /img/forum/go_quote.gif 
_What I find disingenuous is that it was implied (at least the way I read your initial post) that all that was required was a little resourcefulness. If 99% of the population is not going to have access to the resources no amount of drive or desire is going to change that. So the fact remains that for most folks a two-channel build, even using some surplus and free parts, is going to run double (or more) than your estimate. 

 Don't get me wrong, it's great that you're able to do it so cheaply, but it's likely a feat that cannot be duplicated. I have a pretty extensive list of connections and I know I couldn't pull it off. You have to realize that people around here are simply going to look at that number and start parroting it around the various forums. Before you know it someone will ask "What's the best $200 amp" and someone will answer the beta22 and reference you as the source of the information._

 



 Right..i understand now.
 Just to make it clear here..I did get most of the parts for a planned balanced 4 channel B22 , dual S22 build from India from the store where I used to buy my DIY supplies for many years prior to me arriving here in the US. The total cost for about 80% of the BOM components came up to about 70$.
 If I am pressed for time (and cause of the EHHA) I might end up selling these components for the same price I got them for so someone else can benefit from this. I know Chris has first dibs on this already. It has taken me 6 months to get them cause of variosu concerns the people who brought hem over had (customs and **** and all and cause all my friends are brown skinned and come from the east might have something to do with it 
	

	
	
		
		

		
		
	


	




 )

 In any case this gives you an idea as to how cheap it must be for companies getting their stuff manufactured in China must be.


----------



## amb

Quote:


  Originally Posted by *ShinyFalcon* /img/forum/go_quote.gif 
_Just making sure my multimeter's not going crazy with the 1N5291..._

 

I don't know what you're asking but a CRD is not a regular diode and cannot be tested like one with a DMM.


----------



## SemiAudiophile

what's the average build time to build a B22 from scratch? month? 2 months? i'm guessing most of the time would be spent waiting on supplies to come in like enclosures and stuff? based on hours, would it be possible to build one within 50 hours?


----------



## oneplustwo

50 hours is certainly doable. Again, there's a big range given the number of channels, wiring scenarios, inputs/outputs, and different casework options available, but 50 hours to put a simple B22 together should be fine. (Assuming you don't make any mistakes... trouble shooting could take 50 hours in itself potentially.)


----------



## Good Times

Me 
	

	
	
		
		

		
		
	


	




 I'm thinking of building a 4 board. I'm just looking at the page count for this thread and dreading the 'research' time here - although know it will pay off.


----------



## nattonrice

Quote:


  Originally Posted by *Good Times* /img/forum/go_quote.gif 
_Me 
	

	
	
		
		

		
		
	


	




 I'm thinking of building a 4 board. I'm just looking at the page count for this thread and dreading the 'research' time here - although know it will pay off._

 

U should've seen the three threads at headwize O.O


----------



## linuxworks

headwize?

 I remember that.

 I think.


----------



## nattonrice

Quote:


  Originally Posted by *linuxworks* /img/forum/go_quote.gif 
_headwize?

 I remember that.

 I think.




_

 

I know hey! 
 Just typing that made me realize how long it has been outta commision...
 It had the b24 thread I really wanted to read too


----------



## Hayduke

I never did finish reading all the B22 threads there 
	

	
	
		
		

		
		
	


	




 Is he gonna bring the site back?

 I still prefer this forum engine by a large margin, but there is a lot of good info over at headwize. I hope it comes back


----------



## n_maher

Quote:


  Originally Posted by *Hayduke* /img/forum/go_quote.gif 
_Is he gonna bring the site back?_

 

Last I knew, yes, he was still planning to put the site back up but his last update was over a month ago now and was that he was moving and wouldn't be working on it for a while. If nothing else I hope he's able to restore a static version of the old site so that data could be mined from some of the really good threads that were there.


----------



## amb

Yes, Chu is busy but headwize will come back eventually. He still has to add some anti-spam code to the forum software.


----------



## Hayduke

Quote:


  Originally Posted by *n_maher* /img/forum/go_quote.gif 
_Last I knew, yes, he was still planning to put the site back up but his last update was over a month ago now and was that he was moving and wouldn't be working on it for a while. If nothing else I hope he's able to restore a static version of the old site so that data could be mined from some of the really good threads that were there._

 

 Quote:


  Originally Posted by *amb* /img/forum/go_quote.gif 
_Yes, Chu is busy but headwize will come back eventually. He still has to add some anti-spam code to the forum software._

 

Good to know. Thanks guys 
	

	
	
		
		

		
		
	


	




 I read through his posts about the problems he was having, but it seemed like there were big gaps between them. I'm glad to hear he's just busy and Headwise will be back.


----------



## krmathis

Quote:


  Originally Posted by *amb* /img/forum/go_quote.gif 
_Yes, Chu is busy but headwize will come back eventually. He still has to add some anti-spam code to the forum software._

 

This is great news!
 I miss the forum. But had it not been for the headwize forum downtimes we may never have got Head-Fi.


----------



## DoYouRight

i heard the 3,000 post B22 thread there said people had B22s that blew up? randomly, how likely is this?


----------



## naamanf

Quote:


  Originally Posted by *DoYouRight* /img/forum/go_quote.gif 
_i heard the 3,000 post B22 thread there said people had B22s that blew up? randomly, how likely is this?_

 

There is usually a reason things blow up, it doesn't just happen randomly. The B22 has no short protection and my guess is that this could have been a cause for some of the failures. TRS jacks can cause a momentary short when plugging/unplugging and this can lead to failed output devices that fail to a shorted condition.


----------



## DoYouRight

is the neutrik multi jack, the one with balanced and a 1/4 in the middle one that would cause that issue?


----------



## amb

DoYouRight, _any_ TRS jack has that potential problem. It's the nature of its design -- when you insert or remove the plug, the different portions of the plug would cause undesirable short circuits in the jack. As long as you turn the volume down before plugging/unplugging, then there is no risk of damage.


----------



## DoYouRight

ok, I always turn it down to min before unplugging so I should be fine


----------



## FallenAngel

DoYouRight - that doesn't change anything - it simply shorts the input signal to ground. 
	

	
	
		
		

		
		
	


	




 The TRS jack still shorts the right signal to ground and that is the danger. Leave it in that stage for too long (I don't remember the exact time though I remember reading the calculations somewhere before) and you will blow the output MOSFETs.


----------



## DoYouRight

so what should I do to make this not happen. Unplug it unless Im running it? just tell me what to do to protect my baby! so much cash has gone into it already and im not half way done lol.


----------



## naamanf

I would just turn it off to be extra safe. For the balanced outputs you can plug/unplug all day with no problem.


----------



## ShinyFalcon

I was thinking about going 4-pin XLR, which I believe should prevent any shorts from happening. As for sudden removal, I don't know how the amp will handle that. And as for different types of headphones, I can easily make a 1/4" -> 4-pin XLR converter too... 

 I was surprised at how long the 1/4" Neutrik plug was as well. I wasn't expecting a 3-4" plug at all, it made my mini ->1/4" look puny in comparison. However when plugged in their respective jacks, the Neutrik 1/4" and the Neutrik XLR are about the same length. Maybe it'll be a r eason to try out the K1000 one day? O_O


----------



## amb

As long as the volume is turned all the way down (and the amp is adjusted to have low DC offsets), it's safe to plug/unplug the TRS headphone while the power is on. I do it all the time on my own β22. Yes, it will still cause a momentary short circuit, but if there is no significant voltage (whether signal or DC offset) at the output, then there will be negligible current flow, nowhere near the 17A rating of the output MOSFETs to cause any damage.

 None of the XLR connectors (3 pin or 4 pin) have the short circuit problem.


----------



## DoYouRight

can I just clip the tail of my headphone cable and add a 4pin or do I need to recable?


----------



## naamanf

Quote:


  Originally Posted by *DoYouRight* /img/forum/go_quote.gif 
_can I just clip the tail of my headphone cable and add a 4pin or do I need to recable?_

 

I would do some research on how your headphones are cabled to begin with. That should give you a good idea on what you have to do.


----------



## smeggy

After fretting about the heat of running the S22 with two amps simultaneously I caved in and stuck a small 4" silent fan in the case blowing over the S22 and Beta boards, much cooler now


----------



## DoYouRight

man your combo is just too sexy Smeggy Im jealous. I want both of those amps, and a buffalo32s and havana so I have SS and Tubes covered. your halfway there! .... living on a prayer


----------



## smeggy

It's easy, all you need is a degree in reckless stupidity and crossed fingers hoping it doesn't blow up in your face 
	

	
	
		
		

		
		
	


	




 I'm gonna stuff the zobels in tonight for the speaker posts, order bigger sinks for the S22 for tougher loads and secure the fan properly. I also need to look into wiring up the EHHA heater delay and figuring where to mount the Pico board in there. 

 I'd love to have a buffalo to stuff in too it but sadly, more than I can stretch to.

 BTW, on my shopping trip I could only find 2W 20 Ohm resistors rather than 22, will they do instead?


----------



## fishski13

i just finished placing an order from Ti for a 2-channel B22. i can't wait!


----------



## smeggy

Congrats, you'll love it I'm sure.


----------



## DoYouRight

he is building it for you? that's awesome 
	

	
	
		
		

		
		
	


	




 luckyyy


----------



## smeggy

Ok, I have a strange problem that I don't understand, maybe someone could shed some light on it.

 I wired up the speaker outs with zobel last night but something is very wrong somewhere. The speaker outs are wired from the headphone exits so they;re off when phones are plugged in. Wires go from there to the zobel and posts. Now, testing continuity and resistance, it all looks perfect. No continuity with phones in, continuity with phones out. I check the posts to chassis, open, I play something and I get a reading from positive to chassis.

 I have no idea why this is, and what;s coming out of them is very quiet, distant and has a weird out of phase, sorta mono sound. 

 It looks right, it just doesn't work for some reason.


----------



## amb

I don't recommend wiring the speaker outs that way. Most "switched" headphoen jacks do so on the "ground" leg, and all you're getting when iyou plug in the headphones is to lift that ground. But the speaker "grouhds" are still connected to each other, so you have, in effect, both speakers now in series across the L and R output terminals. What you're hearing is the difference signal between the left and right channels.

 To make this work you'd need a headphone jack with two switches so you could "disconnect" the left and right speaker grounds independently, but even if you could find such a jack, would its switch contacts be rated high enough for speaker use?


----------



## smeggy

Hmm, so what is the reccomended way to go about it? It's for going to the stax box the same as if I plug it into the headphone socket.

 It's a standard neutric which lifts all three contacts when plugged in and closes them when unplugged so no signal passes with headphones in and all three pass without. Whichever way I look at it it still doesn't make sense as it;s essentially just an extension of the jack which I'm using in another amp to switch from 1/4 to 1/8" phone jacks. Only one can be active at a time.


----------



## DoYouRight

what is the populated board height and width of the B22. I was trying to do the imaging in my head about the chassis for a 6 board but everything else like the KrMathis. So 12x12x4 wouldnt work but if I put 1 more up higher maybe 12x12x6? Or 16x16x6 I cant tell what I would need. The boards are in OH and Im in NC.


----------



## FallenAngel

And how exactly do you plan to put 6 boards into that case? Just look at _amb_'s site - the boards are 3" x 7" each (though 2 can be arranged to be stacked and end up being 5.6" x 7" per pair).

 Honestly, you ask a LOT of questions and 9 times out of 10, you can find the answer yourself if you only bothered to look.


----------



## DoYouRight

well the dimensions I could find, but not necessarily how high to stack them and you guys since having built with alot of the same parts would have more idea. The headqwize forum of b22 is gone and it had alot of info that would help me. I just see how so many others have input to help, and I would like to have a similar oppourtunity.

 EDIT: also on searching here, I only found my own posts of questions, or someone saying BUILD IT, when I searched for 6 board B22. I just wanted to help to have as few roadbumps along the way, and not have to ship a chassis back and forth


----------



## oneplustwo

You may need to take into account any height below the board for standoffs/terminal blocks also. Otherwise, you will need to keep in mind that jacks/pots/switches/etc. take up real estate as well so it's not just the boards. My reco would be to go one size bigger than you think you'll need. Better to have too much room than not enough. Also, having extra space may make your life easier when trying to wire everything up.


----------



## Karu

I've been lately thinking about ecological solutions. I know that class A amplifier is inherently anything but ecological. 

 Let's assume that we have a 6 board β22 with 2 σ22s as power supply. The regular solution would be to use each σ22 to power 3 β22 boards with the power switch on the AC side. I've been thinking of putting 2 separate power switches for those situations where I want to use the β22 unbalanced and need only one headphone. The problem is how to conveniently switch the power off from the active ground boards when I want to use β22 in balanced mode?

 I've gathered that it is a bad idea to use a switch for this purpose on the DC side as it wears the components on those boards when they are switched back on.


----------



## smeggy

x2


----------



## fishski13

Quote:


  Originally Posted by *DoYouRight* /img/forum/go_quote.gif 
_well the dimensions I could find, but not necessarily how high to stack them and you guys since having built with alot of the same parts would have more idea. The headqwize forum of b22 is gone and it had alot of info that would help me. I just see how so many others have input to help, and I would like to have a similar oppourtunity.

 EDIT: also on searching here, I only found my own posts of questions, or someone saying BUILD IT, when I searched for 6 board B22. I just wanted to help to have as few roadbumps along the way, and not have to ship a chassis back and forth 
	

	
	
		
		

		
		
	


	


_

 

before you buy a chassis, populate 3 boards and stare at them. then stare at them some more. sketch out some 1:1 drawings on graph paper. lay out the boards on the drawings and stare at them some more. seriously, you need to put some effort into this.


----------



## johnwmclean

One of the reason’s I opted to build a Beta22 was the huge support provided be the Headwize site. Three massive threads covering lots of issues and topics in fine detail. I managed to get through my build with that help, I couldn’t imagine doing it without, so I feel for anyone at the moment taking on the Beta22 without that knowledge.


----------



## digger945

I got a clear work mat from the local United Educational Arts store, it is marked with lines 1 inch apart. You can cut it with a knife or sling solder on it and it holds up pretty good. They come in different sizes, mine is 13x19. 
 Makes it easy to lay unpopulated pcb's and stuff on top and see how it's gonna work out and how much room you've got.


----------



## amb

Quote:


  Originally Posted by *smeggy* /img/forum/go_quote.gif 
_Hmm, so what is the reccomended way to go about it? It's for going to the stax box the same as if I plug it into the headphone socket._

 

You could use a high-current DPDT switch, or a DPDT relay activated by a smaller switch), or the relay activated by the switch in the headphone jack...

  Quote:


 It's a standard neutric which lifts all three contacts when plugged in and closes them when unplugged so no signal passes with headphones in and all three pass without. Whichever way I look at it it still doesn't make sense as it;s essentially just an extension of the jack which I'm using in another amp to switch from 1/4 to 1/8" phone jacks. Only one can be active at a time. 
 

What is the exact part number for that jack? And how did you hook it all up? A diagram would help.


----------



## amb

Quote:


  Originally Posted by *Karu* /img/forum/go_quote.gif 
_I've been lately thinking about ecological solutions. I know that class A amplifier is inherently anything but ecological._

 

Speaking "ecological" and "class A" in the same sentence? Heh...
 If you want to save power, build a class D amp. 
	

	
	
		
		

		
		
	


	




  Quote:


 Let's assume that we have a 6 board β22 with 2 σ22s as power supply. The regular solution would be to use each σ22 to power 3 β22 boards with the power switch on the AC side. I've been thinking of putting 2 separate power switches for those situations where I want to use the β22 unbalanced and need only one headphone. The problem is how to conveniently switch the power off from the active ground boards when I want to use β22 in balanced mode? 
 

There is no convenient way to do it if you divide the power supplies up this way.

  Quote:


 I've gathered that it is a bad idea to use a switch for this purpose on the DC side as it wears the components on those boards when they are switched back on. 
 

Correct, see related post.


----------



## fishski13

Quote:


  Originally Posted by *digger945* /img/forum/go_quote.gif 
_I got a clear work mat from the local United Educational Arts store, it is marked with lines 1 inch apart. You can cut it with a knife or sling solder on it and it holds up pretty good. They come in different sizes, mine is 13x19. 
 Makes it easy to lay unpopulated pcb's and stuff on top and see how it's gonna work out and how much room you've got._

 

i like butcher block from Ikea.


----------



## Gatsu

Well its finally done.
 The front panels arrived yesterday from FPE so I was able to fit them last night.
 I went with dual colour Bulgin momentary switches for the mode buttons.
 Blue




 Green













 The control of the amp is done using a Picaxe18+driver chip to handle the LEDs as well as the input/output/muting relays. 
 The volume control is a Joshua Tree. I migrated the parts from original boards to the custom control board. The relay boards were left unchanged.

 As I mentiond before, this build was heavily inspired by one of Namaanf's previous Beta22s. 
	

	
	
		
		

		
		
	


	




 Now I need to convert all my phones to balanced


----------



## FallenAngel

Beautiful build, congrats!


----------



## rds

Wow, that is awesome on so many levels 
	

	
	
		
		

		
		
	


	




 Very nice font too!


----------



## Gatsu

Thanks guys
	

	
	
		
		

		
		
	


	




 Just don't look under the control board, its a mess with the modifications I had to make.


----------



## johnwmclean

Gatsu, LEGENDARY BUILD. I would love to see the psu innards as well. How long in the making? Congratulations


----------



## DoYouRight

That is gorgeous! What are the dimensions? And I wonder how you setup lights for SE and balanced. My god man! Nicest black build Ive seen


----------



## Gatsu

I started getting things together and ordering parts in February this year. Most of the time was waiting for various parts to arrive.
 The cases are Par Metal 12x12x4 Series 20 in Black. The front panels are done by Front Panel Express.
 The button lights are set up so that Balanced is Blue and SE is Green. The same goes for the 'phone/Preamp switch, Blue is Headphones, Green is Preamp. The Blue/Green lines above/below the switch don't light up even though it looks like they do in a couple of the photos.

 The PSU is the same one I had images of back here. Initially I was using painted plywood as a mockup front panel, just to make sure I got everything just where I wanted it, in the recent images it has its shiny new front panel on it 
	

	
	
		
		

		
		
	


	



 I should probably take some new photos of its insides.

 Next thing I need to do is gather all the documentation and design notes I have made during the process and put it onto a couple of SD cards to keep in the cases. I've had problems previously with stuff I have made years ago, when it eventually fails and I open the case I find myself wondering "What the hell was I thinking when I did *that*?!" Hopefully keeping everything inside the amp will prevent that from happening later on down the track 
	

	
	
		
		

		
		
	


	




 I have no idea how much its cost so far... I'm not even entirely sure I want to know


----------



## smeggy

Gatsu, amazing build! Truly spectacular, well done.

 AMB
 I got it all sorted out, I fitted a 120v 5A switch on-off-on between speakers and phones and it all works now. Zobel in place and everything is hunky dory.

 Thanks.


----------



## amb

Gatsu, congrats on an impressive build!


----------



## Karu

Quote:


  Originally Posted by *amb* /img/forum/go_quote.gif 
_There is no convenient way to do it if you divide the power supplies up this way._

 

Yeah, that's kind of what I figured. Just wanted to make sure I didn't miss out something. The explanation in related post that you linked to was quite explicit on why. 

  Quote:


  Originally Posted by *amb* /img/forum/go_quote.gif 
_Correct, see related post._

 

Thanks.


----------



## Karu

Gatsu, great build! Pictures like that do get me impatient to finish mine. 
	

	
	
		
		

		
		
	


	




 I'm curious about the headphone/preamp switch. Does it do something more than just redirect the output of the amplifier from front to the back?


----------



## mattcalf

Beautiful build Gatsu!! 
	

	
	
		
		

		
		
	


	




 Care to share any of the stuff that is going to go onto those SD cards, I'm sure it'll benefit a fair few head-fiers! (I'll be one eventually, hopefully..)


----------



## fishski13

Gatsu,
 looks gorgeous!


----------



## Hayduke

Great build Gatsu!

 I'm with Matt in wanting to see those files you're putting inside the case.

 I'm building a B22 in the next few weeks, and there are a lot of design elements in yours that I wanted to incorporate into my build.

 Since Headwize is still down, is there a head-fi thread for discussing builds, or is this it?


----------



## amb

Quote:


  Originally Posted by *Hayduke* 
_Since Headwize is still down, is there a head-fi thread for discussing builds, or is this it?_

 

This is it.


----------



## smeggy

quickie, does the zobel change the sound characteristics of low impedance phones? It might be my imagination but thought I'd ask.


----------



## amb

Quote:


  Originally Posted by *smeggy* /img/forum/go_quote.gif 
_quickie, does the zobel change the sound characteristics of low impedance phones?_

 

It shouldn't.


----------



## smeggy

Very odd, I could swear I'm getting louder bass.


----------



## Gatsu

I'll likely get some time to put the files together over the weekend, so hopefully I'll have something for you guys after that. I'll try to update things as well to reflect the additional changes I made during the build.

 I'll try to include stuff like part numbers for the case, switches, knob etc .

 Karu, yes thats pretty much all the Headphone/Preamp switch does. (through a relay)


----------



## DoYouRight

Would the TRS short issue be nullified if I made a 4 pin xlr adapter to 1/4 and plugged the 4 pin side to the B22 and the female end 1/4 to my SE headphones?


----------



## FallenAngel

Yep, but why not just recable your headphones to 4-pin xlr?


----------



## amb

Quote:


  Originally Posted by *DoYouRight* /img/forum/go_quote.gif 
_Would the TRS short issue be nullified if I made a 4 pin xlr adapter to 1/4 and plugged the 4 pin side to the B22 and the female end 1/4 to my SE headphones?_

 

Yes, but only if you only plug/unplug the XLR side. If you plug/unplug the TRS side then the same problem would still exist.


----------



## Gatsu

For those that were interested in a little more information on my Beta build I've attached the files. Due to the forum attachment size limit I've had to split them up. 

 What IS included:
 Schematics for the Beta22 control board and Sigma22 control board.
 Source code for the picaxe controllers I used.
 FPE designs for the front panels I used
 List of parts I used for the case and where I got them from (I think I have them all in there).

 What ISN'T included:
 The board layouts. Couple of reasons, the boards that you see in my photos of the completed build aren't the original boards I got made, they've been modified - the schematics have been updated appropriately. Also the layout for the Beta22 board is too large to be edited in the Light version of Cadsoft Eagle.
 Source code for the Volumite chip - its not mine and I don't have it.

 Software you will need:
 Cadsoft Eagle : Probably the best schematic drawing package I've come across for its price (Free!). There is a Lite (Free) version which is usable for most things, it does have restrictions however:
 The useable board area is limited to 100*x*80*mm (4*x*3.2*inches). Only two signal layers can be used (Top and Bottom).The schematic editor can only create one sheet.
CadSoft Online: EAGLE Layout Editor
 Which I later had made at BatchPCB - Home

 Picaxe Programming Editor : if you are going to learn about picaxe microcontrollers then you will need this. However I would probably recommend getting a picaxe starter kit.
PICAXE

 Front Panel Express Designer : Fairly simple. Just remember MEASURE EVERYTHING. I didn't measure my volume knob properly, and when the panel came I found it didn't fit in the recess. All because I *thought* I knew how large it was. (god that was a lot of innuendo...)
Front Panel Express, LLC > Front Panel Service for North America

 If you want to get your own circuit boards made, here is some light reading 
	

	
	
		
		

		
		
	


	




 This is where I got all my information from on how to make my boards.
SparkFun Electronics
How-to: Prepare your Eagle designs for manufacture - Hack a Day

 Heres the list of parts for those just interested in that:
 2x Par Metal Series 20 12"x12"x4" Black (Par Metal - 20-12124B)
 1x MPI002/TERM/BL Bulgin Ring Illuminated Blue (Farnell - 430-3088)
 2x MPI002/TERM/D5 Bulgin Ring Illuminated Blue/Green (Farnell - 145-4954)
 1x 1.4" Goldpoint knob custom machined aluminium (Goldpoint eBay Store)
 2x NCJ9FI-S Neutrik 3pin XLR-TSR socket (Farnell - 500-8396)
 1x NC4FD-LX-B Neutrik 4pin XLR socket (Farnell - 139-0122)
 2x NLT8FX-BAG Neutrik Speakon 8pin socket (Farnell - 999-1964)
 2x NLT8MP-BAG Neutrik Speakon 8pin plug (Farnell - 999-1980)
 1x Evergreen Goldsnake speaker binding posts (VT4C - SPC-02B)
 1x Solid State Relay (Jaycar - SY4084 - Hongfa JGX-1505FB)
 2x "Conrad" heatsinks (Jaycar - HH8550, Altronics - H0535)
 1x PCB mount toroid transformer 2x 7.5V, 10VA (Altronics - M4315)
 8x HiFi feet (Jaycar - HP0834)

 Oh, and finally a better photo of the Beta control board:




 Phew!


----------



## digger945

Let me be the first to say "Bravo, outstanding" *cue applause*
 Thanks for sharing with the community Gatsu *clap clap clap*


----------



## DoYouRight

wow great way to introduce your own board! would you happen to have a spare?


----------



## mattcalf

Quote:


  Originally Posted by *digger945* /img/forum/go_quote.gif 
_Let me be the first to say "Bravo, outstanding" *cue applause*
 Thanks for sharing with the community Gatsu *clap clap clap*_

 

Ditto.

 Thanks a heap gatso.


----------



## fishski13

Gatsu,
 looks brill, and thanks for the tutorial!


----------



## oneplustwo

Quote:


  Originally Posted by *amb* /img/forum/go_quote.gif 
_Just to remind you that it's not D12 that you need to replace, it's Q26._

 

Amb - I replaced Q26... twice... and I'm still getting 29 volts across D12. Any suggestions for next steps? Thanks!


----------



## amb

oneplustwo, try reflowing the solder joints at CR8, and make sure there is no solder bridge or a short across C10. Also make sure neither of these are mounted in the wrong direction.


----------



## oneplustwo

That did the trick! Had a cold CR8 joint apparently. Now I have 4 working boards! Time to finish up wiring and case work! (Still have to fix the second Sigma though... need to replace at least Q4/Q5 I think.)


----------



## smeggy

Oh happy friggin day, I turned on the amp this morning and was instantly met with the smell of burning as yet another board goes pop. I'm officially calling it a day on the Beta.


----------



## amb

Sorryto hear about that, smeggy. Things don't just burn up without a reason. Can you visually identify any obviously burnt parts? If so which is it? Is there a short circuit in there somewhere (marginal wiring, solder joints, or loose bits? Also, you said you wired in a switch for headphones/speakers selection. Did you completely undo all the previous wiring to the switching headphone jack? I never trust using the switch on the jacks for this purpose, because the switch is activated by the plug, and on most such jacks could also cause an additional point of momentary short circuit as you plug and unplug the headphones. Also make sure you got the extra switch wired correctly.


----------



## smeggy

It's a new switch, new jack, new wiring, new ground layout, new zobel and it's been running fine for a week with no problems functionally as far as the boards go. 

 I turned it on and pop, nothing visually stood out. It's still making sound like you get from a partially blown driver. The sinks are cold but if you turn it up you can still get sound out but it's very distorted. 

 I appreciate your concern but I'm past the point where I want to sink any more time, money or effort into what seems like a lost cause, for me anyway.


----------



## johnwmclean

Quote:


  Originally Posted by *smeggy* /img/forum/go_quote.gif 
_It's a new switch, new jack, new wiring, new ground layout, new zobel and it's been running fine for a week with no problems functionally as far as the boards go. 

 I turned it on and pop, nothing visually stood out. It's still making sound like you get from a partially blown driver. The sinks are cold but if you turn it up you can still get sound out but it's very distorted. 

 I appreciate your concern but I'm past the point where I want to sink any more time, money or effort into what seems like a lost cause, for me anyway._

 

Smeggy, I’m really sorry to hear about your amp. My advice is to take a breather get some fresh air, leave it alone for a couple of days. I don’t think you should give up, it’s all a learning process - even though at the moment it’s as frustrating as hell there is a positive.
 You don’t want to have that amp lying around reminding you that it beat you, so snap out of it. Pick up you DDM and give that sucker what for. You can do it mate.


----------



## ShinyFalcon

smeggy, what resistor did you end up using for the zobel?


----------



## smeggy

Quote:


  Originally Posted by *ShinyFalcon* /img/forum/go_quote.gif 
_smeggy, what resistor did you end up using for the zobel?_

 

I used 2W 20 Ohm as there were no 22s in Frys.


----------



## digger945

Dang bubba, you come a long way to be givvin up now aint ya.
 Jus think of the sound and you can muster the intestinal fortitude.


----------



## amb

Quote:


  Originally Posted by *smeggy* /img/forum/go_quote.gif 
_I used 2W 20 Ohm as there were no 22s in Frys._

 

While the resistance is ok, you need to make sure that it's a non-inductive type. I don't know which resistors you got from Fry's, but the Zobel network is intended to provide a form of high frequency compensation, and if the resistor is inductive, then it effectively nullifies the function of the Zobel.


----------



## Gatsu

Quote:


  Originally Posted by *DoYouRight* /img/forum/go_quote.gif 
_wow great way to introduce your own board! would you happen to have a spare?_

 

I only had one board made as I knew I would make a mistake somewhere, and boy did I!

 If you notice in the photo the board has V3.0 on it, the schematic I uploaded is V3.3. I made quite a few stuff ups on that first version.

 Some changes from the V3.0 to V3.3:
 * Fixed the picaxe programming circuit
 * Added in the output switching relays (yes I managed to forget to include them)
 * Changed the circuit from having 4 independant LEDs for showing status to using 2 bidirectional LEDs (I originally was going to have the status LEDs very similar to namaanf's, but I wanted all of the buttons on the two cases to be the same, so it made sense to use them as indicators as well.)

 You can't actually see the changes I made for these in the final pictures as they are underneath the board.


----------



## askforwhy

I've tested 4 Sigma22s today and so far, 2 good, 2 dead
	

	
	
		
		

		
			







 Problem Sigma22 No.1:
 I reversed CR2-CR4 J508/J511. Holy crap, I guess I will have to replace ALL the CRDs/BJTs/MOSFETs then? I shouldn't have rush like this.
 Problem Sigma22 No.2:
 Everything seemed fine at first, I used DMM to check the DC Voltage then. Suddenly fire and smoke came up from Q15.
 Maybe I shorted V- to G by my probe accidently.
	

	
	
		
		

		
		
	


	



 Resistors seems OK, so I guess I am replacing the MOSFETs only.
 Any advice will help, thanks.


----------



## El_Doug

Quote:


  Originally Posted by *askforwhy* /img/forum/go_quote.gif 
_Problem Sigma22 No.2:
 Everything seemed fine at first, I used DMM to check the DC Voltage then. Suddenly fire and smoke came up from Q15.
 Maybe I shorted V- to G by my probe accidently.
	

	
	
		
		

		
		
	


	



 Resistors seems OK, so I guess I am replacing the MOSFETs only.
 Any advice will help, thanks._

 

this sounds EERILY familiar (read: exactly the same things happened to me). 

 however, after replacing all 4 mosfets as well as Q1 and Q2, I still did not have a working s22. upon testing even more of the transistors, I found Q3 had somehow blown itself - however, all that desoldering caused me to lift a trace, and I called it quits on that board. I'm now in the process of building another one


----------



## FallenAngel

Could be my imagination but when since I installed the Zobel network in the balanced Beta22, I think it's been running hotter. Does this make sense?


----------



## Nebby

Take the zobel out and do some measurements with and without it


----------



## FallenAngel

Easier said than done 
	

	
	
		
		

		
		
	


	




 Oh, and of course it gets hotter with low impedance headphones.


----------



## smeggy

Quote:


  Originally Posted by *amb* /img/forum/go_quote.gif 
_While the resistance is ok, you need to make sure that it's a non-inductive type. I don't know which resistors you got from Fry's, but the Zobel network is intended to provide a form of high frequency compensation, and if the resistor is inductive, then it effectively nullifies the function of the Zobel._

 

I'm not certain I got the exact type specified on your site but I think so, however, the amp was set to no output when it was turned on, ie, the 'phone/speaker switch was set to off in it's center position. I don't know if this makes a difference.


----------



## amb

Quote:


  Originally Posted by *smeggy* /img/forum/go_quote.gif 
_the amp was set to no output when it was turned on, ie, the 'phone/speaker switch was set to off in it's center position. I don't know if this makes a difference._

 

It shouldn't make a difference, if everything is wired up correctly. Why not post some clear pics of your internal wiring?


----------



## smeggy

I can't, the whole thing is now stripped out and the S22 and EHHA are in another case so there is just a pair of Beta boards in an mostly empty case.

 It's now an abandoned project as I really don't have the time or knowledge to continue with it.


----------



## qkizz

It has been very weird thing happening to one of my beta22 boards. When the board is placed horizontally 75mV on R34 is pretty much stable, but as soon I flip it to vertical voltage is skyrocketing (within few seconds) to 120mV and up, when I flip it back to horizontal it takes few seconds for voltage to drop to preset value. I've inspected board visually and found nothing wrong. 

 I've noticed it during heatsinks change for a larger ones 2.5". I have 5-ch balanced/SE version. Firstly I built 3ch and later on I decided to add 2 more boards and make balanced. To fit two more boards I had to place a new ones vertically and decided to add larger heatsinks to compensate for loss of heat dissipation. And than I've find out that one of vertical boards is overheating after few months of normal functioning. What could be the problem? Thanks


----------



## amb

qkizz, the heatsink fins dissipate heat most effectively when it's oriented veritcally (helps convection). If you change the board orientation then the temperature will inrease. Normally the MOSFETs should compensate for the increase a bit by their negative thermal coefficient, but you may still need to re-adjust VR2 to turn down the bias.


----------



## qkizz

amb, I understand that. What is surprising to me, is that voltage start rising (2mv/s) the same second I flip the board. Within few seconds when it is happening the temp on heatsink won't even rise and I'm already at about 100mV. Would such a sudden change in heat dissipation off heatsinks trigger sudden change in bias?


----------



## qkizz

BTW, The other board bias seems to be immune to change of heat dissipation (just a few mV difference and about 5Cdeg hotter that vertical)


----------



## amb

Hard to say what's really hapenning. Maybe there is an interference that's being picked up when your board changes orientation? Or a cold joint somewhere (either on the board, or the wiring) that exhibits itself when you move it?


----------



## qkizz

I just answer to one of the questions. Change of air convection/heat dissipation it does make a sudden bias change. The moment the air circulation around heatsinks changes, the bias changes at the same time. The reason why two identical boards reacts differently is still a bit mystery. Thanks AMB


----------



## qkizz

All the boards heatsinks are at 60C, just this one 10C more from whatever reason....Hope the 2.5" heatsinks are enough.


----------



## amb

70C is pretty hot. You should turn down the bias some.


----------



## qkizz

Voltage on R34 jumps up to 200mV on all my boards as soon as I plug the XLR cable at output. Also turning potentiometer up/down let me see vast change in voltage. 

 Now I remember having weird problems, when I first built 3-ch version, which experienced hissing noise depended from headphone/cable combination and volume level. I don't hear any noise this time, maybe because signal is balanced. 

 Advised by AMB I populated Zobel Network and it was fine. When I changed to balanced version I removed Zobel. Maybe that's the problem. Anyway I'll try to install it back again.


----------



## ShinyFalcon

In what order should I mount the MOSFETs? In one bag there is a matched pair of Z24 and Z34, so do I just install this bag to Q21 and Q22, and a new bag into Q23 and Q24?


----------



## oneplustwo

yes, that's right. if you look at amb's site under "device matching" it should become clear.


----------



## ShinyFalcon

The schematic did throw me off a bit but I now see where they connect! Now I feel silly...


----------



## qkizz

Installed Zobel and everything is OK. Bias is stable, temp. is at 50C. Why, would I need Zobel for preamp/head amp?


----------



## pompon

What is the build cost for a 4 channels B22 + O22 ? (excluding the case and connectors).

 How long to calculate to assemble one unit (without the case fitting ... ) ?


----------



## johnwmclean

Check out Glass Jar Audio for kit prices, building time depends on your experience. Going slowly populating the boards and taking continuity measurements between joints to the traces as you go - estimate 10 hours a board that includes testing. So 50 hours all up.


----------



## pompon

Those kit seem to not have all the required parts.
 Just an illusion or all the parts are in the kits ?
 Just need case, connectors, cables ?


----------



## Beefy

Quote:


  Originally Posted by *pompon* /img/forum/go_quote.gif 
_Those kit seem to not have all the required parts.
 Just an illusion or all the parts are in the kits ?
 Just need case, connectors, cables ?_

 

...... I don't mean to sound rude, but I think you need to do some serious research of your own first before even considering the Glass Jar kits.

 It is a bit difficult with Headwize down, but the B22 is not something that should be considered lightly.


----------



## pompon

You not rude at all .. I just take some information. 
 Those "ready kit" are not the ideal solution ? Price consideration or parts quality consideration ?


----------



## sachu

I think you should look into building a balanced EHHA if you don't mind getting into hybrids. Am eagerly waiting for impressions of the balanced version against the balanced B22 from the Denver meet in a couple of weeks.


----------



## Beefy

Quote:


  Originally Posted by *pompon* /img/forum/go_quote.gif 
_You not rude at all .. I just take some information. 
 Those "ready kit" are not the ideal solution ? Price consideration or parts quality consideration ?_

 

The 'kits' are a good solution for getting all the parts easily. But they only come as a bag of parts and will NOT help you build the amp.

 Quite a few people have managed fantastic B22's on early DIY attempts, but many do not. And the amp is complex enough that even very experienced builders sometimes have severe trouble.


----------



## qkizz

Zobel on ε22 > 3channel active ground is installed between outputs and active ground channel. In balanced between positive and negative. How should I wire zobel correctly if I have 3ch-active ground with ε22 + 2ch for balanced? I'm using Beta22 as preamp - not speaker amp.


----------



## DoYouRight

I read about the bass being way better on HD800s at that LA meet by IpodPJ and I have read it elsewhere, is that all from design or maybe different components used? Also, what is the default gain you guys use?


----------



## johnwmclean

Quote:


  Originally Posted by *DoYouRight* /img/forum/go_quote.gif 
_I read about the bass being way better on HD800s at that LA meet by IpodPJ and I have read it elsewhere, is that all from design or maybe different components used? Also, what is the default gain you guys use?_

 

DoYouRight I wouldn’t be taking those impressions too seriously, especially under meet conditions. The Beta22 has earnt it’s rightful place as the best solid state headphone amp.
 The recommended and best components are listed on the amb site, you’ve been around here long enough not to ask that question 
	

	
	
		
		

		
			





 Boutique components are a waste of time with this build and could actually sound worse.
 Gain come on you should know this...


----------



## DoYouRight

Well I was just curious about what he used, I had a good feeling it was better. I am curious about that.

 For Gain I know that balanced is double single ended, but I noticed that one guy made his so that it wasn't as loud but could microtune the volume compared to other b22s.


 EDIT: I never got a chance to view the Headwize threads, is there any chance they will be back soon? Or anyone has a backup or some of the best parts saved to files?


----------



## johnwmclean

DoYouRight, I went for gain 2 (a total of 4 for balanced). I listen around 11 - 3 with my volume control. It is ideal, I would hate to be limited to 10 before becoming too loud, the attenuator increments are much closer together in volume and I have a wider setting to pick from.
 I sent a pm to the guy who build the Beta22 for the LA meet to get specs, standard parts only were used exactly to spec. A standard volume pot (no fancy attenuator), also he’s running only one Sigma22. On top of all that it’s a single enclosure. Very standard build.


----------



## amb

Quote:


  Originally Posted by *qkizz* /img/forum/go_quote.gif 
_Installed Zobel and everything is OK. Bias is stable, temp. is at 50C. Why, would I need Zobel for preamp/head amp?_

 

Sometimes the specifics of your wiring might introduce enough inductance at the output to upset the amp's stability. A zobel network swamps that inductance. This is not just β22, many wideband amps are similar. The reason why a zobel is not on the PCB is because unbalanced and balanced setups require different connections, and the parts are best mounted right at the jacks, _after_ the wiring (even though there is more wiring in the headphone cable/interconnect/speaker cable, but that's external).


----------



## DoYouRight

thanks John, I think Ill use that since everything youve done has been pretty much in line with what I like, even on your buffalo, if I lived in AUS I would try out your stuff as I built if at all possible  I don't want high gain as I have alot of efficient cans, though most amps Ive used or had the gain was 8-12ish so even tho that is alot lower I think itll be better, just out of curiousity what kind of attenuator did you use?


----------



## johnwmclean

Quote:


  Originally Posted by *DoYouRight* /img/forum/go_quote.gif 
_thanks John, I think Ill use that since everything youve done has been pretty much in line with what I like, even on your buffalo, if I lived in AUS I would try out your stuff as I built if at all possible  I don't want high gain as I have alot of efficient cans, though most amps Ive used or had the gain was 8-12ish so even tho that is alot lower I think itll be better, just out of curiousity what kind of attenuator did you use?_

 

DACT CT2, also DACT knob feels really nice and the attenuator is very quite.


----------



## oneplustwo

Hey folks... back again for some trouble shooting help. On one of my beta boards, I get the 4.5V across R9 but can't get anything above zero at R34. I did the initial setup of the trim pots with VR1 and VR2 at zero and VR3 in the middle. The voltage at the V+, V- pads is correct (about 29V) and nothing seems to be getting unduly hot or smoky or anything like that.

 Problem board #2 gives me little to no voltage at the V+ and V- pads and the sigma gets hot quickly (only on one side though). Seems like a short somewhere but I didn't measure one at either V+ or V-.

 Thanks for the help!


----------



## El_Doug

Quote:


  Originally Posted by *DoYouRight* /img/forum/go_quote.gif 
_thanks John, I think Ill use that since everything youve done has been pretty much in line with what I like, even on your buffalo, if I lived in AUS I would try out your stuff as I built if at all possible  I don't want high gain as I have alot of efficient cans, though most amps Ive used or had the gain was 8-12ish so even tho that is alot lower I think itll be better, just out of curiousity what kind of attenuator did you use?_

 

i have also built my b22 boards to a gain of 2 each, for a total of 4. 

 i chose this, based on my LD MK VI's gain of 5 (switchable to 10 for the likes of the K1000). when using this amp, I find myself turning the volume knob no further than 11 o'clock during high-volume reference listening sessions. I figured that I'd like to make the most of my stepped attenuator's more gradual mid-region at around the same volume I typically listen to. 

 the DACT's are EXPENSIVE, though worth it in terms of the longevity of their "clickiness." many of us use the "alternatives," here is the one I have in my build: Balance XLR 23 stepped attenuator volume control 250K - eBay (item 290325370654 end time Jul-18-09 22:52:11 PDT)

 It is a tried-and-true attenuator, works perfectly, and will save you very significant amounts of money. Honestly, if I were to spend more, I'd go with a Joshua Tree WAY before I even considered a DACT.


----------



## amb

Quote:


  Originally Posted by *oneplustwo* /img/forum/go_quote.gif 
_Hey folks... back again for some trouble shooting help. On one of my beta boards, I get the 4.5V across R9 but can't get anything above zero at R34. I did the initial setup of the trim pots with VR1 and VR2 at zero and VR3 in the middle. The voltage at the V+, V- pads is correct (about 29V) and nothing seems to be getting unduly hot or smoky or anything like that._

 

Search this thread about measuring the voltage across D11 and D12 to verify whether Q25 and Q26 are good.

  Quote:


 Problem board #2 gives me little to no voltage at the V+ and V- pads and the sigma gets hot quickly (only on one side though). Seems like a short somewhere but I didn't measure one at either V+ or V-. 
 

- Do you have the V+ and V- wires reversed?
 - Make sure you didn't mix up the N and P channel MOSFETs anywhere (on the amp board as well as the PSU).
 - Measure the resistance between V+ and G, G and V- and V+ and V-. Any shorts?
 - Measure the MOSFETs themselves for shorts too.


----------



## johnwmclean

Quote:


  Originally Posted by *El_Doug* /img/forum/go_quote.gif 
_It is a tried-and-true attenuator, works perfectly, and will save you very significant amounts of money. Honestly, if I were to spend more, I'd go with a Joshua Tree WAY before I even considered a DACT._

 

El_Doug, sure DACT's are expensive, and it's overkill. But so is a Beta22. The DACT is truly a precision piece, it feels like a million dollars compared to those cheaper eBay jobs. Just as a Rolex is expensive, cheaper watches tell you the same time, they both have the same functionality, one just has a hell of a lot more ownership pride. It's easy to critise something that might be financially unattainable. For me they make arguably the best speced attenuator in existence.


----------



## El_Doug

If my words sounded like criticism, I apologize. I simply remember DoItRight stating that he went overbudget for the month, and wanted to let him know that the cheaper alternatives arent complete crap


----------



## johnwmclean

Quote:


  Originally Posted by *El_Doug* /img/forum/go_quote.gif 
_If my words sounded like criticism, I apologize. I simply remember DoItRight stating that he went overbudget for the month, and wanted to let him know that the cheaper alternatives arent complete crap 
	

	
	
		
		

		
			



_

 

El_Doug, don't be silly - and no need to apologize, I'm never precious about any of this. Just thought you might counter my post with a good debate. Now you've taken the wind from sails.


----------



## n_maher

If someone wanted to knock a good chunk (1/3) off the price of a real DACT they'd only have wander by Headamp's DIY parts section... It's still an expensive piece but for something that is 100% in the signal path and absolutely critical to the function of the amp it seems like an area worth throwing $$ at.


----------



## askforwhy

Quote:


  Originally Posted by *El_Doug* /img/forum/go_quote.gif 
_this sounds EERILY familiar (read: exactly the same things happened to me). 

 however, after replacing all 4 mosfets as well as Q1 and Q2, I still did not have a working s22. upon testing even more of the transistors, I found Q3 had somehow blown itself - however, all that desoldering caused me to lift a trace, and I called it quits on that board. I'm now in the process of building another one_

 

Thanks El_Doug, I've just finished fixing those two burnt Sigma22 and it took me about 5 hours. Since this Beta22 is my first DIY project, I bet most of you can do it better than me.
	

	
	
		
		

		
		
	


	



 2 MOSFETs and 2 BJTs were blown in the sigma22 that I reversed 3 CRDs, and the sigma22 that I accidently shorted V- to G by probe, I had to replace 8 BJTs and the MOSFETs. It is painful to solder and desolder, especially you have to be very careful not to lift any trace. I actually did but luckily the board is not damaged.
 The good news is my 6 Beta22 boards passed initial check days ago, and I've been enjoying the temporarily-build 3-channel Beta22. The sound is STUNNING!
	

	
	
		
		

		
		
	


	



 Still waiting for my case to come.


----------



## askforwhy

Forget to mention, my sigma22 is hotter than my beta22(3-ch/1 psu), kinda like 60'C to 50'C, ambient temperature around 30'C.


----------



## askforwhy

Quote:


  Originally Posted by *pompon* /img/forum/go_quote.gif 
_You not rude at all .. I just take some information. 
 Those "ready kit" are not the ideal solution ? Price consideration or parts quality consideration ?_

 

The Glass Jar Kit is wonderful, many head-fiers take the kit to finish their first beta22. 
 I guess Beefy is trying to tell you if you don't have enough experience, it will be really tough to solve some problem if encounter any.


----------



## dude_500

Parts coming tomorrow! Can't wait to build it and come up with a nice enclosure.


----------



## oneplustwo

Quote:


  Originally Posted by *amb* /img/forum/go_quote.gif 
_
 - Do you have the V+ and V- wires reversed?
 - Make sure you didn't mix up the N and P channel MOSFETs anywhere (on the amp board as well as the PSU).
 - Measure the resistance between V+ and G, G and V- and V+ and V-. Any shorts?
 - Measure the MOSFETs themselves for shorts too._

 

All checked out fine. Maybe I'll try again... or are there other places I should check for shorts?


----------



## amb

Quote:


  Originally Posted by *oneplustwo* /img/forum/go_quote.gif 
_All checked out fine. Maybe I'll try again... or are there other places I should check for shorts?_

 

Is the PSU working properly without the amp board connected?
 If so, then there has to be either a wiring error, or a short somewhere on the main rails for it to behave the way you described, and the measurements I listed should have brought to light what it might be.


----------



## oneplustwo

Hmm, ok. I'll take a closer look at the PSU. The same PSU worked for the other boards that tested out fine. Also, here's another piece of info. Turns out that of the 8 boards I have, 2 of them have the short problem and 2 of them have the biasing problem. Not sure if that makes a difference in trouble shooting.


----------



## linuxworks

short problem? shorted pc board traces? can you show photos?


----------



## DoYouRight

Thanks guys, yes I did go overboard this month, atleast I didn't order a HD800 yet, todd helped me ease into waiting a bit. The one on ebay is nice, though I might go with the Headamp dact as it is a good deal under msrp. Thanks 
	

	
	
		
		

		
		
	


	




 Im hoping it makes a difference in the sound.


----------



## mp101

Hi guys, still getting parts together to build mine, but building an M3 first with Sigma 11. Just trying to get the internal wiring now, but don't know what to get, what thickness etc? should I bother with silver to the audio connectors?

 Sure I asked Ti this on Headwize, but its still not active, anyone know when its going to be back up?
 Cheers
 Marc


----------



## El_Doug

No idea when headwize will be back - i used to be optimistic, but at this rate i'm not holding my breath 
	

	
	
		
		

		
		
	


	




 For thickness, i typically wire the power with 18gauge and the audio with 22-24 gauge. silver never hurt anyone, and may help increase resale value - whether you think it is necessary is for you to decide 
	

	
	
		
		

		
		
	


	




 I've personally never had a problem with stranded copper


----------



## mp101

Thanks ElDoug


----------



## ShinyFalcon

Couple of grounding questions:

 - The ground pins on the potentiometer should be connected, right? There is no continuity between the two pins unless I bridge it. If I leave them unconnected, then RCA ground and signal ground (on β22) are not connected.
 - With the pot ground connected together, should there be ground continuity throughout the entire case, between signal input and signal ground on the β22, and the voltage grounds?
 - Would ground hum occur for broken continuity? Like for my case, the panels aren't really connected to the main case, unless I connect them with wire. I didn't run into problems with my M³ which was cased in cardboard.
 - And looking at the e27 schematics seems to verify my claims...


----------



## linuxworks

yes, the pins on the pot for ground should be electrically connected (by you, they don't come that way from the factory; how is the factory to know you want a common ground on a dual gang pot?) 
	

	
	
		
		

		
			





 you need to re-review the diagrams (most helpful) on amb's site. once you look at all the diagrams, I think you'll see what needs to be connected and what floats.

 the first question is: is the PS inside the amp box or outside it? actually, toroid inside or out? s22 inside or out?

 mine is: toroid outside but s22 inside. in that situation, I have the analog rca inputs connected TO the metal case. I run wires from the analog-in to the pot and the ground pins on the pot are connected to the ground at the line-in (chassis) point.

 I don't actually have a pot in my b22 anymore (I use external vol control) and so the line-in goes directly to the 2 molex connectors on the b22 boards. I do NOT ground the inputs again, I let them get their ground from the long-ish cable run from the line-in point.

 I also don't connect the s22 ground to the chassis. big no-no, I think, at least in my config.

 the s22 ground goes directly (one non-shared wire) to the phones-out ground. that's for my 2ch b22, of course.

 the s22 has ground wires (and + and -) going direct to each b22 board. those grounds do NOT touch chassis, btw.

 that's what worked for me. I have no audible hum anymore.


----------



## ShinyFalcon

I have three cases, for the β22, σ22, and the toroid. I could make the toroid fit in the σ22 but it would've been more trouble than it's worth (have to either chop up the heatsink or drill the holes at an odd position). If I wanted a single chassis solution I would probably buy one of the Hammonds, but I'm done with purchases for now.

 For the toroid case, I have the four secondaries as an umbilical to the σ22, and a 7-wire (for V+, V-, G and SG) umbilical for the β２２．I haven't thought about how to connect the IEC ground yet. I'm thinking about connecting the IEC ground to the toroid case, then going to the σ22 case through the umbilical.

 The RCA ground contacts the case, and goes to the pot where the grounds are connected, and goes into the boards. 

 I'll be back in a bit, I'm noticing an oddity with my AC mains. It's fluctuating between 125V and 130V. My air conditioning unit gets much louder and my ceiling fan makes a high pitched noise when the AC goes up to 130V.


----------



## linuxworks

on the subject of power, its interesting to see how the b22 warms up and causes a DECREASE in power consumption!

 I have a kill-o-watt lcd meter on my b22. when I first turn it on, cold, it starts out at about 55watts at 110vac. in about a minute its down to 40w and eventually it settles at 30w!

 it almost halves in a matter of 5 minutes or so. amazing!

 someday I'll built a 'tweet a watt' so that I can graph this stuff over time. all I've done so far is just visually watch the lcd change as the 5 minutes or so progresses.

 mosfets are funny creatures


----------



## fsrick

Quote:


  Originally Posted by *linuxworks* /img/forum/go_quote.gif 
_on the subject of power, its interesting to see how the b22 warms up and causes a DECREASE in power consumption!

 I have a kill-o-watt lcd meter on my b22. when I first turn it on, cold, it starts out at about 55watts at 110vac. in about a minute its down to 40w and eventually it settles at 30w!

 it almost halves in a matter of 5 minutes or so. amazing!

 someday I'll built a 'tweet a watt' so that I can graph this stuff over time. all I've done so far is just visually watch the lcd change as the 5 minutes or so progresses.

 mosfets are funny creatures 
	

	
	
		
		

		
		
	


	





_

 

I guess when the b22 heats up, the resistance in the devices increases and hence reduce the current. so the power drops. not sure though.


----------



## fsrick

I am planning on building a balanced beta 22 with seperated power case. i am thinking about using silver wire in my build. do you guys think this will have any improvement in terms of sound quality. since sliver wire now is only $3 dollar/ft for 18 guage and $1 dollar/ft for 24 guage, i do not thinkg this will add up the cost much, $50? maybe. do you think this is worthy fro the upgrade? Thanks.


----------



## amb

Quote:


  Originally Posted by *fsrick* /img/forum/go_quote.gif 
_I guess when the b22 heats up, the resistance in the devices increases and hence reduce the current. so the power drops. not sure though._

 

MOSFETs have a negative thermal coeffient -- as the temperature rises the current through them decrease (given a constant bias voltage). This is an attractive characteristic to keep the amplifier thermally stable. See the β22 website "Tech highlights" section.


----------



## dude_500

I got my sigma-22 and first beta-22 board up without a problem. On the second board, I powered it up with no problems. Set VR1 based on R9,10,11,12 fine, then went to do VR2 and put probes on R34 and R35 and both of them give 0.0mV on my meter. I gave VR2 about 5 turns to the right and it remained 0.0mV at which point I figured I better stop going further since nothing was happening and something might be damaged if I continued. All parts seem to be correct and I can't find any bad solder joints. Any suggestions at what I should specifically look at?


----------



## amb

dude_500, search this thread about measuring the voltage across D11 and D12 to verify whether Q25 and Q26 are good. Also make sure you didn[t forget to install the R30/R31 wire jumpers. Visually inspect all parts to make sure the correct ones are installed and in their proper orientations. Check solder joints too.


----------



## fsrick

if i want to use b22 as a preamp or speaker amp, do i need to make any changes to the board (besides heatsink) ? or i can just simply connect the outputs to the RCA connectors in the back.


----------



## dude_500

D11 and D12 start at 20-25 volts on first power up and within about 10 seconds D11 stabilizes at 3.8 volts and D12 at 2.2 volts. This was with trimpots set to default starting 0, 0, 50%... I've checked joints twice under a bright light looking very carefully and can't find any errors. Checked all the transistors and they're all correctly installed. Diodes are correct polarity.

 MOSFET's are cold after operation long enough to heat up the other channel


----------



## dude_500

Wow, somehow I am blind enough to have thus far not seen that CR6 was installed backwards (J201). Can I just flip this or would that have damaged something else?


----------



## mp101

Where are you guys buying your silver wore from, or your copper for that matter, any good fleabay suppliers?


----------



## amb

Quote:


  Originally Posted by *fsrick* 
_if i want to use b22 as a preamp or speaker amp, do i need to make any changes to the board (besides heatsink) ? or i can just simply connect the outputs to the RCA connectors in the back._

 

No changes to the board necessary... did you read the "Other options" section of the β22 website?

  Quote:


  Originally Posted by *dude_500* 
_Wow, somehow I am blind enough to have thus far not seen that CR6 was installed backwards (J201). Can I just flip this or would that have damaged something else?]_

 

Just flip it and see if it works.


----------



## dude_500

The amp is now working great after switching CR6 around, no other damage was caused by the error. This amp is amazing, it is worlds better than my old tube amp that I build last year. Though I am going to be still using my tube phono stage as that puts out great sound, listening to it right now through the Beta-22... Thanks AMB for this awesome design. I'll post more pictures when I work out some sort of an enclosure, just on plywood right now.


----------



## Lifthanger

Quote:


  Originally Posted by *mp101* /img/forum/go_quote.gif 
_Where are you guys buying your silver wore from, or your copper for that matter, any good fleabay suppliers?_

 

look for navships on ebay.


----------



## fsrick

Quote:


  Originally Posted by *mp101* /img/forum/go_quote.gif 
_Where are you guys buying your silver wore from, or your copper for that matter, any good fleabay suppliers?_

 

VT4C studio. i think the price there is fairly low.


----------



## fsrick

Quote:


  Originally Posted by *amb* /img/forum/go_quote.gif 
_No changes to the board necessary... did you read the "Other options" section of the β22 website?


 Just flip it and see if it works._

 


 Thanks amb, i was looking at the balance/unbalance graph, total ignore the the first one.


----------



## dude_500

The amp has been working great until a few minutes ago. I was listening then it died out. I checked and the fuse was blown. The output plug was dangerously close to the grounded volume knob and most likely touched (lesson learned, get those enclosures done). Anyways, I moved the jack away from the knob and replaced the fuse. The LED's came on for a second (the one on the left channel was pretty dim) and then the fuse blew again. Where should I begin on the repair/diagnosis?

 Update: All 4 mosfet's are blown on the left channel that shorted. Are there other parts that would need to be replaced most likely when this happens?


----------



## johnwmclean

Quote:


  Originally Posted by *dude_500* /img/forum/go_quote.gif 
_The amp has been working great until a few minutes ago. I was listening then it died out. I checked and the fuse was blown. The output plug was dangerously close to the grounded volume knob and most likely touched (lesson learned, get those enclosures done). Anyways, I moved the jack away from the knob and replaced the fuse. The LED's came on for a second (the one on the left channel was pretty dim) and then the fuse blew again. Where should I begin on the repair/diagnosis?_

 

This wouldn't cause a fuse to blow, as it's only audio ground/wiring. I suggest you look elsewhere for the fault - starting at the IEC. Disconnect the amp boards and test the psu unloaded.


----------



## amb

Quote:


  Originally Posted by *dude_500* /img/forum/go_quote.gif 
_Update: All 4 mosfet's are blown on the left channel that shorted. Are there other parts that would need to be replaced most likely when this happens?_

 

Check the PSU with the amp boards disconnected and see if it's still ok.
 Check the 0.47 ohm resistors too. Are there any parts that show any sign of overheating/burning?


----------



## linuxworks

Quote:


  Originally Posted by *dude_500* /img/forum/go_quote.gif 
_Update: All 4 mosfet's are blown on the left channel that shorted. Are there other parts that would need to be replaced most likely when this happens?_

 

I replaced mine as a set. just easier that way..

 same with the .47's. I wasn't sure if I blew all of them but some were really toasty looking, yet some didn't look that bad. I didn't want to trust it, so I reinstalled THOSE as well. I do recommend it, its easier to bulk replace things than have more 'daisy chain' failure modes. in for a penny, in for a pound, I say 
	

	
	
		
		

		
			





 bulk unsolder. get a hakko 808 if you don't already have one. mine got QUITE a workout on my b22 boards.


----------



## dude_500

I'm listening to the right channel right now, sounds great and PSU works fine clearly based on this. If I plug in the other channel, it blows the fuse. All of the mosfet's on that board read a short circuit so those are definitely burned. The .47's are still reading fine on my meter. 

 So it's not likely that the other smaller transistors would be damaged by this?


----------



## amb

Quote:


  Originally Posted by *dude_500* /img/forum/go_quote.gif 
_So it's not likely that the other smaller transistors would be damaged by this?_

 

Not likely.


----------



## fsrick

if i would like to use balanced beta 22 as a speaker amp. can i just use two sigma with 2 80VA transformer. one sigma for each beta is too much for me. or is it better to use 2 100VA transformer? thanks.


----------



## amb

Quote:


  Originally Posted by *fsrick* /img/forum/go_quote.gif 
_if i would like to use balanced beta 22 as a speaker amp. can i just use two sigma with 2 80VA transformer. one sigma for each beta is too much for me. or is it better to use 2 100VA transformer? thanks._

 

There is no simple answer. It all depends... Have you looked through the rest of this thread (and others too)?


----------



## TimmyMac

Quote:


  Originally Posted by *fsrick* /img/forum/go_quote.gif 
_if i would like to use balanced beta 22 as a speaker amp. can i just use two sigma with 2 80VA transformer. one sigma for each beta is too much for me. or is it better to use 2 100VA transformer? thanks._

 

I used 2 160VA transformers from Apex Jr (cheap!), feeding 2 sigma22 boards and it works great for my 4-channel build powering 8-ohm speakers. Probably don't try to drive low sensitivity 4-ohm speakers though.


----------



## dude_500

I just got new MOSFET's in and replaced them and powered up and it worked great. I then had to go somewhere, came home and hot glued the sockets onto my temporary enclosure, powered up and there were two different noises in the left ear, both static noises but not distinctly 60hz. I then went to probe resistors and a fuse blew (I'm sure I didn't short anything). Replaced fuse, powered on fine. Powered off and back on, blew a fuse.

 What could be causing all this? The MOSFET's are still fine and the power supply works fine isolated and puts out +- 28.4 volts


----------



## digger945

Have you ohmed out the +30/GND/-30 terminals on the amp board with everything powered down/unplugged/disconnected?

 Checked for solder bridges or shorted output wiring?

 VR1 and VR2 trimpots set to middle positions?


----------



## dude_500

Quote:


  Originally Posted by *digger945* /img/forum/go_quote.gif 
_Have you ohmed out the +30/GND/-30 terminals on the amp board with everything powered down/unplugged/disconnected?

 Checked for solder bridges or shorted output wiring?_

 

All power inpuit/audio output ohm readings check out to what they've always been and match on the two channels


----------



## digger945

Were you able to measure the DC voltage across R34 and R35 before the fuse blew?


----------



## dude_500

Quote:


  Originally Posted by *digger945* /img/forum/go_quote.gif 
_Were you able to measure the DC voltage across R34 and R35 before the fuse blew?_

 

No, I did R9, R10, turned it off, cliped onto R34, turned on, and then the lights dimmed out with a blown fuse.

 Checked for shorts, didn't find anything, replaced the fuse, powered on and it stayed on, then I powered off/on and it blew another fuse.


----------



## digger945

Quote:


  Originally Posted by *dude_500* /img/forum/go_quote.gif 
_No, I did R9, R10_

 

and your readings were approximately 4.5V?

 What size fuse are you using?


----------



## dude_500

Quote:


  Originally Posted by *digger945* /img/forum/go_quote.gif 
_and your readings were approximately 4.5V?

 What size fuse are you using?_

 


 4.4V and 4.55V on 9 and 10, so yes... 2A fuse from the hardware store. I only have 1 more and they cost $1.99 locally so I'd rather figure this out beore I waste the last one


----------



## digger945

The only step I have skipped is measuring the resistance from the output pad to ground, and making certain the V+ and Gnd and V- are connected properly. The next few steps require powering on.
 You could go back and check VR2 to make sure it's in the middle of it's travel and/or check it's resistance.


----------



## dude_500

V+/-/gnd are connected with continuity tested to the board. No short on the outputs.

 Ok, I'll try resetting the board-of-suspicion to it's original pot positions and try powering up and reconfiguring


----------



## digger945

Since you seem to be good on R9 and 10 I would not readjust VR1.
 If you are satisfied with your resistance/short measurements then I would connect the test clips to R34 or R35 before powering up and limit the time with power on to just enough to get a mV reading.


----------



## dude_500

One other note is that since I replaced the mosfet's after my last burn-out, the LED on the replaced board takes about half a second longer to come on fully than the other board. On first build last week they came on simultaneously


----------



## digger945

Have you tried swopping sigmas to see if the problem follows?


----------



## dude_500

It's powering on now, ~4.5V on R9 10 11 12 and .65mv on R34,35. I still have a nasty hiss/buzz on the left channel though. It is not volume related and is full-on at zero volume. It is at listening loudness

 I don't have any other sigma-22 boards


----------



## amb

Regarding buzzing noise -- ground problem? Also, make sure DC offset is nulled to zero before plugging in headphones.

 Btw, what's your power supply configuration? One or two transformers? What is the transformer spec? You said 2A fuse, is it slow-blow?


----------



## linuxworks

Quote:


  Originally Posted by *dude_500* /img/forum/go_quote.gif 
_One other note is that since I replaced the mosfet's after my last burn-out, the LED on the replaced board takes about half a second longer to come on fully than the other board. On first build last week they came on simultaneously_

 

bad electro cap somewhere? can't think of what would cause a 'slow start' other than that.


----------



## dude_500

Hard to believe I built a pair of beta-22's and then found 3 bad joints on my epsilon-27. I've had a really hard time soldering onto that board, not sure why. Also not the slightest clue how that blew the fuse. I think they are fast blow which I'll replace with slow, but they're not blowing now.

 Anyways, it's working like it did last week on first start. *Ears are happy again*

 I've always had a problem where if I turn up the volume beyond about 1/3 level I start to hear background noise (the same noise that was there with the faulty signal connections only quieter) and it gets progressively louder with volume. At about 2/3 it impedes clean listening. I have my PC maxed with the beta-22 at about 10% but I'd like to have it fully functional. I attached a schematic of my grounding which I believe is correct. Did I do anything obviously wrong?


----------



## ShinyFalcon

Is the β22 suppose to turn off smoothly when cutting the power? After flipping the switch the music continues for 1/2 a second before turning off with a funny squeak. Turn the σ22 back on and the music fades back in, very nice effect.

 If it helps, I have seven conductors as an umbilical, so maybe some imbalance in length there... wiring's a mess.






 dude_500, is your PSU and amp cased in the same enclosure? It looks like you tied IEC ground to signal ground, which I believe isn't a good thing.


----------



## linuxworks

Quote:


  Originally Posted by *ShinyFalcon* /img/forum/go_quote.gif 
_Is the β22 suppose to turn off smoothly when cutting the power? After flipping the switch the music continues for 1/2 a second before turning off with a funny squeak. Turn the σ22 back on and the music fades back in, very nice effect._

 

I think it depends on how exactly things are balanced (matched, transistors and components).

 I've heard amb's actual b24 (same basic idea) and its smooth up and smooth down. no turn on thuds or anything.

 on my own b22, its not quite as perfect but still nothing 'violent' in on/off noises.

 normal to have it take a second or so to drain out at turn-off time.


----------



## amb

Quote:


  Originally Posted by *ShinyFalcon* 
_Is the β22 suppose to turn off smoothly when cutting the power? After flipping the switch the music continues for 1/2 a second before turning off with a funny squeak. Turn the σ22 back on and the music fades back in, very nice effect._

 

Yes, that's a beauty of the fully-complementary topology combined with a tracking power supply (there are other benefits too, but this is an obvious one). The final "squeak" happens when the transistors lose their bias and turn off.

  Quote:


 dude_500, is your PSU and amp cased in the same enclosure? It looks like you tied IEC ground to signal ground, which I believe isn't a good thing. 
 

Yup, there is probably a ground loop now.


----------



## dude_500

It's all mounted on a piece of plywood until I build an enclosure. I suppose it is mounted as though it were all in one enclosure, though there's no actual enclosure.

 Should the IEC ground not be used at all in this situation?


----------



## amb

Quote:


  Originally Posted by *dude_500* /img/forum/go_quote.gif 
_Should the IEC ground not be used at all in this situation?_

 

Yes, since there is no chassis to tie it to, just leave it unconnected.


----------



## boinger

im considering building a beta22

 i have an obh21 se psu would that work for the beta ? or is it recommended to just stick with the sigma 22 psu setup

 also should i order extra boards? or will anything i do wrong be able to be repaired without a spare board?


----------



## dude_500

Quote:


  Originally Posted by *boinger* /img/forum/go_quote.gif 
_im considering building a beta22

 i have an obh21 se psu would that work for the beta ? or is it recommended to just stick with the sigma 22 psu setup

 also should i order extra boards? or will anything i do wrong be able to be repaired without a spare board?_

 

You don't absolutely have to use the sigma-22, but it is suggested and if you don't you might have some difficulties with power supply induced noise unless your supply is giving a very clean DC signal.

 You don't need extra boards unless you mess up horrible and put every part in the wrong spot or something. Just be careful and you'll be fine.



 Regarding my noise problem, cutting the IEC ground removed 99% of it. Now there is a barely audible hiss on max volume which I'm guessing will go away when I put it in two metal grounded cases.


----------



## boinger

Quote:


  Originally Posted by *dude_500* 
_You don't absolutely have to use the sigma-22, but it is suggested and if you don't you might have some difficulties with power supply induced noise unless your supply is giving a very clean DC signal.

 You don't need extra boards unless you mess up horrible and put every part in the wrong spot or something. Just be careful and you'll be fine.



 Regarding my noise problem, cutting the IEC ground removed 99% of it. Now there is a barely audible hiss on max volume which I'm guessing will go away when I put it in two metal grounded cases._

 

ah thanks that is very reassuring =)
 i think i will go for the sigma 22 

 what would you recommend the balanced 4 channel or the active grounded 3 channel ?
 i have senn hd650's and an m-audio firewire 410 as my source


----------



## dude_500

Quote:


  Originally Posted by *boinger* /img/forum/go_quote.gif 
_ah thanks that is very reassuring =)
 i think i will go for the sigma 22 

 what would you recommend the balanced 4 channel or the active grounded 3 channel ?
 i have senn hd650's and an m-audio firewire 410 as my source_

 


 Your answer to that would vary with everyone you ask, but I personally have a 2 channel and it sounds great on my HD600's. I could possibly justify 3-channel but in my personal opinion (I will admit I have never heard a 4-channel setup), a 4 channel is totally overkill and a waste of money (unless you are using speakers, then it gives 50Watts vs. 18Watts, irrelevant for headphones). Some would claim it is a noticable improvement, but I think it's not worth it because you would also need a new source that gives a balanced output.

 Without a balanced source which it sounds like you fit this situation, if you have plenty of money I guess go with 3 channel but 2 is still an awesome amp.


----------



## digger945

dude, do you have your source hooked up or no, and what source is it?
 Perhaps you could ground the inputs and then see if you have any hiss or hum.
 By "cutting the IEC ground" do you mean disconnecting all other grounds from the IEC ground(earth ground)?


----------



## dude_500

Quote:


  Originally Posted by *digger945* /img/forum/go_quote.gif 
_dude, do you have your source hooked up or no, and what source is it?
 Perhaps you could ground the inputs and then see if you have any hiss or hum.
 By "cutting the IEC ground" do you mean disconnecting all other grounds from the IEC ground?_

 

Source is a Gamma-1... the static is with the source plugged in but nothing playing. With the source removed, I get nasty buzzes (unless I touch the volume knob column, then it goes silent). How exactly would I ground the inputs? They are already grounded through the gnd of the two input wires on each beta-22 aren't they?

 I had the IEC ground going to a ground return on the sigma-22 which helped a bit to remove


----------



## digger945

Do you use the Gamma 1 with usb input from a computer?
 I have never tried connecting the Sigma22 ground to IEC ground before, I use the IEC ground connected to the Sigma PS metal chassis to make sure if a high voltage wire comes loose it will trip the breaker for that 110V home circuit(as it is shown on the Sigma 22 wiring page at amb.org).

 The other question about shorting the inputs on the Beta boards isn't necessary really, I was just wondering if you tried shorting the input signal to the input ground to see if it made a difference with the source disconnected.

 What kind of attenuator are you using, if it's an alps it may need to be grounded to everything else like you see here in step 5 , in addition to all signal grounds tied to all other grounds.


----------



## amb

Quote:


  Originally Posted by *dude_500* 
_How exactly would I ground the inputs?_

 

Have you looked at the "Wiring & ground" section of the β22 website? There are diagrams telling you exactly what to do. If you have no enclosure, then the volume pot body needs to be explicitly connected to the input ground.

 As for checking for noise, wait until you case it. At the very least, turn the volume pot all the way down to minimum if there is no source connected. An open input will pick up all kinds of noise/interference.


----------



## dude_500

I have the alps pot... I have it grounded through one of the two screws to the input ground as suggested. It's wired according to what the B22 wiring section shows.

 I can easily listen to it; it's silent under 50% volume, so I'll just wait until it's cased up and grounded in a metal chassis before I worry about noise.


----------



## digger945

Give us a song that you have listened to and enjoyed today, and how good it sounds.


----------



## dude_500

Quote:


  Originally Posted by *digger945* /img/forum/go_quote.gif 
_Give us a song that you have listened to and enjoyed today, and how good it sounds._

 

Listening to Emmylou Harris - For No One right now, the bass sound stage is incredibly defined, but what I've never heard in any other amp is how crisp and clear the higher midrange is. Lovin' every song I throw at it.

 Now I just need to get a quieter water-pump in my computer so that my HD600's aren't drowned out so much... sometimes it has it's disadvantages to be a water-cooled pc nerd and an audiophile... some conflicting audio situations there


----------



## nattonrice

Lol it can't be as bad as my RD-30 at my feet here :S


----------



## boinger

Quote:


  Originally Posted by *dude_500* /img/forum/go_quote.gif 
_Your answer to that would vary with everyone you ask, but I personally have a 2 channel and it sounds great on my HD600's. I could possibly justify 3-channel but in my personal opinion (I will admit I have never heard a 4-channel setup), a 4 channel is totally overkill and a waste of money (unless you are using speakers, then it gives 50Watts vs. 18Watts, irrelevant for headphones). Some would claim it is a noticable improvement, but I think it's not worth it because you would also need a new source that gives a balanced output.

 Without a balanced source which it sounds like you fit this situation, if you have plenty of money I guess go with 3 channel but 2 is still an awesome amp._

 

Hmm thanks for your reply I think I will go with the 3 channel kit from glass jar then. As I they dont have an option for a 2 channel, and I cant source the parts very easily locally since I am in india. 

 Thanks for your advice / help / future help =)

 as I'm sure I'll be needing some help when it arrives.


----------



## dude_500

Quote:


  Originally Posted by *boinger* /img/forum/go_quote.gif 
_Hmm thanks for your reply I think I will go with the 3 channel kit from glass jar then. As I they dont have an option for a 2 channel, and I cant source the parts very easily locally since I am in india. 

 Thanks for your advice / help / future help =)

 as I'm sure I'll be needing some help when it arrives._

 


 Just be extremely careful placing parts... triple check correct parts in positions and polarities, and you should have an excellent and event free build. Also don't build at 3am as I did, that's when the mistakes happen


----------



## boinger

Quote:


  Originally Posted by *dude_500* /img/forum/go_quote.gif 
_Just be extremely careful placing parts... triple check correct parts in positions and polarities, and you should have an excellent and event free build. Also don't build at 3am as I did, that's when the mistakes happen 
	

	
	
		
		

		
		
	


	


_

 

haha I'll probably be doing that exactly... although I find I work better at night. Yea I do plan on triple checking parts maybe even more. It will definately take me sometime to build as I can't afford to make errors and fry a board. Importing costs will be simply too much to allow for mistakes. Especially considering I am prone to misread things in a hurry I'll have to slow myself down. 

 The advantage is I should be able to get a wood enclosure made here relatively cheap. maybe no more than $50-$100 US.

 edit: its ok to use wood for the beta right ? heat wont be a prob?


----------



## boinger

Another question do you recommend wearing gloves / working on a rubber mat between you and the ground? is it necessary with this build? 

 or if you get shocked will it be more like a jolt? 

 I have never worked with Ac line voltage before


----------



## amb

If you use wood (or any non-metal material) as the enclosure, consider using an aluminum plate as the base so it could serve as the chassis ground. It will provide some RFI shielding as well. β22 produces quite a bit of heat (it's class A, after all), so your enclosure needs to be well ventilated.

 If you've never worked with AC mains before, then I strongly recommend having someone experienced to help you. AC line voltage could kill or start a fire if not handled properly. Rubber gloves are no substitute for knowledge and common sense.

 Perhaps you should try building a less complex and ambitious amp first to gain the needed skills and experience, and defer the β22 for the future.


----------



## boinger

I am building a mini 3 first and was going to build an M3 after that , but after budget considerations I cant afford to build a M3 and a beta22 

 I have been doing some reading on electrical safety and procedures and am comfortable trying it out. 

 How much voltage is in the beta 22 amp? So i know how to prepare.


----------



## amb

boinger, you need to read the β22 website thoroughly. Many of your questions are answered there.


----------



## boinger

I read the site again just now i see that it operates at 24V - 30V DC 

 i feel im comfortable working on that. I was just asking as to what is the risk involved. Thanks for your help. 

 just trying to get all the information i can before i order. i dont want to be too overwhelmed after purchasing it.


----------



## Beefy

Quote:


  Originally Posted by *boinger* /img/forum/go_quote.gif 
_I read the site again just now i see that it operates at 24V - 30V DC_

 

Yeah, but what about the mains voltage for the power supply?


----------



## boinger

Quote:


  Originally Posted by *Beefy* /img/forum/go_quote.gif 
_Yeah, but what about the mains voltage for the power supply?_

 

Thats 240 V here in india. I'm a bit wary working on that but I dont think i have a choice. I was asking about the voltage in the b22 as i was wondering if it spiked as i have been reading on electrical safety. 

 What precautions do you all take before working on this amp?


----------



## Beefy

Quote:


  Originally Posted by *boinger* /img/forum/go_quote.gif 
_What precautions do you all take before working on this amp?_

 

Years of experience is the best precaution you can take.


----------



## boinger

Quote:


  Originally Posted by *Beefy* /img/forum/go_quote.gif 
_Years of experience is the best precaution you can take._

 

unfortunately i dont have that or anyone that is around in bangalore that i can work with. If i follow safety tips like one hand only / rubber gloves / matt / shoes / discharge all capacitors and unplug it? 

 will i be safe? or is it best to maybe hire an electrician to help ?


----------



## boinger

i have been reading through the amb site over and over. does the beta 22 have a capacitor bleed? or a jumper set up to bleed the caps ? if not do you guys drain each cap manually with a resistor ?


----------



## m1abrams

Quote:


  Originally Posted by *boinger* /img/forum/go_quote.gif 
_i have been reading through the amb site over and over. does the beta 22 have a capacitor bleed? or a jumper set up to bleed the caps ? if not do you guys drain each cap manually with a resistor ?_

 

Keep in mind the only place that you should have 240V is from the primary leads of the transformer in the power supply back to the wall. If you use an IEC that has builtin switch and fuse then you will greatly minimize any risk of exposure to high voltage. Still work safe and always triple check your connections.


----------



## digger945

When you turn the amp off, simply check the voltage from each rail to ground(amp and PS connected) and you should see that the voltage will quickly fall to less than a volt.
 The Sigma 22 will take a few seconds to fully discharge if it is not connected to a load.


----------



## boinger

Quote:


  Originally Posted by *m1abrams* /img/forum/go_quote.gif 
_Keep in mind the only place that you should have 240V is from the primary leads of the transformer in the power supply back to the wall. If you use an IEC that has builtin switch and fuse then you will greatly minimize any risk of exposure to high voltage. Still work safe and always triple check your connections._

 

Ah thanks I had figured that but thats quite reassuring. Either way im not gonna be working alone and will always have someone nearby while testing. 

 I have been reading the thread and it is my understanding that the caps discharge after about 30 seconds when the power has been switched off?

 Edit: 

  Quote:


  Originally Posted by *digger945* /img/forum/go_quote.gif 
_When you turn the amp off, simply check the voltage from each rail to ground(amp and PS connected) and you should see that the voltage will quickly fall to less than a volt.
 The Sigma 22 will take a few seconds to fully discharge if it is not connected to a load._

 

ah thanks you answered my question before i saw your post. =)


----------



## digger945

I would think 30 seconds would be plenty of time. 
 Maybe 1 minute for a properly working unloaded Sigma 22.





*EDIT*: I just timed one of my spec Glass Jar kit Sigma 22's(unloaded/not connected to a load) and from turn off it took 27 seconds to fully discharge.


----------



## boinger

Quote:


  Originally Posted by *digger945* /img/forum/go_quote.gif 
_I would think 30 seconds would be plenty of time. 
 Maybe 1 minute for a properly working unloaded Sigma 22._

 

Ah thats good to know 

 thanks for your information this makes me much more comfortable building my main concern was safety not the difficulty.


----------



## dude_500

30 volts out of a capacitor is not going to kill you, at worst you'll get a little tingle in your finger. There's really nothing on this board that I would feel like my life were threatened touching while the device is even turned on. (Not that I suggest it). The discussion of bleeding capacitors is somewhat irrelevant on this amp in terms of safety. 

 This does NOT include the primary winding on the transformer which is the hazard. At 240 you would probably be killed if you touched both leads of 240 with different hands. Insulate all 240 joints between IEC/fuse/power switch and leave nothing exposed and you should be fine.


----------



## johnwmclean

This discussion has renewed my respect when working with mains voltage. I think I've become complacent after a few builds which is not a good idea, and knowing that instant death lurks around the corner whenever we build, is a very important thing to keep in mind.
 Bolinger being so cautious is a very good thing, it will pay big life saving dividends. This has been a very good fresher.


----------



## ting.mike

I have a 3 board beta that I'm upgrading to a 4 board. I've ordered an additional gain-5 board, and extra s22 & toroid, plus replacement parts for: 
 - 1xAG board to be a gain-5 board
 - 2xgain-8 board to be a gain-5 board

 Do I need to replace anything else, especially like the JFETs which is supposed to be matched (on all 4 boards?)

 Thanks!


----------



## Beefy

I don't think that the FETs need to be matched between the boards.


----------



## boinger

for senn hd 650 's what gain is recommended?


----------



## dude_500

the glass-jar default 8 is fine... you could go lower but it's not necesary, you can just turn down the volume a bit. I either have my amp on 10% with pc near max or turn the PC way down and then turn up the amp. That's with the 8 gain


----------



## boinger

ah ok cool ... just have to figure out a way to get the parts down here now...


----------



## Beefy

Quote:


  Originally Posted by *dude_500* /img/forum/go_quote.gif 
_I either have my amp on 10% with pc near max or turn the PC way down and then turn up the amp. That's with the 8 gain_

 

Controlling the volume at the PC is a very bad way of doing things. You are losing information in the digital domain, then amplifying a less than perfect signal. You should always have the volume at maximum out of your PC in both the O/S and playback software. Even better, use something like ASIO or kernel streaming to bypass all of these software controls to get bit-perfect sound to the output.

 And if you do have to turn down the volume this much on the PC, then your gain is definitely too high. The worst area to use a volume pot is right down at the bottom, and you will never 'stress' an amp by having the volume pot too high.


----------



## ting.mike

Quote:


  Originally Posted by *Beefy* /img/forum/go_quote.gif 
_I don't think that the FETs need to be matched between the boards._

 

thanks!


----------



## linuxworks

Quote:


  Originally Posted by *boinger* /img/forum/go_quote.gif 
_for senn hd 650 's what gain is recommended?_

 

8 is too much for this. I started with 8 and then backed down to 5, I think, to keep the noise level down.


----------



## TimmyMac

Quote:


  Originally Posted by *dude_500* /img/forum/go_quote.gif 
_30 volts out of a capacitor is not going to kill you, at worst you'll get a little tingle in your finger. There's really nothing on this board that I would feel like my life were threatened touching while the device is even turned on. (Not that I suggest it)._

 

Keep in mind the sigma22 actually operates at 60V rail to rail... which has the potential to cause burns or death.


----------



## boinger

Hmm I have been reading a lot. And I want to significantly up my audio equipment. Now I am set on building this and have begun sourcing the parts. However I wanted opinions 

 I was thinking about upgrading from my senn 650 to senn hd 800's. Or I could invest in a better source DAC something like the buffalo or upcoming gamma 2 

 Keep in mind I can only get one for the time being, I would really like to get the 800's but I dont know if that is a wise thing to get first. Although this will probably be one of my only opportunities to get the 800's and I could probably get the DAC in a few months after.


----------



## aloksatoor

5 for me also... this with a HD650 and K701


----------



## amb

Bear in mind that the difference between gain of 8 and 5 is only 4dB.


----------



## amb

Quote:


  Originally Posted by *TimmyMac* /img/forum/go_quote.gif 
_Keep in mind the sigma22 actually operates at 60V rail to rail... which has the potential to cause burns or death._

 

60VDC might give you a tingle on the fingers, not enough to kill... And you shouldn't be doing any electronics work with wet hands anyway...


----------



## Beefy

Quote:


  Originally Posted by *amb* /img/forum/go_quote.gif 
_Bear in mind that the difference between gain of 8 and 5 is only 4dB._

 

On a typical stepped attenuator, that is two extra clicks to play with before things get too loud......

 [EDIT] Or up to an 'hour' extra turn on the humble RK27.


----------



## linuxworks

Quote:


  Originally Posted by *amb* /img/forum/go_quote.gif 
_Bear in mind that the difference between gain of 8 and 5 is only 4dB._

 

when I was having hum problems, one of my decisions was to cut the gain back to help with that, as well as noise.

 I don't think I'd build with gain=8 for my senn's.

 I like picking the lowest gain that will do the job. almost never do I need to hit 0db, so I think for me, 5x gain was just right.


----------



## boinger

Quote:


  Originally Posted by *linuxworks* /img/forum/go_quote.gif 
_when I was having hum problems, one of my decisions was to cut the gain back to help with that, as well as noise.

 I don't think I'd build with gain=8 for my senn's.

 I like picking the lowest gain that will do the job. almost never do I need to hit 0db, so I think for me, 5x gain was just right._

 

Ah ok will be sure to get that in the kit. 

 Would you recommend this for the hd 800's as well ?


----------



## wolf18t

Quote:


  Originally Posted by *linuxworks* /img/forum/go_quote.gif 
_when I was having hum problems, one of my decisions was to cut the gain back to help with that, as well as noise.

 I don't think I'd build with gain=8 for my senn's.

 I like picking the lowest gain that will do the job. almost never do I need to hit 0db, so I think for me, 5x gain was just right._

 

Same here. Initially built with 8x gain. Got faint hiss using my DT-880. Lowered it to 5x to solve this. When I got my RS-1, the hiss problem got back. Lowered the gain to 2x and hiss gone with the RS-1. Recently tried hiss prone 25ohm/sensitive Denon (D5000) and no hiss. 

 Until I add a high Z/very low sensitive HP in my inventory, I'm sticking to 2x gain. And as a bonus I benefit of the full range use of my TKD pot.


----------



## wolf18t

Quote:


  Originally Posted by *boinger* /img/forum/go_quote.gif 
_Would you recommend this for the hd 800's as well ?_

 

I tried the HD-800 with my B22 set at 2x gain and that was OK out of an Audio Research CDP. I had to set the volume pot at 2 or 3 oclock position to get a loud level.

 I don't know the output voltage of your source so if I was you:

 1. 5x gain if building 2 or 3 channels SE version
 2. 2x gain if building 4 channels (balanced) version. The balanced configuration doubles the boards gain settings so you will get 4x gain here.

 In any case order all the parts need for 2x, 5x or 8x gain. It will cost you a few bucks but save shipping later if you change your mind.


----------



## boinger

Quote:


  Originally Posted by *wolf18t* /img/forum/go_quote.gif 
_I tried the HD-800 with my B22 set at 2x gain and that was OK out of an Audio Research CDP. I had to set the volume pot at 2 or 3 oclock position to get a loud level.

 I don't know the output voltage of your source so if I was you:

 1. 5x gain if building 2 or 3 channels SE version
 2. 2x gain if building 4 channels (balanced) version. The balanced configuration doubles the boards gain settings so you will get 4x gain here.

 In any case order all the parts need for 2x, 5x or 8x gain. It will cost you a few bucks but save shipping later if you change your mind._

 

Ah yes thats good advice i will do that. I been reading its better to do a balanced source for the hd 800's 

 but will they work just as well on a unbalanced amp? The main problem for me would be to acquire a source thats balanced. 

 I will eventually down the road plan on building a DAC that will give me balanced outputs but i dont know when that will be. Was thinking about a buffalo DAC.


----------



## amb

Quote:


  Originally Posted by *boinger* 
_I been reading its better to do a balanced source for the hd 800's

 but will they work just as well on a unbalanced amp? The main problem for me would be to acquire a source thats balanced._

 

An unbalanced amp will not accept a balanced source, unless you put in a balanced-to-unbalanced converter in between, or simply drop the "cold" signal. In either case you lose the benefit of the balanced source.


----------



## boinger

oh I just meant will the hd 800's perform ok on an unbalanced amp ?


----------



## dude_500

Yes. You might gain a slight quality increase with balanced, but HD800's with a dual-channel beta-22 is still one of the best headphone situations you can have


----------



## digger945

If two people each gave you their honest opinion, and each was different, which opinion would you take?
 Would you then want to hear with your own ears?


----------



## boinger

Well its a huge investment for the hd 800's and I dont have an opportunity to listen to them here. I contacted a dealer and he said that if i were to buy he would order from sennheiser but beyond that he cant offer much.


----------



## dude_500

You already have HD650's correct? Honestly in my opinion I don't think it's worth it to upgrade that, you already have great cans and the 800's, in my wallet, don't justify an upgrade even over my HD600's. I'll be waiting for the next generation.


----------



## boinger

yes i have the Hd 650's 

 I am truely happy with them. Would you reccon i should go for a nice dac? like the buffalo 32 sabre ?


----------



## dude_500

I haven't actually heard that DAC, but most people seem to think it's quite good. It is balanced correct? I think you'd better be spending your money on a nice balanced DAC and a 4-channel Beta-22, and you'll still come out ahead financially of buying a pair of HD800's.


----------



## boinger

yea its a balanced dac, if i go for that i would plan on going for a 4 channel beta 22, I think i will probably end up doing that.

 Either that or I may pick up a PS Digital Link III its around the same price range as teh buffalo before case work. 

 Although i cant find anything on how these 2 compare.


----------



## Possede

Hey guys. 
	

	
	
		
		

		
			





 I decided that I would like to tackle a Beta 22 build. I was just wondering if a case of dimensions 415mm (width) x 350mm (depth) x 80mm (height) will accommodate a 3-channel set-up and Sigma 22 power supply in the same chassis. I will be using the Glass Jar Audio Kit, so I believe the heatsinks provided in the kit should fit into this chassis (It's the one at the bottom). I'm thinking of getting a DACT TC2 stereo pot and Front Panel Express front and back machined panels. 

 Any input would be much appreciated.


----------



## johnwmclean

Quote:


  Originally Posted by *Possédé* /img/forum/go_quote.gif 
_Hey guys. 
	

	
	
		
		

		
		
	


	




 I decided that I would like to tackle a Beta 22 build. I was just wondering if a case of dimensions 415mm (width) x 350mm (depth) x 80mm (height) will accommodate a 3-channel set-up and Sigma 22 power supply in the same chassis. I will be using the Glass Jar Audio Kit, so I believe the heatsinks provided in the kit should fit into this chassis (It's the one at the bottom). I'm thinking of getting a DACT TC2 stereo pot and Front Panel Express front and back machined panels. 

 Any input would be much appreciated._

 

My recommendation would be to put the transformer and PSU in a separate enclosure. Your spending a lot of money on the enclosure, panels and attenuator - you might have hum and noise problems you can’t get rid of from not going the extra length.


----------



## Possede

Quote:


  Originally Posted by *johnwmclean* /img/forum/go_quote.gif 
_My recommendation would be to put the transformer and PSU in a separate enclosure. Your spending a lot of money on the enclosure, panels and attenuator - you might have hum and noise problems you can’t get rid of from not going the extra length._

 

Ah, I thought this would be the case (no pun intended). Looks like I'll be doing it in separate cases then!


----------



## ting.mike

Quote:


  Originally Posted by *boinger* /img/forum/go_quote.gif 
_Hmm I have been reading a lot. And I want to significantly up my audio equipment. Now I am set on building this and have begun sourcing the parts. However I wanted opinions 

 I was thinking about upgrading from my senn 650 to senn hd 800's. Or I could invest in a better source DAC something like the buffalo or upcoming gamma 2 

 Keep in mind I can only get one for the time being, I would really like to get the 800's but I dont know if that is a wise thing to get first. Although this will probably be one of my only opportunities to get the 800's and I could probably get the DAC in a few months after._

 

I've never heard of the Buffalo DAC, but I suspect that you'd get better sound spending money on that DAC + Balanced B22 + HD650 rather than the HD800. 

 Going from the HD650, you'll truly miss the bottom end and impact of the HD650. 
 I'd probably choose a more coloured amplifier to go with the very neutral HD800.


  Quote:


  Originally Posted by *linuxworks* /img/forum/go_quote.gif 
_8 is too much for this. I started with 8 and then backed down to 5, I think, to keep the noise level down._

 



  Quote:


  Originally Posted by *wolf18t* /img/forum/go_quote.gif 
_Same here. Initially built with 8x gain. Got faint hiss using my DT-880. Lowered it to 5x to solve this. When I got my RS-1, the hiss problem got back. Lowered the gain to 2x and hiss gone with the RS-1. Recently tried hiss prone 25ohm/sensitive Denon (D5000) and no hiss. 

 Until I add a high Z/very low sensitive HP in my inventory, I'm sticking to 2x gain. And as a bonus I benefit of the full range use of my TKD pot._

 

Please help me out here, I thought that the higher you go on the pot (DACT stepper in my case), the higher noise you get, cause there are less resistance between signal and ground? 

 I'm building my B22 with 5x gain (10 effective). My headphones will be HD650 and Ms Pro. My source's balanced out is 4Vrms. I'm using a 50KOhm DACT attenuator. 

 I'm thinking if I should go with 2x gain (4 effective) instead. 

 The problem is, classical CDs have lower volume level than most other genres, so... 2x gain, or 5x gain?

 Of course I can just order parts for both gain settings.


----------



## Beefy

Quote:


  Originally Posted by *ting.mike* /img/forum/go_quote.gif 
_Please help me out here, I thought that the higher you go on the pot (DACT stepper in my case), the higher noise you get, cause there are less resistance between signal and ground?_

 

I hadn't heard that - shall look into it. 

  Quote:


 I'm building my B22 with 5x gain (10 effective). My headphones will be HD650 and Ms Pro. My source's balanced out is 4Vrms. I'm using a 50KOhm DACT attenuator.

 I'm thinking if I should go with 2x gain (4 effective) instead. 
 

FWIW, I know a guy who has a 3-channel B22, DACT, 5x gain, unbalanced source outputting less than 2VRMS. He finds it extremely difficult to get the right volume level with his Grado RS-1, which are essentially the same as the MS-Pro.

 IMHO, 10x is going to be FAR too high for those phones. Not sure about the HD650 though.


----------



## ting.mike

hmmm... you're saying I should go with gain 2 (4 eff) ?

 I'm not so worried about not being able to get the right volume level using an attenuator, compared to not having enough loudness when I plug in my HD650. 

 What's strange is that despite the difference in impedance (32ohms v. 300ohms), I don't find the volume level on my amps too diffference between the HD650 and the Ms Pro. Perhaps a difference of 1 hour of turn -- and this with different amps.


----------



## Beefy

Not saying you should do anything, just giving you food for thought


----------



## ting.mike

thanks. 
	

	
	
		
		

		
		
	


	




 I think I'll get extra parts for the other gain setting as well..


----------



## askforwhy

Quote:


  Originally Posted by *ting.mike* /img/forum/go_quote.gif 
_hmmm... you're saying I should go with gain 2 (4 eff) ?

 I'm not so worried about not being able to get the right volume level using an attenuator, compared to not having enough loudness when I plug in my HD650. 

 What's strange is that despite the difference in impedance (32ohms v. 300ohms), I don't find the volume level on my amps too diffference between the HD650 and the Ms Pro. Perhaps a difference of 1 hour of turn -- and this with different amps._

 

I think that really depend on the sensitivity of headphones, rather than impedance.
 I currently use 5X for my K701, and for pop music, I turn 1/2 on my volume attenuator(like 10 steps out of my 23 steps attenuator), for classic music, 14 steps is more than enough.


----------



## ting.mike

is that in SE or balanced?


----------



## johnwmclean

Quote:


  Originally Posted by *ting.mike* /img/forum/go_quote.gif 
_is that in SE or balanced?_

 

2 x gain (Balanced) + HD650 = Perfect

 I've had tried the HD650's and now HD800's, listening levels most of the time is 12, classical 2 with some low output cases.


----------



## ting.mike

thanks, John.


----------



## FallenAngel

4Vrms gain of 10x is HUGE, WAY too much. I'm lowering the output on my Buffalo32 to 2Vrms so I can use the volume control a bit!


----------



## ting.mike

Quote:


  Originally Posted by *FallenAngel* /img/forum/go_quote.gif 
_4Vrms gain of 10x is HUGE, WAY too much. I'm lowering the output on my Buffalo32 to 2Vrms so I can use the volume control a bit!_

 

hahaha... on certain matters, it's nice to have someone tell you what to do. 

 well if gain 2 turns out to be lacking, I'm gonna blame you for it.


----------



## Possede

I'm sourcing parts for my build, and would like to confirm that this transformer is suitable for a 3-channel build. It is rated at 65VA, although AMB recommends 80VA for a 3-channel build. I found this one which may be more suitable. Any input would be appreciated.


----------



## n_maher

The second option looks better to me, I see no need to run the rails at 30V if a headphone amp is what you're after.


----------



## Possede

Quote:


  Originally Posted by *n_maher* /img/forum/go_quote.gif 
_The second option looks better to me, I see no need to run the rails at 30V if a headphone amp is what you're after._

 

Cheers, I thought that would be the case. Can't wait to relieve my wallet of some hard-earned cash.


----------



## linuxworks

I would go with the lower voltage rails. I opted for the higher, myself, but its just wasted heat, imho.


----------



## boinger

Quote:


  Originally Posted by *linuxworks* /img/forum/go_quote.gif 
_I would go with the lower voltage rails. I opted for the higher, myself, but its just wasted heat, imho._

 

What about for a 4 channel headphone amp only build?


----------



## Beefy

Quote:


  Originally Posted by *boinger* /img/forum/go_quote.gif 
_What about for a 4 channel headphone amp only build?_

 

Balanced drive gives you double the voltage swing, so there is even less of a requirement for having high voltage rails.

 And because you are running twice as much quiescent current, you have to make sure your transformer can supply enough current.


----------



## boinger

So a one 100 VA @ 24V should work fine?


----------



## Beefy

Most people would recommend two sigma 22's for a balanced build. In this case, a single 100VA @ 24V might not be sufficient.


----------



## boinger

Im getting pretty close up to my budget limits, I still am trying to decide whether to go with a pot / attenuator. 

 2 sigma's huh ? so 2 sigma's with 100VA @ 24V would work ? 

 What are the advantages with 2 sigmas with a balanced build vs 1 sigma ? I read on the amb site that 1 sigma could power all 4 boards.


----------



## Beefy

Quote:


  Originally Posted by *boinger* /img/forum/go_quote.gif 
_I read on the amb site that 1 sigma could power all 4 boards._

 

You can, but most people don't.

  Quote:


 What are the advantages with 2 sigmas with a balanced build vs 1 sigma ? 
 

Better thermal characteristics.


----------



## boinger

so you think it would be worth while to skip the attenuator and go for a second sigma?


----------



## Beefy

You can't just 'skip' the attenuator. You have to have _something_ there.

 Unless you mean traditional volume pot, versus stepped attenuator? You should clarify, as they are _both_ attenuators.


----------



## fsrick

if it is the traditional pot versus stepped attenuator,I will go for a second sigma first, and wait till you can afford a better stepped attenuator. attenuator is very important since it is in the signal path. but it is easy to replace. once you have all the case work done, adding a second sigma is not that convenient.


----------



## oneplustwo

Also, just to clarify, you would want 2 trafos, one for each sigma. In which case, you would be fine with two 50VA ones vs one 100VA one.


----------



## boinger

Yes i meant the traditional pot, and i think i will go for 2 sigmas instead. 

 oneplustwo thanks for that tip now can these 50VA be @ 24 V or should they be at 30 V ?


----------



## boinger

any recommendations regarding this layout ?


----------



## Beefy

You really should consider a separate chassis for the transformers.


----------



## oneplustwo

I think the layout is fine. Couple thoughts:

 1. With a single enclosure, you need to know there is a good chance of transformer hum. Either 1) go with a separate enclosure, 2) get shielded units (like from sumR) or 3)make the enclosure bigger just to move the trafos farther away.
 2. This is going to be a big box! Make sure it will fit where you are going to put it. It may be even bigger if you follow option 3 above.
 3. I know this is just a schematic, but make sure you take into account the space the jacks, switches, etc. will take up.


----------



## boinger

Yea i was debating the layouts, whether i want a seperate enclosure or all in one. Question if i separate the transformers and put it in a box underneath / over the B22 box will i still get hum ? or should it be in another location altogether?


----------



## oneplustwo

Under or over is typically fine. The enclosures effectively shield everything. (Assuming you're not using wood or plastic enclosures.) Also, just for balance sake, you might want to put both the trafos and the sigmas in the separate enclosure. Be sure to take note of the different wiring standards on Amb's site for whatever way you choose.


----------



## amb

On the issue of gain and "hot" sources, I want to remind you all that I once posted the following solution for a switchable input attenuator:
http://www.head-fi.org/forums/5714385-post856.html

 This is a convenient way to change the amp's effective gain without swapping parts on the board, to allow the amp to be used with different sources and headphones.


----------



## boinger

Yea I think I will end up seperating the trafo's, I actually was planning on using a wooden enclosure but with an aluminum plate at the bottom as a chasis ground.


----------



## fsrick

after reading the amb website, I still have some questions about the preamp/speaker setting. I am building a 4 board balanced B22. so if my input is single endeed (SE), then all my output will be SE. if my input is balanced, all my outputs are balanced, right? so if the preamp output is balanced from my B22, then i will need a balanced power amp also, i cannot use whatever power amp I have, am I right? just want to verify my confusion.
 damn, after readin more and more, i feel like i have mroe questions too


----------



## amb

Mixing balanced and unbalanced equipment in the same chain is always a messy proposition, no matter how you cut the mustard.

 When connecting an unbalanced output to a balanced input, you must use a converter (active circuitry or transformer).

 When connecting a balanced output to an unbalanced input, you must either use a converter (active circuitry or transformer), or drop the cold signal altogether.

 All these are not without their vices.


----------



## fsrick

Hi amb, 
 can you briefly explain how the epsilon 24 switch board works (without the thermal protection). since the momentary pushbutton switches only gives you a pulse when you press it. how can this circuit hold the relay on forever after i press the switch? i have looked through it for a while, but still cannot understand.

 and also, if i combine the balanced and unbalanced in the 4 board B22, from the graph in your web, i do not think i need a switch to make it work, is it right? but i recalled someone point out the reason to use a switch there, but i cannot find the post now. Thanks.


----------



## fsrick

sorry, more questions. I knwo that the B22 already has the function to prevent the turn on /off noise, if I use a epsilon 12 for B22, it only helps for the DC offset protection, right? Thanks again.


----------



## amb

Quote:


  Originally Posted by *fsrick* 
_can you briefly explain how the epsilon 24 switch board works (without the thermal protection). since the momentary pushbutton switches only gives you a pulse when you press it. how can this circuit hold the relay on forever after i press the switch? i have looked through it for a while, but still cannot understand._

 

A bit off-topic for this thread, but here goes (I'll skip the thermal sensing stuff):

 ε24's D1, C1, U1 and C2 form its power supply section to give 12V DC.

 When powered up, ε24's Q2 base is connected to 12V through the load and R5; Q3 gate is connected to about 10V (the potential at the R1-R2 junction). The significant gate capacitance of the MOSFET coupled with the high R1 value delays Q3 turn-on, Q2 switches on first and pulls Q3 gate low keeping it off.

 With Q2 on, any charge in C3 leaks away through R2; if the momentary switch is pressed, Q2 base voltage is pulled low, turning Q2 off and allowing Q3 to turn on, switching the load (relay coil) to full power instead of the few microamps it's been limited to by the path through R5 and Q2.

 With Q2 off, capacitor C3 charges up to 12V through R1 and R2, so when the button is pressed again, it applies its voltage to Q2 base through R6 turning Q2 back on and so turning Q3 and the load off.

 Diode D3 is to prevent damage from back-EMF pulses from the relay coil.

  Quote:


 if i combine the balanced and unbalanced in the 4 board B22, from the graph in your web, i do not think i need a switch to make it work, is it right? but i recalled someone point out the reason to use a switch there, but i cannot find the post now. 
 

The switched solution allows you to have the balanced and unbalanced sources to be connected simultaneously (which you cannot do without the switch). Also, the switched solution lets you use an unbalanced source to drive the 4-channel amp and still be able to listen with balanced headphones.

  Quote:


 I knwo that the B22 already has the function to prevent the turn on /off noise, if I use a epsilon 12 for B22, it only helps for the DC offset protection, right? 
 

β22 doesn't have any specific "function" to prevent turn on/off noise. It emits negligible noise in these situations due to its intrinsic design architecture. If you use a ε12, it will still provide a turn-on delay muting which isn't required for the β22, _and_ it adds DC offset protection for your headphone in case there is a malfunction in the amp.


----------



## JamesL

Quote:


  Originally Posted by *oneplustwo* /img/forum/go_quote.gif 
_Under or over is typically fine. The enclosures effectively shield everything._

 

From what I understand, a grounded enclosure only screens against radio-frequency interference, but not static or low frequency magnetic interference such as that emitted by a transformer. 
 Isn't that why magnetically shielded transformers use layers of high-permeability material such as electrical/laminated steel?


----------



## ting.mike

Quote:


  Originally Posted by *boinger* /img/forum/go_quote.gif 
_any recommendations regarding this layout ?




_

 

x2 on the 2 cases. 

 also, what I am doing with my case is to put the attenuator at the back right by the input jacks to minimize cable length. I am going to use a shaft similar to DACT's extension shaft that extends to the actual volume knob on the front panel. 

 if you really want to make it a one case solution, try sourcing a copper plate to go in between the toroids and the boards. I was told that copper is very effective in blocking noise in this kind of application. I'm actually getting a plate of copper to go in between the two toroids, since my PSU casing is quite compact and the two toroids are placed quite close together.

  Quote:


  Originally Posted by *amb* /img/forum/go_quote.gif 
_On the issue of gain and "hot" sources, I want to remind you all that I once posted the following solution for a switchable input attenuator:
http://www.head-fi.org/forums/5714385-post856.html

 This is a convenient way to change the amp's effective gain without swapping parts on the board, to allow the amp to be used with different sources and headphones._

 


 This is such a great solution. I actually was thinking of implementing similar methods, but it's good to hear it directly from you, Ti!


  Quote:


  Originally Posted by *amb* /img/forum/go_quote.gif 
_Mixing balanced and unbalanced equipment in the same chain is always a messy proposition, no matter how you cut the mustard.

 When connecting an unbalanced output to a balanced input, you must use a converter (active circuitry or transformer).

 When connecting a balanced output to an unbalanced input, you must either use a converter (active circuitry or transformer), or drop the cold signal altogether.

 All these are not without their vices._

 

Again, I was also thinking about this issue, since everyone asked me to put unbalanced inputs (for them to try out the amp during meets). Now that you've mentioned it, I think I'll stick to balanced exclusively.


----------



## fsrick

Thank you very much for your information.
 actually i am thinking if i use the ε12 board, then there will be more components in my signal path. this actually will add more noise to the amp. it seems this is a trade-off.

  Quote:


  Originally Posted by *amb* /img/forum/go_quote.gif 
_A bit off-topic for this thread, but here goes (I'll skip the thermal sensing stuff):

 ε24's D1, C1, U1 and C2 form its power supply section to give 12V DC.

 When powered up, ε24's Q2 base is connected to 12V through the load and R5; Q3 gate is connected to about 10V (the potential at the R1-R2 junction). The significant gate capacitance of the MOSFET coupled with the high R1 value delays Q3 turn-on, Q2 switches on first and pulls Q3 gate low keeping it off.

 With Q2 on, any charge in C3 leaks away through R2; if the momentary switch is pressed, Q2 base voltage is pulled low, turning Q2 off and allowing Q3 to turn on, switching the load (relay coil) to full power instead of the few microamps it's been limited to by the path through R5 and Q2.

 With Q2 off, capacitor C3 charges up to 12V through R1 and R2, so when the button is pressed again, it applies its voltage to Q2 base through R6 turning Q2 back on and so turning Q3 and the load off.

 Diode D3 is to prevent damage from back-EMF pulses from the relay coil.


 The switched solution allows you to have the balanced and unbalanced sources to be connected simultaneously (which you cannot do without the switch). Also, the switched solution lets you use an unbalanced source to drive the 4-channel amp and still be able to listen with balanced headphones.


 β22 doesn't have any specific "function" to prevent turn on/off noise. It emits negligible noise in these situations due to its intrinsic design architecture. If you use a ε12, it will still provide a turn-on delay muting which isn't required for the β22, and it adds DC offset protection for your headphone in case there is a malfunction in the amp._


----------



## amb

Quote:


  Originally Posted by *ting.mike* /img/forum/go_quote.gif 
_if you really want to make it a one case solution, try sourcing a copper plate to go in between the toroids and the boards. I was told that copper is very effective in blocking noise in this kind of application. I'm actually getting a plate of copper to go in between the two toroids, since my PSU casing is quite compact and the two toroids are placed quite close together._

 

The effectiveness of a copper plate will be limited. The fields emanating from the transformer isn't just in the direct line between it and the amp circuitry and wiring, but rather it's quite 3D and will wrap around above and below the plate.

  Quote:


  Originally Posted by *fsrick* 
_actually i am thinking if i use the ε12 board, then there will be more components in my signal path. this actually will add more noise to the amp. it seems this is a trade-off._

 

All that the ε12 adds to the signal path is a relay contact. It doesn't add any noise. But if you think that a few milliohms of additional contact resistance will affect sound quality, then don't use it.


----------



## linuxworks

you'd need mu-metal. not easy to source or deal with.

 you need ferrous material. not copper or alum.

 best to get a shielded toroid or move it far away.


----------



## boinger

Thanks for all the help fellas. So I have found a person here that will make me a custom chasis out of aluminum relatively cheap. I was thinking of going with a case the size of 12"x14" x 2 or is that unecessarily large? or should I go with something like 9" x 14"? 

 I was actually gonna mix unbalanced and balanced outs. Will that affect sound quality, or should I also go balanced only.


----------



## royalflush

Has anyone actually had any success keeping the torroid with 3-channels in the same chassis without noise? How'd you do it? Could really use the money saved by using only one enclosure.


----------



## amb

Quote:


  Originally Posted by *boinger* 
_I was actually gonna mix unbalanced and balanced outs. Will that affect sound quality, or should I also go balanced only._

 

The β22 would be happy to drive balanced and unbalanced headphones at the same time. It's only a matter of how you choose to implement unbalanced outputs -- passive or active ground.

  Quote:


  Originally Posted by *royalflush* 
_Has anyone actually had any success keeping the torroid with 3-channels in the same chassis without noise? How'd you do it? Could really use the money saved by using only one enclosure._

 

Using a toroid with built-in shielding, and locating it as far away in the chassis as possible from the amp boards is the only sensible way to minimize hum in a single-chassis configuration. You still don't get one of the advantages of seaparate chassis, though -- AC ground and signal ground can be completely isolated in the 2-box solution, minimizing AC ground noise intrusion.


----------



## boinger

I was going with a passive ground setup, but if it affects SQ I'd prefer not to do it.


----------



## fsrick

Quote:


  Originally Posted by *amb* /img/forum/go_quote.gif 
_The switched solution allows you to have the balanced and unbalanced sources to be connected simultaneously (which you cannot do without the switch). Also, the switched solution lets you use an unbalanced source to drive the 4-channel amp and still be able to listen with balanced headphones._

 

why i cannot connected the balanced and unbalanced sources simultaneously without the switch if i follow the connection in the amb web? is that the source problem? if i use an unbalanced source to drive the 4-channel amp, then i use switch to short the input of the negative channel?


----------



## digger945

As you can see, if you connect both balanced and unbalanced sources at the same time, without a switch to allow only one to be connected at a time, then you end up with the signal from one source physically connected to the other sources output. Imagine if the other sources output components somehow had a negative effect on the signal before the amp, even if the other source was powered down. 
 Would you not want only one source connected, and the signal from that source alone to be the only thing your amping?

 And yes, the switch that amb described does ground the inputs of the negative amps.


----------



## aloksatoor

wont goin balanced cause even the hum noise to be rejected even in same chassis. its common mode rejection right so the noise wud be on both the +ve and -ve for each channel thus cancelling it out completely


----------



## digger945

Not in my experience, no.


----------



## boinger

I have been doing some research over attenuator's etc. 

 it is my understanding that with the buffalo 32 dact I can use this 
Volumite - A Simple I2C/SPI Volume Control 

 and have a passive B22 setup so I can control volume directly through my buffalo (this would help me save some significant amount of money)


----------



## oneplustwo

I've asked this question before and have heard that it's best to have a "hot" signal coming into the amp and then attenuate from there. My understanding is that you want the best S/N ratio coming out of your source before amplifying it. That being said, I don't know if there's much of a practical difference.


----------



## amb

oneplustwo is correct. Also, if you skip the volume control on the amp, then it becomes only usable with sources that have volume controls. Not too flexible...


----------



## boinger

well the price difference is about $250 ish. So if it doesnt make a huge difference i wouldnt mind going that route.


----------



## boinger

Quote:


  Originally Posted by *amb* /img/forum/go_quote.gif 
_oneplustwo is correct. Also, if you skip the volume control on the amp, then it becomes only usable with sources that have volume controls. Not too flexible..._

 

But will something like the buffalo be able to do that ? with the volumiter its a 30 dollar part so if it can control the volume at the source it would work well.


----------



## oneplustwo

Yes, the buffalo is designed to work with the volumite. Actually, some people use the output directly out of the buffalo for headphone use and are very happy with it. I'm personally still sorting out my buffalo and my balanced B22 and hope to get a little more clarity for myself on this. Initial indications are that the buffalo by itself is very good. Not sure it's going to hold up to a comparison when the B22 is thrown into the mix, but for many, it may be good enough.


----------



## Beefy

Quote:


  Originally Posted by *boinger* /img/forum/go_quote.gif 
_well the price difference is about $250 ish. So if it doesnt make a huge difference i wouldnt mind going that route._

 

Look, I've got to ask...... what are you trying to achieve in building this amp?

 You seem to want to build a 'reference' amp; you seem to constantly be looking to cut corners to save money. These two ideas don't go together, even in the DIY world.

 If you _really_ want to build an all-out-take-no-prisoners-build, save some extra money and do it properly. Cheap out now and you will only regret it later...... seriously, no attenuator at all to save money? Not a good idea in my book.

 Alternatively if your budget _is_ absolutely fixed, then be content with a well executed 3-channel build.


----------



## digger945

Does the volumite attenuate in the analog or digital?


----------



## JamesL

digital it seems


----------



## digger945

Yes, and how many times have we read posts here about digital attenuation being a SQ no-no.


----------



## amb

Quote:


  Originally Posted by *digger945* /img/forum/go_quote.gif 
_Does the volumite attenuate in the analog or digital?_

 

The Volumite itself does not do any attenuation. All it is, is a little controller that converts the pot setting into an I2C or SPI serial control stream. When connected to the Sabre or Opus, the DAC takes the I2C (Sabre) or SPI (Opus) data and performs the attenuation in the digital domain. However, when the Volumite is connected to the Joshua Tree (via I2C), the attenuation is done in analog by relays.


----------



## amb

I should also add that if you skip the volume control at the amp (be it a pot or stepped attenuator), then the source output drives the amp "wide open". Even though the volume might be attenuated within the DAC digitally, the noise floor of the DAC's analog output stage comes through into the amp unattenuated. Ditto any interference picked up by the interconnect cables. With sensitive headphones, these noises could be audible.

 With a volume control at the amp input, as you lower the volume, it also attenuates the noise from the source. You get much better S/N ratio this way.


----------



## Beefy

Quote:


  Originally Posted by *digger945* /img/forum/go_quote.gif 
_Yes, and how many times have we read posts here about digital attenuation being a SQ no-no._

 

The Buffalo32 is an interesting case here. It runs a very wide internal data path that allows for significant digital attenuation before you start losing bits, and it also has a very high dynamic range on the analogue outs. This combo of factors means it is good enough to at least consider for some applications.

 But in this case, I still wouldn't want to rely on it 100% for the reasons that AMB mentions.


----------



## dbfreak

A question on shielded signal wiring for Beta22. Does any of the shielding have to be connected any part of the Beta22?


----------



## amb

Quote:


  Originally Posted by *dbfreak* /img/forum/go_quote.gif 
_A question on shielded signal wiring for Beta22. Does any of the shielding have to be connected any part of the Beta22?_

 

Yes, if the shield isn't connected to signal ground, then it doesn't really shield.


----------



## dbfreak

Quote:


  Originally Posted by *amb* /img/forum/go_quote.gif 
_Yes, if the shield isn't connected to signal ground, then it doesn't really shield._

 

Thanks AMB!


----------



## boinger

Hmm I see what you guys are saying. I guess I will have to fork up for a joshua tree then. I really dont wnat to invest $50 + 200 later so I'd rather spend the $200 now, as to what I'm trying to achieve with this amp, I would like a good build. I was going to go for a 3 channel + an hd800 but people advised it was better to go balanced, but that resulted me in having to invest a good amount in a new balanced source + the 4 board sigma kit. So hence been trying to cut where it wont hurt to much. But I guess all the cutting is now gone. 

 What would you recommend is better with the beta joshua tree or a goldpoint. I can go for either.


----------



## amb

Quote:


  Originally Posted by *boinger* /img/forum/go_quote.gif 
_What would you recommend is better with the beta joshua tree or a goldpoint. I can go for either._

 

Whichever floats your boat... a rotary switch that has distinct steps, or a smooth pot and clickety-clack relays. The Goldpoint is an all-passive, single-piece solution whereas Joshua Tree involves multiple PCBs and another power supply.


----------



## digger945

Quote:


  Originally Posted by *boinger* /img/forum/go_quote.gif 
_Hmm I see what you guys are saying. I guess I will have to fork up for a joshua tree then. I really dont wnat to invest $50 + 200 later so I'd rather spend the $200 now, as to what I'm trying to achieve with this amp, I would like a good build. I was going to go for a 3 channel + an hd800 but people advised it was better to go balanced, but that resulted me in having to invest a good amount in a new balanced source + the 4 board sigma kit. So hence been trying to cut where it wont hurt to much. But I guess all the cutting is now gone. 

 What would you recommend is better with the beta joshua tree or a goldpoint. I can go for either._

 

You don't really need 4 sigmas to power a balanced Beta 22 amp. 2 would do the job handily.
 It is not a must to use a balanced source with a balanced Beta 22 amp, you could listen to an unbalanced source in the interim.
 This would give you more time to read and compare DAC choices.
 Another possible attenuator choice would be the DACT CT-4 for $229 plus shipping. You could also use the Goldpoint MCV4 and populate the resistors yourself.


----------



## fsrick

after reading the DACT CT-4 datasheet, i think that is for the balancing between 2 channels. it is not for what we need. you actually need the CT-2 balanced stereo one, which has 4 channels. But both DACT and goldpoint are serial type. I would prefer a ladder type myself which has the shortest signal path and constant input impedance. the Joshua Tree has constant output impedance, but not sure what type of stepping topology they are using.

  Quote:


  Originally Posted by *digger945* /img/forum/go_quote.gif 
_You don't really need 4 sigmas to power a balanced Beta 22 amp. 2 would do the job handily.
 It is not a must to use a balanced source with a balanced Beta 22 amp, you could listen to an unbalanced source in the interim.
 This would give you more time to read and compare DAC choices.
 Another possible attenuator choice would be the DACT CT-4 for $229 plus shipping. You could also use the Goldpoint MCV4 and populate the resistors yourself._


----------



## Beefy

DACT attenuators are all CT-2, and they come in 1, 2, 4, 6 or 8 channel models: DACT audio attenuators

 DACT CT-4 are balance controls: DACT audio balance controls

 The $229 CT-4 on the Headamp page seems to be a misunderstanding or typo, but I'm quite sure that is exactly what you need for a balanced amp.


----------



## boinger

If I put in 2 100 VA 30V transformers for a 4 channel config would I be able to drive speakers as well?


----------



## johnwmclean

Quote:


  Originally Posted by *boinger* /img/forum/go_quote.gif 
_If I put in 2 100 VA 30V transformers for a 4 channel config would I be able to drive speakers as well?_

 

Very amply, so to speak. Some members are driving speakers effectively with 2 board builds. Efficiency will depend on size of room, how loud and long you may wish to listen for and of course your choice of speakers.


----------



## Beefy

Quote:


  Originally Posted by *johnwmclean* /img/forum/go_quote.gif 
_Very amply, so to speak. Some members are driving speakers effectively with 2 board builds. Efficiency will depend on size of room, how loud and long you may wish to listen for and of course your choice of speakers._

 

...... and how efficiently the B22 and S22 are heatsinked and ventilated.


----------



## boinger

Hmm I think for now I will stick it to driving headphones maybe in the future ill get some more psu's and then convert it to speakers. 

 If I do chose to go with the 100VA trafo for the 4 boards would you recommend 2.5" heatsinks vs the standard 1.5"? or something even larger ?


----------



## johnwmclean

Quote:


  Originally Posted by *boinger* /img/forum/go_quote.gif 
_Hmm I think for now I will stick it to driving headphones maybe in the future ill get some more psu's and then convert it to speakers. 

 If I do chose to go with the 100VA trafo for the 4 boards would you recommend 2.5" heatsinks vs the standard 1.5"? or something even larger ?_

 

I'd go larger if your thinking of driving speakers at a later date, the 1.5's are perfectly adequate for headphones though.


----------



## fsrick

how thick is the wire you guys used in the signal path inside the B22. Is 22 guage enough for headphones or speakers. The length will not be longer than 1 feet.


----------



## johnwmclean

Quote:


  Originally Posted by *fsrick* /img/forum/go_quote.gif 
_how thick is the wire you guys used in the signal path inside the B22. Is 22 guage enough for headphones or speakers. The length will not be longer than 1 feet._

 

You’ll get a lot of differing opinions, 22 gauge is spot on for signal even 24 should be fine. I use silver coated 19 strand teflon, regarding length AMB recommendation is to shield if longer lengths than a few inches.


----------



## dallan

Well since this thread is who is building or thinking of building a Beta-22, I am thinking of commissioning one of my friends who is an engineer in a depressed state and out of work to put one together for me during the next 4-6 months and I don't even know where to start. I guess look at kits or something, All I know is the one at the meet in Los Angeles blew my socks off and I wouldn't mind having a balanced solid state to use with my 800s in addition to the Zana SE. Kind of investigating at this point but what i have read of the thread is a bit over my head i think, I can do some stuff, messed with radios a bit but no diy yet, thus my friend.

 Any suggestions on where to start?


----------



## fsrick

what is the good place to buy shilding sleeves for cables? thanks

  Quote:


  Originally Posted by *johnwmclean* /img/forum/go_quote.gif 
_You’ll get a lot of differing opinions, 22 gauge is spot on for signal even 24 should be fine. I use silver coated 19 strand teflon, regarding length AMB recommendation is to shield if longer lengths than a few inches._


----------



## amb

Quote:


  Originally Posted by *dallan* /img/forum/go_quote.gif 
_...
 Any suggestions on where to start?_

 

A good place to start is the official β22 website.


----------



## Beefy

Quote:


  Originally Posted by *amb* /img/forum/go_quote.gif 
_A good place to start is the official β22 website._

 

Who would have thought?


----------



## fsrick

Quote:


  Originally Posted by *digger945* /img/forum/go_quote.gif 
_




 As you can see, if you connect both balanced and unbalanced sources at the same time, without a switch to allow only one to be connected at a time, then you end up with the signal from one source physically connected to the other sources output. Imagine if the other sources output components somehow had a negative effect on the signal before the amp, even if the other source was powered down. 
 Would you not want only one source connected, and the signal from that source alone to be the only thing your amping?

 And yes, the switch that amb described does ground the inputs of the negative amps._

 

for using the balanced XLR with unbalanced source, I think we also need to switch the -L and -R in the connector to PSU ground, right? otherwise, the -L and -R board will serve as active ground board and the boarding setting is not right.


----------



## digger945

Quote:


  Originally Posted by *fsrick* /img/forum/go_quote.gif 
_for using the balanced XLR with unbalanced source, I think we also need to switch the -L and -R in the connector to PSU ground, right? otherwise, the -L and -R board will serve as active ground board and the boarding setting is not right._

 

I'm not sure if I understand the question but if you are using an unbalanced source then you would probably, in most circumstances, use the rca plug inputs on the amp, and then if you wanted to listen to that unbalanced source with your headphones that have balanced terminations plugged into the front of the amp, then the switch amb describes(I'll provide a link when I get home) would be used to ground the two negative amp boards inputs so that those amps will try to hold those connections to your headphone at ground, and you would be listening to the positive amps signals on the other hot wires going to the headphones.

 You could also listen to the unbalanced source with your balanced amp using a trs terminated headphone(unbalanced) and use the amps two hot amp boards with the headphone ground returning to power supply ground.

 That diagram is copied from the Beta 22 website btw(amb.org/audio), which has many more wiring diagrams and options to study.


----------



## ting.mike

I'm getting some problems with DC Power cabling... 

 My beta22 3ch has been running caseless for a while now, as I'm still waiting for more parts to complete into a 4ch build, and the casing is still also in design process. 

 Tonight I tried doing some tests for the Umbilical connectors for the DC power. Normally the S22 power is wired directly to the B22 boards. This time I soldered them to Neutrik Speakon connectors, and I used the umbilical cable I had prepared, and out into another Speakon connector and into the B22 boards. Just like a simulation of what it would be when I finish the casing. 

 The umbilical cable I use is high grade Kimber PK10 AC Power cable, cut short to about 20" long, terminated into Speakon connectors.

 In summary it goes like this:

 S22 board > hookup wire > Speakon connectors > Kimber PK10 AC Power cable > Speakon connectors > hookup wire > B22 boards

 When I plug everything in, the amplifier has lost bottom end impact and punch. It's as if the B22 has lost its power. 

 I know the problem is in the Umbilicals. I'm just trying to guess if it's the length of the cable, or the type of cable used. FYI the Kimber PK10 cable's wire is very thick about 4mm in diameter for each core, but it is normally an AC Power cable. 

 The Speakon connectors (4 terminals - I use only three for Line, Neutral, Ground):






 The cables (about 20" long each):










 The Kimber PK10 itself is a very fine cable and gives a very expansive soundstage, and very organic sounding whether used on my source or my amp. And it normally doesn't kill the bottom end.


----------



## aloksatoor

you sure the problem is not in the speakon connectors? Did you try running the power cord direct to the b22 boards? maybe a bit late since u already hooked up the connectors to the kimber


----------



## DoYouRight

this has me worried as well I didnt think the umbilicals would have that much impact on sound, very interested in knowing which those of you masters have used, JohnWmClean, AMB, FallenAngel, etc.


----------



## Beefy

I have a _very_ hard time believing it would have that much of an impact, unless something was done incorrectly, or it is picking up significant interference.

 If you still have the same voltages at the amp boards, and you aren't measuring significant resistance from start to finish, how could it possibly have an effect?


----------



## amb

A cursory web search finds no info on what the Kimber PK10's wire gauge is, other than that it's "optimized for AC power applications" which this is not. Maybe the cable is very inductive? While I don't know if the problem is in the cable, and sorry you had already spent the money on the expensive Kimber, but ordinary 16-18AWG stranded copper wire in a nice Techflex sheath would have worked very well.


----------



## linuxworks

Quote:


  Originally Posted by *DoYouRight* /img/forum/go_quote.gif 
_this has me worried as well I didnt think the umbilicals would have that much impact on sound, very interested in knowing which those of you masters have used, JohnWmClean, AMB, FallenAngel, etc._

 

maybe I'm an etc. etc is fine ;

 this etc uses belden 5 conductor cable and 2 sets of 4-pin mic (ham, cb) jacks and plugs. in fact the 4pin mic connectors used to be from radio shack; really bog standard things.

 they are not meant for power but they do pretty well for themselves. the connector is nicely keyed, too, which is important.

 I sent the dual 30vac windings (2 of them) over that set of plugs/jacks and some belden wire. just any old wire that seemed thick enough and flexible enough. 

 I have a rather long bit of the belden on it, too; perhaps 12' or so. I can 'remote' the power supply brick quite far away, now. and carrying ac that far is not a problem (better to carry unreg voltage 'far' than the regulated side).

 then, in the amp cabinet is the s22 PS. that's at the other end of the 4 pin mic jack.

 really simple and the wire was a few dollars, and so were the connectors (each). no big deal. doesn't have to be a big deal, either


----------



## DoYouRight

thanks linux, you helped me awhile back with getting linux audio stuff up and running, and your custom diy designs are amazing!


----------



## johnwmclean

Quote:


  Originally Posted by *DoYouRight* /img/forum/go_quote.gif 
_this has me worried as well I didnt think the umbilicals would have that much impact on sound, very interested in knowing which those of you masters have used, JohnWmClean, AMB, FallenAngel, etc._

 

LOL, that's very flattering - even though linuxworks is merely an etc. I agree, Belden is a good cheap choice. I used Amphenol connectors. The umbilical merely needs to serve a function, and if it's within spec then the cable will not affect sonics. 
 ting.mike, I would try AMB's recommendation purely as an experiment, get some cheap 18AWG cable and try that. I don't want to diminish your beliefs but save your wallet.


----------



## dbfreak

Although, I haven't gone to the power up phase of my B22 build, I'll be using Carol 3 conductor/14 gauge wire with Ampenol connections.


----------



## ting.mike

Quote:


  Originally Posted by *aloksatoor* /img/forum/go_quote.gif 
_you sure the problem is not in the speakon connectors? Did you try running the power cord direct to the b22 boards? maybe a bit late since u already hooked up the connectors to the kimber_

 

Thanks. Do you really think that the connectors are the problem? I'll try to look into that. 

  Quote:


  Originally Posted by *DoYouRight* /img/forum/go_quote.gif 
_this has me worried as well I didnt think the umbilicals would have that much impact on sound, very interested in knowing which those of you masters have used, JohnWmClean, AMB, FallenAngel, etc._

 

Of course it'll have impact on sound. It carries the DC signal that powers your amplifiers.


  Quote:


  Originally Posted by *Beefy* /img/forum/go_quote.gif 
_I have a very hard time believing it would have that much of an impact, unless something was done incorrectly, or it is picking up significant interference.

 If you still have the same voltages at the amp boards, and you aren't measuring significant resistance from start to finish, how could it possibly have an effect?_

 

Actually, I didn't hear any interference and the whole thing sounded very clean, even without a ground and a casing. 

 I guess this is why people say some B22 just sings and some don't sings that well. Little things does matter. 



  Quote:


  Originally Posted by *amb* /img/forum/go_quote.gif 
_A cursory web search finds no info on what the Kimber PK10's wire gauge is, other than that it's "optimized for AC power applications" which this is not. Maybe the cable is very inductive? While I don't know if the problem is in the cable, and sorry you had already spent the money on the expensive Kimber, but ordinary 16-18AWG stranded copper wire in a nice Techflex sheath would have worked very well._

 

I bought the Kimber used for a reasonably cheap price, and it was a 2.5meters long cable, so I cut some out to make this umbilical. Thought I would get great sound, but I didn't. So you think the problem is not in the length (20 inches), but more in the type of cable? 

 I will test it again using the same speakons but different cable for the umbilicals.

  Quote:


  Originally Posted by *johnwmclean* /img/forum/go_quote.gif 
_LOL, that's very flattering - even though linuxworks is merely an etc. I agree, Belden is a good cheap choice. I used Amphenol connectors. The umbilical merely needs to serve a function, and if it's within spec then the cable will not affect sonics. 
 ting.mike, I would try AMB's recommendation purely as an experiment, get some cheap 18AWG cable and try that. I don't want to diminish your beliefs but save your wallet._

 

Thanks, John. I did have cheap 18AWGs running just fine. That's how I was able to get a reference point. But now I'm trying to find a good cable for the final build. 


 Thanks for the inputs everyone, I'm going to test it with the same speakon connectors but a different cable. BTW, the only Beldens we can get here is Coax cables, no store stocks the Belden power cable that you guys are using.


----------



## ting.mike

Quote:


  Originally Posted by *linuxworks* /img/forum/go_quote.gif 
_maybe I'm an etc. etc is fine ;

 this etc uses belden 5 conductor cable and 2 sets of 4-pin mic (ham, cb) jacks and plugs. in fact the 4pin mic connectors used to be from radio shack; really bog standard things.

 they are not meant for power but they do pretty well for themselves. the connector is nicely keyed, too, which is important.

 I sent the dual 30vac windings (2 of them) over that set of plugs/jacks and some belden wire. just any old wire that seemed thick enough and flexible enough. 

 I have a rather long bit of the belden on it, too; perhaps 12' or so. I can 'remote' the power supply brick quite far away, now. and carrying ac that far is not a problem (better to carry unreg voltage 'far' than the regulated side).

 then, in the amp cabinet is the s22 PS. that's at the other end of the 4 pin mic jack.

 really simple and the wire was a few dollars, and so were the connectors (each). no big deal. doesn't have to be a big deal, either 
	

	
	
		
		

		
		
	


	


_

 

12' huh? I did think of this before too, cause I would love to save space on my desk. However, DC power signal doesn't travel distances very well.
 Maybe AMB can comment more on this issue.

 Have you tested your set up with a better quality cable in shorter length?


----------



## Beefy

Quote:


  Originally Posted by *ting.mike* /img/forum/go_quote.gif 
_Of course it'll have impact on sound._

 

...... how?

  Quote:


 It carries the DC signal that powers your amplifiers. 
 

So?

 I mean I can partially understand the whole cable thing with interconnects carrying small signals at high frequencies (even though I've never seen a convincing scope trace between two supposedly different interconnects). But we're talking about high current, high voltage, relatively constant signal.

 Unless the resistance is really high, or the cable is really inductive/capacitative, what could possibly be going wrong?

  Quote:


  Originally Posted by *ting.mike* /img/forum/go_quote.gif 
_However, DC power signal doesn't travel distances very well._

 

What voltage do you get at the terminals of the S22? And at the amp boards? With the amp off, what do you measure as the resistance from the terminals on the S22 to the amp boards?


----------



## linuxworks

Quote:


  Originally Posted by *ting.mike* /img/forum/go_quote.gif 
_Have you tested your set up with a better quality cable in shorter length?_

 

no.

 I left the cable long since its easier to cut than extend (lol).

 until I find a need to cut it, I'll leave her long 
	

	
	
		
		

		
		
	


	




 the PS unit can be stashed away, even hidden behind things. mine is pretty much just the toroid, ac power inlet, fuse, front switch and led. and connector and whole lotta cable out the other end.

 keeping the s22 local to the amp boards meant I did NOT have to have remote ground-runs thru the umbilical. that made mucho sense to me. plus keeping the PS boards very close to the amp boards meant the 'critical' dc cabling was more controlled and carefully routed, then fixed there. the long tangly ac line to my b22 box is not all that different from a long tangly ac line that used to run 110vac. its just now runs 2 lines of 30vac. still, a long tangly line should be ac, I think, and not dc. 

 I bought a 2nd s22 board and maybe if I can find a new box, I'll put a single b22 amp on a single s22 board, then the same again, all in 1 box. in the remote 'floor box' would be *two* toroids and a buncha wires going to the amp box. sort of a dual monoblock config, sharing a single physical chassis but nothing else.


----------



## ting.mike

Hi Beefy, 
 I'll try to take measurements tonight (maybe quite late) and I'll post updates. 

 Let's not get into cables argument now. It's unpleasant.


----------



## ting.mike

Quote:


  Originally Posted by *linuxworks* /img/forum/go_quote.gif 
_no.

 I left the cable long since its easier to cut than extend (lol).

 until I find a need to cut it, I'll leave her long 
	

	
	
		
		

		
		
	


	




 the PS unit can be stashed away, even hidden behind things. mine is pretty much just the toroid, ac power inlet, fuse, front switch and led. and connector and whole lotta cable out the other end.

 keeping the s22 local to the amp boards meant I did NOT have to have remote ground-runs thru the umbilical. that made mucho sense to me. plus keeping the PS boards very close to the amp boards meant the 'critical' dc cabling was more controlled and carefully routed, then fixed there. the long tangly ac line to my b22 box is not all that different from a long tangly ac line that used to run 110vac. its just now runs 2 lines of 30vac. still, a long tangly line should be ac, I think, and not dc. 

 I bought a 2nd s22 board and maybe if I can find a new box, I'll put a single b22 amp on a single s22 board, then the same again, all in 1 box. in the remote 'floor box' would be *two* toroids and a buncha wires going to the amp box. sort of a dual monoblock config, sharing a single physical chassis but nothing else._

 

Oh, if the s22 is on the same casing as the b22 boards, then yes, the umbilical cable length is fine. I was thinking s22 + toroid on one case, b22 on another case.

 I thought about doing that as well, since i'd really like to have the PSU box far on the ground, not cluttering my desk. But having 2 s22 boards and 4 b22 boards on one casing, would make a pretty big casing itself. But if that works for you, then -- great!


----------



## DoYouRight

So I have my b22 done basically, boards are stuffed, and I have it up and running. Just sitting loose tho on a scrap aluminum sheath until I get my FPE panels. All I can say is, W..O...W

 This is amazing, I might ask a question or two when putting it in the case and might change some gain things, but thanks for the info here and through pm's. Honestly couldn't have done it without people here. Especially FallenAngel and Johnwmclean. John thanks for that wiring diagram! Oh man that helped alot!

 My buffalo is about the same stage, I can honestly say I have never heard music sound so great at a home setting. I have heard insane speaker rigs, but headphones give an intimacy that is unsurpassed. The detail, authority, and pure bliss from this setup is mindblowing and to think it wasn't made by someone else, if it were a company I could see these 2 selling over $5000.

 Thanks AMB and especially the group build for KrMathis which set me on this path. Awesome stuff guys! I now only really desire HD800s and maybe a higher grado but for now Im pretty much done worrying about gear and focused purely on the music


----------



## royalflush

..got any pics?


----------



## johnwmclean

Congrats DoYouRight, you sound very happy with it - awesome combo, and an amazing achievement.


----------



## ting.mike

Quote:


  Originally Posted by *DoYouRight* /img/forum/go_quote.gif 
_So I have my b22 done basically, boards are stuffed, and I have it up and running. Just sitting loose tho on a scrap aluminum sheath until I get my FPE panels. All I can say is, W..O...W

 This is amazing, I might ask a question or two when putting it in the case and might change some gain things, but thanks for the info here and through pm's. Honestly couldn't have done it without people here. Especially FallenAngel and Johnwmclean. John thanks for that wiring diagram! Oh man that helped alot!

 My buffalo is about the same stage, I can honestly say I have never heard music sound so great at a home setting. I have heard insane speaker rigs, but headphones give an intimacy that is unsurpassed. The detail, authority, and pure bliss from this setup is mindblowing and to think it wasn't made by someone else, if it were a company I could see these 2 selling over $5000.

 Thanks AMB and especially the group build for KrMathis which set me on this path. Awesome stuff guys! I now only really desire HD800s and maybe a higher grado but for now Im pretty much done worrying about gear and focused purely on the music 
	

	
	
		
		

		
		
	


	


_

 

congrats!
 B22 truly is the amp that makes you focus on the music.


----------



## amb

Quote:


  Originally Posted by *ting.mike* /img/forum/go_quote.gif 
_12' huh? I did think of this before too, cause I would love to save space on my desk. However, DC power signal doesn't travel distances very well.
 Maybe AMB can comment more on this issue._

 

As already explained by linuxworks, his setup runs AC through the umbilical from the transformer secondary to the PSU board which resides in the amp chassis, so it's not the same scenario as yours. His configuration could tolerate much, much longer wiring.

 My recommendation for a DC umbilical is to make it as long as needed to prevent the two cases from being too close (to avoid transformer-induced hum), but not gratuitously long. Excessively long DC cabling would raise the output impedance of the PSU regulator and impact its load regulation performance and bandwidth. But 20" is not excessive at all. My own umbilicals are about 36" long.


----------



## nattonrice

Quote:


  Originally Posted by *ting.mike* /img/forum/go_quote.gif 
_BTW, the only Beldens we can get here is Coax cables, no store stocks the Belden power cable that you guys are using._

 

Australia is a PITA in that respect too... which is why ebay came to my rescue quite recently with this:

40ft of Belden 19364 for DIY Audiophile Power Cables - eBay (item 160353299332 end time Aug-13-09 06:36:53 PDT)

 they are a great bunch of people to buy off and communication was very good.
 Thou now I have tens of feet of the damn stuff... guess I'll make new iec power cords for me and my friends computers lol


----------



## Karu

While reading the recent posts in this thread I remembered that there is something I have meant to ask, but always forgotten.

 What is the benefit of having five-board setup that I see recommended sometimes? Is there some drawbacks to connecting two of the boards to ground for occasional unbalanced use versus adding an extra board specifically for active ground usage?


----------



## DoYouRight

I will post pics when my babies are cased up. Im extremely proud of them and will definately show them off when they are done. Basically mine are clones of FallenAngels, Johnwmclean, but with my buffalo has a buffalo logo. And since my beta22 is 6 board the case is going to be a fair bit larger when done. 
	

	
	
		
		

		
		
	


	




 The texture of bass now is unreal. I can finally get an image of direction of a drumset without closing my eyes and trying to focus very hard. Its just easy now 
	

	
	
		
		

		
		
	


	




 AMB, thank you so much for this amazing design, your generousity for releasing this design free when you could have made TONS of money on it is truly remarkable. Thank you.
 Evan


----------



## amb

Quote:


  Originally Posted by *Karu* /img/forum/go_quote.gif 
_What is the benefit of having five-board setup that I see recommended sometimes?_

 

Before answering this I need to answer the next one first.

  Quote:


 Is there some drawbacks to connecting two of the boards to ground for occasional unbalanced use versus adding an extra board specifically for active ground usage? 
 

Refer to the diagram here.
 Unbalanced headphones have only one common ground. You cannot connect both the left and right "-" amps together to provide this common ground, as the amps will fight each other and will likely be damaged. The "-" amps swing the inverted signal of the "+" amps when the input switch is set to balanced, and become "active grounds" only when the switch is set to unbalanced. The "-" amps are used only with balanced headphones due to their separate left and right "ground" returns. Unbalanced headphones' common "ground" return either goes to power supply ground (for a 4-channel configuration, with passive ground for unbalanced headphones), or to the output of a dedicated ground channel amp (the fifth, or even sixth channel, if you have two unbalanced jacks and want to use separate active grounds for each unbalanced headphone output).

 Note that the switch only selects the input between balanced and unbalanced. In this setup, all headphones (balanced and unbalanced) can be used individually or simultaneously. I.e., you can select either an unbalanced or balanced source, and both unbalanced and balanced headphones can be used with that source.


----------



## Karu

Quote:


  Originally Posted by *amb* /img/forum/go_quote.gif 
_Refer to the diagram here.
 Unbalanced headphones have only one common ground. You cannot connect both the left and right "-" amps together to provide this common ground, as the amps will fight each other and will likely be damaged._

 

AMB, Thanks for answering my question, but seems I may have been anomanously obfuscate in presenting my question.

  Quote:


  Originally Posted by *Karu* /img/forum/go_quote.gif 
_What is the benefit of having five-board setup that I see recommended sometimes? Is there some drawbacks to *connecting two of the boards to ground* for occasional unbalanced use versus adding an extra board specifically for active ground usage?_

 

(Emphasis added.) The post that you referred to seems to refer to the case I'm asking about.

  Quote:


  Originally Posted by *amb* /img/forum/go_quote.gif 
_A follow up to my post above...
 Note that when switched to unbalanced inputs, *the - amps have their inputs grounded*, so that they become active ground buffers similar to a 3-channel active ground amp (except in this case there is a separate ground amp per channel). In this mode, the "balanced" headphones are actually driven with unbalanced signals, only the + terminals of the headphone transducers "see" a varying signal. The - terminal is held to zero volts._

 

(Emphasis added.) I cannot see the benefit for the fifth board if as you say "_that they become active ground buffers similar to a 3-channel active ground amp_".


----------



## FallenAngel

Karu - Think of 5-channel vs 4-channel for *unbalanced* use as simply 3-channel vs 2-channel for unbalanced use.


----------



## rhester

Great news in that Gamma 1 Full++ is all acsed up and sounding glorious. But when there is good news, there always seems to be bad news. My dog pulled headphne cables out of my Beta22. Thought all was cool, hooked all back up and powered up, got green light out of Full++ feeding the Beta. Got LED on the Beta 22, put the 701s on and only had music from one channel. Thought I had still messed up a solder joint on the Full++. Changed sources and still there. Onpened up the Beta22 (3 channel active ground) and have one channel with both + and - LEDs burning, one with only + burning and one with only - burning. Miss my amp.

 Where is the first place to start looking?


----------



## amb

rhester, I assume "burning" means "illuminated". The β22 board's LED+ and LED- are powered directly by the V+ and V- rails. Does your amp have only one σ22 PSU (i.e., shared by all channels)? If so, then the only way that one board would show both LEDs on while the other channels don't, is a continuity problem between the PSU and the amp boards, or defective LEDs. Measure the rail voltages at each board to see what they are.

 Does anything look obviously damaged?


----------



## digger945

Quote:


  Originally Posted by *Karu* /img/forum/go_quote.gif 
_(Emphasis added.) I cannot see the benefit for the fifth board if as you say "that they become active ground buffers similar to a 3-channel active ground amp"._

 

The active ground buffers that amb refers to are for the negative(cold) signal lines(within the balanced amp) going to your balanced headphones, and are not the same as the active ground board(the 3rd or 5th board) that is used to buffer the single ground on your unbalanced TRS terminated headphones.


 In the wiring diagram below, just remove one of the two active ground boards. It does not include the switch that amb is referring to for switching between balanced and unbalanced sources.




 ^This wiring diagram is copied from the page in the second link below.

 It is not absolutely necessary to have the 3rd or 5th board for the active buffering of the unbalanced headphones ground, an alternate wiring method would be to run the ground wire of the unbalanced headphones back to the power supply ground as amb recommends. Note that amb gives graphs showing the results, and benifits, of using the active ground channel somewhere in this thread I believe.



The &beta;22 Stereo Amplifier
The &beta;22 Stereo Amplifier


----------



## ShinyFalcon

Is 120F/49C (+/- 10C) internal temp a bit too warm for a 6" x 8.5" x 3" case? I stuck a digital house thermometer in my amp and it stops displaying a temp above a certain level. The bias is set at around 50mV, with one channel drifting 10mV below. The outermost heatsinks are pretty hot to touch, while the middle heatsinks are a bit tolerable for up to maybe four seconds.

 Case is indeed ventilated but maybe there aren't enough holes. I drilled 0.25" holes, one row consisting of eight holes spaced 1" apart, three rows per heatsink row.


----------



## dude_500

I burned out the MOSFET's on my left channel again by plugging in my cans while it was on. I thought people say this is ok and shouldn't really be a problem. I am also careful to do plugging in and unplugging VERY fast. It was on for hours all warmed up and I needed to test another amp so I unplugged them with the amp on, came back in 10 minutes, plugged in and the fuse blew with dead mosfet's on one channel. Does this imply something is wrong with that channel? It's the same channel that had a hard short last time when I burned out the fet's the first time, and it still has a "Delayed start" where the power LED on that board turns on a quarter second slower than the other channel. Also the audio on that channel starts a quarter second after right channel.


----------



## FallenAngel

Turn the volume all the way down before connecting/disconnecting TRS plugs. Of course it is better to turn the amp off altogether for safety, it really sucks blowing up something this good (and expensive).


----------



## amb

ShinyFalcon, 49C is certainly not cool, but the more important metric is what the devices' junction temperatures are. You can calculate that to a certain level of accuracy using the formulas found at the β22 website (under "Board & heatsinks").

 You couid also get a reasonable sense of whether things are ok by the heatsink surface temperatures. Try to keep them below 65-70C.


----------



## FallenAngel

For the layman of us - 65C is too hot to touch for over a second. As long as your finger doesn't burn on touching it for a second or two, you're "likely" fine.


----------



## ShinyFalcon

As a reference the heatsinks on the β22 feel more or less hotter than my desktop computer's northbridge heatsink, both of which I can't poke for more than a second. I have a fan controller for my desktop and used its thermal probes, and the northbridge seems to be floating around 70C. If I open up my desktop again I'll probably see what the β22's heatsinks sit at. Note that I don't trust the probes.

 Here are my calculations:
  Code:


```
[left]P = V * I V(amp) = 8V V(cas) = 22V Po = 18W I? = sqrt( 18W / 8 ) * 0.30 = 0.45W I = .120 A P(amp) = 3.6W P(cas) = 9.9W Tj = Ta + ( P * (Rjc + Rcs + Rsa) ) Ta = 28C Rjc = 3.3C/W Rcs = 0.92W/m C Rsa = 2.0C/W Tj(amp) = 50.392C Tj(cas) = 89.578C[/left]
```

Since I more than likely made a mistake somewhere, here are my settings:
 σ２２　voltage = 30V
 Bias = 50mV / <120mA
 Stock 1.5" heatsink, Thermasil III pads (4880SG)

 Anyways, I feel that it may be okay to leave everything as is, but I will probably lower the bias down to 100mA, drill more holes (my σ22 has more holes spaced 0.5"), and maybe reduce the voltage down to 24V. I'm really more worried about the electrolytics and film caps than the MOSFETs.


----------



## Karu

Quote:


  Originally Posted by *FallenAngel* /img/forum/go_quote.gif 
_Karu - Think of 5-channel vs 4-channel for *unbalanced* use as simply 3-channel vs 2-channel for unbalanced use._

 

 Quote:


  Originally Posted by *digger945* /img/forum/go_quote.gif 
_The active ground buffers that amb refers to are for the negative(cold) signal lines(within the balanced amp) going to your balanced headphones, and are not the same as the active ground board(the 3rd or 5th board) that is used to buffer the single ground on your unbalanced TRS terminated headphones._

 

Thanks FallenAngel and digger945 for trying to explain this to me.

 I have understood that β22 can be run in either of the following modes:
 1. 3-board unbalanced in/out active ground
 2. 4-board unbalanced in + balanced (separate active grounds) out (AMB's earlier post)

 If we look at the input side of modes 1. and 2., there is little difference. Both are active ground type solution. It is the option for connecting unbalanced phones with active ground to the output side that can drive people to the five board setup.

 Now, back to (reformulated) original question. Is there difference in SQ between 1. and 2. if I connect balanced headphones to either one?

 Please note:
 - In 1. both (-) wires will be connected to ground
 - In 2. there is no shared ground that will produce fighting between amps.


----------



## DoYouRight

SQ differences weren't readily answered via 4 board or higher so I just wanted to be safe and made 6 board since not all of my phones will get balanced treatment. Its a great amp even with 2 boards so don't sweat small stuff either go all out of choose which is best for you. This thing has OODLES of power. Taught me little worries about small issues turn out to be pointless if it's well built a B22 kicks ass regardless, as long as the psu doesnt sit close to the boards causing hum.


----------



## ting.mike

Quote:


  Originally Posted by *Beefy* /img/forum/go_quote.gif 
_...... how?



 So?

 I mean I can partially understand the whole cable thing with interconnects carrying small signals at high frequencies (even though I've never seen a convincing scope trace between two supposedly different interconnects). But we're talking about high current, high voltage, relatively constant signal.

 Unless the resistance is really high, or the cable is really inductive/capacitative, what could possibly be going wrong?



 What voltage do you get at the terminals of the S22? And at the amp boards? With the amp off, what do you measure as the resistance from the terminals on the S22 to the amp boards?_

 


 just an update, since I promised measurements a few days ago. really haven't had the time to touch the amp since then.


----------



## linuxworks

Quote:


  Originally Posted by *DoYouRight* /img/forum/go_quote.gif 
_, as long as the psu doesnt sit close to the boards causing hum._

 

trafo.

 ps boards are fine close by.

 trafo has to be remote.


----------



## linuxworks

Quote:


  Originally Posted by *FallenAngel* /img/forum/go_quote.gif 
_Turn the volume all the way down before connecting/disconnecting TRS plugs. Of course it is better to turn the amp off altogether for safety, it really sucks blowing up something this good (and expensive)._

 

I have an easy way out 
	

	
	
		
		

		
		
	


	




 my amp has a switch on the front for spkr/phones. just a dumb simple dpdt toggle switch. BUT it doubles as a 'protect me!' switch 
	

	
	
		
		

		
		
	


	




 if I'm thinking of inserting or removing the phones, I first switch to spkr mode, then do the TRS plug (take as long as you want, lol) and then switch back.

 its the SHORTING that causes broken mosfets. not the switching. so if you switch contacts off, do your plugging and then switch on, you're fine. no need to even touch the vol control


----------



## boinger

Anyone use a gluegun / glue to fasten spacers between the case and the mounting panel?

 Also can I use the simple mains type switch mounted to the front to interrupt the power supply as an off switch? (my iec has no switch but does have a fuse)

ARCOLECTRIC SWITCHES|C7053AFNAB|SWITCH, DPST, GREEN | Farnell India


----------



## Beefy

Quote:


  Originally Posted by *boinger* /img/forum/go_quote.gif 
_Anyone use a gluegun / glue to fasten spacers between the case and the mounting panel?_

 

If you are considering gluing anything, then pack up the DIY and buy something off the shelf. Seriously.


----------



## boinger

.... it was just a question honestly... I have done plenty of diy... 

 I was asking about glue because tools / various parts are hard to get here and glue would be an easy alternative...


----------



## smeggy

pah, glue and duct tape are the very foundation of DIY!!


----------



## linuxworks

I've used hot-melt glue for a lot of temporary jobs. but for a final finished job, probably not.

 when I lay things out on wooden breadboard, I'll often glue standoffs to the wood just to save from drilling again and again. it holds well. but again, its just for testing prototypes.

 what do you mean by spacers, exactly? what are you thinking of doing?


----------



## Beefy

Quote:


  Originally Posted by *boinger* /img/forum/go_quote.gif 
_.... it was just a question honestly... I have done plenty of diy..._

 

Look, I'm a relative DIY noob, but I'm experienced enough to come to the solid conclusion from all of the questions you are asking that you probably shouldn't be undertaking a build of this magnitude.

 I will post no further on the matter, or your questions..... and only suggest that you start with something MUCH less ambitious, that you ARE able to get all the parts for easily.


----------



## boinger

Quote:


  Originally Posted by *linuxworks* /img/forum/go_quote.gif 
_I've used hot-melt glue for a lot of temporary jobs. but for a final finished job, probably not.

 when I lay things out on wooden breadboard, I'll often glue standoffs to the wood just to save from drilling again and again. it holds well. but again, its just for testing prototypes.

 what do you mean by spacers, exactly? what are you thinking of doing?_

 

standoff's pretty much just for holding the pcb's


----------



## Karu

Quote:


  Originally Posted by *DoYouRight* /img/forum/go_quote.gif 
_SQ differences weren't readily answered via 4 board or higher so I just wanted to be safe and made 6 board since not all of my phones will get balanced treatment. Its a great amp even with 2 boards so don't sweat small stuff either go all out of choose which is best for you. This thing has OODLES of power. Taught me little worries about small issues turn out to be pointless if it's well built a B22 kicks ass regardless, as long as the psu doesnt sit close to the boards causing hum._

 

I do wholeheartedly agree with you sentiments, but I also like to know the reason why something is the way it is. This time I'm curious whether there is a difference between input left floating and input being connected to ground. I very much enjoy this project, not only for the expectation of the end result, but for the collected eclectic arcana and the journey.


----------



## amb

Quote:


  Originally Posted by *Karu* /img/forum/go_quote.gif 
_...
 but I also like to know the reason why something is the way it is. This time I'm curious whether there is a difference between input left floating and input being connected to ground._

 

An amp input should never "float". A floating input (i.e., not terminated to ground via a low resistance) will act like an antenna and pick up noise.


----------



## DoYouRight

Linux, my bad, I meant the trafo which to me is the big silver hockey puck of power


----------



## dbfreak

As stated in the Beta22 instructions _"Also, the ground channel board's input "GND" pad
 should be connected to signal ground as they are for the left and right channel boards,* but leave its "Input" pads unconnected.*"_

 My question is, I noticed that anytime I've seen a picture of the Beta22 (3 board -active ground configuration) with Backplane board, both pads are connected. Does this apply when the Backplane board is part of the Beta22 configuration?


----------



## amb

dbfreak, since R1 is not populated on the active ground amp board, the input pad serves no purpose. You could connect it to the backplane board (which gives it ground, but it doesn't actually go anywhere on the amp board). R2 on the board is a low value on the ground amp, which terminates its "input" to signal ground.


----------



## dallan

Quote:


  Originally Posted by *amb* /img/forum/go_quote.gif 
_A good place to start is the official β22 website._

 

Thanks for the link, just got back from Shoreline amp concert last night this afternoon so couldn't get back on line to say it till now. Always been told there is no such thing as a dumb question so thought i would ask even though i expected at least one sarcastic reply. I'll look it over and seen it off to my diyer, cool. Eventually maybe i will get one together with help.


----------



## dbfreak

Quote:


  Originally Posted by *amb* /img/forum/go_quote.gif 
_dbfreak, since R1 is not populated on the active ground amp board, the input pad serves no purpose. You could connect it to the backplane board (which gives it ground, but it doesn't actually go anywhere on the amp board). R2 on the board is a low value on the ground amp, which terminates its "input" to signal ground._

 

Thanks, I should have known. It was late and I was suffering from trim pot fatigue.


----------



## askforwhy

Too bad, I'm still waiting for my case.
	

	
	
		
		

		
		
	


	



 They told me they would finish them by four days ago, but now I guess I will be kept waiting for another four days.
 Gee, my beta22s and sigma22s were finished and tested a month ago.


----------



## FallenAngel

Quote:


  Originally Posted by *askforwhy* /img/forum/go_quote.gif 
_Too bad, I'm still waiting for my case.
	

	
	
		
		

		
		
	


	



 They told me they would finish them by four days ago, but now I guess I will be kept waiting for another four days.
 Gee, my beta22s and sigma22s were finished and tested a month ago.
	

	
	
		
		

		
		
	


	


_

 

Don't sweat it, my balanced Beta22 took about a year from start to finish.


----------



## nattonrice

I second FallenAngel~
 My case saga was meant to only take 3 weeks two months ago...
 I only just today got a quote for all the cutting work :S

 I can say the practice from a build of this size has made my planing of an ungodly number of successor projects a lot quicker than this one went.


----------



## fault151

Quote:


  Originally Posted by *FallenAngel* /img/forum/go_quote.gif 
_Don't sweat it, my balanced Beta22 took about a year from start to finish._

 

I started mine last June 2008 and i'm still building it! Still got the panels to design yet. When I first started thinking about making this amp, I couldn't believe it took people a year to make it, now I see why!


----------



## askforwhy

Thanks guys, I'm just too excited about this upcoming beast, and I'm not a very patient person.
	

	
	
		
		

		
		
	


	



 I started this project on March, hopefully it will be finished this month, because I will have to go to school soon.


----------



## fault151

Quote:


  Originally Posted by *askforwhy* /img/forum/go_quote.gif 
_Thanks guys, I'm just too excited about this upcoming beast, and I'm not a very patient person.
	

	
	
		
		

		
		
	


	



 I started this project on March, hopefully it will be finished this month, because I will have to go to school soon.
	

	
	
		
		

		
		
	


	


_

 

Good luck, stick some pics up when you're done :0)


 Mine has taklen so long as unfortunately I have to work each day. Doh! I'm getting there though


----------



## askforwhy

Quote:


  Originally Posted by *fault151* /img/forum/go_quote.gif 
_Good luck, stick some pics up when you're done :0)


 Mine has taklen so long as unfortunately I have to work each day. Doh! I'm getting there though 
	

	
	
		
		

		
			



_

 

Sure!
	

	
	
		
		

		
		
	


	



 Also good luck to your build, it is a valuable experience.


----------



## jtostenr

How difficult would it be to combine this input attenuator with the balanced/unbalanced switch described in this post?

http://www.head-fi.org/forums/f6/rol...ml#post4665889

 Been reading through all the Headwize B22 posts now that the forum is back and I'm afraid my brain is going numb 
	

	
	
		
		

		
		
	


	




 Edit: If I understand this correctly, I would need 3 DPDT switches (or a 6PDT??? switch) for the input attenuator...

 Jeff

  Quote:


  Originally Posted by *amb* /img/forum/go_quote.gif 
_If you're using a source that is "too hot", then you might want to add an input attenuator at the amp. Here is a schematic of a switchable attenuator. It is drawn for an unbalanced (2 or 3 channel) amp, for a 4-channel balanced amp you'll need to double everything for the negative signal, and use either a 4PDT switch, or two DPDT switches.






 If you use the same value for all the resistors, then the attenuator will drop the effective gain of the amp by one half (-6dB). A good value to use is anywhere from 10K to 47K._


----------



## FallenAngel

Quote:


  Originally Posted by *jtostenr* /img/forum/go_quote.gif 
_How difficult would it be to combine this input attenuator with the balanced/unbalanced switch described in this post?

http://www.head-fi.org/forums/f6/rol...ml#post4665889

 Been reading through all the Headwize B22 posts now that the forum is back and I'm afraid my brain is going numb 
	

	
	
		
		

		
		
	


	




 Edit: If I understand this correctly, I would need 3 DPDT switches (or a 6PDT??? switch) for the input attenuator...

 Jeff_

 

Not "too" hard in theory, but wiring will be a pain in the a**. I strongly suggest mapping it out on paper first.


----------



## digger945

Quote:


  Originally Posted by *jtostenr* /img/forum/go_quote.gif 
_How difficult would it be to combine this input attenuator with the balanced/unbalanced switch described in this post?

http://www.head-fi.org/forums/f6/rol...ml#post4665889

 Been reading through all the Headwize B22 posts now that the forum is back and I'm afraid my brain is going numb 
	

	
	
		
		

		
		
	


	




 Edit: If I understand this correctly, I would need 3 DPDT switches (or a 6PDT??? switch) for the input attenuator...

 Jeff_

 

If I had to attack this right now, I would use the attenuator switch first and then the source selector after that in series.
 First question for you would be are you planning on implementing this into a 2 or 3 channel amp or 4 channel balanced config? Obviously since you inquired about using the two switches together and the Bal/Unbal switch is for use with a balanced amp then I would assume you are looking in that direction.


----------



## jtostenr

Yep, 4 channel balanced config for mainly speaker use. Right now all I have for headphones are some Sony MDR-7506. I would like to be able to use any type of headphones in the future should I decided to upgrade from the Sonys, so I wanted to be able to drop the gain (I know it's not actually changing the gain, but you know what I mean).

 Jeff


----------



## jtostenr

Hmmm....just thinking maybe I would be better off putting something together with relays. I seem to remember somebody doing this with a kit for the balanced/unbalanced switch. Maybe I could expand on that.


----------



## digger945

Quote:


  Originally Posted by *jtostenr* /img/forum/go_quote.gif 
_Yep, 4 channel balanced config for mainly speaker use. Right now all I have for headphones are some Sony MDR-7506. I would like to be able to use any type of headphones in the future should I decided to upgrade from the Sonys, so I wanted to be able to drop the gain (I know it's not actually changing the gain, but you know what I mean).

 Jeff_

 

I think everyone here understands what you mean, both with respect to the gain of the amp itself and the attenuation desired for the impedance of your future headphone(s).

  Quote:


  Originally Posted by *jtostenr* /img/forum/go_quote.gif 
_Hmmm....just thinking maybe I would be better off putting something together with relays. I seem to remember somebody doing this with a kit for the balanced/unbalanced switch. Maybe I could expand on that._

 

Definitely a possibility to use relays.
 I had about two paragraphs written but have decided to wait until I sketch it out to comment further. Shouldn't take long.


----------



## jtostenr

I see now...yes, if I put the input attenuator before the balanced/unbalanced switch, I don't need a 6PDT switch. Just 2 4PDT switches for the whole deal, unless I decide to build something with relays.

 Jeff


----------



## digger945

I was thinking the opposite, and I may be wrong on the proper placement of the input attenuator switch, not sure yet if it is ok to place it before or after the volume attenuators.
 I was thinking that if you use the Bal/Unbal switch first then you are left with only 4 signal lines(or poles on your switch), and that would mean you would only need another 4PDT switch to then further attenuate or not.






 Same idea as what you had, only two 4PDT switches.


----------



## jtostenr

Wouldn't that require 4 signal lines for the balanced connection and 2 more for the unbalanced? Otherwise, I think the input attenuator would only be used when the balanced input was selected.

 Edit: yep, your modified schematic looks like what I was thinking.


----------



## digger945

See the crude diagram I added to the above post.


----------



## jtostenr

Thanks for the help digger495! 
	

	
	
		
		

		
		
	


	




 I'm just starting my B22 and have only populated the boards and purchased the case. I don't expect to finish it this year, but I'm trying to work some things out with the design before I continue building.


----------



## digger945

Amb does all the work, and thusly deserves all the credit. 
 A wise choice, I think, to go slow with your build, and take a look at all the great casework that the other members here have shared.


----------



## dbfreak

Finished my B22 last night (it fired up without a hitch). Will post final build photos and a summary with first listening impressions in the near future (I'll do my best as I am not real familiar with all of the audiophile jargon). One thing that I can say is, it sounds AWSOME!
	

	
	
		
		

		
		
	


	




 Oh, thanks AMB for sharing your design and offering it to the public. Along with your very detailed instructions and a couple of personal questions, it went flawlessly.


----------



## amb

Referring to the diagram that digger945 posted above (post #1479) -- it doesn't really matter whether the switched attenuator comes before or after the volume pot, but you should be consistent between the hot ("+") and cold ("-") sides. As currently drawn, the switched attenuator is before the pot on the hot sides but reversed on the cold sides.


----------



## n_maher

Just wanted to post a quick note in this thread that Headwize is partially back online. You can't post, but you can search and get to the old beta22 threads (or at least appear to be able to).


----------



## DoYouRight

Yes it is very nice just a little too late to help me somewhat, however it is still great for troubleshooting.


----------



## ting.mike

When do you really need 30V output power on the s22? 

 The website said this: 
_"β22 is designed to operate between ±24V to ±30V DC rail voltages. Highest output voltage swing and output power is attained at ±30V, while ±24V will make the amplifier run cooler. "
_

 I'm currently setting it on 24V, but I do like a high voltage swing for my HD650. Of course I can just change R10 and hear the effect, but just curious if anyone has an answer.

 Another thing that I want to ask, I saw AMB's group build Balanced B22 for krmathis, and noticed that the attenuator is enclosed in its own housing. Does doing this have any benefits?


----------



## TeraHz

Ok, I've ordered my boards from amb.org and doing some final adjustments on the rest of the components. I took the time (1 day) to create a spreadsheet for the b22 project. It allows you to put mouser/digikey part numbers and the number of b22, o22 and e24 boards you want and it will create a copy-and-paste EZ Imports for both mouser and digikey. You can also include the quantity of certain parts you already have. Assumes all boards are for channel, 8x gain and 30V sigma. Also it doesn't include case, volume control, power buttons and headphone/speaker connectors.

http://joro.geodar.com/code/b22%20BOM.zip

 I'll be happy to make revisions if someone points out a problem.

 Currently all entered items are in stock and I've tried to keep the price low.

*NB1*: I'm using Numbers on a mac for this spreadsheet. The included .xls version is exported from Numbers, so keep that in mind. 
*NB2*: I don't know yet if my selection of parts works! I've tried to follow the official β22/σ22/ε24 instructions on amb.org, but given the amount of parts and the amount of copy/paste I've been doing, this might have errors. 

 Just for the people who are new and are asking for the price of this amp, only the minimal parts (no extras) for a 2xβ22 + 1xσ22 build are ~$150 from mouser + ~$100 from amb.org + about ~$30 from digikey. That excludes case and volume control. Total: $280. So far, I believe linuxworks has made the cheapest case ($15 + $5 panels) if I remember correctly. oneplustwo has put his b22 in a cookie tin ($10 with cookies) So it should be possible (if you are perfect with your build and don't need replacement parts) to have a 2 channel β22 for < $300.

 EDIT: I've fixed a few bugs with the spreadsheet. The parts on it seem to work so far (amp not completely finished yet, but boards are populated and the sigmas power up. Have not tried the betas). I've added some additional items, like standoffs, screws, umbilical cable plugs, fuse etc. Also the spreadsheet is adding 1 to all items just in case. I do suggest you check the discounting on some items for volume purchasing. For example it is worth investing in 100 of the Q1,Q2 transistors as they are 2-3 cents each and you can do some matching as suggested on amb.org, plus these seem to be the first to die when you make a mistake.


----------



## oneplustwo

My "case" was a cookie tin which was free (or $10 if you want to be strict about the cost of the cookies.) So cheaper than linuxworks, not as "official", but certainly unique. (see sig)


----------



## mourip

Hi,

 I am beginning to get the B22 bug and am starting to plan it out. Have any of you gone the Glass Jar Audio route? How did it work out for you?

 Thanks,

 Paul


----------



## ting.mike

I've gotten all my parts from Glass Jar. It's been great. 

 I've also shop for my friends from Glass Jar too. Jeff Rossel is the man!


----------



## ShinyFalcon

I ordered my σ22 from them, particularly because of the included transformer. Much less hassle then searching for who sells them. Worked well so far! But I wish he included a 10K ohm resistor for the option of 24V. A 6.8K ohm is included for 30V.

 Funny thing, I didn't like the color of the yellow caps, and since I ordered from amb directly I got red Wimas for my β22. The red looks so much better.


----------



## ting.mike

I think Glassjar sometimes have red Wimas as well in their kits. Just have to ask Jeff.


----------



## mourip

Quote:


  Originally Posted by *ting.mike* /img/forum/go_quote.gif 
_I've gotten all my parts from Glass Jar. It's been great. 

 I've also shop for my friends from Glass Jar too. Jeff Rossel is the man!_

 

Thanks Mike! How is your own B22 coming along?


----------



## ting.mike

Quote:


  Originally Posted by *mourip* /img/forum/go_quote.gif 
_Thanks Mike! How is your own B22 coming along?_

 

the 3 channel build has been making music for about a month now..
 still waiting for parts for balanced upgrade. 
 still deciding on what case to use. 






 Anyway, since this hasn't found an answer yet:

*When do you really need 30V output power on the s22? 
*
 The website said this: 
 "β22 is designed to operate between ±24V to ±30V DC rail voltages. Highest output voltage swing and output power is attained at ±30V, while ±24V will make the amplifier run cooler. "


 I'm currently setting it on 24V, but I do like a high voltage swing for my HD650. Of course I can just change R10 and hear the effect, but just curious if anyone has an answer.

 Another thing that I want to ask, I saw AMB's group build Balanced B22 for krmathis, and noticed that the attenuator is enclosed in its own housing. Does doing this have any benefits?


----------



## johnwmclean

Quote:


  Originally Posted by *ting.mike* /img/forum/go_quote.gif 
_the 3 channel build has been making music for about a month now..
 still waiting for parts for balanced upgrade. 
 still deciding on what case to use. 




_

 

Wow ting.mike I’d love to get you impressions SE vs Balanced.


----------



## ShinyFalcon

It's probably to shield the attenuator from noise. Some other things I can think of is length constraints (lesser wiring is better), or a structure to hold the attenuator in place, or a bit of all three.


----------



## amb

Yes, it's all three. Plus it also looks neater that way.


----------



## nattonrice

Quote:


  Originally Posted by *ting.mike* /img/forum/go_quote.gif 
_*When do you really need 30V output power on the s22? 
*
 The website said this: 
 "β22 is designed to operate between ±24V to ±30V DC rail voltages. Highest output voltage swing and output power is attained at ±30V...._

 

When you want the "Highest output voltage swing and output power".
 If you were going to drive a K1K or efficient speakers then this is probably desirable. 

 All things considered if your case isn't vented enough for 30v operation then it probably means it needs more vents anyway.
 The hotter the inside of the case the lower the life things like electrolytic caps have.
 Piece of mind I guess.


----------



## ting.mike

Quote:


  Originally Posted by *johnwmclean* /img/forum/go_quote.gif 
_Wow ting.mike I’d love to get you impressions SE vs Balanced._

 

cool. I will definitely post a short impression. The difficult part is that my balanced interconnect are really fancy, while my SE interconnect is just plain CAT6 cable. 

 btw, John,
 what voltage are you running on your S22?


----------



## mourip

Quote:


  Originally Posted by *ting.mike* /img/forum/go_quote.gif 
_I've gotten all my parts from Glass Jar. It's been great. 

 I've also shop for my friends from Glass Jar too. Jeff Rossel is the man!_

 

Mike. Do you contact Jeff by directly by email. I tried asking him a question a couple of days ago using his "Contact" web form but have not heard back. Perhaps he's on vacation?

 Thanks...


----------



## johnwmclean

Quote:


  Originally Posted by *ting.mike* /img/forum/go_quote.gif 
_btw, John, what voltage are you running on your S22?_

 

2 x S22 @ 30V. Runs cool-warm never hot, I don’t think I even challenge it since it’s only forking out for headphone duties.


----------



## nattonrice

Quote:


  Originally Posted by *mourip* /img/forum/go_quote.gif 
_Mike. Do you contact Jeff by directly by email. I tried asking him a question a couple of days ago using his "Contact" web form but have not heard back. Perhaps he's on vacation?

 Thanks..._

 

He's a pretty busy guy and can take a couple of days to answer.
 The wait is worth it 'cause he's such a nice dude


----------



## fault151

Guys, is there a gallery/thread anywhere, other than ambs site that has loads of pics of just b22 amps? Just after looking at some other pics by builders.


----------



## DoYouRight

i searched through the diy threads and this one for pics and got a load of em fault.


----------



## ting.mike

Quote:


  Originally Posted by *mourip* /img/forum/go_quote.gif 
_Mike. Do you contact Jeff by directly by email. I tried asking him a question a couple of days ago using his "Contact" web form but have not heard back. Perhaps he's on vacation?

 Thanks..._

 

X2 what nattonrice said. busy, but very nice guy.



  Quote:


  Originally Posted by *johnwmclean* /img/forum/go_quote.gif 
_2 x S22 @ 30V. Runs cool-warm never hot, I don’t think I even challenge it since it’s only forking out for headphone duties._

 

thanks, john.


----------



## fault151

Quote:


  Originally Posted by *DoYouRight* /img/forum/go_quote.gif 
_i searched through the diy threads and this one for pics and got a load of em fault._

 


 Yeh i just thought it would be cool to set up a dedicated gallery as there must be loads of us building the b22 by now.

 Its ok with them within posts but you have to trawl through loads of messages to locate pics.


----------



## jtostenr

For the bal/unbal switch, input atten, and speaker/phone switch, would these be appropriately current ratings for relays? Too high? Too low?

 bal/unbal - 2A
 input atten - 2A
 speaker/phone - 10A

 Thanks,
 Jeff


----------



## amb

The input stuff doesn't need much current at all (actual current is in the microamps), but those ratings look fine.


----------



## amb

Quote:


  Originally Posted by *fault151* /img/forum/go_quote.gif 
_Yeh i just thought it would be cool to set up a dedicated gallery as there must be loads of us building the b22 by now._

 

The one at the β22 website is _it_. Builders are encouraged to submit pics.


----------



## fault151

Quote:


  Originally Posted by *amb* /img/forum/go_quote.gif 
_The one at the β22 website is it. Builders are encouraged to submit pics._

 

Ok cool, i love seeing what people build. 

 Hopefull if i ever get mine done, i'll submit it too.


----------



## jtostenr

Would it be ok to put all three circuits on the same pcb, or should I put the speaker/phones switch on it's own pcb?

 Jeff


----------



## amb

Not sure what you're asking, are you making your own PCB? If so, your specific case layout, panel component arrangement and wiring routing plan would dictate how to do it.


----------



## devin_mm

I still have my 6 b22 PCBs and 2 e22 PCBs now that I have the proper setup to do some work it should go much quicker. Is it worth it to be a 6 channel active ground b22? or will 4 channel sound the same?


----------



## jtostenr

I'm thinking about making a pcb that would have all three circuits on it. One of my concerns is that I'm not sure if I would want to run the high current circuit for the headphone/speaker switch on the same pcb as the other two circuits.

 Jeff


----------



## devin_mm

Is this what you mean?

The &epsilon;22 Amplifier Backplane Board


----------



## jtostenr

No, not the B22 circuits...

 I am going to incorporate a balanced/unbalanced switch, input attenuator switch and a speaker/headphone switch into my B22 build. Just not sure if it's ok to have all three on the same pcb.

 Jeff


----------



## FallenAngel

Quote:


  Originally Posted by *devin_mm* /img/forum/go_quote.gif 
_I still have my 6 b22 PCBs and 2 e22 PCBs now that I have the proper setup to do some work it should go much quicker. Is it worth it to be a 6 channel active ground b22? or will 4 channel sound the same?_

 

Well... 4 boards are used for balanced so in a 6-channel, 2 boards are unused when driving balanced headphones. Guess that should answer your question.


----------



## digger945

Quote:


  Originally Posted by *devin_mm* /img/forum/go_quote.gif 
_I still have my 6 b22 PCBs and 2 e22 PCBs now that I have the proper setup to do some work it should go much quicker. Is it worth it to be a 6 channel active ground b22? or will 4 channel sound the same?_

 

To add to what FallenAngel said above, the 6 channel amp would be built to listen to 2 pairs of unbalanced headphones with active ground channel concurrently, irregardless of your choice of source. This in addition to balanced listening of course.


----------



## devin_mm

Thanks


----------



## amb

jtostenr, there is no problem with having it all on the same PCB as long as you keep the high current stuff away from the low signal stuff. Also, they must not share ground traces/wires.


----------



## jtostenr

Any reason you recommend non-latching relays instead of latching?


----------



## amb

Quote:


  Originally Posted by *jtostenr* /img/forum/go_quote.gif 
_Any reason you recommend non-latching relays instead of latching?_

 

I don't "recommend" one over another. Non-latching relays are easier to use, but has a constant current draw when it's coil is energized. This may or may not be an issue depending on where it's used. Latching relays save power, but is tricker to apply (you need more circuitry to drive it).


----------



## jtostenr

I see....I figured there must be a good reason you only had non-latching types listed on your website.

 Thanks again,
 Jeff


----------



## mattcalf

Quote:


  Originally Posted by *fault151* /img/forum/go_quote.gif 
_Yeh i just thought it would be cool to set up a dedicated gallery as there must be loads of us building the b22 by now.

 Its ok with them within posts but you have to trawl through loads of messages to locate pics. 
	

	
	
		
		

		
			



_

 

I've 165ish photos, notes, PDFs, BOMs that I've found around the place in preparation for my build. (A non-existant build that will hopefully occur around 2012)


----------



## fault151

Quote:


  Originally Posted by *mattcalf* /img/forum/go_quote.gif 
_I've 165ish photos, notes, PDFs, BOMs that I've found around the place in preparation for my build. (A non-existant build that will hopefully occur around 2012)
	

	
	
		
		

		
		
	


	


_

 

Cool, it always helps to get a bit of inspiration first befiore buioding. Thats what i do.


----------



## jtostenr

Thought there was an Epsilon 24 thread on Head-Fi, but couldn't find it, so I'll ask here.

 Is there any reason I shouldn't run 3 or 4 E24s off of a single trafo like the Avel-Lindberg Y236002 (15VA 12+12)? Would I need to use a different trafo?

 Jeff


----------



## fault151

Jeff. I ran 2 e24 boards of a small 12v .75 VA trafo and it worked ok, but it did get a bit hot. I then swapped them out for two instead. Im guessing 4 of a 15va will be ok.

 (Edit - these were used with powering relay boards and not mains relay switches.)


----------



## amb

Quote:


  Originally Posted by *jtostenr* /img/forum/go_quote.gif 
_Is there any reason I shouldn't run 3 or 4 E24s off of a single trafo like the Avel-Lindberg Y236002 (15VA 12+12)? Would I need to use a different trafo?_

 

It should work fine, as long as the relay coil currents are within the load limits of the transformer so that the secondary voltage do not sag and cause the ε24s' onboard 7812 voltage regulators to fall out of regulation.


----------



## ShinyFalcon

I have remeasured values on my B22 after warming up for a while and found out that R9-12 on both channels drifted up to around 4.9V, both channels about .1V apart from each other. I put it back down to 4.5V. Should I be worried?

 Is there a specific formula for the conversion between mV -> mA? Would Ohm's law work here? It seems different for the M³ and the B22, but for the B22 all I have to do is multiply the DC by 2.16 for a rough estimate... Also, how low is too low for class A?

 Last question, should adjustments to VR1 and VR2 change the offset at the output? As eerie as it sounds, the offset was spot on 0mV on first turn on. Minor adjustments did bring the offset up or down, so I'm certain that my multimeter's not lying. Also, because I stacked my boards I can't easily access one board's input ground, so I don't know if that will make any difference, but I don't think it should.


----------



## amb

Quote:


  Originally Posted by *ShinyFalcon* /img/forum/go_quote.gif 
_I have remeasured values on my B22 after warming up for a while and found out that R9-12 on both channels drifted up to around 4.9V, both channels about .1V apart from each other. I put it back down to 4.5V. Should I be worried?_

 

Not to worry. The target is 4.5V, but 4.9V won't damage anything. It just causes the input stage to run a bit more current than the design calls for.

  Quote:


 Is there a specific formula for the conversion between mV -> mA? Would Ohm's law work here? It seems different for the M³ and the B22, but for the B22 all I have to do is multiply the DC by 2.16 for a rough estimate... 
 

Yes, Ohm's Law applies here. If you're referring to the output stage quiescent current (while measuring the voltage across R34 and R35) -- the resistors are 0.47 ohms, thus the current through the output stage is:

 I = V / R
 where R is 0.47 ohms, V is the voltage drop across the resistor (in Volts), and I is the current (in Amperes).

 For example, if you measure 60mA across R34, then
 I = 0.06A / 0.47 ohms = 0.128A = 128mA

  Quote:


 Also, how low is too low for class A? 
 

It's output voltage and load-dependent. To remain in class A (for a push-pull output topology like the β22), the quiescent current must be at least half the maximum required peak output current. Let's assume that the "maximum" is the full available output voltage (which for each β22 channel is about 22V peak on +/-30V rails), and assume that the load impedance is 32 ohms, then the peak output current would be 22V / 32 ohms = 690mA. Thus the amp must quiesce at 350mA to be in class A under the specified conditions. BUT, that is a rather unreasonable condition -- 22V is way too much voltage swing for most 32 ohm headphones (your ears would bleed, if the headphone doesn't burn out first).

 Instead, let's work backwards and assume that you biased the amp to quiesce at 120mA. This means that the amp will be able to deliver twice that amount of peak current before it drops out of class A. Using Ohm's Law, we can determine what peak voltage that is:
 V = I * R = 0.24A * 32 ohms = 7.7V.

 7.7V and 0.24A is over 1.8W of peak output power into 32 ohms. Consider that many 32 ohm headphones give you 90-something dB SPL with a mere 1mW of power, I'd say that is more than sufficient.

 With a high-Z headphone load (such as 300 ohms Sennheisers), the amp will be able to deliver the full output voltage without dropping out of class A. You can do the math based on the example above.

 The reason why the recommended quiescent current is so high, is not so much to keep things in class A (which it does, very deeply), but because MOSFETs sound better when biased heavily.

  Quote:


 Last question, should adjustments to VR1 and VR2 change the offset at the output? 
 

It shouldn't, at least not significantly.

  Quote:


 As eerie as it sounds, the offset was spot on 0mV on first turn on. Minor adjustments did bring the offset up or down, so I'm certain that my multimeter's not lying. Also, because I stacked my boards I can't easily access one board's input ground, so I don't know if that will make any difference, but I don't think it should. 
 

The DC offset could drift a little depending on the temperature gradient across certain devices, especially the input JFET quad. So it's not abnormal to see it change slightly as the amp warms up. However, on a properly-functioning amp I don't expect it to drift more than a couple of mVs, which is miniscule and perfectly safe.


----------



## Possede

I'm just buying last minute components for my build (have already spent over £500 and that's without fabricated panels!). I'm trying to find a suitable DC connector. I'll be using this setup:






 (Image from AMB website)

 This may sound like a silly question, but why are people using 6-pole/8-pole connectors when there are only 3 connections? Are they simply using 3 of the pins and leaving the rest unused. I've been trying to find a suitable 3-pole connector, but I'm having trouble. I have been looking at Amphenol and Neutrik connectors. If anyone could link me to a suitable connector (male and female) that would be appreciated.


----------



## Beefy

I'm pretty sure that I provided the four required part numbers for Amphenol connectors somewhere in this thread. Happy searching!


----------



## fault151

@Possédé - People tend to use the 4pole / 8pole as they need more wires going from case to case. I use x2 8pole conncetions as i need 14 wires fromt he dual psu's through to my amp, switch boards and joshua tree. They tend to mount up quickly as you introduce nice bits in to the amp design.


----------



## digger945

Amphenol Ecomate.


----------



## Possede

Thanks guys. Guess I'll have to skim over the thread again.


----------



## Beefy

Quote:


  Originally Posted by *Possédé* /img/forum/go_quote.gif 
_Thanks guys. Guess I'll have to skim over the thread again. 
	

	
	
		
		

		
		
	


	


_

 

Just to save you the trouble, here is what I posted in another thread regarding my MMM umbilical. Exact same should apply for the B22, but you would obviously connect all three wires.

 *

 They are Amphenol Ecomate from Mouser. Pricey, but worth every cent! They are configured so that you can never touch a live wire.....
 Socket out of PSU: C016 20G003 100 12
 Plug PSU side: C016 20H003 100 12
 Plug amp side: C016 20D003 100 12
 Socket in to amp: C016 20C003 100 12
 The datasheets at Mouser are incorrectly linked. Just remove the '1' after the www to get to the right page.

 I have them wired with 3x 17AWG standard hookup wire. Only two of those are actually connected on the sockets, the third is just for strength.

 *


----------



## Possede

That's just what I was looking for. Cheers! 
	

	
	
		
		

		
		
	


	





  Quote:


  Originally Posted by *Beefy* /img/forum/go_quote.gif 
_Just to save you the trouble, here is what I posted in another thread regarding my MMM umbilical. Exact same should apply for the B22, but you would obviously connect all three wires.

 *

 They are Amphenol Ecomate from Mouser. Pricey, but worth every cent! They are configured so that you can never touch a live wire.....
 Socket out of PSU: C016 20G003 100 12
 Plug PSU side: C016 20H003 100 12
 Plug amp side: C016 20D003 100 12
 Socket in to amp: C016 20C003 100 12
 The datasheets at Mouser are incorrectly linked. Just remove the '1' after the www to get to the right page.

 I have them wired with 3x 17AWG standard hookup wire. Only two of those are actually connected on the sockets, the third is just for strength.

 *_


----------



## digger945

Quote:


  Originally Posted by *Beefy* /img/forum/go_quote.gif 
_They are Amphenol Ecomate from Mouser. Pricey, but worth every cent!_

 

 Yes, I will agree that for some they can easily be considered pricey but I have looked at many different kinds of dedicated connectors like this one and have found none like them any cheaper. When I finished building my amp and power supply with these and stepped back to have a look I was very pleased with them. The alternative metal ones are, in some places, more than twice the price. They have well marked pin sockets and are super easy to solder. They can also be had in a number of different sizes to accommodate different gauge wire as well as the number of wires.


----------



## johnwmclean

Amphenol connectors are very nice, the only thing that I would haved liked is the option to solder. The termination is screw only...


----------



## Beefy

I think that the 6 connector models have solder tabs.


----------



## johnwmclean

Quote:


  Originally Posted by *Beefy* /img/forum/go_quote.gif 
_I think that the 6 connector models have solder tabs._

 

Locked in for my next Beta22 build...


----------



## nattonrice

Quote:


  Originally Posted by *johnwmclean* /img/forum/go_quote.gif 
_Locked in for my next Beta22 build..._

 

HAHA there is so much LOL there I don't know where to begin!
 Mind, after building one it probably would take you 1/3 of the time and effort to do another.
 Much of the major thinking would have been done already.


----------



## FallenAngel

Uhum.. I've built 2, second wasn't much easier. Now I'm planning third build. 
	

	
	
		
		

		
		
	


	




 I think I'll use the OTTO to control switching between Headphone and Pre-Amp outputs. Just a thought.


----------



## oneplustwo

^^ I concur. Actually, for whatever reason, my first beta went off without a hitch. On the other hand, the second and third both gave me problems. Here's hoping #4 goes smoothly!


----------



## johnwmclean

Quote:


  Originally Posted by *FallenAngel* /img/forum/go_quote.gif 
_Uhum.. I've built 2, second wasn't much easier. Now I'm planning third build. 
	

	
	
		
		

		
			





 I think I'll use the OTTO to control switching between Headphone and Pre-Amp outputs. Just a thought._

 

I saw your new Beta22 up on the FS forum 
	

	
	
		
		

		
		
	


	




 so what do you intend to do different this time around?


----------



## FallenAngel

I want a Beta24 
	

	
	
		
		

		
		
	


	




 so my next one will not have speaker outputs or unbalanced input but will have loop-out and pre-out. I'm also thinking of going with a Joshua Tree attenuator instead of the DACT.


----------



## devin_mm

Quote:


  Originally Posted by *FallenAngel* /img/forum/go_quote.gif 
_Uhum.. I've built 2, second wasn't much easier. Now I'm planning third build. 
	

	
	
		
		

		
		
	


	




 I think I'll use the OTTO to control switching between Headphone and Pre-Amp outputs. Just a thought._

 

What is the benefit of the OTTO over say a Darwin?


----------



## oneplustwo

OTTO is simply a 2:1 (or 1:2) switch. The Darwin is a 6 source, 2 output switch. Check out the website for details. Sounds like fallenangel would only need an OTTO for his application. No need for the Darwin.


----------



## ting.mike

isn't the OTTO an I2S switch?

_The OTTO Switching module is a simple 2:1 switch which allows you to connect two I2S input modules (or any other I2S sources) and feed a single Opus DAC (or other I2S consumer). The switch is triggered by connecting the module's V+ terminal to the TR (trigger) terminal, which can be done by a simple switch or by a microcontroller._

_Darwin is a is a relay switched 6 source 2 output source selector with integrated optional loop. It can be controlled simply by means of a power supply and a switch, or via a micro controller. The kit comes with one (S/E) or two (Balanced) Darwin relay board(s), a 6-position rotary switch to control inputs, and a 3 position rotary switch to control outputs. No audio signals go through the switches.
 A 5V supply is required (not in kit). Each relay board requires a maximum of 60mA.
_


----------



## amb

No. Otto is not much more than just a 4PDT relay-on-a-board. You could use it to switch I2S, but you could also use it to switch just about anything.


----------



## Possede

Just a quick post to ask if anyone has a spare ε22 backplane that they are willing to sell please PM me. I know this is a shot in the dark but I
 thought I would at least ask.


----------



## linuxworks

Quote:


  Originally Posted by *ting.mike* /img/forum/go_quote.gif 
_isn't the OTTO an I2S switch?_

 

4pole double throw relay.

 it will 'switch' anything, I would guess 
	

	
	
		
		

		
		
	


	




 its just a relay. yes? or is there magic somewhere?


----------



## Possede

I thought I would ask here instead of starting a thread. I have ordered parts for the ε24, and I could not find the exact 7812 voltage regulator (TO-220) listed on AMB's website (Mouser 512-LM7812CT, Digi-Key MC7812ECT-ND). I have instead bought this and this. If someone could confirm that either of these are suitable replacements that would be appreciated.


----------



## ting.mike

The other day I found out that the ground cable connection to one of the board's ground pad may be a little insecure, so I resoldered the thing. Now I have a feeling that particular ground connection might not be so solid (from potentiometer ground to the right channel B22 ground pad), cause I'm feeling a slightly condensed soundstage (it may just be my feeling). What's the best way to find out that I have a solid connection there?


----------



## digger945

Quote:


  Originally Posted by *Possédé* /img/forum/go_quote.gif 
_I thought I would ask here instead of starting a thread. I have ordered parts for the ε24, and I could not find the exact 7812 voltage regulator (TO-220) listed on AMB's website (Mouser 512-LM7812CT, Digi-Key MC7812ECT-ND). I have instead bought this and this. If someone could confirm that either of these are suitable replacements that would be appreciated._

 

A quick scan of the datasheets shows that they have the same pinouts and specs so yes, they would work fine. I used the Nat. Sem. LM7812C on mine, same 12V reg. with same pinouts.


----------



## amb

ting.mike, how about measuring the resistance?

 Possédé, the 78xx sereis voltage regulators are fairly generic and are made by many manufacturers. Use whichever available, as long as it's in the TO-220 package and has the correct pinout.


----------



## Possede

Quote:


  Originally Posted by *digger945* /img/forum/go_quote.gif 
_A quick scan of the datasheets shows that they have the same pinouts and specs so yes, they would work fine. I used the Nat. Sem. LM7812C on mine, same 12V reg. with same pinouts._

 

 Quote:


  Originally Posted by *amb* /img/forum/go_quote.gif 
_ting.mike, how about measuring the resistance?

 Possédé, the 78xx sereis voltage regulators are fairly generic and are made by many manufacturers. Use whichever available, as long as it's in the TO-220 package and has the correct pinout._

 

Thanks for your input guys, I just wanted to be 100% sure before I started my build. 
	

	
	
		
		

		
		
	


	






*EDIT:* I've already posted, but I (again) want to make sure I've bought the right transformer. I bought this one. I know AMB recommends a 80VA transformer for a 3-channel build, but the closest one I could find was that with a 24V output (no need for 30V, I've heard it's just wasted heat). I'm not sure what the 100VA means. I understand you put in 230V and the transformer brings the voltage down to 24V. What does the 100VA represent? 

 Cheers.


----------



## oneplustwo

Quote:


  Originally Posted by *Possédé* /img/forum/go_quote.gif 
_Thanks for your input guys, I just wanted to be 100% sure before I started my build. 
	

	
	
		
		

		
		
	


	






*EDIT:* I've already posted, but I (again) want to make sure I've bought the right transformer. I bought this one. I know AMB recommends a 80VA transformer for a 3-channel build, but the closest one I could find was that with a 24V output (no need for 30V, I've heard it's just wasted heat). I'm not sure what the 100VA means. I understand you put in 230V and the transformer brings the voltage down to 24V. What does the 100VA represent? 

 Cheers._

 

100VA is the power of the trafo:

Volt-ampere - Wikipedia, the free encyclopedia

 So the bigger the number, the bigger stuff you can drive. 100VA should be fine for any headphones for sure and good enough for most bookshelf speakers. Just make sure your heatsinks are up to the task.


----------



## Possede

Quote:


  Originally Posted by *oneplustwo* /img/forum/go_quote.gif 
_100VA is the power of the trafo:

Volt-ampere - Wikipedia, the free encyclopedia

 So the bigger the number, the bigger stuff you can drive. 100VA should be fine for any headphones for sure and good enough for most bookshelf speakers. Just make sure your heatsinks are up to the task._

 

Thanks for clearing that up oneplustwo. So in a sense it's similar to wattage. Eek, I'm using the standard 1.5" heatsinks that come with glassjaraudio kits. Maybe I should send it back and find a transformer with a lower VA rating.


----------



## amb

Quote:


  Originally Posted by *Possédé* /img/forum/go_quote.gif 
_Thanks for clearing that up oneplustwo. So in a sense it's similar to wattage. Eek, I'm using the standard 1.5" heatsinks that come with glassjaraudio kits. Maybe I should send it back and find a transformer with a lower VA rating._

 

Why? The VA rating of a transformer is a recommended maximum, not what it will actually run at. The MOSFETs' temperature is determined by hot much quiescent you bias them to (as well as how much output current you might call on them to deliver, if driving speakers). It has nothing to do with the transformer size.


----------



## Possede

Quote:


  Originally Posted by *amb* /img/forum/go_quote.gif 
_Why? The VA rating of a transformer is a recommended maximum, not what it will actually run at. The MOSFETs' temperature is determined by hot much quiescent you bias them to (as well as how much output current you might call on them to deliver, if driving speakers). It has nothing to do with the transformer size._

 

Okay, that makes better sense. I was getting a bit confused there. Sorry for these inane questions, and I'm the one starting a degree in electronics and electrical engineering next month! 
	

	
	
		
		

		
			





 Cheers AMB, and once again thanks for shipping out my order so quickly.


----------



## fishski13

i'm sorting through my final order from Digikey but haven't decided on a transformer yet for the sigma22 - i'm a little confused about transformer specs. let's say if a TX secondaries are rated at 30VAC in *series*, or 15VAC in *parallel*, does this equal 30Vx2?

 here's what i'm looking at:
Digi-Key - 182M15-ND (Hammond Manufacturing - 182M15)


----------



## johnwmclean

Quote:


  Originally Posted by *fishski13* /img/forum/go_quote.gif 
_i'm sorting through my final order from Digikey but haven't decided on a transformer yet for the sigma22 - i'm a little confused about transformer specs. let's say if a TX secondaries are rated at 30VAC in *series*, or 15VAC in *parallel*, does this equal 30Vx2?

 here's what i'm looking at:
Digi-Key - 182M15-ND (Hammond Manufacturing - 182M15)_

 


 That transformer is for use as 15V + 15V parallel or 30V in series. NOT 30V + 30V.


----------



## fishski13

Quote:


  Originally Posted by *johnwmclean* /img/forum/go_quote.gif 
_That transformer is for use as 15V + 15V parallel or 30V in series. NOT 30V + 30V._

 


 ahh...so i would need 2 of them. i guess there are cheaper solutions a la Avel Lindberg.


----------



## TwinFinnley

I'm sure I'm going to be flamed for asking this, but for the life of me I can't find the LEDs I'm looking for: 430-460nm (dark/er blue) for my σ22 and β22 boards... Anyone know a good place to look? I have been searching in Mouser and the web in general, but I keep coming up empty-handed. I must not be using the right keywords or something. Thanks all!


----------



## amb

TwinFinnley, look at these two:
 Mouser 78-TLHB4400 (diffused)
 Mouser 78-TLHB4200 (non-diffused)

 Diffused provides a wider viewing angle and is preferable for panel display.


----------



## TwinFinnley

Quote:


  Originally Posted by *amb* /img/forum/go_quote.gif 
_TwinFinnley, look at these two:
 Mouser 78-TLHB4400 (diffused)
 Mouser 78-TLHB4200 (non-diffused)

 Diffused provides a wider viewing angle and is preferable for panel display._

 

Ti, you have come to my rescue once again. I was looking in the totally wrong place on the Mouser site...  Thanks for pointing me in the right direction!

 Edit: Deleted last question.


----------



## TwinFinnley

I'm having a heck of a time sourcing an Avel-Lindberg Y23 series transformer... I couldn't find them on Mouser or online except at parts express and I couldn't find the one I think I need; can someone point me in the right direction? Quick specs - making sure I have this figured out correctly as well: β22 3 channels ->*80VA*; (R10=10KΩ) -> ±24V -> *dual 25V or 50VCT*? Do I have that right or am I just confused?


----------



## amb

You can buy directly from Avel-Lindberg. Just call them on the phone.
 The Y23 series (AFAIK) only comes in dual primary and dual secondary configuration, not center-tapped.


----------



## TwinFinnley

K, thanks. As far as I can see, I would be needing the Y236355, is that correct?


----------



## amb

Quote:


  Originally Posted by *TwinFinnley* /img/forum/go_quote.gif 
_K, thanks. As far as I can see, I would be needing the Y236355, is that correct?_

 

Yes, for ±24V rails, that one is good to use.


----------



## TeraHz

TwinFinnley, I ordered from them directly on Thursday. If nobody is answering the phone just leave them a voice mail and they will call you back.

 I ordered two Y236405 (100VA, 30+30), one for each sigma @±30V, and one Y236002 (15VA, 12+12) for aux stuff. Price for shipping was reasonable.


----------



## TwinFinnley

50 or 100 ppm for resistors? I guess the question is: is more ppm better or just different for varying situations?

 Edit: 100 ppm. But I still don't know why; something to do with its thermal change properties?


----------



## dbfreak

Here's a an explination:

http://www.riedon.com/us - Understanding Temperature Coefficient of Resistance


----------



## amb

The lower the tempco the better, because the resistance will change less as a function of temperature. But there is no tangible advantage to use anything better than the Vishay-Dale RN55D series here.


----------



## TwinFinnley

@ dbfreak and amb:

 Very helpful guys, thanks so much. I love learning all this and I'm sure its making me a better DIYer.

 Another question though, I'm now planning the β22 boards and am looking at the trimpots - are the Bourns 3296W better than the Vishay here? I'm trying to find an explination for the price diffeneces. I have found that more expensive does not always = better quality.


----------



## ShinyFalcon

Possibly more accurate tracking, resistance to higher temperatures (my β22 was likely subject to heat changing the resistor value, but I think it's just the amp burning in) resistor quality, quality of plastic, quality of knob, quality of ink, color of the case, company name...


----------



## TwinFinnley

Quote:


  Originally Posted by *ShinyFalcon* /img/forum/go_quote.gif 
_Possibly more accurate tracking, resistance to higher temperatures (my β22 was likely subject to heat changing the resistor value, but I think it's just the amp burning in) resistor quality, quality of plastic, quality of knob, quality of ink, color of the case, company name... 
	

	
	
		
		

		
		
	


	


_

 

EDIT: Rephrase-

 Are you saying they really are a better trimpot or are you giving _possible_ reasons why they would be more expensive? If its the former, then that's the direction I want to go. Also, is there something else out there that would give appreciable gains to SQ in lieu of the Bourns?


----------



## ShinyFalcon

Possible reasons, of course!

 It has been stated that the β22 does not need boutique components to sound its best (exception being the wiring and the attenuator). I wouldn't worry about it too much.


----------



## TwinFinnley

Quote:


  Originally Posted by *ShinyFalcon* /img/forum/go_quote.gif 
_Possible reasons, of course!

 It has been stated that the β22 does not need boutique components to sound its best (exception being the wiring and the attenuator). I wouldn't worry about it too much._

 

Sweet, you also answered my next question before I even asked it 
	

	
	
		
		

		
		
	


	




 As it is, I'm planning all Nichicon caps (is there a difference between Nichicon and Nichikon?) and Vishay resistors as listed by AMB, unless someone recommends differently. 

 The Khozmo attenuator as discussed in this thread is very appealing to me, pending reviews.

 I'm at a loss for which wiring to use, however; I still need to look into that and would love to look at some threads covering that topic. I'm open to suggestions, but I want to research it out as well.


----------



## FallenAngel

That thing just looks pretty - there is absolutely no impressions of it yet and honestly, it's a little unnerving when the manufacturer can't line up resistors in the same direction


----------



## TwinFinnley

Quote:


  Originally Posted by *FallenAngel* /img/forum/go_quote.gif 
_it's a little unnerving when the manufacturer can't line up resistors in the same direction_

 

You saw that too? Haha, I was trying to figure out why they did it that way, but it appears as though there is no rhyme nor reason to it... just not cost efficient to keep them unidirectional? I still want to hear what people say about them and how they hold up to others. At $100 for stereo and $150 for balanced, its hard to not be curious.


----------



## DoYouRight

true, but hopefully that was just a prototype error. They are sexy as hell I might trade my DACT for one if they are quality. Someone needs to get one already!


----------



## m1abrams

Quote:


  Originally Posted by *DoYouRight* /img/forum/go_quote.gif 
_true, but hopefully that was just a prototype error. They are sexy as hell I might trade my DACT for one if they are quality. Someone needs to get one already!_

 

Seriously you are that concerned over the direction of the resistors? When I build my own stuff I personally like the lined up the same way but I do it for myself, I know it has not benefit beyond that.


----------



## TwinFinnley

Quote:


  Originally Posted by *TwinFinnley* /img/forum/go_quote.gif 
_I'm at a loss for which wiring to use, however; I still need to look into that and would love to look at some threads covering that topic. I'm open to suggestions, but I want to research it out as well._

 

I have spent several hours on searching for what to do for wires. Quite frankly, there is just too much info out there. Solid core vs stranded, purity, teflon coated, cotton unbleached, silver, copper, silver-plated copper... I'm feeling a bit overwhelmed 
	

	
	
		
		

		
		
	


	




 Not to mention trying to find a store for all this. I know of Parts ConneXion, Percey Audio, Johns Wire Shop even Handmade Electronics, the latter 3 in US I think. 

 I'm officially asking for help on this one. I would like something fairly high grade and probably in the 20-24 gauge range (22?). Preferably something here in the US to cut on shipping costs, etc. Also, I would like to get some shielding. Please help 
	

	
	
		
		

		
		
	


	




 Any suggestions?

 Thanks

 Edit: added links


----------



## FallenAngel

Quote:


  Originally Posted by *DoYouRight* /img/forum/go_quote.gif 
_true, but hopefully that was just a prototype error. They are sexy as hell I might trade my DACT for one if they are quality. Someone needs to get one already!_

 

"Sexy" really shouldn't be a requirement for a volume control. 
	

	
	
		
		

		
		
	


	




 Unless of course they want to have the same ad campaign as skullcandy. 
	

	
	
		
		

		
		
	


	




  Quote:


  Originally Posted by *m1abrams* /img/forum/go_quote.gif 
_Seriously you are that concerned over the direction of the resistors? When I build my own stuff I personally like the lined up the same way but I do it for myself, I know it has not benefit beyond that._

 

It's a simple matter of taking care in their product. To me this shows that they don't.

  Quote:


  Originally Posted by *TwinFinnley* /img/forum/go_quote.gif 
_I have spent several hours on searching for what to do for wires. Quite frankly, there is just too much info out there. Solid core vs stranded, purity, teflon coated, cotton unbleached, silver, copper, silver-plated copper... I'm feeling a bit overwhelmed 
	

	
	
		
		

		
		
	


	




 Not to mention trying to find a store for all this. I know of Parts ConneXion, Percey Audio, Johns Wire Shop even Handmade Electronics, the latter 3 in US I think. 

 I'm officially asking for help on this one. I would like something fairly high grade and probably in the 20-24 gauge range (22?). Preferably something here in the US to cut on shipping costs, etc. Also, I would like to get some shielding. Please help 
	

	
	
		
		

		
		
	


	




 Any suggestions?

 Thanks

 Edit: added links_

 

Teflon is easy to work with - strips easily and does not melt while soldering. I like Percy for some wire options, eBay for SPC.

 For power wiring, 22awg should be enough, 20awg might be a little safer if you want to send A LOT of current, for signal, 24awg is fine.


----------



## amb

TwinFinnley,
 I used the Vishay-Sfernice T93YA trimpots in my own builds and they are just fine.

 I recommend stranded copper wires rather than solid because they're less likely to break. For low signal wiring I use 24AWG (sometimes even thinner). For power and ground I use 18AWG. I don't use anything boutique, just ordinary hookup wiring for electronics. If it makes you feel better, you could use something fancier.


----------



## linuxworks

Quote:


  Originally Posted by *FallenAngel* /img/forum/go_quote.gif 
_It's a simple matter of taking care in their product. To me this shows that they don't._

 

maybe they don't get them all lined up in the tube from the vendor.

 maybe their on-sertion machine doesn't keep parts aligned. maybe they have a human doing it? could be, in that case there's no excuse 
	

	
	
		
		

		
		
	


	




 but this isn't supposed to be user visible so I would not fault them one tiny bit for not caring about parts orientation. I would care more about bad solder joints or misaligned parts (I always like to look at smb pc boards and see how well the vendor aligned the parts to the pads).


----------



## linuxworks

Quote:


  Originally Posted by *TwinFinnley* /img/forum/go_quote.gif 
_I have spent several hours on searching for what to do for wires. Quite frankly, there is just too much info out there. Solid core vs stranded, purity, teflon coated, cotton unbleached, silver, copper, silver-plated copper... I'm feeling a bit overwhelmed_

 

don't drive yourself nuts.

 wire is wire. come on 
	

	
	
		
		

		
			





 work-ability matters more to me. teflon, so it won't melt as you solder it, is #1 to me. stranded since its more robust under flexing. any size that fits the holes (22, 24 ga is often fine).

 the anti-melt factor is my issue; but other than that, I could care less.


----------



## TwinFinnley

Ah, thank you all! I can get caught up in the details sometimes and lose sight of the whole project. But I'm sure I will have more questions to follow 
	

	
	
		
		

		
		
	


	




 Until then...


----------



## Beefy

Quote:


  Originally Posted by *TwinFinnley* /img/forum/go_quote.gif 
_Johns Wire Shop_

 

I use the 22AWG Teflon/SPC from John for signal and low-current power wiring, and it is perfect for my needs. I see no need to spend more money on anything else.

 [EDIT] And at the moment, he has some good colours in stock. Red, white and violet would be a good mix......


----------



## DoYouRight

The magic of this amp, is the details that I freaked out on also really don't matter. This amp is amazingly designed to run on normal components and blast them to extremes.


----------



## fishski13

i ordered a SumR 30+30V 80VA with a shielded can. 

 i'm finalizing my chassis drawings tonight. it will be a "single" chassis, framed with walnut and a walnut divider between the TX/sigma22 and B22 proper. they will each have their own aluminum top and bottom plates, isolated from each other. 

 is it safe to assume that each will have separate chassis ground and no need for a ground loop breaker?


----------



## amb

Quote:


  Originally Posted by *fishski13* /img/forum/go_quote.gif 
_is it safe to assume that each will have separate chassis ground and no need for a ground loop breaker?_

 

If the "chassis" metal of the two sections are isolated from each other, then it's electrically equivalent to two separate boxes, so no ground loop breaker is needed.


----------



## fishski13

Quote:


  Originally Posted by *amb* /img/forum/go_quote.gif 
_If the "chassis" metal of the two sections are isolated from each other, then it's electrically equivalent to two separate boxes, so no ground loop breaker is needed._

 

cool. i can't wait to finally get started.


----------



## Possede

We are seeing if there is enough interest to justify another ε22 Backplane group buy. If you are interested post in this thread.

 Cheers.


----------



## dbfreak

Quote:


  Originally Posted by *Possédé* /img/forum/go_quote.gif 
_We are seeing if there is enough interest to justify another ε22 Backplane group buy. If you are interested post in this thread.

 Cheers._

 

I'd like to see a backplane board that supports four B22 boards for a balanced configuration.


----------



## DoYouRight

that would take a whole new design. Someone made one himself for 6 board balanced but it is very specific but it looks cool.


----------



## fault151

@ do you right, i noticed in your signature you use the buffalo 32s with your b22 amp, did you just buy the dac as standard and use it as is with your b22? Im after buying one my self to replace my older version of the buffalo dac.


----------



## TeraHz

Quote:


  Originally Posted by *DoYouRight* /img/forum/go_quote.gif 
_that would take a whole new design. Someone made one himself for 6 board balanced but it is very specific but it looks cool._

 

Would it work if you just use two e22 and leave the ground slot empty? That way one e22 is cold and hot for L and the other is cold and hot for R? Maybe use the third slot for a sigma board?

 Is that how it would work or am I writing nonsense?

 THz


----------



## Beefy

Quote:


  Originally Posted by *TeraHz* /img/forum/go_quote.gif 
_Would it work if you just use two e22 and leave the ground slot empty? That way one e22 is cold and hot for L and the other is cold and hot for R? Maybe use the third slot for a sigma board?_

 

Would be an awful waste of case space......


----------



## DoYouRight

a new design would have to go for the 4 channel builds. I do not believe the e22 could hold the sigmas in the active ground plane due to channels in the pcb. However those who run 6board active ground for SE and balanced can use 2. It probably won't fit the way Id like. But its worth a try to rid myself of some extra cabling space


----------



## nattonrice

s22 PC boards are wider than a b22 board so it wouldn't fit...

 not to mention that puts ac carrying lines very close to the input stages ect @@

 I'm not an expert but it would probly result in hum central hehe


----------



## FallenAngel

For those and other reasons, one hasn't been made yet and likely wouldn't be. 
	

	
	
		
		

		
			





 Too many ways lay out the boards, including some creative stacking ways to fit it into a 12" case (which I have done and plan to do again).


----------



## dbfreak

Out of curiosity, is there a burn-in time for the Beta22?


----------



## Beefy

I doubt it. No coupling caps, so there isn't anything to burn in.


----------



## johnwmclean

In regards to burn in I didn’t notice any significant improvement if anything, as for amp warm up, the amp sounds great after a minute or two.


----------



## naamanf

About 42 seconds.


----------



## johnwmclean

Quote:


  Originally Posted by *naamanf* /img/forum/go_quote.gif 
_About 42 seconds._

 

I beg to differ, I found around the 56 - 58 second is optimum, the soundstage is much narrower and detail seems smeared listening anywhere before this time.


----------



## nattonrice

The exact time is going to be highly dependent on your case's ventilation and the efficiency of your choice of heat sinks~


----------



## johnwmclean

Quote:


  Originally Posted by *nattonrice* /img/forum/go_quote.gif 
_The exact time is going to be highly dependent on your case's ventilation and the efficiency of your choice of heat sinks~_

 

as opposed to getting warmer (hotter) or sounding optimum?
 ...reminder I must put red beckon next to my sacrastic posts 
	

	
	
		
		

		
		
	


	




 Well, what’s the status?


----------



## askforwhy

I found my B22 sound a little richer and smoother after, I guess, 100hrs.
 Anyway you can build one and test it yourself.


----------



## dbfreak

I had orignally asked, because I find that I am hearing transients I've never heard before (after 20 hours of B22 play time) on my SACD's.


----------



## Pars

Quote:


  Originally Posted by *naamanf* /img/forum/go_quote.gif 
_About 42 seconds._

 

That's for balanced, right? I was figuring about 20 seconds for a single ended...


----------



## nattonrice

Quote:


  Originally Posted by *johnwmclean* /img/forum/go_quote.gif 
_as opposed to getting warmer (hotter) or sounding optimum?
 ...reminder I must put red beckon next to my sacrastic posts 
	

	
	
		
		

		
		
	


	




 Well, what’s the status?_

 

Hehe sorry I thought you were both referring to the amp coming up to "operational" temperature.

 It's getting there... wiring and Ph.D. work are slowing things down a tad.
 This weekend's excuse is 120 assignments to mark and a paper I need to finish to get published lol


----------



## fishski13

maybe wrong thread...

 finally...started cutting/routing my chassis (no glue/clamping yet). i decided to scrap the one chassis idea even though i have a canned toroid from SumR coming my way. each chassis is 9.5x11" I.D., with 3/8" walnut wrap around with a "tube" aesthetic - maybe i should have had a custom wound EI core TX instead of the toroid 
	

	
	
		
		

		
		
	


	




. the front and back have routered 1/2" round-overs on the sides. the top and bottom plates will be aluminum. the front and back will have smaller and thinner aluminum "faceplates" where the switches, pot, jacks, LED etc... will be mounted. 

 the B22 has been on my mind for a year... i've spent the last 9 mo. building stuff for friends. it's nice to get down to work for myself...take my time and enjoy the learning experience. i'm glad Headwize is up again 
	

	
	
		
		

		
		
	


	




.


----------



## nattonrice

That is gonna be smexy as all hell when it is done! 
	

	
	
		
		

		
		
	


	




 Gah you think routing is bad... wait till you start wiring it all up.
 I'm really anal when it comes to stuff like this so it is taking me forever lol


----------



## TeraHz

Here is a mock-up of my β22 case (or at least how I'd like to make it 
	

	
	
		
		

		
		
	


	




). Volume knob will be solid, most likely. Inputs and speaker outputs will be on the back. The σ22 case will be same size. Let's see how close to the design I can make it.


----------



## boinger

Just built my first sigma22 earlier today! =)

 Got it working 











 This is my first major solering job.


----------



## linuxworks

not sure if this has been covered or not (large thread) 
	

	
	
		
		

		
		
	


	




 I have a 2ch b22 that currently has 1 s22 PS. I built a 2nd s22 and I'm thinking of powering each single b22 board (just keeping it at 2 for now) by its own private s22 supply.

 here's the question: how do you link the 2 PS's so that they track each other? or, is there a way to tweak one so that it manually matches the other in voltage out?

 I wonder if the voltage variation between any 2 s22 units would cause slight gain diffs in the b22 boards?

 with 1 s22 powering 2 b22 boards, life was easy 
	

	
	
		
		

		
		
	


	




 I knew that each board got the same exact voltage as the other. but with 2 s22's, what do you do?

 I'm trying to get something like 2 monoblocks, this way. no common ground; I want each b22 to get its private ground from its own s22 board.


----------



## amb

Quote:


  Originally Posted by *linuxworks* /img/forum/go_quote.gif 
_...
 here's the question: how do you link the 2 PS's so that they track each other? or, is there a way to tweak one so that it manually matches the other in voltage out?

 I wonder if the voltage variation between any 2 s22 units would cause slight gain diffs in the b22 boards?_

 

There is absolutely no reason to match the power rail voltages between channels because the amp gain is not dependent on supply rail voltage.

  Quote:


 I'm trying to get something like 2 monoblocks, this way. no common ground; I want each b22 to get its private ground from its own s22 board. 
 

The monoblock concept doesn't make a whole lot of sense with a 2-channel passive ground amp with TRS unbalanced headphones because the output ground is shared. Which PSU would you connect the TRS return to? If you bridge the two PSUground together then you would have created a mini ground loop because the input ground is aldo common.

 Monoblock makes sense for speakers where the ground return is independent, and for balanced 4-channel configurations where the return current doesn't even go to ground.


----------



## linuxworks

your first comment pretty much answered what I needed to know 
	

	
	
		
		

		
		
	


	




 for the 2nd, I was thinking more of using the monoblocks for speakers (maybe only for spkrs OR balanced phones, like you said). pretty much, once I do the monoblock thing, I commit to having 4 wires instead of 3 and all loads must be true to that 
	

	
	
		
		

		
		
	


	




 so I guess there is no problem to be solved since the gain is not dependant on voltage level.


----------



## musick7

Quote:


  Originally Posted by *johnwmclean* /img/forum/go_quote.gif 
_as opposed to getting warmer (hotter) or sounding optimum?
 ...reminder I must put red beckon next to my sacrastic posts 
	

	
	
		
		

		
		
	


	




 Well, what’s the status?_

 



 OH. Oh... I got it.


----------



## FallenAngel

Debating that OTTO switch for preamp/headphone output. Any drawbacks to hooking up both in parallel? Power amp will likely be Beta24 with 5K input impedance, will that screw with the headphone impedance?

 Also, how is this for power? http://www.mouser.com/ProductDetail/...YYo1iU/Vhu0%3d


----------



## amb

Quote:


  Originally Posted by *FallenAngel* /img/forum/go_quote.gif 
_Debating that OTTO switch for preamp/headphone output. Any drawbacks to hooking up both in parallel? Power amp will likely be Beta24 with 5K input impedance, will that screw with the headphone impedance?_

 

β22 will have no trouble driving 5K ohms in parallel with any additional headphone load. However, the sensitivities of the power amp + speaker combo and headphones will be different. Without some kind of switch, otto or otherwise, if you leave the headphones plugged in while playing on speakers, the headphones may be blasting loud. Also, if you listen to headphones you must turn off the power amp in order to disable the speakers.

  Quote:


 Also, how is this for power? ... 
 

Looks fine, especially if it's for a β22 acting as preamp + headphone amp only.


----------



## FallenAngel

Awesome, thanks Ti.


----------



## n_maher

Quote:


  Originally Posted by *FallenAngel* /img/forum/go_quote.gif 
_Also, how is this for power? C091-31S008-100-2 Amphenol Tuchel Circular Connectors_

 

Stock: 0 
 On Order: 0
 Factory Lead-Time: 10 Weeks

 That doesn't look very good to me.


----------



## boinger

Question regarding C1-C5 

 For 2x gain it is recommended to use 100pF for C2-C5 

 So I would still use 33pF for the C1 and C2-C5 use the 100pF 

 Am I right? Because on the parts list it says that for C1-C5 see table below... So I'm wondering if the C2-C5 was a typo?


----------



## johnwmclean

Quote:


  Originally Posted by *boinger* /img/forum/go_quote.gif 
_Question regarding C1-C5 

 For 2x gain it is recommended to use 100pF for C2-C5 

 So I would still use 33pF for the C1 and C2-C5 use the 100pF 

 Am I right? Because on the parts list it says that for C1-C5 see table below... So I'm wondering if the C2-C5 was a typo?_

 

Correct. C1 33pF, C2-C5 100pF. Effective 2X gain.


----------



## fault151

Hi guys i am currently desiging my panels for my b22 amp, I need to export the files but when I do so it says I am missing the plugins required to export. Does anyone have the plugins that I could get a copy of please?

 cheers


----------



## MrMajestic2

Quote:


  Originally Posted by *fault151* /img/forum/go_quote.gif 
_Hi guys i am currently desiging my panels for my b22 amp, I need to export the files but when I do so it says I am missing the plugins required to export. Does anyone have the plugins that I could get a copy of please?

 cheers_

 

I think it would be helpful if you told us what software you are using and what you are trying to export to


----------



## fault151

Quote:


  Originally Posted by *MrMajestic2* /img/forum/go_quote.gif 
_I think it would be helpful if you told us what software you are using and what you are trying to export to 
	

	
	
		
		

		
		
	


	


_

 

Sorry I forgot that bit. I'm using Front panel designer (by Front Panel Express) to design my panels. I could do with exporting as pdf of some other equivelant.

 Thanks.


----------



## MrMajestic2

Quote:


  Originally Posted by *fault151* /img/forum/go_quote.gif 
_Sorry I forgot that bit. I'm using Front panel designer (by Front Panel Express) to design my panels. I could do with exporting as pdf of some other equivelant.

 Thanks._

 

The only export filter option is DXF and that has to be ordered from Schaeffer. To print PDF you need some software installed and then print it. I tried this and the scaling was a bit off.


----------



## fault151

Quote:


  Originally Posted by *MrMajestic2* /img/forum/go_quote.gif 
_The only export filter option is DXF and that has to be ordered from Schaeffer. To print PDF you need some software installed and then print it. I tried this and the scaling was a bit off._

 

OK well i'll give that a miss then, it was only to export to a friend to look over the design.

 Yeh i tried the printing and I too got UN-accurate results with scale.


----------



## 32y0

I'm thinking of building a four channel balanced B22 powered by two sigma22. I'm thinking about the Glassjar kits. The source will be an opus dac wich I'm building at the moment.
 I'm wondering how it will sound with a HD600 and DT880 (600ohm).
 Really looking forward to start building.


----------



## fault151

Quote:


  Originally Posted by *32y0* /img/forum/go_quote.gif 
_I'm thinking of building a four channel balanced B22 powered by two sigma22. I'm thinking about the Glassjar kits. The source will be an opus dac wich I'm building at the moment.
 I'm wondering how it will sound with a HD600 and DT880 (600ohm).
 Really looking forward to start building._

 

Hi, i bought a kit from glass jar for my balanced b22,i also have the balanced opus dac and a buffalo dac + hd650 + hd600 and they all go together so nicely! I'm pretty sure you will also like the set up when u get built. I'm nearing the end of my build and i can't wait to get the panels made.


----------



## 32y0

Yes, with panels it will look great and you'll save a lot of time (but not money
	

	
	
		
		

		
			





).


----------



## TwinFinnley

I'm almost done sourcing all of the parts for a 3-channel "active ground" but there are still a few parts that I could use some suggestions on. 

 1. 1/4 jack - I am looking for something that is a step or two up from the neutrik $0.80 jack.

 2. RCA - I am currently thinking about getting the Cardas RCA's but if there is something better out there I would like to know. (Vampire vs Cardas? (I don't know which is better or better hyped or both...)

 3. IEC power entry receptacle with fuse - I have this part sourced, but (here is where the 'noob'ness really comes out) I want to have something that can be compatible with 110 and 220, but I want to have the power switch on the front of the enclosure and not on the unit itself if possible. Truth is, I have no idea how this really works.

 All comments welcome and thanks for the help in advance!


----------



## amb

The IEC receptacle is standard for all world voltages and frequencies, only the power cord needs to be changed to fit the wall outlet of any particular country you're in. The two primary windings of your power transformer need to be wired differently for 115V AC than for 230V (parallel for 115V, series for 230V). If you're using Avel-Lindberg Y23 series, there is a diagram showing these configurations.


----------



## 32y0

Quote:


  Originally Posted by *TwinFinnley* /img/forum/go_quote.gif 
_I'm almost done sourcing all of the parts for a 3-channel "active ground" but there are still a few parts that I could use some suggestions on. 

 1. 1/4 jack - I am looking for something that is a step or two up from the neutrik $0.80 jack._

 

I really like these: Neutrik - Audio - Locking 1/4" Phone Jacks

  Quote:


  Originally Posted by *TwinFinnley* /img/forum/go_quote.gif 
_2. RCA - I am currently thinking about getting the Cardas RCA's but if there is something better out there I would like to know. (Vampire vs Cardas? (I don't know which is better or better hyped or both...)_

 

I never used the RCA's you mention, so I can't give you an answer on that.

  Quote:


  Originally Posted by *TwinFinnley* /img/forum/go_quote.gif 
_ 3. IEC power entry receptacle with fuse - I have this part sourced, but (here is where the 'noob'ness really comes out) I want to have something that can be compatible with 110 and 220, but I want to have the power switch on the front of the enclosure and not on the unit itself if possible. Truth is, I have no idea how this really works._

 

About the power switch; take a look at this:






 It shows you how you can wire the powerswitch, so you can place it in front of the enclosure (just make the wires longer).

 I hope this helped you somewhat.


----------



## TwinFinnley

Quote:


  Originally Posted by *amb* /img/forum/go_quote.gif 
_The IEC receptacle is standard for all world voltages and frequencies, only the power cord needs to be changed to fit the wall outlet of any particular country you're in. The two primary windings of your power transformer need to be wired differently for 115V AC than for 230V (parallel for 115V, series for 230V). If you're using Avel-Lindberg Y23 series, there is a diagram showing these configurations._

 

Ahh... I understand now. Once again, AMB comes to the rescue 
	

	
	
		
		

		
		
	


	




  Quote:


  Originally Posted by *32y0* /img/forum/go_quote.gif 
_I really like these: Neutrik - Audio - Locking 1/4" Phone Jacks

 ...

 I hope this helped you somewhat._

 

Thanks and yes, it did help. As for the jack, I guess I'm just not a fan of Neutrik. If anyone knows of other options, I would love to hear them. Again for a 1/4" plug. 

 I would still like to hear what people think of the RCAs.


----------



## 32y0

I'm glad I could help you.
 You could take a look at switchcraft for the 1/4'' plug, that's the only other option that I can think off.
 .


----------



## amb

Asking people's opinion on RCA and 1/4" jacks are like a little bit like asking about their jewelry preference. 
	

	
	
		
		

		
		
	


	




 There are many good RCA jacks out there, some very expensive and others less so, use whatever you like. For 1/4" headphone jacks, there aren't as many boutique-grade stuff, but both Switchcraft and Neutrik make good quality jacks. If your front panel is metal and will connect to ground, then you need to use an isolated jack (the sleeve must not contact the chassis).


----------



## TeraHz

I've reached a dead end with my b22. I'll need some help. 

 So far I have my σ22 wired up with ε24 for power switch ready to deliver 30V. Test at the output pads shows solid ±29.8V. 

 When I connect a β22 board(tried with 2 boards separately), and turn on the power I can see 29.xV for a fraction of a second at the β22 pads, then it drops to 23V (LEDs become a little dimmer) and starts to slowly rise up (about .1V per second). Meanwhile all heatsinks and the transformer start to heat up. The β22 ones went up to about 160℉ and the σ22 + transformer to about 110℉ in less than 10 seconds. Oh, and a 2A fuse died with first power up <- which was my first hint of something being wrong, which I changed with a 2.5A one so I can at least measure the V at the β22 board.

 VR1 and 2 are at minimum, and VR3 is about the middle.

 I did a second power up for a few seconds to measure V across R9: it is at about 3.5V for less than a second then jumps up to 7.x and increases slowly. 

 I've checked for shorts (visually) and could not see any. V+/G/V- are not shorted (tested).

 Here is what the board looked like before the MOSFETs(only missing parts) were installed:
http://joro.geodar.com/pics/albums/b22/b22-089.jpg

 Any help would be much appreciated. I will take some more pictures if needed.


----------



## digger945

D7 in the lower board in your pic. 
 I'm still looking.
 Gotta ask if you have all adjustment pots set according to the initial check on amb.org?


----------



## digger945

nvm, I couldn't see the silkscreen on D5.


----------



## digger945

With your adjustment pots VR1, VR2 and VR3 installed opposite to the silkscreen you may need to adjust them exactly opposite to the instructions to begin your initial setup, 1 and 2 anyway to begin with. VR3 would be OK for now.


----------



## TeraHz

Quote:


  Originally Posted by *digger945* /img/forum/go_quote.gif 
_With your adjustment pots VR1, VR2 and VR3 installed opposite to the silkscreen..._

 

Man, this is like debugging code. You read, you read and you can't see the bug in front of you. Someone else stops by, takes a peak and points out: hey your pointers are reversed!

 Thanks! I always knew a fresh pair of eyes helps with any problem. I'll report back soon when I make the amp sing later today (hopefully).


----------



## digger945

Wait 'till you get the bill
	

	
	
		
		

		
			





 j/k, it works the same way with me. Sometimes I just go outside and do something else for a while and then come back to it later. 

 Can't wait to read what ya think about it when your done.


----------



## n_maher

Quote:


  Originally Posted by *TeraHz* /img/forum/go_quote.gif 
_Oh, and a 2A fuse died with first power up <- which was my first hint of something being wrong, which I changed with a 2.5A one so I can at least measure the V at the β22 board._

 

Future advice, if you blow the correctly rated fuse at start up stop until you figure out why the fuse blew. Moving to another larger size is like asking why your house burned down when you threw gas on the fire.


----------



## TeraHz

Quote:


  Originally Posted by *n_maher* 
_Future advice, if you blow the correctly rated fuse at start up stop until you figure out why the fuse blew._

 

Noted. I thought it blew because it was fast blow... I'm still learning. Thanks for the advise.

  Quote:


  Originally Posted by *digger945* 
_Can't wait to read what ya think about it when your done._

 

It's alive! Just on time for my new built uFonken mini speakers.

 β22:





 σ22:





 Wiring 
	

	
	
		
		

		
		
	


	








 Tried with SR-80s and my new speakers and is a blast. I noticed that the last 3%-5% of the pot are the only useful ones. Below that there is no sound in the speakers (of course plenty of sound in the headphones). I'll have to increase the gain and put some kind attenuator circuit with a switch between headphones and speakers.

 EDIT:
 Here is a video of the first test with speakers:
http://joro.geodar.com/videos/b22_alive.html

 As you can see the volume doesn't work properly. Even with the Grados, there is a very slow volume increase for 80%-90% of the range, with a sharp increase after that.


----------



## fishski13

TeraHz,
 love the uFonkens!!! i'm helping a friend build a pair that will be driven by a Gainclone i built. unfortunately it been a slow process because he wants a piano black-gloss finish. 

 cut some aluminum tonight. i'm hoping to have the majority of my 2 chassis done by the end of next week.


----------



## TwinFinnley

Quote:


  Originally Posted by *TeraHz* /img/forum/go_quote.gif 
_
 Tried with SR-80s and my new speakers and is a blast. I noticed that the last 3%-5% of the pot are the only useful ones. Below that there is no sound in the speakers (of course plenty of sound in the headphones). I'll have to increase the gain and put some kind attenuator circuit with a switch between headphones and speakers.

 EDIT:
 Here is a video of the first test with speakers:
b22 Amp first test with speakers

 As you can see the volume doesn't work properly. Even with the Grados, there is a very slow volume increase for 80%-90% of the range, with a sharp increase after that._

 

Out of curiosity, what is your gain set to? It may not have anything to do with it, I'm a noob myself, but I am curious.

 Wish me luck, I'm about to order all my parts some time today or tomorrow. The DIY addiction has begun.


----------



## TeraHz

Quote:


  Originally Posted by *TwinFinnley* /img/forum/go_quote.gif 
_Out of curiosity, what is your gain set to? It may not have anything to do with it, I'm a noob myself, but I am curious._

 

My gain is set to 8 (default). That should be more the enough for my headphones

 I'm still very confused with how the volume acts. For the the most part of the pot's range there is quite low volume even in my headphones (nothing in the speakers), little bit before the end of the range there is a sudden increase in volume (too much for my grados, just a touch over the normal listening volume for my speakers). I tested the pot with the DMM and looks fine: 
 0% - 49.8ΩKΩ
 25% - 49ΩKΩ
 50% - 43ΩKΩ
 75% - 29ΩKΩ
 100% - 0Ω

 I'll start working on the case and proper wiring now and come back to that problem later.


----------



## amb

Are those really Ω rather than KΩ?


----------



## TeraHz

Sorry, fixed my post. KΩs


----------



## digger945

Check the input signal and signal ground wires at the Beta 22 pcb to make sure they are not reversed.
 Make sure signal grounds on all boards are daisy chained with the attenuator grounds.


----------



## Possede

So I have the β22 and σ22 boards populated. Now it is time to work on the wiring (the part I dread!). Now, what I'm about to ask may sound like a silly question, but I need some help. I will be using a ε22 backplane and thus Molex connectors. How are you guys attaching your stranded wire to these crimp terminals? I do not understand the concept of 'crimping'. Surely crimping cannot provide a secure connection. Is it possible to just solder the wire to the crimp terminals and then fit it into the Molex housing? If I need to purchase a crimp tool, would there be a specific one for these terminals? Sorry if this sounds silly.

 Here's a picture of what I have done so far. I'm going to order my cases from modushop.biz and some nice 10mm panels at the end of this week.


----------



## johnwmclean

Tin your wire first, then solder to the crimp use only a little. Take note of the crimp end that interlocks with molex header, it should snap together.


----------



## TwinFinnley

My wife and wallet are hating me right now - I just took the plunge and ordered all my parts to build my B22. I'm seriously considering a wood enclosure and am thinking of using either curly/tiger maple or bird's eye maple with a dark wood horizontal stripe going through the center of the faceplate. Or just all mahogany with some sort of brass inlay. I don't know for sure. Tell me what you all think and if you have ideas let me know, I'd love to hear other opinions


----------



## Possede

Quote:


  Originally Posted by *johnwmclean* /img/forum/go_quote.gif 
_Tin your wire first, then solder to the crimp use only a little. Take note of the crimp end that interlocks with molex header, it should snap together._

 

Thanks for your answer. 
	

	
	
		
		

		
		
	


	




 I purchased a roll of silver-coated copper wire, insulated in PVC. I hate PVC! It's a pain to strip, and when I do strip it, the PVC just looks shredded. I have mostly been using Canare starquad for interconnectors, and was wondering if I could use it as hookup wire within the amplifier. It's 24awg and is much easier to work with. Any thoughts?


----------



## MoodySteve

Quote:


  Originally Posted by *Possédé* /img/forum/go_quote.gif 
_How are you guys attaching your stranded wire to these crimp terminals? I do not understand the concept of 'crimping'. Surely crimping cannot provide a secure connection. Is it possible to just solder the wire to the crimp terminals and then fit it into the Molex housing? If I need to purchase a crimp tool, would there be a specific one for these terminals? Sorry if this sounds silly._

 

Not silly at all - there are special Molex crimpers. I got this one here (Open Barrel Crimp Tool). Molex connectors are rather difficult to crimp with standard tools.

 Also, you seem disenchanted by the notion of crimping as a means of getting a solid mechanical connection - a proper crimp will provide a VERY secure connection, much stronger and less brittle than a solder joint.


----------



## rshuck

Quote:


  Originally Posted by *TwinFinnley* /img/forum/go_quote.gif 
_My wife and wallet are hating me right now - I just took the plunge and ordered all my parts to build my B22. I'm seriously considering a wood enclosure and am thinking of using either curly/tiger maple or bird's eye maple with a dark wood horizontal stripe going through the center of the faceplate. Or just all mahogany with some sort of brass inlay. I don't know for sure. Tell me what you all think and if you have ideas let me know, I'd love to hear other opinions 
	

	
	
		
		

		
		
	


	


_

 

I would personally prefer it the opposite - dark wood with a light wood/brass strip in the middle. I would just be careful with this due to the drilling through the sandwich and the fact that wood has a tendency to expand and contract with heating/cooling, which could break your glue joints. Otherwise I think it'd be the bee's knees.

 FYI - would be great if you did a modified through-dovetail. I've unleashed my artistic skills here in MS Paint to show what I mean...






 Sorry for the highjack, guys.


----------



## linuxworks

I never bother crimping. I solder my molex pins to the wires.

 what works for me is some tweezers that hold onto the pins (locking tweezers) then I tin the molex, place the wire (also tinned) inside and let it cool. in a few seconds, I can release the wire and connector from the tweezer and do the next one. when all are soldered, insert into molex header.

 I can't be bothered with special one-off tools like purpose-made crimpers. bah!


----------



## Pars

I crimp mine with needlenose pliers and then solder them 
	

	
	
		
		

		
		
	


	




 BTW, in your pic (of 0.156" KK molex pins, not the more-used 0.100"), the smaller pair of crimp flaps are for the conductor while the larger back flaps are to go around the insulation, just so that is clear. I looked at the Molex ratcheting crimp tool for the 0.100" series on Digikey and it was $324 
	

	
	
		
		

		
		
	


	




 I made the mistake of buying one of the manual simple crimp tools for these only to find out I can do a much better job with needlenose pliers... don't bother with these.


----------



## fsrick

while i am building the beta 22, i just want to confirm the value of C1,
 is C1 always 33pF no matter what gain you use? since C1 is on the feedback path and i guess it is for the compensation,so I thought it will be depend on the gain. But it seems only C2-C5 changes with different gain. so just want to double check with you guys. Thanks


----------



## amb

Quote:


  Originally Posted by *fsrick* 
_is C1 always 33pF no matter what gain you use?_

 

Yes.


----------



## MisterX

Quote:


  Originally Posted by *Possédé* /img/forum/go_quote.gif 
_ How are you guys attaching your stranded wire to these crimp terminals?_

 

Digi-key offers a "cheap" crimp tool that works very well. 
 Here is the link----> 
Digi-Key - WM9900-ND (Manufacturer - W-HT-1921)


----------



## Pars

Quote:


  Originally Posted by *MisterX* /img/forum/go_quote.gif 
_Digi-key offers a "cheap" crimp tool that works very well. 
 Here is the link----> 
Digi-Key - WM9900-ND (Manufacturer - W-HT-1921)_

 

Hmm, that's the one that doesn't work worth a crap for me... it does not consistently bend the two tabs inward and crimp them. I do better with pliers.


----------



## Possede

Thanks MoodySteve, linuxworks, Pars, and MisterX for your input. I will try the various methods posted here and see which one works best for me.


----------



## MoodySteve

For what it's worth, the tool that I linked to works with every Molex size I've tried (0.100" and 0.156") and only costs around $40 shipped. It does perfect crimps.

 $324 for a one-size crimp tool?! Ouch.


----------



## Possede

Quote:


  Originally Posted by *MoodySteve* /img/forum/go_quote.gif 
_For what it's worth, the tool that I linked to works with every Molex size I've tried (0.100" and 0.156") and only costs around $40 shipped. It does perfect crimps.

 $324 for a one-size crimp tool?! Ouch._

 

I'll take a look and see if I can see any alternatives I can purchase in the UK. I have found this one which looks like it could do the job. I'd like to get a crimping tool anyway, you never know when it could come in handy.


----------



## Pars

Quote:


  Originally Posted by *MoodySteve* /img/forum/go_quote.gif 
_Not silly at all - there are special Molex crimpers. I got this one here (Open Barrel Crimp Tool). Molex connectors are rather difficult to crimp with standard tools.

 Also, you seem disenchanted by the notion of crimping as a means of getting a solid mechanical connection - a proper crimp will provide a VERY secure connection, much stronger and less brittle than a solder joint._

 

 Quote:


  Originally Posted by *MoodySteve* /img/forum/go_quote.gif 
_For what it's worth, the tool that I linked to works with every Molex size I've tried (0.100" and 0.156") and only costs around $40 shipped. It does perfect crimps.

 $324 for a one-size crimp tool?! Ouch._

 

The one you linked does look better. I seem to have run across this one before, but bought the Molex one from Digikey instead. Mistake. Might have to get the linked one as I do use KK .100" alot.

 Possede: not sure about the crimper you linked to; jaws don't look quite right


----------



## digger945

Quote:


  Originally Posted by *Pars* /img/forum/go_quote.gif 
_I crimp mine with needlenose pliers and then solder them 
	

	
	
		
		

		
		
	


	


_

 

FTW.


----------



## dhaninugraha

having listened to a friend's 3ch B22, now I'm saving up to build one for myself


----------



## Possede

I just want to get confirmation that I can use this solid state relay, as I am from the UK (230V mains). I'm still trying to get my head around some things. Cheers for any input.


----------



## Iniamyen

Quote:


  Originally Posted by *Possédé* /img/forum/go_quote.gif 
_I just want to get confirmation that I can use this solid state relay, as I am from the UK (230V mains). I'm still trying to get my head around some things. Cheers for any input._

 

What you're interested in is the control and load voltages, which is what's going to get hooked up directly to the relay. Your mains voltage doesn't matter, unless you're hooking up mains voltage directly to the relay.


----------



## DoYouRight

Does anyone know where to find a volume knob with a finger slider that is indented not sticking out like the Tyco ones. I want it to be like when you can have a fingertip on the indent and slide the knob around 1 finger.


 EDIT: If you goto Ti's site on the gallery 3rd page the knob like Loops build but with a bigger indention.


----------



## amb

Quote:


  Originally Posted by *Possédé* /img/forum/go_quote.gif 
_I just want to get confirmation that I can use this solid state relay, as I am from the UK (230V mains). I'm still trying to get my head around some things. Cheers for any input._

 

To be used with a ε24?

 The Crydom D1240 is what I have in my β24. Its AC load voltage is rated 140V max. You should choose one that's rated higher than your mains voltage. Also, for a β22, the 40A rating is overkill. You can go with a smaller current rating. If the rating is too mismatched to the actual current use, the SSR may not turn on.


----------



## Possede

Quote:


  Originally Posted by *amb* /img/forum/go_quote.gif 
_To be used with a ε24?

 The Crydom D1240 is what I have in my β24. Its AC load voltage is rated 140V max. You should choose one that's rated higher than your mains voltage. Also, for a β22, the 40A rating is overkill. You can go with a smaller current rating. If the rating is too mismatched to the actual current use, the SSR may not turn on._

 

Yes, to be used with my ε24. So I should be looking for one that's rated at above 230V. So something like this? If I'm still not getting it, I would appreciate it if you could link me to one on Farnell. 
	

	
	
		
		

		
			





 Thanks guys.


----------



## amb

Possédé, this one won't work either because it requires an AC control voltage. You need one that takes a DC control voltage, such that 12V DC will trigger it (see ε24 website). 

 There are many usable ones at Farnell, rather than pointing you to one, I suggest that you use the parametric search feature on their site. You should learn how to do that.


----------



## Possede

Quote:


  Originally Posted by *amb* /img/forum/go_quote.gif 
_Possédé, this one won't work either because it requires an AC control voltage. You need one that takes a DC control voltage, such that 12V DC will trigger it (see ε24 website). 

 There are many usable ones at Farnell, rather than pointing you to one, I suggest that you use the parametric search feature on their site. You should learn how to do that._

 

Thanks for replying to my [brainless] posts so quickly. I have been getting mixed up with how I am going to wire the σ22, ε24, and σ24 up. I think I have it sorted now. Linky. 4.5-32V DC Control, 48-280V Load. 25A max load. If this isn't right I think I will cry in the corner of my room.


----------



## amb

Yeah, that would work. No need to cry now.


----------



## Possede

Quote:


  Originally Posted by *amb* /img/forum/go_quote.gif 
_Yeah, that would work. No need to cry now. 
	

	
	
		
		

		
		
	


	


_

 

Phew, that was tense. Thanks Ti.


----------



## EugeneK

I'm building a balanced B22 with a 30V sigma-22 with a twisted pear joshua tree. 2 boxes, 4 B22 boards and the Joshua tree in one and the 30V sigma-22 with transformer in the other.

 I can't think of a way to get 7V - 24V to the joshua tree without getting another transformer, so I'm thinking of splicing in a wallwart to the amp box for the Joshua tree.


----------



## rshuck

Quote:


  Originally Posted by *EugeneK* /img/forum/go_quote.gif 
_I'm building a balanced B22 with a 30V sigma-22 with a twisted pear joshua tree. 2 boxes, 4 B22 boards and the Joshua tree in one and the 30V sigma-22 with transformer in the other.

 I can't think of a way to get 7V - 24V to the joshua tree without getting another transformer, so I'm thinking of splicing in a wallwart to the speaker box for the Joshua tree._

 

You could always get a transformer with dual secondaries and have a proper power supply for the lot.


----------



## EugeneK

Quote:


  Originally Posted by *rshuck* /img/forum/go_quote.gif 
_You could always get a transformer with dual secondaries and have a proper power supply for the lot._

 

Because a wallwart is $7, and the joshua tree doesn't need a clean power supply to sound nice.


----------



## rshuck

Quote:


  Originally Posted by *EugeneK* /img/forum/go_quote.gif 
_Because a wallwart is $7, and the joshua tree doesn't need a clean power supply to sound nice._

 

Gotcha - I had this vision of a DC jack AND an AC jack on the back of your b22! I'm a bit of a stickler for aesthetics.


----------



## EugeneK

Yes, my B22 is going to have a DC jack for the wallwart and a DC jack from my power supply box. I don't really care about aesthetics - I'm getting the cheapest (and ugliest) case I could get my hands on, cause it'd cut my casing budget by 50%. 
	

	
	
		
		

		
		
	


	




 Hehe, if I sell it and not include instructions, the amp would work just fine without the wallwart power supply, you just wouldn't be able to adjust the volume. XD


----------



## mugdecoffee

You could put the wallwart inside the case and wire up the plug to the IEC socket. A very rough hack but it'd look better from the outside.


----------



## EugeneK

Well, putting a wallwart inside the amp box would defeat the purpose of having a separate power box.


----------



## mugdecoffee

You could put it in the power box.


----------



## Pars

I'd use a Tread and something like this for the transformer. I've used one and it is not a bad transformer at all. Sorry, but the wallwart thing just seems so kludgy, especially with a separate DC connector


----------



## luvdunhill

Quote:


  Originally Posted by *Pars* /img/forum/go_quote.gif 
_Sorry, but the wallwart thing just seems so *kludgy*_

 

not quite the word I was thinking...


----------



## boinger

I did a continuity test between the G V+ V- and output pads and didnt get any beeps that means i have nor solder shorts correct? 

 I was getting a bunch of readings when i measured the resistance but on the continuity test i got nothing.


----------



## Pars

That means you don't have any solder shorts from V+ or V- to ground, or I would guess the outputs to ground (you weren't clear where you measured there). You could still have solder shorts though; always good to test as you did, and to look the board over good. The power ones are usually the most catastrophic, so always good to test for these before powering it up.


----------



## boinger

yes i did 

 g - v+
 g - v-
 g - output 

 should i also do output to v ?


----------



## linuxworks

Quote:


  Originally Posted by *luvdunhill* /img/forum/go_quote.gif 
_not quite the word I was thinking... 
	

	
	
		
		

		
		
	


	


_

 

how about a dc-dc converter? I've seen some small sealed modules that take 'large' voltage in and produce 5v or 12v out. for the relay banger, even a switched PS is fine enough.


----------



## jazzist

Quote:


  Originally Posted by *luvdunhill* /img/forum/go_quote.gif 
_not quite the word I was thinking... 
	

	
	
		
		

		
		
	


	


_

 

Isn't that what Singlepower do? 
	

	
	
		
		

		
		
	


	




http://csbd.org/~danchow/SS1/SS1_internal_ps_02.png


----------



## EugeneK

Quote:


  Originally Posted by *linuxworks* /img/forum/go_quote.gif 
_how about a dc-dc converter? I've seen some small sealed modules that take 'large' voltage in and produce 5v or 12v out. for the relay banger, even a switched PS is fine enough._

 

When I did a google search for switched power supply, I got a bunch of wallwarts and PC power supplies, do you have a link of what you're refering to?

 I was thinking of using a wallwart for the relay banger, but a lot here seem opposed to it.

 Thanks!


----------



## KingStyles

Can the beta 22 have unbalanced rca's in and then have balanced xlr output like some of the tube amps?


----------



## amb

Quote:


  Originally Posted by *KingStyles* /img/forum/go_quote.gif 
_Can the beta 22 have unbalanced rca's in and then have balanced xlr output like some of the tube amps?_

 

Of course you can, but there are different ways to do this.

 Assuming you'll be using a 4-channel balanced β22, you can do one of these:
 1. Use an unbalanced-to-balanced converter at the input, which could either be an active circuit based on a DRV134, THAT1606 or similar chip, or a passive conversion transformer. Each solution has its benefits and drawbacks.
 2. Wire up the amp according to the "Switch-selectable balanced/unbalanced input" as shown on the β22 website, under "Other options".

 But keep in mind that since the source is unbalanced, either way you go, you aren't reaping the full benefits of balanced outputs. This is a general statement, not specific to β22.


----------



## boinger

I am having some trouble with my build i tested out a few boards one is a ok ... 

 however with one board im having some trouble getting r9 to 4.5 v

 its reading -1.8 only and its only going further negative 

 I did hear a pop when measuring r9 but as i read somewhere earlier in the thread i measured d11 and i am getting the expected 29.xx V 

 any thoughts?

 edit: oh and the heatsinks arent getting warm at all.


----------



## digger945

Pics?


----------



## boinger

what shall i take pics of ? 

 and also strange on my sigma voltage suddenly dropped from 29 to 22 ? 

 dont know how that happened


----------



## digger945

Quote:


  Originally Posted by *boinger* /img/forum/go_quote.gif 
_what shall i take pics of ?_

 

Something like this.

  Quote:


 and also strange on my sigma voltage suddenly dropped from 29 to 22 ? 

 dont know how that happened 
 

First unplug the sigma from the wall.
 Have you looked the boards over to see if every part is the correct value and that diodes are installed with the correct orientation?
 When you measure R9 you will get a positive reading with the DMM leads connected one way and a negative reading with the leads reversed. You need to verify that the sigma is OK first though.


----------



## boinger

err yea i had swapped the grounds on the trafo input avel lindbergs i went yellow red orange black... and after the sigma warmed up im back at 29 

 for the bad board if i measure across r9 i am gettin ~ 500 mv

 Edit: 

 I think i may have found it if i measure the d11 diode on the non banded side i am getting -1.8 V instead of 29

 So i should replace q19 / q25 according to the circuit diagram correct?


----------



## digger945

The sigma should need no time for warm up.
 Is your wall voltage 110V?


----------



## digger945

How are you measuring D11, with the DMM leads across the two diode terminals or from each side of the diode to ground?


----------



## amb

boinger, if you're measuring ~29V _across_ D11 then Q25 is blown. Your DMM probe probably pierced through the soldermask and shorted to the ground plane while measuring R9.


----------



## boinger

im measureing d11 with reference to the ground 

 i did hear a pop when measuring r9 so i do believe q25 is blown 

 ill measure across and see what i get

 and my wall voltage is 230 v


----------



## boinger

just measured im getting 31 V across d11


----------



## digger945

The only reason for asking the wall voltage was to help with transformer wiring, but obviously you have it correct. Was going to mention about being careful not to pierce the solder mask when measuring R9 as one side of it is connected to V+. Minigrabbers are cheap compared to mishaps, even at Radio Shack prices.


----------



## boinger

i actually have mini grabbers but i soldered the resistors too close to the board to use them so started using aligator clips instead... good to know for my next build though. 

 good news is the other 3 boards are setup and reading correctly. so will have to order q25s before i can repair this.


----------



## digger945

eBay.com.sg: POMONA 5053-24-2 MICROGRABBER to STACKABLE BANANA Qty 3 (item 220456608522 end time Jul 30, 2009 23:59:21 SGT)

 I don't have these in micrograbber size, but I do in minigrabber size, and they work great. I have the BNC to micrograbber and the micro is a little smaller than the mini.


----------



## boinger

Ah I'll have to get some of those when i come state side. Thanks =)

 Sent the order for the replacements lets see when they get here.. wont be able to work on it for about a week though going to goa.


----------



## alamakazam

has anyone tried using SLA batteries as the power supply? like red wine audio


----------



## amb

Quote:


  Originally Posted by *alamakazam* /img/forum/go_quote.gif 
_has anyone tried using SLA batteries as the power supply? like red wine audio 
	

	
	
		
		

		
		
	


	


_

 

SLA batteries will not only be inconvenient, it would perform worse than σ22 in just about every way.


----------



## alamakazam

Quote:


  Originally Posted by *amb* /img/forum/go_quote.gif 
_SLA batteries will not only be inconvenient, it would perform worse than σ22 in just about every way._

 

uhmm how about any tips to make it a speaker and headphone amp with 2 channel board

 splitting the output to 2 ways with a switch, or is there any other better way?


----------



## nattonrice

My preamp outs are not switched, they are always "on" just like the headphone jack.
 As long as you're the only one to be using it then I don't see it as a problem.


----------



## jtostenr

Won't you have to unplug the speakers if you want to listen to your 'phones?


----------



## MoodySteve

Quote:


  Originally Posted by *jtostenr* /img/forum/go_quote.gif 
_Won't you have to unplug the speakers if you want to listen to your 'phones?_

 

Only if the preamp outs are connected to powered speakers - more likely he'd shut his amplifier off.


----------



## DoYouRight

I am starting to question if 6 boards is necessary. I have 2 e22s coming, yet extra volume controls, and everything just to give me balanced and also active grounds for SE. It is becoming a huge headache, and I havent heard definately if it makes audible difference. I try switching stuff around but cant really tell a difference in sound for SE but what if different cans later would reveal such differences.

 Anyone who has a 2 channel b22 does a 3 channel make much difference? I think Ferrari had built a 2,3, and 4 channel B22,
 Thanks


----------



## digger945

The only advantage to having 6 would be to listen to *2 headphones* with active ground *at the same time*.

 I think linuxworks upgraded to 3 not long ago, and I'm sure he commented on the difference.


----------



## DoYouRight

I know what it does, just dont know if the hassle of the chassis on this is worth the negligible SQ increase.


----------



## digger945

SQ would be absolutely no different from 3 channels.
 I am sure Ti posted a graph with the different measurements comparing 2 to 3.
 What kinda B22 is in your sig?


----------



## digger945

http://www.head-fi.org/forums/f6/4-b...ml#post5787509


----------



## DoYouRight

In my sig I have 6 boards rigged all crazy with no chassis in use atm. I have it all over and use my buffalo for volume lately. Its been driving me nuts -_-


----------



## nattonrice

Quote:


  Originally Posted by *MoodySteve* /img/forum/go_quote.gif 
_Only if the preamp outs are connected to powered speakers - more likely he'd shut his amplifier off._

 

Indeed! My yet-to-actually-be-built b24 would be turned off.
 Besides you can always just pull the xlrs out to disconnect completely on one side (headphones or pre-out).
 Working up pre-amp out on off switches seemed like a complete pita, I like things simple.


----------



## alamakazam

would it make any sense... if I have unbalanced input, and have a balance headphone out?


----------



## MrMajestic2

Quote:


  Originally Posted by *alamakazam* /img/forum/go_quote.gif 
_would it make any sense... if I have unbalanced input, and have a balance headphone out?_

 

Not much, if that's your only input. No point in having balanced phones if you don't have a balanced source.


----------



## jtostenr

Quote:


  Originally Posted by *MoodySteve* /img/forum/go_quote.gif 
_Only if the preamp outs are connected to powered speakers - more likely he'd shut his amplifier off._

 

Just relaized what I posted.....wasn't quite awake at the time lol.


----------



## TeraHz

Re: Who's built a beta22:

I have





 and it sounds great!


----------



## alamakazam

is there a off-the shelf power supply for b22? I do have a 24vdc 1.5a power supply, suitable for speaker setup?


----------



## amb

β22 needs a dual-rail supply. If you have a single-rail 24V supply then it won't work. 1.5A is also not sufficient for speaker use. Read the β22 website "Power supply" section, and also the σ22 website:


----------



## liwei

I'll be starting my B22 build soon and was wondering if an ESD safe station is a must have. Currently have a Weller WTCPN which is temperature controlled and grounded. 

http://www.lafiel.com/wtcpntechsheet.pdf


----------



## linuxworks

that weller will be fine (I lived with the wtcpn for some 20 yrs before it finally gave up.)

 ground yourself (touch grounded metal, like a pc case) and sit still and you won't have any static to worry about.


----------



## TeraHz

Hey, just wanted to thank Ti for the design and everyone else who shared their experience with the build Without it I wouldn't have had a working amp now.

 The amp has been working great for a week now and I've had no overheat issues with single sigma driving my speakers. Temperature stays below 60℃ (140℉) even if the volume is up for a long time. 

 Short story with lots of pics about the build: Georgi’s Blog
 Lots of pics during the build: Georgi's Pics - b22 Class A Amp
 And my BOM spreadsheets: http://joro.geodar.com/code/b22%20BOM.zip


 Best,
 THz


----------



## johnwmclean

Quote:


  Originally Posted by *TeraHz* /img/forum/go_quote.gif 
_Hey, just wanted to thank Ti for the design and everyone else who shared their experience with the build Without it I wouldn't have had a working amp now.

 The amp has been working great for a week now and I've had no overheat issues with single sigma driving my speakers. Temperature stays below 60℃ (140℉) even if the volume is up for a long time. 
_

 

Congrats TeraHz, nice work mate. Excellent blog, hope you get years of enjoyment from it.


----------



## fishski13

excellent job TeraHz! i've decided to build a pair of uFonkens for myself as well. although my B22 will be for HP use only.


----------



## danne

Alright so Im having thoughts in building a 4 board balanced beta 22 now and without reading 117 pages, could someone tell me what the best place to order parts from is?

 Ive seen that Glass Jar Audio sells a complete kit wich seems really nice?
 But they have an option called gain that you gotta chose before ordering, anyone know what this gain options means?


----------



## Beefy

Quote:


  Originally Posted by *danne* /img/forum/go_quote.gif 
_Alright so Im having thoughts in building a 4 board balanced beta 22 now *and without reading 117 pages*, could someone tell me what the best place to order parts from is?_

 

See, you have already just made your first mistake. Read first, ask questions on anything you don't understand later, *then* consider buying.

 This strategy is pretty good for avoiding any further mistakes.


----------



## n_maher

Quote:


  Originally Posted by *danne* /img/forum/go_quote.gif 
_Ive seen that Glass Jar Audio sells a complete kit wich seems really nice?
 But they have an option called gain that you gotta chose before ordering, anyone know what this gain options means?_

 

Don't take too much offense but if you don't know what "gain" refers to you have no business attempting this project.


----------



## DoYouRight

^ what he said


----------



## MrMajestic2

Quote:


  Originally Posted by *danne* /img/forum/go_quote.gif 
_Alright so Im having thoughts in building a 4 board balanced beta 22 now and without reading 117 pages, could someone tell me what the best place to order parts from is?

 Ive seen that Glass Jar Audio sells a complete kit wich seems really nice?
 But they have an option called gain that you gotta chose before ordering, anyone know what this gain options means?_

 

If you want some guidance you can contact me via PM, in Swedish


----------



## Possede

I would be most grateful if someone could confirm that these are the correct pads to jumper on the ε24. I presume that the pads go 1, 2, 3... down the left hand side and 6, 7, 8... down the right hand side.


----------



## Ferrari

Quote:


  Originally Posted by *Possédé* /img/forum/go_quote.gif 
_I would be most grateful if someone could confirm that these are the correct pads to jumper on the ε24. I presume that the pads go 1, 2, 3... down the left hand side and *6, 7, 8... down the right hand side*.




_

 

NO!

 Assuming you want to skip the thermal-shutdown function, you need to wire jumper pins 2-3 and 8-9 of the relay K1.
 From the upper side of the ε24 PCB, counting counter-clockwise: pin number 1 starts at the “+” sign of the relay and pin number 10 is at the opposite of pin number 1. Take also a look at the data sheet!
 The J2C jumper is correct, BTW.


----------



## Possede

Quote:


  Originally Posted by *Ferrari* /img/forum/go_quote.gif 
_NO!

 Assuming you want to skip the thermal-shutdown function, you need to wire jumper pins 2-3 and 8-9 of the relay K1.
 From the upper side of the ε24 PCB, counting counter-clockwise: pin number 1 starts at the “+” sign of the relay and pin number 10 is at the opposite of pin number 1. Take also a look at the data sheet!
 The J2C jumper is correct, BTW._

 

Thanks for clearing that up Ferrari. I had a quick skim through the datasheet on Mouser, but couldn't see anything. I probably scrolled right past it.


----------



## fishski13

i can see the light at the end of the tunnel with the 2 chassis builds. one more coat of tung oil on the walnut and some light sanding on the back-plates. i've finalized my face-plate designs from FPE and will be placing my order on Monday. the SumR potted TX arrived in the mail yesterday and i've started soldering the sigma22.

 i found some really nice-n-cheap rubber feet - excellent quality and highly recommended for any DIY build: MNPCTech! BEEFY Rubber Case Feet Products Model: MNPCTECH-CFR [MNPCTECH-CFR] : Performance-PCs.com, ... sleeve it and they will come. yes, they're beefy with nice mounting hardware to boot! 

 Ti,
 why is the (-) leg of the LED tied to V- and not just ground, omitting R17? is it because of the current draw on only one rail vs. spreading it equally over both rails? 

 i can't wait to hear this sucker.


----------



## amb

Quote:


  Originally Posted by *fishski13* /img/forum/go_quote.gif 
_(σ22)
 why is the (-) leg of the LED tied to V- and not just ground, omitting R17? is it because of the current draw on only one rail vs. spreading it equally over both rails?_

 

It's done that way so that when the power is turned off, the LED will source current from the V+ rail and sink into the V- rail, which helps to discharge the rail capacitors more symmetrically.


----------



## mminutel

Whew! I am finally done reading this thread. I am still thinking about jumping into this build, but I have a few questions. I have built a few CMOYs, a crossfeed, and a PIMETA. I also am an Engineering student at WVU, so I don't think I would have too much of a problem finding help if I find myself completely over my head.

 I just bought the Denon D2000s, and I really like them so far. Do you think this amp is a complete overkill for these midrange phones? 

 I have only seen a couple of posts about people enclosing the B22s in wood cases. I like the look of wood a lot. I have all of the tools to work with it, etc. What are the disadvantages of enclosing it in wood? A few posts ago, someone said something about the interference from the trafo being able to easily go through the wood which would make the amp noisy? Where would I connect the S22 ground since I wouldn't have a metal case?

 How much better is this amp compared to something like a PIMETA? What about an M3? I don't plan on upgrading my headphones for a while. I am just trying to find out if the money spent on the B22 is going to be worthwhile given my current phones, etc.

 Thanks,
 Michael


----------



## johnwmclean

Hey Michael, I think the post your referring too was regarding a one chassis build, if you go the two chassis route (separating the transformer from the amp) there’s much less likely hood of having humming or hissing amp.
 There would be no disadvantages building from wood.


----------



## TwinFinnley

Quote:


  Originally Posted by *mminutel* /img/forum/go_quote.gif 
_I just bought the Denon D2000s, and I really like them so far. Do you think this amp is a complete overkill for these midrange phones?_

 

I love the way my D2000 sound with this amp, I just finished the internals 3 days ago and it really makes them sing. Mind you, I have done much of the MarkL mod on them and it really helps bring them to a new level.

  Quote:


  Originally Posted by *mminutel* /img/forum/go_quote.gif 
_I have only seen a couple of posts about people enclosing the B22s in wood cases. I like the look of wood a lot. I have all of the tools to work with it, etc. What are the disadvantages of enclosing it in wood?_

 

 Quote:


  Originally Posted by *johnwmclean* /img/forum/go_quote.gif 
_There would be no disadvantages building from wood._

 

I beg to differ on there being no disadvantages. One of them is how wood reacts to heat over time. As wood is heated up and then cooled repeatedly it will tend to warp especially if there are stresses on the wood, ie the weight of the transformer and circuit boards pressing down.[/URL] There are some woods that are more resistant to this, but I can't name them. Dovetailing and insulation helps keep the box true as well. 

 Another disadvantage is as Michael mentioned, there is no ground. You have to implement one into the box; AMB suggested I place an aluminum sheet at the bottom when I asked him what to do. This also helps with shielding. Another way to do it, and I could be way wrong with this, is to run dedicated ground wires in the boxes and have all the grounds connect to it throughout. Just make sure it is connected to the ground on your IEC. **if that is wrong please correct me!**

 Wood also does not shield against EMI. Even if you have the s22 and b22 in different enclosures, there will still be some interference if they are close to each other unless you have some sort of shielding between the two. I found this out when doing some prelim testing - I still don't have my enclosure finished, but I'm also doing wood.

 Also, depending on the price of the wood you plan to use and the amount of time you plan to invest (decide how much time you think it will take to make the box and multiply by 3 - it always happens this way with wood), it may just be cheaper to go metal, even with a custom face plate. If that is not a factor in why you are going wood, then have fun with it, but realize it will take gobs of time to do it right and make a box that will last as many years as this amp will.

 Another huge disadvantage is that with a well made and beautiful wood enclosure, you will draw the attention of many covetous admirers. This could prove annoying if you are inundated with pms 
	

	
	
		
		

		
		
	


	




.


----------



## mminutel

The reasons I want to go with wood are that I like the look of it versus metal casees (hammond anyway). I also have plenty of Black Walnut and Cherry to work with. When I say that I have plenty, I mean plenty. I like woodworking just about as much as electronics, so I would like to incorporate a couple of my hobbies.


----------



## dbfreak

That my philosophy also. I enjoy making the case just as much as populating the boards. I've done wood, metal and my latest was an acrylic B22.


----------



## DoYouRight

casework is the most PITA but also most rewarding and fun part for me aside from listening. Because its where the true DIY and specially your gear moment happens.


----------



## johnwmclean

Quote:


  Originally Posted by *TwinFinnley* /img/forum/go_quote.gif 
_I beg to differ on there being no disadvantages. One of them is how wood reacts to heat over time. As wood is heated up and then cooled repeatedly it will tend to warp especially if there are stresses on the wood, ie the weight of the transformer and circuit boards pressing down.[/URL] There are some woods that are more resistant to this, but I can't name them. Dovetailing and insulation helps keep the box true as well._

 

So you need good ventilation.

  Quote:


  Originally Posted by *TwinFinnley* /img/forum/go_quote.gif 
_Another disadvantage is as Michael mentioned, there is no ground. You have to implement one into the box; AMB suggested I place an aluminum sheet at the bottom when I asked him what to do. This also helps with shielding. Another way to do it, and I could be way wrong with this, is to run dedicated ground wires in the boxes and have all the grounds connect to it throughout. Just make sure it is connected to the ground on your IEC. **if that is wrong please correct me!**_

 

This goes without saying.

  Quote:


  Originally Posted by *TwinFinnley* /img/forum/go_quote.gif 
_Wood also does not shield against EMI. Even if you have the s22 and b22 in different enclosures, there will still be some interference if they are close to each other unless you have some sort of shielding between the two. I found this out when doing some prelim testing - I still don't have my enclosure finished, but I'm also doing wood._

 

Shield the Transformer.

  Quote:


  Originally Posted by *TwinFinnley* /img/forum/go_quote.gif 
_ Also, depending on the price of the wood you plan to use and the amount of time you plan to invest (decide how much time you think it will take to make the box and multiply by 3 - it always happens this way with wood), it may just be cheaper to go metal, even with a custom face plate. If that is not a factor in why you are going wood, then have fun with it, but realize it will take gobs of time to do it right and make a box that will last as many years as this amp will._

 

mminutel, has all the tools and skill necessary, I think he likes wood.


----------



## fishski13

sigma22 up and running.


----------



## DoYouRight

nice fishski go !


----------



## fishski13

Quote:


  Originally Posted by *DoYouRight* /img/forum/go_quote.gif 
_nice fishski go !_

 

thanks. it was cool to use my new variac for the first time - less stress too.


----------



## homolupus

Hello,

 Perhaps somebody is located in london and has a matched input JFETs quad they could spare? Managed to knock of one lead due to DC offset troubles in ground channel and given the mail strikes, not too confident about ordering anything via mail 
	

	
	
		
		

		
		
	


	



 Sounds simply fantastic without ground channel, yet still - better to finish off the beast in the config it was planned to be 
	

	
	
		
		

		
		
	


	




 BR,
 Karils


----------



## linuxworks

just as a heads up to those that fight with low-ohm R's 
	

	
	
		
		

		
		
	


	




 I had an s11 burn out the 2 .47 ohm R's and not even TELL me about it. ie, the r's looked perfectly fine with no burn signs on them. but they tested as open circuits ;(

 they were 2watt vishay dale parts that looked, to me, rather physically small. but they said vishay on them; trustable, right?? no! not in this case.

 if they burn, at least LOOK burned so I can know. these didn't.

 stick with the larger sized 2w parts, such as the pany (matsu****a) ones. I've had good luck with those and they SHOW when they are burned out 
	

	
	
		
		

		
		
	


	




 my s11 is back up again. no other damage but 2 bad .47's.

 lesson learned. can't always tell when a part that SHOULD look broken, is.


----------



## Dougie085

Anyone built this and the SOHA II? I know they are different technologies but kind of curious as to what the strengths and weaknesses are between the 2. I'd imagine if I post this in the SOHA II thread I'd get a bunch of people that like it over the B22 and here the opposite....but figured I'd ask anyways as I'm kind of thinking between these 2. Kind of been interested in a good tube product though and it seems the SOHA is just that. I'd be looking to build a balanced version of both as my DAC is balanced outputs only atm. Also I'd be driving a pair of Alessandro MS Pro's.


----------



## FallenAngel

I doubt you'll get a lot of people saying SOHA2 over Beta22. I do really like the SOHA2, it's a great amp, too bad it's not as popular (casework isn't super easy), but the Beta22 is on a whole new level.


----------



## DoYouRight

what about a balanced EHHA?


----------



## sachu

Quote:


  Originally Posted by *DoYouRight* /img/forum/go_quote.gif 
_what about a balanced EHHA?_

 

The SOHA 2 is quite good but I agree that the B22 is better. However a B22 is like 3-4 times more expensive than a SOHA2.

 Regarding the EHHA..those who have built it and have heard the B22 as well or who have built both will testify that the EHHA is in the same league as the B22 or will eclipse the B22 (including yours truly)..and at just a bit more than half the price.

 It is a matter of sound signature preference and budget. Rest assured you won't be disappointed with building either of these amps.


----------



## Dougie085

WEll was looking through the EHHA thread and I have to say I'm very interested now. GlassJar doesn't seem to have kits anymore just the PCB's but that's not a huge deal. I'll have to post in the EHHA thread for the other questions.


----------



## wolf18t

Quote:


  Originally Posted by *Dougie085* /img/forum/go_quote.gif 
_Anyone built this and the SOHA II? I know they are different technologies but kind of curious as to what the strengths and weaknesses are between the 2. I'd imagine if I post this in the SOHA II thread I'd get a bunch of people that like it over the B22 and here the opposite....but figured I'd ask anyways as I'm kind of thinking between these 2. Kind of been interested in a good tube product though and it seems the SOHA is just that. I'd be looking to build a balanced version of both as my DAC is balanced outputs only atm. Also I'd be driving a pair of Alessandro MS Pro's._

 

OK I've built and I use both. See my sig. The SOHA II is a fun, easy to build and inexpensive amp. With the right tubes I use it regularly with my Grado RS-1 and sometime (depending of my mood) with my PS-1000. But when it comes to good recordings and want a very neutral presentation (straight wire with gain) it is not in the same level of my B22. The B22 also have a more precise soundstage, the instrument are easier to pinpoint and you have better sense of depth.

 So here are the plus point of both amps:

 SOHA II:
 - Easy to build. If it's your first build take this seriously into account.
 - Inexpensive. You still can add some boutique parts and customize it (as I've done)
 - Tube rolling. It's very fun to tailor some sound signature that match your personal taste, mood and headphones.
 - You will likeky impress almost all your friends and family. It got tubes!
 - While it's inexpensive it still sounds great.

 B22
 - High end sound quality and neutrality.
 - Will drive almost (if any) headphones ever made.
 - You will impress your geek & headphones addicts friends at meets. 
	

	
	
		
		

		
		
	


	




 Both are great design from well kown and respected designers. Alex Cavalli and Ti Kan. Both are very well documented and supported.


----------



## Dougie085

Yeah I kind of want to build a tube based amp first, I think I'll likely build the EHHA or SOHA II and then later build the B22. You have the RS-1's which are similar to the Alessandro MS Pro's so your input is very much appreciated.


----------



## Possede

I am currently putting the boards through the 'Initial setup & adjustments' steps, listed on the AMB website. Out of the three boards, only the ground channel passes every step listed. The right and left channel boards measure around 15mV AC at the output, the ground channel only measuring ~0.1mV. However, they pass each other step. I am wondering what the cause of this may be. I have a feeling I'll be desoldering at some point...


----------



## amb

Possédé, are you measuring with the inputs shorted to ground, if not, then that's what would be expected.


----------



## Possede

Quote:


  Originally Posted by *amb* /img/forum/go_quote.gif 
_Possédé, are you measuring with the inputs shorted to ground, if not, then that's what would be expected._

 

I am measuring each board individually, connected only to the power supply. Is there a reason that the ground channel only measures ~0.1mV AC, whereas the right and left channels measure ~15mV. Thanks for the quick response.


----------



## linuxworks

ground channel is an amp channel with its input 'perm shorted to ground'. right? so there should never be ac 'wiggle' off the ground channel, or even dc offset from the ground channel to input signal ground.


----------



## amb

As the β22 website says, you need to short the input to ground for the initial checks. Otherwise the floating input will act as an antenna and pick up noise. The ground channel has its input already connected to ground because of its special part value for R2.


----------



## Possede

Doh! Just redid the measurements and everything is within range! 
	

	
	
		
		

		
		
	


	




 Oh, and my cases came in the post! If anyone is wondering they are the Galaxy Maggiorato GX388. My garbage photography skills don't exactly do the cases any justice, but I thought I'd share a picture. 






 Thanks for the help.


----------



## Dougie085

Those enclosures look fantastic...I so wish they didn't cost so much to ship here!!!


----------



## DoYouRight

I really like that better than the parmetal. the sisdes are cool can you post more pics from different angles?


----------



## Dougie085

Yes it's very much better then the par-metal enclosures but unfortunately many times more expensive due to shipping costs and what not.


----------



## DoYouRight

well as long as you can send in the panels to FPE the same. Why not?


----------



## nattonrice

Looks like you got the aluminium tops... much better than the stock steel ones imo.


----------



## TwinFinnley

I'm trying to decide how to do some shielding. I have been thinking of either shielding just the transformer, or placing shielding through out the boxes of both beta22 and sigma22. I am using wood enclosures so I need to do something for sure. I would prefer it if I could find some sort of container for the transformer alone, but I can't find anything yet and I don't know which material is best ie: copper, iron, steel, etc...


----------



## amb

It's hard to shield a transformer well, after the fact. n_maher did that on his first β22 build, and it wasn't trivial (involving a totally enclosed box, lined with special material from EMF Safety Superstore- "Electromagnetic Field Detection & Protection". ). It would have been much better to use a toroid that was manufactured twith built-in shielding.

 But that shouldn't be an issue for you since you're using separate enclosures for the amp and PSU. Just keep them some distance apart.


----------



## Dougie085

I was going to say if you want to shield just use Mu-Metal and line the chassis for your PSU. Or the chassis for the AMP it self.


----------



## Beefy

Quote:


  Originally Posted by *amb* /img/forum/go_quote.gif 
_It's hard to shield a transformer well, after the fact. n_maher did that on his first β22 build, and it wasn't trivial (involving a totally enclosed box, lined with special material from EMF Safety Superstore- "Electromagnetic Field Detection & Protection". ). It would have been much better to use a toroid that was manufactured twith built-in shielding.

 But that shouldn't be an issue for you since you're using separate enclosures for the amp and PSU. Just keep them some distance apart._

 

For what its worth, I bought a shielded and encapsulated transformer from SumR for my MMM. The amp now has less background hum with the shielded transformer sitting directly on top of the amp box than it did with the old unshielded transformer some distance away from the amp.


----------



## TwinFinnley

Quote:


  Originally Posted by *amb* /img/forum/go_quote.gif 
_It's hard to shield a transformer well, after the fact. n_maher did that on his first β22 build, and it wasn't trivial (involving a totally enclosed box, lined with special material from EMF Safety Superstore- "Electromagnetic Field Detection & Protection". ). It would have been much better to use a toroid that was manufactured twith built-in shielding.

 But that shouldn't be an issue for you since you're using separate enclosures for the amp and PSU. Just keep them some distance apart._

 

The toroid I bought was the Avel Lindberg Y236355 (25+25V @ 80VA). I have no idea if it has "built-in" shielding, but I'm guessing that it doesn't - it looks pretty bare-bones.

 So Mu-Metal is the best way to go or the stuff that n_maher used?


----------



## TwinFinnley

Quote:


  Originally Posted by *Beefy* /img/forum/go_quote.gif 
_For what its worth, I bought a shielded and encapsulated transformer from SumR for my MMM. The amp now has less background hum with the shielded transformer sitting directly on top of the amp box than it did with the old unshielded transformer some distance away from the amp._

 

Thanks Beefy, looking them up right now.

 EDIT: I'm looking at some material that I might use to line a box dedicated to the transformer, would this work?


----------



## Beefy

I'll save you the trouble: SumR - Richard Sumner Technology

 For my custom transformers, I just sent Richard an email. I asked for fully shielded and encapsulated, in the ratings, primary and secondary config I needed...... he quoted, I paid, I received transformers.

 Easy as pie. Even easier if you can just ask him to shield and encapsulate one of his off-the-shelf models. You would probably want the RC0080 924 2 as listed here: SumR - Richard Sumner Technology:: Power Dual


----------



## Dougie085

Mu-metal has been said to have the best shielding properties. There was a place over seas that sold sheets of it. Not really sure about state side, maybe someone on ebay has some? I'm not sure about what n_maher used. I've just been told several times that Mu-Metal is the best to use? There is some test data out there if you look.


----------



## Dougie085

Quote:


  Originally Posted by *Beefy* /img/forum/go_quote.gif 
_I'll save you the trouble: SumR - Richard Sumner Technology

 For my custom transformers, I just sent Richard an email. I asked for fully shielded and encapsulated, in the ratings, primary and secondary config I needed...... he quoted, I paid, I received transformers.

 Easy as pie. Even easier if you can just ask him to shield and encapsulate one of his off-the-shelf models. You would probably want the RC0080 924 2 as listed here: SumR - Richard Sumner Technology:: Power Dual_

 

How much are his shielded units? I imagine its a good bit more then the standard ones.


----------



## TwinFinnley

Quote:


  Originally Posted by *Dougie085* /img/forum/go_quote.gif 
_How much are his shielded units? I imagine its a good bit more then the standard ones._

 

They are around $80 +/- for 80VA with shielding.


----------



## Dougie085

Ah that's not to bad then. 80VA might not work for a power amp of course


----------



## Beefy

Quote:


  Originally Posted by *Dougie085* /img/forum/go_quote.gif 
_How much are his shielded units? I imagine its a good bit more then the standard ones._

 

 Quote:


  Originally Posted by *TwinFinnley* /img/forum/go_quote.gif 
_They are around $80 +/- for 80VA with shielding._

 

Sounds about right. I paid just over CA$60 each for 30VA units.


----------



## linuxworks

anyone buy a 24v trafo for an *m3*, while we're on the subject?

 I'm thinking that the lowest they offer on the standard page (20va) is going to be enough; for the m3 that won't be (ever) driving spkrs, just phones.

 I have not bought a SUMR yet but I might try a shielded one for the m3, first.

 any recs for which one to get?


----------



## Beefy

Quote:


  Originally Posted by *linuxworks* /img/forum/go_quote.gif 
_anyone buy a 24v trafo for an *m3*, while we're on the subject?_

 

Yes, I bought one for mine as stated above...... 30VA, 115+115 primary, 12+12 secondary.

 I bought the 30VA because the encapsulation was the same physical size for both ratings and moar is betterer.

 I think that the RC0030 912 2 is what I got, plus fully shielded and encapsulated, for just over CA$60.


----------



## linuxworks

and let me put a plug in for a VERY remote install; putting JUST the trafo in a box and throwing that on the floor way far away from the main amp:











 and then the s22 goes in the same case as the amp boards.

 no hum at all


----------



## linuxworks

Quote:


  Originally Posted by *Beefy* /img/forum/go_quote.gif 
_Yes, I bought one for mine as stated above...... 30VA, 115+115 primary, 12+12 secondary.

 I bought the 30VA because the encapsulation was the same physical size for both ratings and moar is betterer._

 

good point. thanks! I may just order this


----------



## TwinFinnley

I was just looking at some of Thrice's Rockhopper b22 builds and got to wondering about what ever happened to him? Anyone know? Seemed like he made some really solid amps.


----------



## DoYouRight

dunno he did make a kickin 6 board b22. He is awol though.


----------



## nattonrice

Quote:


  Originally Posted by *Dougie085* /img/forum/go_quote.gif 
_How much are his shielded units? I imagine its a good bit more then the standard ones._

 

Don't quote me but usually it was something like ~$16 extra depending on the size of the box/tub used.


----------



## n_maher

Quote:


  Originally Posted by *nattonrice* /img/forum/go_quote.gif 
_Don't quote me but usually it was something like ~$16 extra depending on the size of the box/tub used._

 

IIRC it was more than that. I think the price was at least $25 higher when I ordered a potted/shielded unit compared to "stock". There's also typically a longer production time for the potted trafos, in case that matters.


----------



## Beefy

Quote:


  Originally Posted by *n_maher* /img/forum/go_quote.gif 
_IIRC it was more than that. I think the price was at least $25 higher when I ordered a potted/shielded unit compared to "stock". There's also typically a longer production time for the potted trafos, in case that matters._

 

Yep, it was $20 to to shield/encapsulate the 30VA models so $16 is low-balling it.

 The base transformer also costs a bit more than, say, an Avel Lindberg equivalent...... but I'm still very happy with the results


----------



## fishski13

Quote:


  Originally Posted by *TwinFinnley* /img/forum/go_quote.gif 
_They are around $80 +/- for 80VA with shielding._

 

yup, $91 with shipping for my encapsulated 30+30V 80mA to MN. it took about 2.5 wk from ordering to doorstep.


----------



## linuxworks

80mA?

 you mean VA.


----------



## Possede

Here are a couple more pictures of the case that DoYouRight requested. It is a beautiful case, the pictures do not do it any justice. I am also using the 2mm aluminium top and bottom panels.


----------



## dbfreak

Possédé;6036236 said:
			
		

> Here are a couple more pictures of the case that DoYouRight requested. It is a beautiful case, the pictures do not do it any justice. I am also using the 2mm aluminium top and bottom panels.
> 
> They are nice cases. Galaxie, if I'm not mistaken. I used one but smaller for my σ22 PSU.


----------



## fishski13

Quote:


  Originally Posted by *linuxworks* /img/forum/go_quote.gif 
_80mA?

 you mean VA.




_

 

doh
	

	
	
		
		

		
		
	


	




.


----------



## DoYouRight

they look nicer than the parmetal, why dont more people use them if they go all the way with FPE and stuff?


----------



## jtostenr

$$$

 Unless you live in Italy they can be quite expensive with shipping. I bought one for an S22 I built and I like it a lot, but my B22 and next S22 will be in Par Metal cases.

 Jeff


----------



## linuxworks

WHY are they so expensive? they don't *look* expensive to make. what's up with this?

 I understand shipping is a lot. but the base units, boxes just seem so simple to make. is it mostly mark-up that accounts for the price? the fact that its a small market or limited interest market? lack of competition?


----------



## Dougie085

They are made of thick aluminum. Par metal enclosures are quite thin and still aren't what I would call "cheap". Also this shipping cost can be more then the chassis it self.


----------



## johnwmclean

Quote:


  Originally Posted by *Dougie085* /img/forum/go_quote.gif 
_They are made of thick aluminum. Par metal enclosures are quite thin and still aren't what I would call "cheap". Also this shipping cost can be more then the chassis it self._

 

I reckon the par metal cases are a better, stronger design. The hi fi 2000 cases have a very annoying arrangement for top and bottom panels, only 4 tiny screws to hold a lot of weight.


----------



## DoYouRight

but the side panels are wicked!


----------



## IPodPJ

I got a question guys. Now that my parts for the 4 Beta22 boards and 2 Sigma22 boards have been ordered (the machining of the case is going to be a whole different animal because it's going to be completely custom machined and lasered based on parts from a high-end amp and preamp manufacturer, 5/8" thick front panels), I need to know about gain.

 Will the default gain of 8 be enough to drive the HD800 to very loud levels and/or have plenty of headroom? We have figured out that it will drive a 300 ohm load to about 666mW and a 600 ohm load to 333mW. This seems more than enough considering the HD800 is rated at 500 mW. I just wanted to make sure, even though I'm not going to be listening at extremely loud levels. I don't want to add unnecessary gain which can increase the noise levels if I don't need to.


----------



## johnwmclean

Quote:


  Originally Posted by *IPodPJ* /img/forum/go_quote.gif 
_I got a question guys. Now that my parts for the 4 Beta22 boards and 2 Sigma22 boards have been ordered (the machining of the case is going to be a whole different animal because it's going to be completely custom machined and lasered based on parts from a high-end amp and preamp manufacturer, 5/8" thick front panels), I need to know about gain.

 Will the default gain of 8 be enough to drive the HD800 to very loud levels and/or have plenty of headroom? We have figured out that it will drive a 300 ohm load to about 666mW and a 600 ohm load to 333mW. This seems more than enough considering the HD800 is rated at 500 mW. I just wanted to make sure, even though I'm not going to be listening at extremely loud levels. I don't want to add unnecessary gain which can increase the noise levels if I don't need to._

 

I think gain 2 is perfect for the HD800’s in balanced mode (total 4 gain), I would not recommend 8, you’ll never pass 9 o’clock on your volume. I’m fairly loud listener, I listen anywhere from 11.30 - 3.00 depending on the recordings output level. 
 Lower gain has more volume ratio over the pot, without being limited to the first 1/3 of the attenuator, therefore your increments between volume settings are more subtle, better for getting the volume just right.


----------



## IPodPJ

Well I want to make sure I have enough gain if I ever get 600 ohm headphones. Also I will have jacks for single ended phones, so I can't discount that either. But I do know what you're saying. It's better to use a lower gain that you max the amp out on than a higher gain with lower volume.


----------



## johnwmclean

Quote:


  Originally Posted by *IPodPJ* /img/forum/go_quote.gif 
_Well I want to make sure I have enough gain if I ever get 600 ohm headphones. Also I will have jacks for single ended phones, so I can't discount that either. But I do know what you're saying. It's better to use a lower gain that you max the amp out on than a higher gain with lower volume. 
	

	
	
		
		

		
		
	


	


_

 

In your particular case a different gain setting might be appropriate. I suppose you’ll have to weight up balanced listening vs SE vs 600 ohm headphones. My attitude is get the best, forget the rest - how much SE time warrants sacrificing a great gain setting for balanced


----------



## IPodPJ

Quote:


  Originally Posted by *johnwmclean* /img/forum/go_quote.gif 
_In your particular case a different gain setting might be appropriate. I suppose you’ll have to weight up balanced listening vs SE vs 600 ohm headphones. My attitude is get the best, forget the rest - how much SE time warrants sacrificing a great gain setting for balanced 
	

	
	
		
		

		
		
	


	


_

 

You're correct. Unfortunately though I don't know what the future will bring and how sensitive new and possibly better headphones might be, balanced or not. I just wanted to make sure I didn't need more than a total gain of 16 (8 per board is default). 16 might be too much though. Jeez, tough decision here.

 Anyone else have any opinions that have balanced Beta22 amps? If AMB could chime in, it would be appreciated as well. 
	

	
	
		
		

		
		
	


	




 Thanks, John.

 Will higher gain raise the potential low level noise of this amp? If everything is assembled properly and grounded properly (and it will be a dual chassis in some very thick cases) will it matter?


----------



## askforwhy

No update recently, but actually my case was finished a week ago.
 No LUCK though.
 I've been fighting the hum noise/hiss for several days due to my lame wiring, and one of my step attenuators broke down. I have to ship the attenuator back to the seller and they may ship a new one for me. 
 Oh, I hate wating.


----------



## MrMajestic2

Quote:


  Originally Posted by *IPodPJ* /img/forum/go_quote.gif 
_You're correct. Unfortunately though I don't know what the future will bring and how sensitive new and possibly better headphones might be, balanced or not. I just wanted to make sure I didn't need more than a total gain of 16 (8 per board is default). 16 might be too much though. Jeez, tough decision here._

 

I had 16 on my first balanced B22 because I wanted to make sure it had enough oomph to cope with the K1000s, and it did 
	

	
	
		
		

		
		
	


	




 Any other headphones would need less gain though.


----------



## johnwmclean

Quote:


  Originally Posted by *MrMajestic2* /img/forum/go_quote.gif 
_I had 16 on my first balanced B22 because I wanted to make sure it had enough oomph to cope with the K1000s, and it did 
	

	
	
		
		

		
		
	


	




 Any other headphones would need less gain though._

 

Balanced?


----------



## MrMajestic2

Quote:


  Originally Posted by *johnwmclean* /img/forum/go_quote.gif 
_Balanced?_

 

Gain 8 unbalanced, so 16 balanced. Or maybe I didn't understand what you're asking


----------



## johnwmclean

Quote:


  Originally Posted by *MrMajestic2* /img/forum/go_quote.gif 
_Gain 8 unbalanced, so 16 balanced. Or maybe I didn't understand what you're asking 
	

	
	
		
		

		
		
	


	


_

 

Thanks for that, that’s was my query.


----------



## Beefy

I don't know whether most non-DIY people appreciate how much volume you could get from an balanced B22 with an effective gain of 16. A standard 2VRMS source is 5.65V P-P. At max volume, you would be trying to push 90.5V P-P, clipping even with a ±30V power supply, and 100% certainly deaf.


----------



## johnwmclean

Quote:


  Originally Posted by *Beefy* /img/forum/go_quote.gif 
_I don't know whether most non-DIY people appreciate how much volume you could get from an balanced B22 with an effective gain of 16. A standard 2VRMS source is 5.65V P-P. At max volume, you would be trying to push 90.5V P-P, clipping even with a ±30V power supply, and 100% certainly deaf._

 

What! ))))))))


----------



## Dougie085

From what I understand going balanced doesn't double the gain I think it's supposed to be like +6dB at least with speakers it is.


----------



## fsrick

+6dB means the gain is double. in log scale, "+" is "x" in linear scale, from (x)db=20*log(Y), for 6 db, Y=2.


----------



## DoYouRight

its a difficult thing the gain settings. you can get extra stuff and try a few settings and settle on one. but thats a huge PITA. I went with what John uses its loud alright. If I get the new beyer flagships I might double what I have.


----------



## Dougie085

Quote:


  Originally Posted by *fsrick* /img/forum/go_quote.gif 
_+6dB means the gain is double. in log scale, "+" is "x" in linear scale, from (x)db=20*log(Y), for 6 db, Y=2._

 

Oh ok that makes since.


----------



## fishski13

Quote:


  Originally Posted by *DoYouRight* /img/forum/go_quote.gif 
_its a difficult thing the gain settings. you can get extra stuff and try a few settings and settle on one. but thats a huge PITA. I went with what John uses its loud alright. If I get the new beyer flagships I might double what I have._

 

i have the dt990/600 and went with the default gain of 8. i'm hoping this will be adequate.


----------



## DoYouRight

are you making a balanced beta22?


----------



## fishski13

no.


----------



## wolf18t

Quote:


  Originally Posted by *fishski13* /img/forum/go_quote.gif 
_i have the dt990/600 and went with the default gain of 8. i'm hoping this will be adequate._

 

Should be just fine but, I suggest you order the parts for 5x gain for a buck or two extra. If you change your mind you'll save on shipping later...


----------



## fishski13

Quote:


  Originally Posted by *wolf18t* /img/forum/go_quote.gif 
_Should be just fine but, I suggest you order the parts for 5x gain for a buck or two extra. If you change your mind you'll save on shipping later... 
	

	
	
		
		

		
		
	


	


_

 

my M3 has the default gain 11x and 12 o'clock is pretty loud for most recordings. i'll hopefully have the B22 cranking tunes by late tomorrow. i just need to finish the chassis wiring.


----------



## fishski13

i have a friend that runs a CNC machine all day long for a mill-work shop. among other "drop cuts", he gave me some perf steel. for the top-plate, is steel a problem in this application with regards to EMI creating noise? should i ground it, or leave it floating?

http://i23.photobucket.com/albums/b3...ki13/010-4.jpg


----------



## Karu

If I have a six board β22 setup and want to use it in different skenarios what is the correct way to connect the ground?

*For unbalanced headphone ground I gather this is the way to do it*
Passive
Ground connected to PSU ground

Active
Ground connected to ground amplifier

Balanced
Ground connected to ground amplifier


*How to connect preamp ground (RCA/XLR) when in balanced mode?*
Passive
Ground connected to PSU ground

Active
Ground connected to signal ground

Balanced
Ground connected to signal ground


 EDIT: I think I got the preamp ground in balanced mode right.


----------



## Fitz

Quote:


  Originally Posted by *Beefy* /img/forum/go_quote.gif 
_I don't know whether most non-DIY people appreciate how much volume you could get from an balanced B22 with an effective gain of 16. A standard 2VRMS source is 5.65V P-P. At max volume, you would be trying to push 90.5V P-P, clipping even with a ±30V power supply, and 100% certainly deaf._

 

This is only true if the balanced output from the source is twice as strong at 4Vrms, which is where the so-called doubling of gain actually comes from. The amplifier when considered by itself still has the same amount of gain... a 2Vrms unbalanced signal into a single board with a gain of 8 yields the same amplitude output as a 2Vrms balanced signal into a pair of boards each with a gain of 8, because each board only "sees" half the signal.

 But regardless, it's not so much that one chooses that much gain to try to get that much volume out of the amp, but that the higher gain will allow one to reach the desired listening volume even if the recording or source is relatively soft.


----------



## askforwhy

Today I've just fix most noise problems, but unfortunately one of my boards may blow some mosfets.
 I turn up the amp, then I found two output resistors on my R+ channel start glowing like a bulb, I turn off the amp ASAP. After some inspection I found the output pad shorted to V-. So I think I will have to replace Q22/Q24, anywhere else I should check with care too?
 Arrrrrh~ PAIN.


----------



## Beefy

Quote:


  Originally Posted by *Fitz* /img/forum/go_quote.gif 
_This is only true if the balanced output from the source is twice as strong at 4Vrms, which is where the so-called doubling of gain actually comes from. The amplifier when considered by itself still has the same amount of gain... a 2Vrms unbalanced signal into a single board with a gain of 8 yields the same amplitude output as a 2Vrms balanced signal into a pair of boards each with a gain of 8, because each board only "sees" half the signal._

 

True. I must admit I don't know much about a lot of sources, but many DIY sources I have looked at do indeed have double the output from their balanced outputs.

  Quote:


 But regardless, it's not so much that one chooses that much gain to try to get that much volume out of the amp, but that the higher gain will allow one to reach the desired listening volume even if the recording or source is relatively soft. 
 

True. But I would imagine that even for the most quiet recordings a gain of higher than 8x is very rarely going to use the whole range of the volume pot.


----------



## amb

Quote:


  Originally Posted by *fishski13* /img/forum/go_quote.gif 
_i have a friend that runs a CNC machine all day long for a mill-work shop. among other "drop cuts", he gave me some perf steel. for the top-plate, is steel a problem in this application with regards to EMI creating noise? should i ground it, or leave it floating?_

 

You'll get better shielding if it's grounded, but depending on whether RFI is a problem in your area, it may or may not make a difference.


----------



## amb

Quote:


  Originally Posted by *Karu* /img/forum/go_quote.gif 
_If I have a six board β22 setup and want to use it in different skenarios what is the correct way to connect the ground?

*For unbalanced headphone ground I gather this is the way to do it*
Passive
Ground connected to PSU ground

Active
Ground connected to ground amplifier

Balanced
Ground connected to ground amplifier

_

 

Not sure what the third bullet refers to. How does an unbalanced headphone get "balanced"?

  Quote:


 *How to connect preamp ground (RCA/XLR) when in balanced mode?*
Passive
Ground connected to PSU ground

Active
Ground connected to signal ground

Balanced
Ground connected to signal ground

 
 

The first bullet is incorrect, and the second bullet is meaningless. Preamp outputs should always have passive ground, and always wired to signal ground.


----------



## amb

Quote:


  Originally Posted by *askforwhy* /img/forum/go_quote.gif 
_Today I've just fix most noise problems, but unfortunately one of my boards may blow some mosfets.
 I turn up the amp, then I found two output resistors on my R+ channel start glowing like a bulb, I turn off the amp ASAP. After some inspection I found the output pad shorted to V-. So I think I will have to replace Q22/Q24, anywhere else I should check with care too?
 Arrrrrh~ PAIN._

 

Start measuring the MOSFETs for shorts.


----------



## ShinyFalcon

Has anyone measured the weight of their β22 setup? I'm interested in the boards + σ２２ + transformer only, but you can include the case weight with the total as well, just show me how much the case weighs.


----------



## askforwhy

Quote:


  Originally Posted by *amb* /img/forum/go_quote.gif 
_Start measuring the MOSFETs for shorts._

 

Thanks, Ti.
 I've just replaced 4 MOSFETs on the board and now my Beta22 sings again.
 Still some hiss/hum noise with my earbuds but as long as I can't hear them with my K701, I will leave it as it is.
	

	
	
		
		

		
		
	


	



 Will post pics next few days, my room is a mess.


----------



## fishski13

for a 2-board passive ground, do i still need to connect RCA ground to chassis, or isolate? as you can see from the pic, i have no RCAs. instead i have one wire for each signal ground (the green wires in the pic) soldered into the pot input ground tabs to connect to the chassis for a 3-board active ground.


----------



## n_maher

I hope you have some strain relief on those wires.


----------



## amb

fishski13, as long as your amp's signal ground is tied to the chassis then it's fine.


----------



## fishski13

Quote:


  Originally Posted by *n_maher* /img/forum/go_quote.gif 
_I hope you have some strain relief on those wires._

 

it's bomber.


----------



## Possede

I've noticed that some people are using a filtered power entry plug, like this one. What are the benefits of using an expensive power entry plug compared to the generic, cheap ones. Do the benefits justify the price?


----------



## Beefy

I use the Schaffner FN282 or FN284 IEC inlets.

 I really can't say whether they 'perform' better...... but for me the benefits of the extra cost included the double fusing and double-pole switching for safety, and the fact that they are all-in-one units for a cleaner panel.


----------



## fishski13

Beefy,
 your avatars always freak me out. thanks, i just had to get that off my chest 
	

	
	
		
		

		
			





.

 chassis wiring is done, although i think i may re-do the PS hook-up wiring to the amp boards. i guess i don't know how important it is to twist the wiring once it's inside the chassis. my unbillical from the sigma22 is shielded 16 awg. i have to spend some time ohming everything out as well before the first power up tomorrow night - wish me luck!!! the sigma22 is tested and working. this build has been too easy up to this point - i hope my luck continues.

 PACE


----------



## DouglasQuaid

Quote:


  Originally Posted by *Possédé* /img/forum/go_quote.gif 
_I've noticed that some people are using a filtered power entry plug, like this one. What are the benefits of using an expensive power entry plug compared to the generic, cheap ones. Do the benefits justify the price?_

 

Some DIYers back in the day swore off the use of filters on the IEC input. Said it killed dynamics. I like to agree and trust a well-designed power supply to take care of noise as opposed to some ridiculously cheap inductor network.


----------



## Beefy

Quote:


  Originally Posted by *DouglasQuaid* /img/forum/go_quote.gif 
_Some DIYers back in the day swore off the use of filters on the IEC input. Said it killed dynamics._

 

Please explain how, in established electronic engineering terms. Thanks.

  Quote:


 *I like to agree* and...... 
 

Which is often the problem.

  Quote:


 well-designed power supply to take care of noise as opposed to some ridiculously cheap inductor network. 
 

And there is something specifically wrong with using both?


----------



## linuxworks

Quote:


  Originally Posted by *DouglasQuaid* /img/forum/go_quote.gif 
_Some DIYers back in the day swore off the use of filters on the IEC input. Said it killed dynamics._

 

no such thing as 'dynamics' in power supplies! lol.

 this is not any kind of explanation. its not even possible. sorry.


----------



## linuxworks

Quote:


  Originally Posted by *Possédé* /img/forum/go_quote.gif 
_I've noticed that some people are using a filtered power entry plug, like this one. What are the benefits of using an expensive power entry plug compared to the generic, cheap ones. Do the benefits justify the price?_

 

I get my iec filters at a local surplus store. they're cheap and so I use them.

 they stop high frequency stuff from getting in; but also people tend to forget that they stop stuff from getting out (if your box is digital, it might dump 'stuff' on the power rails and if you have an iec filter that can suppress some of that getting back into the common ac power line).


----------



## DouglasQuaid

Quote:


  Originally Posted by *Beefy* /img/forum/go_quote.gif 
_Please explain how, in established electronic engineering terms. Thanks.

 And there is something specifically wrong with using both?_

 


 You want me to define hearsay? Okay.

 "evidence based not on a witness's personal knowledge but on another's statement"

 If you don't notice a difference, go ahead and use one.

  Quote:


  Originally Posted by *linuxworks* /img/forum/go_quote.gif 
_no such thing as 'dynamics' in power supplies!_

 

Do you honestly believe power supply quality has no bearing on the dynamics of an amplifier? I suppose you also believe people build discrete power supplies for their amps just because they look cool.


----------



## luvdunhill

Quote:


  Originally Posted by *DouglasQuaid* /img/forum/go_quote.gif 
_You want me to define hearsay? Okay.

 "evidence based not on a witness's personal knowledge but on another's statement"_

 

so, wait, you've tried both then? what was your conclusion? what other variables changed?


----------



## m1abrams

Quote:


  Originally Posted by *DouglasQuaid* /img/forum/go_quote.gif 
_
 Do you honestly believe power supply quality has no bearing on the dynamics of an amplifier? I suppose you also believe people build discrete power supplies for their amps just because they look cool._

 

That is not what he said. A DC power supply should have no dynamics to it. The idea is to be constant. I too am confused how "dynamics" can be removed by filtering the AC going into a DC power supply.

 A good DC PS does one thing provide the most constant ripple free DC Voltage (if it is a constant Voltage source) that it can over various current loads. So it should not have dynamics.


----------



## linuxworks

Quote:


  Originally Posted by *DouglasQuaid* /img/forum/go_quote.gif 
_Do you honestly believe power supply quality has no bearing on the dynamics of an amplifier? I suppose you also believe people build discrete power supplies for their amps just because they look cool._

 

a lot of the time, people build discrete FOR the 'oooh, aaaah!' factor. truly. its irrational but a lot of builders and buyers are. truth!

 the power supply keeps the caps charged and those supply power to the circuit. I'm still not seeing where 'dynamics' enter into it.

 even worse, I'm not seeing - AT ALL - where filter L and C elements at the power line (before the trafo) will hurt a single thing. please give some tech reason for why you feel this rfi filter hampers anything.


----------



## fishski13

WOOT!!!WOOT!!!

 my B22 is up a running 
	

	
	
		
		

		
			





. i had difficulties trimming the DC off-set. i ended up tented a second 1N4148 in series with D3 and D4 in both channels and was able to trim easy-peasy.


----------



## DoYouRight

how do you like it compared to your other amps?


----------



## aloksatoor

the first listen is the sweetest


----------



## fishski13

D.Y.R. and aloksatoor,

 yes, very nice...

 i've been running the B22 through it's paces with my DT990/600ohm: Yabby You, Kruder and Dorfmeister, and Charlie Haden were all on tap for the night.

 transients and note attack are excellent. the treble has a nice sparkle to it - no tizz..tizz..sizzle here. uber-detail top to bottom, but no sand amp sterile haze. i'll post more impressions as the amp continues to burn in.

 i'm having zero noise issues even with the top open. i just need to order the FPE face-plates and cut the aluminum tops and she's done.


----------



## wolf18t

Quote:


  Originally Posted by *fishski13* /img/forum/go_quote.gif 
_D.Y.R. and aloksatoor,

 yes, very nice...

 i've been running the B22 through it's paces with my DT990/600ohm: Yabby You, Kruder and Dorfmeister, and Charlie Haden were all on tap for the night.

 transients and note attack are excellent. the treble has a nice sparkle to it - no tizz..tizz..sizzle here. uber-detail top to bottom, but no sand amp sterile haze. i'll post more impressions as the amp continues to burn in._

 

Good news and congratulations! 

  Quote:


  Originally Posted by *fishski13* /img/forum/go_quote.gif 
_i'm having zero noise issues even with the top open. i just need to order the FPE face-plates and cut the aluminum tops and she's done._

 

From my experience, if you want to be absolutly certain you have no noise (hiss) issues it would be preferable testing with low Z cans like Grado or Denon if available.


----------



## n_maher

Quote:


  Originally Posted by *wolf18t* /img/forum/go_quote.gif 
_From my experience, if you want to be absolutly certain you have no noise (hiss) issues it would be preferable testing with low Z cans like Grado or Denon if available._

 

That's really not a good measuring stick in my experience. Better than using high-impedance cans, sure, but if you want to really get an idea of noise floor throw in some good IEMs and have a listen. Personally I use Ety ER4Ps for this purpose and won't a claim an amp is silent unless it passes that test. I've built a few beta22's, some were up to this challenge, others were not (by design).


----------



## fishski13

good points gents. well, i only have my dt990/600ohms at the moment, but the Brown Santa Claus has a scheduled delivery for a new pair of AKG K271/55ohms today.


----------



## TwinFinnley

Quote:


  Originally Posted by *n_maher* /img/forum/go_quote.gif 
_That's really not a good measuring stick in my experience. Better than using high-impedance cans, sure, but if you want to really get an idea of noise floor throw in some good IEMs and have a listen. Personally I use Ety ER4Ps for this purpose and won't a claim an amp is silent unless it passes that test. I've built a few beta22's, some were up to this challenge, others were not (by design)._

 

Is this silence test in lieu of using an oscilloscope or in addendum?


----------



## amb

Quote:


  Originally Posted by *TwinFinnley* /img/forum/go_quote.gif 
_Is this silence test in lieu of using an oscilloscope or in addendum?_

 

To test for transformer-induced noise, spectrum analyzer software (i.e., RMAA or others) and a good sound card is best. Lacking those, sensitive headphones would work, but it doesn't give any quantifiable results other than "I can hear noise" or "I don't hear noise".


----------



## fishski13

ziltch noise with the K271. straight out of the box these are nice little cans, or maybe it's just the amp 
	

	
	
		
		

		
		
	


	




.


----------



## fishski13

i would like to thank Ti and anyone else involved with the B22, including all the builders here and over at Headwize that have shared their experiences. we DIYers are fortunate to have designers like Ti Kan, Alex Cavalli, and Nelson Pass that are willing to share their ideas and knowledge for all to benefit - not to mention the amazing amount of support they provide to enable "weekend warriors" such as myself to build. 

 needless to say, the B22 continues to impress.

 thanks once again Ti 
	

	
	
		
		

		
		
	


	













 .


----------



## DoYouRight

yes this thing has been the most exciting purchase and project in years. the sound in the end and the fact we build it just makes it so amazing and comparing it to other companies gears and what Id get for the same cash is crazy!


----------



## amb

Enjoy and have fun!


----------



## fishski13

btw, the default gain 8x with my dt990/600ohm is perfect. i'm hovering around 12 to 3 o'clock depending on how hard i want to rock.


----------



## askforwhy

Umm..... another situation is here.
 One channel(R-) of my beta22 has some problem.
 When I turn on the amp, the beta22 capacitors begin to charge, or at least it sounds like, I can hear music from it. After fully charged, like few seconds, it is dead silent! I tested the output pad and it is 0 volt relative to ground. But when I turn off the amp, the caps begin to discharge, the music is back again till fully discharged. Everything else seems fine, and the channel used to be normal, so I am really lost.
 Also one thing bothers me is that other two channels (L-, R+)with some hum noise, but after warm up it become quieter, since the L+ and R- is free from hum so I don't think this is normal. 
 Thanks in advance.


----------



## amb

I don't think it has much to do with any capacitors charging or discharging. The symptoms seem more like a marginal solder joint somewhere, which becomes open circuit as the amp heats up. Check all joints on the problem board carefully, and all wiring to it, on both ends. Also go through all the initial check steps on that board again to make sure it is basically functioning correctly.


----------



## askforwhy

Thank you very much for the quick response. I'll do it later and report back.


----------



## askforwhy

I reflowed all the joints and the problem is solved now, or at least seems to be solved.
 Thanks AMB.


----------



## Karu

The image below contains my signal wiring plan for the left half of a six-board beta22. Does that look sensible or is there something that I should change?


----------



## digger945

1. L and R RCA inputs connected to L + and - balanced input?
 2. L and R line out connected to L balanced input?

 Maybe I'm missing something, it would be great to see the entire diagram.


----------



## Karu

digger945, that is most of the diagram that I have drawn, the other half is symmetric to it.

 1. That is based on the picture on AMB's website. My intention is to be able to alternate between at least two sources regardless of type (B/B, B/U, U/U) without having to recable. I know that it is not possible to have XLR and RCA's connected in the same triad at the same time.

 2. I don't follow. Now the connections on outs have to be coordinated with what is selected as input (B/U). Maybe it would be a good idea to add a switch to select the type of the out so that no re-cabling is needed.


----------



## digger945

Quote:


  Originally Posted by *Karu* /img/forum/go_quote.gif 
_digger945, that is most of the diagram that I have drawn, the other half is symmetric to it.

 1. That is based on the picture on AMB's website. My intention is to be able to alternate between at least two sources regardless of type (B/B, B/U, U/U) without having to recable. I know that it is not possible to have XLR and RCA's connected in the same triad at the same time.

 2. I don't follow. Now the connections on outs have to be coordinated with what is selected as input (B/U). Maybe it would be a good idea to add a switch to select the type of the out so that no re-cabling is needed._

 


 My next question was going to be "will the input select switch be tied to the phone/pre switch, so that if for example you select B input you can only get B output."


----------



## Karu

Quote:


  Originally Posted by *digger945* /img/forum/go_quote.gif 
_My next question was going to be "will the input select switch be tied to the phone/pre switch, so that if for example you select B input you can only get B output."_

 

Good question. 
	

	
	
		
		

		
		
	


	




 I seem to be able to avoid the hassle of recabling if I stay only in balanced or unbalanced setup with ins and outs. I'm wondering whether the added complexity is worth the saved effort of rearranging some cables when having mixed ins.


----------



## Karu

There is an another thing that I'm thinking about as well. Instead of using switches to select the balanced or unbalanced outs to employ some relays. I have some with these ratings:

Rated load: 0.3A @ 125VAC, 1A @ 30VDC
Max. carry current: 1A
Max. operating voltage 125VAC, 60VDC
Max. operating current 1A
Max. switching capacity: 37.5VA, 30W

 They seem to be enough for input, line out, and phones. It is the pre-amp out that I wonder about. Normally when connecting an amplifier there the current is quite small, but if for some reason I end up connecting some speakers, then these might not be enough. What would be the recommended ratings?


----------



## amb

For switching speaker loads I would use relays with contact rating of at least 5-10A.


----------



## digger945

Quote:


  Originally Posted by *Karu* /img/forum/go_quote.gif 
_There is an another thing that I'm thinking about as well. Instead of using switches to select the balanced or unbalanced outs to employ some relays. I have some with these ratings:

Rated load: 0.3A @ 125VAC, 1A @ 30VDC
Max. carry current: 1A
Max. operating voltage 125VAC, 60VDC
Max. operating current 1A
Max. switching capacity: 37.5VA, 30W

 They seem to be enough for input, line out, and phones. It is the pre-amp out that I wonder about. Normally when connecting an amplifier there the current is quite small, but if for some reason I end up connecting some speakers, then these might not be enough. What would be the recommended ratings?_

 

I think someone else could probably give you better guidance with respect to output relay ratings and suggestions. 

 If you are considering powering speaker with this amp then there are two other things that come to mind immediately that should also be considered at this time. 
 1. How many Sigma 22 power supplies will you be using and what will be the power rating of the transformers supplying them?
 I'm thinking the Sigma 22 is good for about 1Ax30V per rail=60W with stock heatsinks.
 2. Will you be using stock(or near stock) Aavid heatsinks or something larger(external)?
 This answer will alter the formula for question 1. Larger heatsinks on both the sigma and beta boards will allow more power.

 A search in this thread for posts made by amb should give additional pointers.


----------



## Karu

digger945, I have quite large Conrad offboard heatsinks, but only 2 sigma22 power supplies with 80VA transformers each. I guess that rules out any light speaker driving duty.

 amb, if I leave out the speaker option, am I happy with the 1A relays even for preamp usage? I have access to some 2A ones as well, but they draw a lot more power. I'm calculating that the power supply needed for switches then needs to be somewhat larger than the one I had in mind.

 One other thing. In my wiring diagram I didn't run the signal ground through the source selector switch. Is there some drawback of doing it that way?


----------



## fishski13

ordered parts for the 3rd channel for active ground. spent the evening cutting aluminum for the top-plates. i should have my FPE face-plates next week 
	

	
	
		
		

		
		
	


	




.

 Ti,
 i hope you don't mind me skanking an extra set of 2sk170/2sj74 for a Pass F5 build 
	

	
	
		
		

		
		
	


	




.


----------



## dude_500

I was working on an unrelated project on my work bench with my beta-22 amp unenclosed and turned on next to me. An uninsulated wire went under the power supply board and I hard some crackling noise and noticed a bit of smoke coming out. I quickly pulled the wire out and music continued on one channel (a bit distorted) for a few seconds and the fuse did not blow, however I turned it off. The wire shorted something in the area of the red circle on the bottom of the board. There is no visual damage.

 I removed the amp boards and plugged in the sigma22 and it gives 30V on the positive rail, but only 2V on the negative rail. Also to note is that days later (happened earlier this week) there was still a 30V charge across Q15 and Q16 which I had to bleed. The FET's don't appear to be blown (they are not shorted). What do you think blew out to cause this?


----------



## amb

Check to make sure both your transformer windings are still putting out a reasonable AC voltage. Also check the rectifier diodes with your DMM's diode check function. Check the 0.47 ohm resistors too.


----------



## dude_500

Transformer, D1-D4, and .47's are all fine.


----------



## amb

Then power up and check the voltage on the negative rail MOSFETs' metal mounting tabs. If they are complements of what you get on the positive side, then check the voltages at R6 and R7 relative to G (it doesn't matter which end of the resistors you test). What do you get?

 Power off and let all capacitors discharge fully, then use the DMM diode check function and check all the BJTs. I posted how to do this earlier in this thread.


----------



## fishski13

i'm placing an order with Digikey tonight and just want to make sure that C1 on the ground channel is 33pF.


----------



## amb

Quote:


  Originally Posted by *fishski13* /img/forum/go_quote.gif 
_i'm placing an order with Digikey tonight and just want to make sure that C1 on the ground channel is 33pF._

 

Yes.


----------



## fishski13

i'm finishing up stuffing the 3rd channel. i'm going to listen to the 2-channel passive ground for one more evening before i slot the 3rd board in tomorrow. i also finished my top-plates today. i'm very happy with how the faux anodized finish turned out.


----------



## DoYouRight

great job love the mesh, as well as one not afraid to do their chassis truly hands on and not just ordered.


----------



## nattonrice

How did you affix the mesh to the panel? 
 I had a similar idea for the top panels back when I started but was worried that without using bolts there was going to be a problem if someone pushed the mesh into the amp.
 (shorting out and such)


----------



## fishski13

Quote:


  Originally Posted by *nattonrice* /img/forum/go_quote.gif 
_How did you affix the mesh to the panel? 
 I had a similar idea for the top panels back when I started but was worried that without using bolts there was going to be a problem if someone pushed the mesh into the amp.
 (shorting out and such)_

 

8 strategically placed small blobs of regular JB Weld epoxy per face-plate 
	

	
	
		
		

		
			





. i weighed the perf steel down with 4 lbs of heatsinks raised up on 1x1" pieces of scrap wood so that there wouldn't be any sagging.


----------



## fishski13

epoxy is like duct tape for chassis work, except for when it sets, it's permanent 
	

	
	
		
		

		
		
	


	




. 

 btw, i scored lines on the backside of the top-plate to line the mesh holes up proper with the vent holes.

 my face-plates from FPE should be here on Monday.

 i'm going to rip out the Supra cable direct connection to the PEC pot and install proper RCAs with cotton sheathed solid silver - i'm a cable dork and need the flexibility of swapping cables.

 anyway...the B22 continues to impress. i can't wait to hear what an active ground channel will do.


----------



## IPodPJ

http://www.head-fi.org/forums/f6/b22...elcome-450901/


----------



## sachu

That's blood brilliant!!..great going on the design.


----------



## IPodPJ

Thanks!


----------



## fc911c

very classy design, well fitting for the B22


----------



## fishski13

iPod,
 very sexy.


----------



## dude_500

-45 and 45V across the FET's heatsink tabs. The negative side doesn't bleed on its own and still has -40V on them an hour later.

 R6 and R7 have only 100mV on them with respect to ground which appears to be wrong. The positive side has 30V on those resistors. Should I proceed to test BJT's based on this data?


----------



## amb

Yes, test the BJTs.


----------



## dude_500

Quote:


  Originally Posted by *amb* /img/forum/go_quote.gif 
_Yes, test the BJTs._

 

Q2 was burned out. I'll just replace them all though since they're cheap and I have to order spares anyways. Is it likely that the current regulators are alright? Can they be tested just as diodes are on a DMM? Those are very costly and I'd rather not order extras if they're not needed.


----------



## amb

The CRDs rarely fail. You cannot test them like diodes because they're not ordinary diodes. They're in fact precision JFETs with their drain on one pin and gate+source on the other.


----------



## KevDo

I'm assuming this amp running at 50watts RMS driving speakers wont be ideal for sustained periods of time due to heat etc, etc? (not that it would be running even near half the full power).

 Would be interested in building a DIY amp and DAC as some point. Might look into this further once I decide to build a headphone rig again.

 Interesting read though 
	

	
	
		
		

		
			





 Some nice DIY'ing going on here.


----------



## dude_500

Quote:


  Originally Posted by *KevDo* /img/forum/go_quote.gif 
_I'm assuming this amp running at 50watts RMS driving speakers wont be ideal for sustained periods of time due to heat etc, etc? (not that it would be running even near half the full power).

 Would be interested in building a DIY amp and DAC as some point. Might look into this further once I decide to build a headphone rig again.

 Interesting read though 
	

	
	
		
		

		
		
	


	




 Some nice DIY'ing going on here._

 

The beta-22 can just barely do 50 watts if it's in a 4-board balanced configuration. It would be much more optimal to build a beta-24 if you want this class of audio, however that is a very expensive build.

  Quote:


  Originally Posted by *amb* /img/forum/go_quote.gif 
_The CRDs rarely fail. You cannot test them like diodes because they're not ordinary diodes. They're in fact precision JFETs with their drain on one pin and gate+source on the other._

 

Got the new JFET's in today, sounding great again! Thanks for the help.


----------



## fsrick

Hi all, I am wondering if it is worthy to upgrade the capacitors on beta22. I am using Nichicon HE series now, upgrading them to KZ (muse) series does not cost much, but just need some work to replace them. have any body done the capacitor upgrade and have noticeable improvement? any information will help, thanks.


----------



## johnwmclean

Quote:


  Originally Posted by *fsrick* /img/forum/go_quote.gif 
_Hi all, I am wondering if it is worthy to upgrade the capacitors on beta22. I am using Nichicon HE series now, upgrading them to KZ (muse) series does not coast much, but just need some work to replace them. have any body done the capacitor upgrade and have noticeable improvement? any information will help, thanks._

 

This thread might help you, it’s all been discussed before...


http://www.head-fi.org/forums/f6/nee...22-amp-338879/


----------



## fsrick

Oos, that thread did not go well......
	

	
	
		
		

		
		
	


	




  Quote:


  Originally Posted by *johnwmclean* /img/forum/go_quote.gif 
_This thread might help you, it’s all been discussed before...


http://www.head-fi.org/forums/f6/nee...22-amp-338879/_


----------



## Beefy

True, but the message is pretty clear...... boutique parts are not necessary at all. The UHE are great power supply caps, so I personally see little need to switch them out.


----------



## fsrick

I got it, thanks to clear this out.

  Quote:


  Originally Posted by *Beefy* /img/forum/go_quote.gif 
_True, but the message is pretty clear...... boutique parts are not necessary at all. The UHE are great power supply caps, so I personally see little need to switch them out._


----------



## IPodPJ

The only required parts I would recommend spending a little more on are custom transformers with electrostatic shielding and potted in a steel can, high quality attenuator, and a high quality input switch. I wouldn't consider Vishay resistors a boutique part since they are on the recommended list and don't cost that much (provided you use the recommended tolerances).


----------



## fsrick

so far, all my components are default from the glass jar audio kit. I did not notice there is a capacitor upgrade option in the order form, otherwise for only 20 dollar more, i will really consider it. (IPodPJ, looks like you have the capacitors upgrade 
	

	
	
		
		

		
		
	


	




)
 I am thinking about the DACT attenuator on headamp, since that is a really great deal. but i might want to build a ladder type myself, personally prefer the shortest signal path from only two resistors.
 If I use a separate chassis for the power unit, is it still necessary to do the shielding? I heard the interference will go away if we place the transformer in a different chassis (it is steel/aluminum, not wood).


----------



## johnwmclean

No shielding is necessary if the transformers are in a separate enclosure. A DACT attenuator is a very nice piece of kit, I’m loving mine


----------



## nattonrice

Quote:


  Originally Posted by *fsrick* /img/forum/go_quote.gif 
_I am thinking about the DACT attenuator on headamp, since that is a really great deal. but i might want to build a ladder type myself, personally prefer the shortest signal path from only two resistors._

 

Unless you use some rather esoteric Vishay resistors your diy ladder is most likely going to be "technically" inferior to the dact.
 Whether you are going to hear this or not will be a different matter.


----------



## luvdunhill

Quote:


  Originally Posted by *johnwmclean* /img/forum/go_quote.gif 
_No shielding is necessary if the transformers are in a separate enclosure. A DACT attenuator is a very nice piece of kit, I’m loving mine 
	

	
	
		
		

		
		
	


	


_

 

surely one cannot make this statement categorically? Perhaps the builder plans on stacking the PSU on top of a low-output moving coil phono stage?


----------



## deerinheadlights

What about the CRDs. My glass jar kit came with the J508 and J511 CRDs. I changed to the 1N5307 and 1N5314 CRDs because they have better specs but I have no idea if it really changed anything for the better.


----------



## johnwmclean

Quote:


  Originally Posted by *luvdunhill* /img/forum/go_quote.gif 
_surely one cannot make this statement categorically? Perhaps the builder plans on stacking the PSU on top of a low-output moving coil phono stage?_

 

Shoot the builder 
	

	
	
		
		

		
			





 otherwise I stand firmly by what I’ve stated, categorically. A shielded transformer is not necessary for a two chassis build.


----------



## amb

Quote:


  Originally Posted by *deerinheadlights* /img/forum/go_quote.gif 
_What about the CRDs. My glass jar kit came with the J508 and J511 CRDs. I changed to the 1N5307 and 1N5314 CRDs because they have better specs but I have no idea if it really changed anything for the better._

 

The benefit of the 1N5xxx CRDs is tighter tolerance and higher voltage rating. Neither of these would result in sound quality differences, but some applications (i.e., 36V output σ22 and σ11) require the higher voltage rating for adequate safety margin. Also, Vishay-Siliconix has stopped manufacturing the J5xx CRDs, so the 1N5xxx series may sometimes be the only option.

  Quote:


  Originally Posted by *fsrick* 
_If I use a separate chassis for the power unit, is it still necessary to do the shielding? I heard the interference will go away if we place the transformer in a different chassis (it is steel/aluminum, not wood)._

 

The whole point is to reduce magnetic field interference from the transformer to the amplifier. If you use a separate chassis to house the transformer(s), then it allows you to put them some distance away from the amp chassis. In that case shielded transformers are not necessary. If you cannot put the transformer far away (i.e., single chassis, or if you must stack one on top of another). then shielded transformers _may be_ needed to prevent hum and noise. A steel chassis (or some other ferrous metal, or mu-metal) might help provide some shielding, but aluminum does not.


----------



## n_maher

Quote:


  Originally Posted by *johnwmclean* /img/forum/go_quote.gif 
_Shoot the builder 
	

	
	
		
		

		
		
	


	




 otherwise I stand firmly by what I’ve stated, categorically. A shielded transformer is not necessary for a two chassis build._

 

And I disagree categorically. There are plenty of situations where shielding would still be beneficial if not necessary.


----------



## johnwmclean

Quote:


  Originally Posted by *n_maher* /img/forum/go_quote.gif 
_And I disagree categorically. There are plenty of situations where shielding would still be beneficial if not necessary._

 

And what situations would they be?


----------



## Pars

Quote:


  Originally Posted by *johnwmclean* /img/forum/go_quote.gif 
_And what situations would they be?_

 

Obviously single chassis, which I still feel has some advantages if you can do it. Stacking the amp and PSU would also be one. Also, any situation where the PSU is near anything else that might pick up EMI, such as sources, etc.


----------



## Beefy

Quote:


  Originally Posted by *johnwmclean* /img/forum/go_quote.gif 
_And what situations would they be?_

 

To my understanding, the benefit of using two cases isn't the shielding the case provides, but the benefit of increasing the distance. So if you had aluminium cases, a shielded transformer might still be very desirable.

 And as mentioned, proximity to sources etc. might cause interference.


----------



## johnwmclean

Quote:


  Originally Posted by *Beefy* /img/forum/go_quote.gif 
_To my understanding, the benefit of using two cases isn't the shielding the case provides, but the benefit of increasing the distance. So if you had aluminium cases, a shielded transformer might still be very desirable.

 And as mentioned, proximity to sources etc. might cause interference._

 

In that case I stand corrected, I actually thought the chassis formed the basis for the shielding within a two case build. 

 Problems with one enclosure builds are clearly documented within these forums where the use of a shielded transformer was necessary, but I have never come across a scenario where a builder has had problems with noise from an unshielded transformer in a two case build.

 Case in point would be the group build, Krmathis stacks his amp and I believe the amp preforms flawlessly, my own amp is another case.


----------



## Beefy

Well according to this first hit from a google search, the magnetic permeability of aluminium is the same as air, and thus no more effective than air for shielding.


----------



## johnwmclean

Quote:


  Originally Posted by *Beefy* /img/forum/go_quote.gif 
_Well according to this first hit from a google search, the magnetic permeability of aluminium is the same as air, and thus no more effective than air for shielding._

 

you got in before my edit, see my above post.


----------



## amb

Quote:


  Originally Posted by *johnwmclean* /img/forum/go_quote.gif 
_...
 Case in point would be the group build, Krmathis stacks his amp and I believe the amp preforms flawlessly, my own amp is another case._

 

Don't forget that krmathis uses high-impedance or low-efficiency headphones (e.g., AKG K1000) with that amp, so any magnetic interference will be rather inaudible. I tested the amp with my HD600s and it's dead silent when the two cases are stacked, but try a low-Z can and see...

 Of course, move the two cases apart and the slight noise disappears for just about any headphone (except perhaps IEMs, which will exhibit a little hiss due to the high amp gain).


----------



## johnwmclean

Thank you for the clarification, I was under the wrong assumption - and I’ve learnt something new - cheers guys


----------



## luvdunhill

Quote:


  Originally Posted by *johnwmclean* /img/forum/go_quote.gif 
_Thank you for the clarification, I was under the wrong assumption - and I’ve learnt something new - cheers guys 
	

	
	
		
		

		
		
	


	


_

 

assumptions make poor categorical statements... categorically speaking, of course


----------



## Possede

I'm thinking of putting one of these on the front panel of my β22 chassis via the ε22 backplane. Their operating current is 6-16mA, so using a 24V σ22, I'd be looking to use ~2kΩ resistor, right? (I = V/R)


----------



## cfcubed

Found myself short a couple 33pf for C1 with 100pfs available... Would be detrimental to use the 100pf for C1s (perhaps until a future parts order)? 

 BTW I do have the proper C2 - C5 for my target gain.

 TIA for any advice.


----------



## amb

Possédé, what you've linked to looks like an incandescent lamp, not LED. If so, its operating current may be highly variable depending on the filament temperature and is difficult to predict. You'd have to experiment to get an appropriate series resistance.

 cfcubed, using 100pF would cut the amp's bandwidth severely. Why not just get the correct 33pF caps? I generally don't recommend putting in "temporary" substitute parts only to replace them later, because it would require desoldering and resoldering, and needlessly stressing the board pads.


----------



## Steve Eddy

Quote:


  Originally Posted by *cfcubed* /img/forum/go_quote.gif 
_Found myself short a couple 33pf for C1 with 100pfs available... Would be detrimental to use the 100pf for C1s (perhaps until a future parts order)?_

 

When I ordered parts for iPodPJ's build, I transposed the quantities for the 33pF and 47pF parts so have some extra 33pF parts.

 PM me a mailing address and I'll send you a couple.

 se


----------



## cfcubed

Quote:


  Originally Posted by *amb* /img/forum/go_quote.gif 
_cfcubed, using 100pF would cut the amp's bandwidth severely. Why not just get the correct 33pF caps? I generally don't recommend putting in "temporary" substitute parts only to replace them later, because it would require desoldering and resoldering, and needlessly stressing the board pads._

 

Thanks - I'll not be using the 100pf. Reason was its a bit of ride (during business hours) to a place I can pick up 33pFs and, not needing any other parts ATM, doesn't warrant yet another parts order...
  Quote:


  Originally Posted by *Koyaan I. Sqatsi* /img/forum/go_quote.gif 
_PM me a mailing address and I'll send you a couple._

 

Thank you very much for the offer... But I'll make tomorrow (Wed) a "work-from-home" day & take a long lunch to get them & a few more things


----------



## Steve Eddy

Quote:


  Originally Posted by *cfcubed* /img/forum/go_quote.gif 
_Thank you very much for the offer... But I'll make tomorrow (Wed) a "work-from-home" day & take a long lunch to get them & a few more things
	

	
	
		
		

		
		
	


	


_

 

Okie doke.

 se


----------



## fishski13

i finally got around to taking some pics: http://www.head-fi.org/forums/f6/pos...ml#post6116283


----------



## rhester

Is that your wood work or somebody else? Looks very well done>


----------



## fishski13

Quote:


  Originally Posted by *rhester* /img/forum/go_quote.gif 
_Is that your wood work or somebody else? Looks very well done>_

 

thanks. my woodwork, done with a router table and chop box - 4 coats of tung-oil. the top and back aluminum plates were sanded with 320 grit and several coats of clear spray paint. i then sanded them down with 0000 steel wool to get an anodized look.


----------



## Possede

Quote:


  Originally Posted by *amb* /img/forum/go_quote.gif 
_Possédé, what you've linked to looks like an incandescent lamp, not LED. If so, its operating current may be highly variable depending on the filament temperature and is difficult to predict. You'd have to experiment to get an appropriate series resistance._

 

Cheers, I never realised that it was an incandescent and not an LED. I found an alternative LED indicator. 

 Now, what I am about to ask may come across as silly... But is there a way of securely fixing the boards and transformer to the case without screws being visible from the bottom. I just don't like the idea of having a big silver M5 screw head sticking out from underneath the black case (And lots of M3 screws). I was thinking of cutting a sheet of aluminium that would fit into the side grooves of the Galaxy Maggiorato, which the boards and transformers can be attached to.

 Another question is, as my case is anodised aluminium (which to the best of my knowledge is a non-conductor of electric current), how do I go about earthing my case. Would all I need to do is attach a wire from the earth terminal to a part of my case which is not anodised? For instance, if I cut a hole in the back of my case, put a screw through it, and wound the earth wire around that screw and tightened it with a nut. 

 Any input would be appreciated.


----------



## amb

Quote:


  Originally Posted by *Possédé* /img/forum/go_quote.gif 
_I found an alternative LED indicator._

 

That things is going to be mighty bright at 7000mCD. Also, looks like it has either an internal resistor or current regulator, so you need to power it with a raw 12-28V. See this thread about using a zener diode to drop the power supply voltage to within those limits.

  Quote:


 Now, what I am about to ask may come across as silly... But is there a way of securely fixing the boards and transformer to the case without screws being visible from the bottom. 
 

Either you conceal them with another panel, or use a _really_ thick bottom plate and have some threaded blind holes (that doesn't go all the way through to the bottom). But why? It's the bottom and you're not going to look at it when it's sitting down...

  Quote:


 Another question is, as my case is anodised aluminium (which to the best of my knowledge is a non-conductor of electric current), how do I go about earthing my case. Would all I need to do is attach a wire from the earth terminal to a part of my case which is not anodised? For instance, if I cut a hole in the back of my case, put a screw through it, and wound the earth wire around that screw and tightened it with a nut. 
 

Only the anodized surface is non-conductive. The aluminum itself is still conductive. If the panels are fixed to each other with screws, then the screw threads should be able to electrically couple all the panels. For anything that needs to connect to the chassis (i.e., the IEC AC ground), you can drill a hole on the bottom plate, crimp or solder the wire to a ring terminal, and secure it to the plate with a short machine screw, serrated lock washer and nut. The lock washer should "bite" through the anodizing and make electrical contact. If not, you can scrape away some of the anodizing around the hole.


----------



## pila405

amb - Can you answer the PM I sent you, please?

 Does anyone have a graph shows the Beta22's frequency response?


----------



## amb

Quote:


  Originally Posted by *pila405* /img/forum/go_quote.gif 
_Does anyone have a graph shows the Beta22's frequency response?_

 

There is a graph in the RMAA test results found in the "Specifications" section of the β22 website. However, that graph does not represent the complete bandwidth of the amp, because it is limited by the computer sound card used for measurement. The actual graph is a ruler flat line from 0Hz to well above audio range, and rolls off to -3dB at 2.5MHz.


----------



## Beefy

Quote:


  Originally Posted by *pila405* /img/forum/go_quote.gif 
_amb - Can you answer the PM I sent you, please?

 Does anyone have a graph shows the Beta22's frequency response?_

 

You're a demanding little ...... person...... aren't you?


----------



## pila405

Quote:


  Originally Posted by *amb* /img/forum/go_quote.gif 
_There is a graph in the RMAA test results found in the "Specifications" section of the β22 website. However, that graph does not represent the complete bandwidth of the amp, because it is limited by the computer sound card used for measurement. The actual graph is a ruler flat line from 0Hz to well above audio range, and rolls off to -3dB at 2.5MHz._

 

WOW! Realy?! It sounds amazing!


----------



## cfcubed

BTW, got those 33pf C1s & my boards seem GTG. All measurements & temps are dead on (now 
	

	
	
		
		

		
		
	


	




 anyway). Built from Jeff's (glassjaraudio) kits. Once again, have to say he's providing a great service to this community. Only one tiny part error (2 x 100pf instead of 33pf) & I'm replacing one blue LED, no biggie considering the pile of parts.

 Of course PCB design, layout, etc. are nicely symmetrical & generally outstanding - sorry Ti if we are overloading you w/kudos lately but they are deserved.

 Initially, only 1 board came up nicely, the other's voltages were off (e.g. offset would not stabilize below 100mv). Although thought I was very methodical in the parallel populating of the boards, on 2nd visual inspection there was a single un-soldered joint.





 A few things drove my choice to give a non-σ22 PS a try, e.g. size of case on-hand, wanting 2-box build advantages w/o 2 boxes, co$t & having 2 matched 24VAC .833A wallwarts. So the PS is a simple non-tracking 7824/7924 affair. Perhaps could have gone w/minimalist tracking bit from Fig 16 of Fairchild DS. Remains to be seen how this thing will perform compared to one w/a "proper" PS or to a proper M³ which would come in somewhat below the cost of this. Counting on β22's high PSRR & keeping transformers out of the case.

 If things continue to go well I'll bring this to Nov 14th NYC meet. We'll see.


----------



## ting.mike

I'm trying to adjust the VR2, while getting the measurements on the R34, supposedly in the range of 55mV to 75mV. I can't seem to pin down an exact reading on the multimeter. The number jumps around from roughly 68mV to 74mV. Is the variation supposed to be that great? 

 This is at amp operating temperature, and following all the guidelines from the amb website.

 I've measured the AC line, and AC voltage is pretty stable at 224-223 volts.
 DC power from the S22 is also pretty stable at 29.8 to 29.9 volts.


----------



## amb

ting.mike, the quiescent current will drift up and down based on heatsink and ambient temperatures. Your readings are not out of line.


----------



## johnwmclean

Quote:


  Originally Posted by *ting.mike* /img/forum/go_quote.gif 
_I'm trying to adjust the VR2, while getting the measurements on the R34, supposedly in the range of 55mV to 75mV. I can't seem to pin down an exact reading on the multimeter. The number jumps around from roughly 68mV to 74mV. Is the variation supposed to be that great? 

 This is at amp operating temperature, and following all the guidelines from the amb website.

 I've measured the AC line, and AC voltage is pretty stable at 224-223 volts.
 DC power from the S22 is also pretty stable at 29.8 to 29.9 volts._

 

Looks good to me, leave it on for 15-20mins then take your reading over R34, it should stabilise a little.


----------



## n_maher

Anyone working on a beta22 should have at least one pair of mini grabbers. Hook the pair to R34, leave the DMM on, take readings for the first hour every 10 minutes or so and see how it goes. Repeatedly sticking probes in there while being blinded by blue LEDs gets old fast.


----------



## cfcubed

Yes, like the pic in amb's initial setup, lots of good info up there... Mounting parts w/a bit of clearance, resistor markings/value up, etc. 
 Clip leads w/those mini grabbers come in very handy too.


----------



## ting.mike

Thanks, all.. yes, I'm using the mini grabbers like in the one told by AMB. 

 The Balanced Beta22 actually has been running flawlessly, and gosh, the sound is out of this world. I've never heard a headphone sounding so three dimensional. I'm just trying to adjust the VR2 to be more precise, but apparently that's quite a challenge due to the voltage always drifting up and down. 

 I'll take pictures and post them soon! 

 Thanks, Ti Kan, for this awesome amp!


----------



## fishski13

Quote:


  Originally Posted by *ting.mike* /img/forum/go_quote.gif 
_Thanks, all.. yes, I'm using the mini grabbers like in the one told by AMB. 

 The Balanced Beta22 actually has been running flawlessly, and gosh, the sound is out of this world. I've never heard a headphone sounding so three dimensional. I'm just trying to adjust the VR2 to be more precise, but apparently that's quite a challenge due to the voltage always drifting up and down. 

 I'll take pictures and post them soon! 

 Thanks, Ti Kan, for this awesome amp!










_

 







 the B22 _is_ an awesome amp.


----------



## cfcubed

Just a little update to my 1st frugal 2-ch b22 post. BTW updated the pic in that post.

 Some quick-n-dirty wire up this morning & she's sounding very sweet. All the good things (absolutely black background, amazing range, Vs & temps on the money).

 "Just" have casework to go (offset protection, $50 fleabay case) and _should_ make it for the NYC Fall meet. BTW, getting two DA-20-24 24VAC 830mA adapters for $15 shipped makes this look to be coming in a bit below $350 USD.


----------



## Anonanimal

Hey all- I'm currently building a 3-channel β22 and I'm wondering if anyone has any input with respect to the use of the ε12 Muting/Protection Circuit. i.e. has anyone found significant turn-on/off noise with their β22s without this circuit? I do understand the usefulness of the circuit as protection from high DC offsets but I'm trying to decide if it's absolutely necessary. Thanks for any and all input!


----------



## ShinyFalcon

Without an ε12, there is no turn on noise (music fades in after power is applied), and _maybe_ a turn off squeak when power is cut off.


----------



## amb

β22 is very well-behaved at turn-on and turn-off. There should be no thump or transients.


----------



## Anonanimal

Excellent. Thank both of you very much for the quick responses.


----------



## Possede

Thanks again for your reply amb. 
	

	
	
		
		

		
		
	


	




 As I do not trust myself with power tools, I am having all my panels sent away to be professionally machined (even the base of my case). 
	

	
	
		
		

		
		
	


	




 amb, I would be most grateful if you could provide the board measurements (the distances between the holes for spacers) for the ε22 backplane and the ε24 power switch driver circuit, like you have for the σ22:


----------



## amb

The ε22 backplane board dimensions and mounting hole locations are found here:
HeadWize: View Post [DIY Workshop » β22: A discrete, cascoded, fully complementary, pure class A amplifier (part 2)]

 The ε24 board dimensions is 2.0" x 1.2". Its four mounting hole centers are at:

 0.2", 0.2"
 1.8", 0.2"
 1.8", 1.0"
 0.2", 1.0"


----------



## Possede

Many thanks for the quick reply. Now I will be able to get this
 project on the way to completion. I'll post an image of my
 panels once I've finalised them to gather some feedback.


----------



## Possede

Delete.


----------



## cfcubed

Well mine is done and working great FWIW.


----------



## Anonanimal

That looks great cfcubed- I love the price point you were able to hit with that build!

 On that note my 3-ch is nearly complete as well. I'm listening to it for the first time right now! Sounds amazing...


----------



## fishski13

Quote:


  Originally Posted by *cfcubed* /img/forum/go_quote.gif 
_Well mine is done and working great FWIW._

 

any working B22 is a beautiful amp. i also prefer the minimalist aesthetic. excellent job on squeezing the components into a small package too. i guess considering your work on the CTH, compactness is your specialty 
	

	
	
		
		

		
			





.


----------



## cfcubed

Thanks guys. Yes, guess I wanted/enjoyed the challenge of building it on a low budget. Looking forward to comparing this to a "proper" 3-ch b22 this weekend.

 @Anonanimal - It is a special time when you pwr up a new build & get to hear for the 1st time
	

	
	
		
		

		
		
	


	




 @fishski13 - re:_considering your work on the CTH, compactness is your specialty_ Guess I like that challenge too... Right up to the point of final assembly
	

	
	
		
		

		
		
	


	




 Then I start wondering why I keep doing these compact builds


----------



## n_maher

Quote:


  Originally Posted by *cfcubed* /img/forum/go_quote.gif 
_Well mine is done and working great FWIW._

 

Nice job! If I could make a suggestion it would be to add additional ventilation to both the top and bottom panels. As crowded as that is on the inside I think you'll want more airflow to keep things working happily in the long term.


----------



## cfcubed

Quote:


  Originally Posted by *n_maher* /img/forum/go_quote.gif 
_Nice job! If I could make a suggestion it would be to add additional ventilation to both the top and bottom panels. As crowded as that is on the inside I think you'll want more airflow to keep things working happily in the long term._

 

Thank you very much for this Nate.... I plan to let 'er heat up for an hour or two tonight w/a temp probe inserted into one of the rear panel 1/4" holes. Using a hand on the (thin) top it's seeming to only get warm after a couple hrs.

 I'm loath to trying to match/expand the small hole pattern in the top, esp w/its extreme thinness. That's why I lined the bottom & back plates w/holes.

 Perhaps you can give her a listen Saturday (& maybe CTH too), I'd appreciate your thoughts on them.






 Notes:
Not a spec of hum detectable w/my most sensitive cans (D2000s). Update: Some hiss tho from 12 -> 4 pot volume (but not @ full volume) w/source muted, well above my listening levels.
W/R34 set to 55mV (~120ma) after 1 hr, drawing a bit less than 500ma from each wallwart. Of course they are in series w/center-tap = tip<->sleeve giving 26-0-26 (52VAC) under load.
Can see shielded cable where it matters (all input wiring, DPDT A/C switch wiring). 1st PS caps & heatsink positioning to further block A/C.
If I keep this PS arrangement will get cable wrap for 2 WW wires & install good 3-cond pwr jack + plug. Those jacks are the weakest physical link ATM.


----------



## Anonanimal

Finished 3-ch sitting on my desk making some sweet, sweet sounds. 
	

	
	
		
		

		
		
	


	




 It's dead silent (input muted) through a full volume sweep when stacked with the power supply, using shielded StarQuad on the input wiring. I used the standard output gain of 8.

 I want to give a *huge* thanks to Amb and the rest of the community for all of the great projects and I look forward to what the future may bring!

 Edit: Sorry the pictures are lame but my camera is old and I don't have a tripod...


----------



## johnwmclean

By golly, that’s a thing of beauty...


----------



## nattonrice

Very excellent =]


----------



## cfcubed

@ Anonanimal very nice & neat build. Great that it sounds as good as it looks.


----------



## Anonanimal

Thanks for the kind words! I know it's not very visually exciting but I was trying to keep it as subdued as I could- and I'm very partial to black vs silver. There's no external LEDs or anything like that- just a faint red glow from inside when it's powered on. I'll try to get a night shot of it when I have a bit more time.


----------



## krmathis

Quote:


  Originally Posted by *Anonanimal* /img/forum/go_quote.gif 
_Finished 3-ch sitting on my desk making some sweet, sweet sounds. 
	

	
	
		
		

		
		
	


	


_

 

Nice, clean build. Well done!


----------



## amphead

Very good job, of putting an excellent sounding amplifier together!


----------



## tintin47

Quick question about power switches. I am looking at this one: Switch The first question is about the current limit, which is 3A. I am not really sure how much a 3 ch. beta will draw driving only headphones. Also, in terms of the design, I am just making sure that latching means that I will press the button and the switch will maintain contact.

 One more question: are there any decent potentiometers in the $40-60 range that are better than the Alps blue velvet? I have one on my CK2III and I would like something beter for the beta.


----------



## MoodySteve

Quote:


  Originally Posted by *tintin47* /img/forum/go_quote.gif 
_Quick question about power switches. I am looking at this one: Switch The first question is about the current limit, which is 3A. I am not really sure how much a 3 ch. beta will draw driving only headphones. Also, in terms of the design, I am just making sure that latching means that I will press the button and the switch will maintain contact.

 One more question: are there any decent potentiometers in the $40-60 range that are better than the Alps blue velvet? I have one on my CK2III and I would like something beter for the beta._

 

The link for the switch doesn't work for me, but I assume it's one of the Bulgin vandal-resistant latching switches. Yes, 'latching' means that if you press it, it stays 'on' until you press it once more. 3A is more than enough for normal operation; where you may get into trouble is transformer inrush, where the transformer (briefly) pulls a relatively large amount of current when it's first energized. This can be minimized by using a thermistor or even a power resistor in line with the primary.

 Regarding replacements for the RK27, there's the Noble AP25 (available on eBay), the TKD 2CP-2511 and the Audio Note Noble equivalent (both available at Parts Connexion). Allen-Bradley probably has some usable ones, though you'd have to look in industrial catalogs (they don't target audio).


----------



## Beefy

Quote:


  Originally Posted by *MoodySteve* /img/forum/go_quote.gif 
_Regarding replacements for the RK27, there's the Noble AP25 (available on eBay), the TKD 2CP-2511 and the Audio Note Noble equivalent (both available at Parts Connexion). Allen-Bradley probably has some usable ones, though you'd have to look in industrial catalogs (they don't target audio)._

 

For not much more - relative to the total project cost anyway - you can get a DACT for $129 from Headamp.


----------



## tintin47

I am not trying to build a budget beta, but I just don't think that I have a good enough ear to warrant $130 on a potentiometer. The main thing that I want is something that feels nicer than the RK27.


----------



## MoodySteve

The DACT is a stepped attenuator, not a pot, so it's probably not suitable for what you want anyway.


----------



## tintin47

^ I know. I don't really differentiate between them in my brain. The function is the same even if the design isn't. I should have bid more on those dual mono goldpoints during the silent auction.


----------



## m1abrams

Quote:


  Originally Posted by *MoodySteve* /img/forum/go_quote.gif 
_The DACT is a stepped attenuator, not a pot, so it's probably not suitable for what you want anyway. 
	

	
	
		
		

		
		
	


	


_

 

Why not? A stepped attenuator works very well for volume control. It does have a different feel when using it. I have not used a DACT one so not sure how they "feel".


----------



## m1abrams

Quote:


  Originally Posted by *tintin47* /img/forum/go_quote.gif 
_I am not trying to build a budget beta, but I just don't think that I have a good enough ear to warrant $130 on a potentiometer. The main thing that I want is something that feels nicer than the RK27._

 

hmm what about the RK27 do you not like? So that people can use that to suggest something.

 Personally I find the RK27 to be very smooth for feel. Maybe using a larger knob would make it feel better? Smaller knobs tend to have a rougher feel when turning the pot.


----------



## MoodySteve

Quote:


  Originally Posted by *m1abrams* /img/forum/go_quote.gif 
_Why not? A stepped attenuator works very well for volume control. It does have a different feel when using it. I have not used a DACT one so not sure how they "feel"._

 

I was under the impression (from talking with tintin at the meet) that he was only interested in potentiometers, not steppers, so that's why i said it wouldn't be what he wanted. I personally prefer to have continuously adjustable volume control, as opposed to the discrete volume levels of stepped attenuators. I also like the smoother feel of non-detented pots.

 He also stated that his budget was around $70 max.


----------



## nattonrice

If you listen quietly then the rk27 can be a complete pita.
 The one I had on an amp of mine had this very annoying channel in-balance which only righted itself at a volume that I didn't like.
 Naturally a stepped attenuator like the DACT does not have this problem and will have essentially perfect matching at the lowest level.

 Something to keep in mind.


----------



## Beefy

Yeah, I certainly wouldn't use an RK27 for super sensitive phones or with a high gain amp.

 But I wouldn't use a DACT under the same circumstances either. Sure, channel matching is extremely good, but the step size is very large at the low end...... your first two steps after mute are -60dB and -50dB, then 4dB steps up to -34dB, then 2dB steps up to 0dB.

 So anything quieter than -34dB will be very hit and miss.


----------



## Pars

TKD CP2500 (or 2511) ~$65 or so. Michael Percy Audio, PartsConnexion (which is having a 20% sale currently). Seductively smooth, and good sounding.


----------



## tintin47

Thanks, everyone, for attempting to answer my poorly formed and incomplete question. I was posting from my phone and I had to go unexpectedly. 

 Beefy and Nattonrice are dead on. The real problem I have with the RK27 is that it is terrible and frustrating to use before about 11 or 12 oclock on the dial. I listen quietly and I use sensitive phones. On my CK2III with a gain of 4 I never get past 11 oclock with my grados, and usually it is around 10. I can't simply build a 2x gain beta because I just bought the HE5, for which I think I'll need a gain of at least 5x if not more. So I'd like a potentiometer that is accurate (or at least channel balanced) from end to end. 

 I have no problems with a stepper and it might be very nice, but I am worried about the step size on the low end as Beefy pointed out.


----------



## boinger

Its been a while since i did any work on my beta.. but im having some problems 

 I have to turn the volume up pretty high to get any sound... im using a joshua tree attenuator... 

 and when it is very low i here an extremely loud pop in my headphones before i can hear anything... 

 and there is also lots of sound distortion its not very clear.. also the volume in the right channel is almost non existent... 

 i have it setup as a test bed right now .. any idea where i should start ?


----------



## MrMajestic2

Quote:


  Originally Posted by *boinger* /img/forum/go_quote.gif 
_Its been a while since i did any work on my beta.. but im having some problems 

 I have to turn the volume up pretty high to get any sound... im using a joshua tree attenuator... 

 and when it is very low i here an extremely loud pop in my headphones before i can hear anything... 

 and there is also lots of sound distortion its not very clear.. also the volume in the right channel is almost non existent... 

 i have it setup as a test bed right now .. any idea where i should start ?_

 

Make sure that the Joshua Tree is working like it should first.


----------



## johnwmclean

Check the psu, is the voltage right? If ok, then double check the wiring to the amp boards. Run each board through an initial check and see what you have.


----------



## ShinyFalcon

Make sure that your β22 hasn't malfunctioned. Lack of bass is a sign of high DC offset, popping from 0 -> low volume can be high DC offset, no sound might indicate a bad board.

 To check your Tree, disconnect your tree and measure resistance from IL to OL, IR to OR, etc and make sure the resistances across (IL/OL) / (IR/OR) channels are the same as the volume goes up/down. Make sure OL, OR and OG are not shorted to each other. 

 If your heatsinks on your β22 are all equally warm, the β22 are probably fine assuming DC offset is low.


----------



## boinger

How precisely do i check my tree i disconnect it from the inputs only or everything ?

 I did do the intial check before wiring up all my readings seemed ok i let it warm up for 10 minutes and all my Dc offsets were 0.0 - 0.1 mv

 i assumed the .1mv is ok ?

 Edit: im double checking it again after letting it warm up some

 also when im measuering from input L / R to output L / R what exactly should i be looking for ?


----------



## ShinyFalcon

You can disconnect just the signal input and signal output on the Tree assuming you didn't hardwire/solder them. We only need the Tree working to make sure it works as intended. Your DC offset is fine.

 We're checking to make sure that the resistance across the respective channel follows the volume. For example, when the volume is at 0%, the resistance across left.input & left.output / right.input & right.output should be a very high number. On any volume, the resistance of the left channel should be similar to resistance on the right channel. 

 If the volume is at 0, we expect very high resistance (for example, 50K ohms or infinity). If the volume is half way, we should see for example 30K ohms. If we maximize the volume, we should see low ohm. The higher the resistance, the lower the volume, and vice versa.


----------



## boinger

ok did that check im getting 1.821 k ohms regardless of volume setting im assuming the amp had to be on ?

 on one board the reading is 1.821k ohm regardless of volume

 second board its 1.821kohms at lowest 

 than 700~ ohms at full

 you think my ribbon cable could be the culprit ? the top cable doesnt look like it sfully through but i cant seem to get it through


----------



## ShinyFalcon

If the power to the I2C shares power with the β22, yes turn it on.

 I attached a picture hoping it makes measurements clearer. Clicky. 

 Did you build the Tree yourself? Maybe some pictures may help.


----------



## boinger

I did build the tree myself and yes thats what im measuring the readings are the same as the top... 

 im taking some pictures now will have em up soon


----------



## boinger

here is what im talkin about

_DSC6432.jpg photo - boinger photos at pbase.com

 the board of which the ribbon cable is on top in that picture is the one that wont budge on the resistance stays at 1.82kohms

 on both + and - rail 

 the board with the ribbon on the bottom changes from 1.82kohms to 700 ohms


----------



## ShinyFalcon

I would give the boards another look and see if you bridged anything or missed a joint, or maybe swapped orientation of a chip. Your ribbon seems to have the red stripe on the left, and according to TPA's site it should be on the right side. 

 In the meantime if you have software volume control you can tie your signal wires together (ground can go through Tree) and see if your β２２ is making some music. I think -60dB is okay; be careful, it can get VERY loud.


----------



## boinger

im redoing my sanity checks and if i have the molex plugged into the board (input) i am getting a different reading as compared to when it is unplugged? any reasons for this... 

 and when its plugged in on the opposing ground pad when im using it to measure dc offset the lowest i can get it is about 30 mv

 but when i unplug the input it can get down to 0 mv 

 you think my source can be adding some voltage to the system my source is a buffalo 32 btw


----------



## MrMajestic2

Quote:


  Originally Posted by *boinger* /img/forum/go_quote.gif 
_
 you think my ribbon cable could be the culprit ? the top cable doesnt look like it sfully through but i cant seem to get it through_

 

It looks like you dont have the cover on the connector which will push the cable down. You seem to be trying to put two ribbon cables on top of each other, it will only take one.


----------



## boinger

i had actually read somewhere that it can take 2 and thats how you were supposed to do the balanced jtree... but they broke =x so i just forced teh cable down on it it is working now i pushed a little harder and i am measuring dif resistances in both boards 

 now im just struggling with my dc offset issue


----------



## johnwmclean

Quote:


  Originally Posted by *boinger* /img/forum/go_quote.gif 
_im redoing my sanity checks and if i have the molex plugged into the board (input) i am getting a different reading as compared to when it is unplugged? any reasons for this... 

 and when its plugged in on the opposing ground pad when im using it to measure dc offset the lowest i can get it is about 30 mv

 but when i unplug the input it can get down to 0 mv 

 you think my source can be adding some voltage to the system my source is a buffalo 32 btw_

 

Your source will add voltage, even more when music is playing, although 4Vp-p (balanced) is idle for the Sabre32.


----------



## boinger

i think i have narrowed down my bad sound quality problems i think it may be my cable from the dac to the b22... is it possible for you to make a cable so bad that it is all garbled... bass sounds like its ripping n generally teh sound is like gurggling.


----------



## johnwmclean

Quote:


  Originally Posted by *boinger* /img/forum/go_quote.gif 
_i think i have narrowed down my bad sound quality problems i think it may be my cable from the dac to the b22... is it possible for you to make a cable so bad that it is all garbled... bass sounds like its ripping n generally teh sound is like gurggling._

 

Check the continuity from the pins.


----------



## boinger

well if the continuity wasnt the same wouldnt it not play ?

 i can hear music just not very well ... or do you think i may have the + - reversed ? will that even work ?

 i did check the resistance and got .2 ohms for every pin


----------



## johnwmclean

Set your DMM to continuity beeper, make sure there is a beep between wires on either end of the cable. Ground to ground and signal to signal etc, if there is a gross error you’ll hear “no beep”. Check continuity between the opposing wires there should be “no beep” again if there is, the cable is probably faulty.
 If this checks out maybe have a look at your Sabre32 outputs and make sure everything is ok there.


----------



## Beefy

....... anybody else see this coming 4 months ago?

http://www.head-fi.org/forums/f6/rol...ml#post5878608


----------



## johnwmclean

Quote:


  Originally Posted by *Beefy* /img/forum/go_quote.gif 
_....... anybody else see this coming 4 months ago?

http://www.head-fi.org/forums/f6/rol...ml#post5878608




_

 

Maybe there’s like a β22 heaven... “my builder didn’t read the the AMB initial check once” the other “DMM probe got me real good” or “rookie builder first attempt, got cap polarity totally screwed”

 Or maybe there’s no such thing, just a lot β22 doorstops.


----------



## boinger

Quote:


  Originally Posted by *Beefy* /img/forum/go_quote.gif 
_....... anybody else see this coming 4 months ago?

http://www.head-fi.org/forums/f6/rol...ml#post5878608




_

 



 you know i havent had nearly as much trouble as you made out i would have,and i generally dont have issues understanding things people tell me to do... if you dont have anything helpful to say so how bout you just not say anything ?

 you act as if having some troubleshooting issues is absolutely unheard of... 


 anyways john i do believe i found the problem the output terminals on my saber are faulty... everything is shorted to everything ie... + ground - all shorted to each other somehow im desoldering them now and gonna wire it up directly n see how that works.


----------



## nattonrice

Did you take that measurement when the buff board was off?

 The board has the "thump buster" relays built in... don't they shunt to ground when the board is off?


----------



## boinger

yes i did actually ok gotta rewire and test it again...


----------



## boinger

i tested the board again while it was on... and it still showing as shorted... 

 on or off

 that is also from the pads terminal removed...


----------



## boinger

after doing a lot of work i have determined that the cable isnt the problem nor the buffalo so back to the jtree / amp will post on twisted pair forums for the jtree..


----------



## johnwmclean

boinger, you original post states “an extremely loud pop in my headphones before i can hear anything” this does not sound like a cable or output problem from passive devices. It’s a careful process of elimination so stop jumping all round the place and consecutively home in on the problem. 
 Go back to the IEC socket and work up, it doesn’t take long and it’s methodical.

 1) Double check all components are installed correctly and are the right values.
 2) Double check and Ohm all cabling.
 3) Check that the (I assume σ22) are the correct output voltages.
 4) Do the initial setup on each β22 board.
 5) Look into jtree for a possible fault.


----------



## ShinyFalcon

Try hooking up something from your home theater system (TV preferred) into your β２２ to rule out the amp and Tree.

 You stated that the Buffalo's outputs are all shorted to each other or ground? Is it with or without the RCA cables connected? Check your RCA cables for shorts, and check your Buffalo/wiring to make sure the outputs are not shorted (with no RCA cables connected to it).


----------



## nattonrice

Quote:


  Originally Posted by *johnwmclean* /img/forum/go_quote.gif 
_It’s a careful process of elimination so stop jumping all round the place and consecutively home in on the problem._

 

This is the best advice yet on your problem.
 When dealing with a circuit that is as complex as the beta22's is you need to be slow and methodical when diagnosing a problem.


----------



## boinger

ya im taking apart the whole amp going back to the drawing board and gonna recheck the circuits using the voltage operating points schematic... will update on how it goes


----------



## tintin47

Quick question: I am looking at a bulgin switch (part no. MP0045/1E2AM012) for my build and I just want to make sure that it will maintain contact when turned on. I am just not familiar with the type of switch or the related terminology. Thanks.


----------



## aloksatoor

Yes this should maintain contact. The other buglin type would be a momentary contact switch which would need a state circuit (like AMBs epsilon 24) this one should not.


----------



## MoodySteve

The MP0045/1E2 series is illuminated and latching (i.e. maintains contact when pressed 'on'), so if you're not going to use the AMB ε24, that's what you'd need.

 I don't know that I'd be comfortable with the inrush current going through the switch...you may want to consider using a relay to do the actual switching.


----------



## tintin47

^ I know that toroidal inrush can be high, but you think that it may be more than 3 amps? If it is, would it damage the switch to be somewhat overloaded for a second right at powerup? 

 Also, if I did use a relay, where would the input current come from? My understanding of a general power relay is that it takes take a small current transmitted through the power switch and use it to close a gate which acts as a switch for the amp itself. Where would the low current signal come from in this case?

 Any recommendations on relays?


----------



## amb

tintin47, yes, the turn-on surge current can be very high, not only due to the transformer initializing its magnetic field, but also from charging the PSU's bulk caps. A relay is a good idea to prevent the switch contacts from wearing out prematurely. The following diagram should speak for itself about how to wire it up. An AC 120V relay is what you'd need, for a "normal" β22/σ22 (i.e., no unusually large transformers) I would recommend a relay that has at least 10A contacts.

 The one we used for the krmathis group build σ22 is a Omron G4B series (Mouser 653-G4B-112T-AC120).

 Oops, see the next post for the schematic.


----------



## amb




----------



## tintin47

Thanks much. Seeing it in schematic form makes a lot of sense.


----------



## boinger

I have the happy news of saying that my beta is perfectly fine and i was just being somewhat of a large idiot... It is singing quite well i must say well the one channel i tested... Just have to finish the final wiring and i should be good to go .... 

 i made the silly mistake of assuming i didnt need to wire the signal ground to the input because I thought that since the headphones didnt need to be wired with the signal ground i assumed that i didnt have to do that... 

 so after not being able to figure out what i had done wrong i just decided to wire it and check it out... and low and behold all my distortion issues were gone.... 

 *smacks face*


----------



## johnwmclean

Well that is good news bolinger, congrats. I'm glad it hasn't ended up as some ugly doorstop. lol.

 Beefys got some word eating to do now. hehehehe


----------



## wink

johnwmclean said:
  Quote:


 Beefys got some word eating to do now. hehehehe 
 

.

 Gee, I hope they're tasty. I hesitate to suggest like beef jerky.
 The inuendos alone are staggering.
 I think we should leave the poor dude alone in light of his good *SOUND* advice in most of his posts...


----------



## Beefy

I stand by my position. I'm glad it is fixed, but this guy shouldn't have done a B22 as his first build.


----------



## johnwmclean

Quote:


  Originally Posted by *Beefy* /img/forum/go_quote.gif 
_I stand by my position. I'm glad it is fixed, but this guy shouldn't have done a B22 as his first build._

 

I’m with you on that Beefy, the earlier comments regarding mains power were very worrying to say the least. Some of my future builds will require working with much higher voltages, I’m currently researching all aspects of safety working under those conditions - to tell you the truth it’s kind of scared me off


----------



## boinger

You know i learned quite a lot from the initial postings and i did a lot of research before commiting to it... was just concerned for my own safety etc.. i have done work on lots of electronics before mainly computers i just didnt know the techincal details etc. i figure rather ask then getting hurt... this was my first audio diy build but i dont regret building the beta22 its much better for me to have done this than done something else and not afford it later i dont have an infinite supply of money. 

 i just believe that if you do your homework and research it well you should be able to gauge whether or not your comfortable doing such a project or not. I am by no means an idiot that was asking for step by step instructions on how to set it up etc. for the most part i got most of it working initially on my own. Aside for me blowing q25 i think it was due to me poking through the soldermask on r9.


----------



## luvdunhill

Ti:

 Given unlimited heatsinking for the pass devices, how much current can the sigma22 provide before the fact that the rectifier diodes aren't heat sinked (and are in relative close proximity) becomes an issue?


----------



## Medel

I just "finished" my 3-channel today (about 2 songs ago)! 
	

	
	
		
		

		
		
	


	




 Remarkably everything worked first time. I had one issue where I keep doing work late at night and read my transformer pinout wrong a few weeks ago on my sigma build, but I caught it even before my fuse blew. I only have my Senn 555s from my e-drum here tonight, but they already sound amazing. I finished it just in time for a week long vaca I'd planned of doing nothing but reading and listening to my 702s on it. I'm so excited! It still needs a volume knob and feet on both cases and it's done. I'd like to clean up the wiring since it's awful, but that would require not listening to it for a bit and that probably won't happen for a while. Thank you all so much for the community here. It was definitely a confidence builder that there was help if I needed it, and Ti's website could not be better! I'll get pics up soon enough in the galleries. Cheers!
 -Mike


----------



## amb

Quote:


  Originally Posted by *luvdunhill* /img/forum/go_quote.gif 
_Given unlimited heatsinking for the pass devices, how much current can the sigma22 provide before the fact that the rectifier diodes aren't heat sinked (and are in relative close proximity) becomes an issue?_

 

You need to qualify what "how much current" means. Is it continuous duty? Or is it short duration peaks? If peaks, then is it repetitive or not? If repetitive, what's the duty cycle?

 Assuming continuous, the current limitation will most likely still be limited by the MOSFETs' thermal resistance (and any isolation pads/thermal compound used) even if you use huge heatsink(s). The total thermal resistance is the sum of the device's own thermal resistance, isolation pad/thermal compound thermal resistance, and heatsink thermal resistance. At some point as you increase the size/efficiency of the heatsink, its thermal resistance becomes a small portion of that sum and the MOSFET's own thermal resistance becomes dominant. This is a factor in the computation of the junction temperature, which is outlined in the "board and heatsinks" section of the σ22 website. You can plug in a very low number for Rsa in the equation and see for yourself.

 Other than that, the rectifier diodes and power transformer are the other limiting factors. Assuming you use MUR820 rectifiers, the forward drop (Vf) is slightly less than 1V, the instantaneous power dissipated on each of them is the current through it multiplied by Vf. But, keep in mind that the current through the rectifier is not continuous, but AC pulses, so the average power is much less. These are rated at 8A, and can pass much higher peak currents. In normal use situations they will not need heatsinking because we'd have reached the thermal limit of the MOSFETs first.

 If the load is pulsive in nature rather than continuous, then σ22 can deliver a lot of peak output current, well beyond the calculations based on continuous duty. How much is "a lot"? Well, it depends on the nature of the load current.


----------



## luvdunhill

Quote:


  Originally Posted by *amb* /img/forum/go_quote.gif 
_You need to qualify what "how much current" means. Is it continuous duty? Or is it short duration peaks? If peaks, then is it repetitive or not? If repetitive, what's the duty cycle?

 Assuming continuous, the current limitation will most likely still be limited by the MOSFETs' thermal resistance (and any isolation pads/thermal compound used) even if you use huge heatsink(s). The total thermal resistance is the sum of the device's own thermal resistance, isolation pad/thermal compound thermal resistance, and heatsink thermal resistance. At some point as you increase the size/efficiency of the heatsink, its thermal resistance becomes a small portion of that sum and the MOSFET's own thermal resistance becomes dominant. This is a factor in the computation of the junction temperature, which is outlined in the "board and heatsinks" section of the σ22 website. You can plug in a very low number for Rsa in the equation and see for yourself.

 Other than that, the rectifier diodes and power transformer are the other limiting factors. Assuming you use MUR820 rectifiers, the forward drop (Vf) is slightly less than 1V, the instantaneous power dissipated on each of them is the current through it multiplied by Vf. But, keep in mind that the current through the rectifier is not continuous, but AC pulses, so the average power is much less. These are rated at 8A, and can pass much higher peak currents. In normal use situations they will not need heatsinking because we'd have reached the thermal limit of the MOSFETs first.

 If the load is pulsive in nature rather than continuous, then σ22 can deliver a lot of peak output current, well beyond the calculations based on continuous duty. How much is "a lot"? Well, it depends on the nature of the load current._

 

Yes, fair point. I was thinking along the lines of use in a Class A power amplifier. For example, the popular First Watt amplifiers by Nelson Pass all use 300VA transformers. He specifies bridges rated at 35A and experience shows that these bridges need to be mounted to thick base, or the heat sinks themselves to handle the current. I just couldn't imagine that the rectifiers in a sigma22 with a similar sized toroid that's being pushed towards it limit of 300VA would be all that happy, having dealt with this particular scenario. I'm not at all suggesting such a use, but it seems that there is an upper limit and I just wanted to get an idea what it was.


----------



## Anonanimal

Quote:


  Originally Posted by *Medel* /img/forum/go_quote.gif 
_I just "finished" my 3-channel today (about 2 songs ago)! 
	

	
	
		
		

		
		
	


	




 Remarkably everything worked first time. I had one issue where I keep doing work late at night and read my transformer pinout wrong a few weeks ago on my sigma build, but I caught it even before my fuse blew. I only have my Senn 555s from my e-drum here tonight, but they already sound amazing. I finished it just in time for a week long vaca I'd planned of doing nothing but reading and listening to my 702s on it. I'm so excited! It still needs a volume knob and feet on both cases and it's done. I'd like to clean up the wiring since it's awful, but that would require not listening to it for a bit and that probably won't happen for a while. Thank you all so much for the community here. It was definitely a confidence builder that there was help if I needed it, and Ti's website could not be better! I'll get pics up soon enough in the galleries. Cheers!
 -Mike_

 

Congrats! I'm happy to hear the build went well and that you're enjoying your new amp.


----------



## Magsy

Can somebody explain the calculation for gain please?

 I think I need something like 6-8 in balanced, so 3-4 per board. These options are not listed on the website and I'm not sure I can just extrapolate the figures to get 3 or 4.

 I have the components for 2 (4 overall) but I am constantly at 12-1 o clock on my M cubed, which has a gain of 11 and I fear 4 won't be enough. My source is 2v unbal or 4v bal. 

 11 is too much on my M cubed but a gain of 4 is almost a third and if that means it'll produce a third of the voulme it won't be enough. I am aware the pot is not linear but I'm too stupid to work it all out. I would like to use all of my attenuators travel with a click or two spare.

 Thanks in advance... :]


----------



## n_maher

Quote:


  Originally Posted by *Magsy* /img/forum/go_quote.gif 
_11 is too much on my M cubed but a gain of 4 is almost a third and if that means it'll produce a third of the voulme it won't be enough._

 

I don't think you have that quite right. It's closer to half as loud since there's less than 10db difference in "gain" between the two configurations. 

 Gain of 4 = 12dB
 Gain of 11 = 20.8dB


----------



## Beefy

Quote:


  Originally Posted by *Magsy* /img/forum/go_quote.gif 
_but I am constantly at 12-1 o clock on my M cubed, which has a gain of 11_

 

Holy crap...... how loud do you listen?!? 
	

	
	
		
		

		
			





 I was driving a _Stax transformer box_ with my MMM which has a gain of just 2, and I wasn't pushing past 2 o'clock on the volume pot.


----------



## n_maher

Quote:


  Originally Posted by *Beefy* /img/forum/go_quote.gif 
_Holy crap...... how loud do you listen?!? 
	

	
	
		
		

		
		
	


	


_

 

I'd really like to know what this rig was sourced with and with what headphones?


----------



## Magsy

My rig? 

 HD650 (and HD580) + M Cubed (gain 11, 50k Pot) + Citypulse DAC 2v SE out (also Emu 0404 the same)

 PC as a source, usually ASIO, via SPDIF (so no volume on the PC side)

 I don't think I'm deaf but 12 o clock is my regular sort of level. If I have quiet music on or a high dynamic range recording / HDCD then 1-2 o clock is needed, if it is compressed pop garbage then 10-11 is enough.

 Thanks for the info, so I guess it will have in theory slightly less than 50% of the volume; it will be very close but I have those parts to hand so I guess I'll start at 2(4 total)...

 I have a Goldpoint balanced attenuator, I'm keen to use all 24 expensive steps, otherwise I'd just build it with a overall gain of 10 to be 'sure'


----------



## Possede

Hey guys, well I have got my panels from Schaeffer and everything fits like a charm. I have put together the case housing the power supply, however I have come across something. What is in the power supply case:

 ε24 power switch driver circuit & σ24 transformer board
 Transformer
 σ22 dual-rail regulated power supply
 Crydom 2425 SSR
 Bulgin Vandal Switch

 When the mains cable is connected (and switched on at the wall) the LED on the σ22 is half lit, and the output measures ~6VDC. The LED on the Bulgin and Crydom Relay do not light. 
 But when the Bulgin switch is pressed both the Bulgin and Crydom Relay LEDs light and the LED on the σ22 emits a brighter light and outputs an expected 24VDC. This is with the β22 unconnected, so the power supply is not connected to a load. If needed I will post some pictures, but maybe there is a simple explanation to why this is happening.


----------



## n_maher

Post pictures, the scenario you're describing seems impossible since with the relay and switch in the "off" position the sigma22 should not be getting any power. You should check your wiring and measure the transformer secondary voltages with just the mains cable plugged in. 

 My suspicion is that you have the primaries wired wrong and therefore switched wrong so that when the mains cable is plugged in you're getting half the expected output voltage and when you activate the switch you're getting the full output voltage.


----------



## Beefy

Quote:


  Originally Posted by *Possédé* /img/forum/go_quote.gif 
_When the mains cable is connected (and switched on at the wall) the LED on the σ22 is half lit, and the output measures ~6VDC. The LED on the Bulgin and Crydom Relay do not light. 
 But when the Bulgin switch is pressed both the Bulgin and Crydom Relay LEDs light and the LED on the σ22 emits a brighter light and outputs an expected 24VDC. This is with the β22 unconnected, so the power supply is not connected to a load. If needed I will post some pictures, but maybe there is a simple explanation to why this is happening._

 

SSR's have a small amount of leakage current in the off state. Maximum for the Crydom 2425 is 10mA (pdf here), which may be enough to give some voltage output on the S22.

  Quote:


  Originally Posted by *n_maher* /img/forum/go_quote.gif 
_My suspicion is that you have the primaries wired wrong and therefore switched wrong so that when the mains cable is plugged in you're getting half the expected output voltage and when you activate the switch you're getting the full output voltage._

 

Also a possibility.


----------



## Possede

Thanks for the very quick replies. As requested here are some photos:


----------



## Magsy

Does anybody have or know the name of the font Ti uses for the 'AMB' logo?

 Ta


----------



## johnwmclean

Possédé, are your secondaries the correct phase? Avel Lindberg is black > red > orange > yellow. I don’t know your transformer it could be correct, but the red cable looks out of order going off Avel Lindberg colour coding... Just a thought


----------



## Possede

I believe they are, although if they are not could this be a cause of the problem? I was thinking it was either SSR leakage as Beefy suggested or I have got the wiring wrong between the transformer, relay and ε24/σ24 as n_maher suggested.


----------



## Beefy

Measure it. Carefully see if you have AC voltage across the switched side of the SSR to the other mains wire with your multimeter.


----------



## johnwmclean

It was only an observation, I don’t know whether it would contribute to your current problem or not in that regard Beefy’s and n_maher’s knowledge far exceeds mine.


----------



## amb

SSRs require some load to work correctly. When your amp is not connected to the power supply, the only load is the PSU LED and is not enough.


----------



## Possede

Thanks for everyone's input, I appreciate it. I was just making sure I wasn't doing anything wrong that could potentially damage any components. All I have left to do it wire up the DACT CT2 and I should be rocking, fingers crossed. I'll get some (hopefully decent) pictures up when it is complete.


----------



## tintin47

I am in the process of stuffing the two channel boards. For a gain of 5x, what are the values of c1-c5? Amb.org says that c1-c5 is 33pf for 8x, and then for 5x gain it specifies that C_2_-c5 is 47pf for 5x gain. What is the value of C1? 33pf?


----------



## sachu

My EHHA S22 died today.
 Went through the test points and the voltages on either side of R4 and R6 aren't matching up right.

 The MOSFETs seem to be ok, i did the basic multimeter short test on them. But replaced them to be sure.

 I am thinking CR3 and CR4 are blown.

 On the S22, I am reading 18.6 (give or take 0.2 volts difference ) volts on either side of R4 and -19.2 volts on either side of R6 with respect to ground.

 The output voltages are reading +/- 13.6 volts or some such.

 The LED light comes on too. I am so bummed. 
	

	
	
		
		

		
			





 Appreciate any inputs on this?


----------



## amb

Quote:


  Originally Posted by *tintin47* /img/forum/go_quote.gif 
_What is the value of C1? 33pf?_

 

Yes.

  Quote:


  Originally Posted by *sachu* 
_I am thinking CR3 and CR4 are blown._

 

Not likely -- the CRDs rarely fail.

  Quote:


 On the S22, I am reading 18.6 (give or take 0.2 volts difference ) volts on either side of R4 and -19.2 volts on either side of R6 with respect to ground.

 The output voltages are reading +/- 13.6 volts or some such. 
 

Measure the voltage across the C-E junctions of Q1 and Q2. If you read more than a couple of volts then that transistor is blown.

 Also measure the voltage on the MOSFET metal mounting tabs (relative to ground). What do you read?


----------



## sachu

Quote:


  Originally Posted by *amb* /img/forum/go_quote.gif 
_Not likely -- the CRDs rarely fail.

 Measure the voltage across the C-E junctions of Q1 and Q2. If you read more than a couple of volts then that transistor is blown.

 Also measure the voltage on the MOSFET metal mounting tabs (relative to ground). What do you read?_

 


 Thanks for the reply Ti.

 The voltage across the transistors are less than 1.5 volts. I presume you meant between the two junctions of the transistor. But which ever way i measure it is at most 1.2V.

 The voltage on all the metal tabs are at +/-41.6 volts.


----------



## amb

Quote:


  Originally Posted by *sachu* /img/forum/go_quote.gif 
_The voltage across the transistors are less than 1.5 volts. I presume you meant between the two junctions of the transistor. But which ever way i measure it is at most 1.2V._

 

Yes, this is ok.

  Quote:


 The voltage on all the metal tabs are at +/-41.6 volts. 
 

This is ok too.

 Chances are some other transistor(s) are blown. With the power off and all capacitors discharged, use your DMM's diode check function to check all the BC546B and BC556B transistors. I described how to do this in another post somewhere, so search for it. Q8 and Q10 B-C junction will appear to "fail" this test but it's normal because these junctions are connected together in the circuit (see schematic).


----------



## johnwmclean

AMB, what would cause BC546B and BC556B transistors blow? Just out of curiosity, as sachu’s σ22 had been functioning properly.


----------



## sachu

Ti, I don't know what changed, but I was measuring the voltages on Q11,12 and a moment later i remeasured the output voltages. It was back to where it should be, at +/- 28.7 volts.
 I am completely stumped but relieved. 
 Rewired the amp up and it seems to be working fine..other than the fact that the AP25 pot seems to be internally grounded on one of the channels. Will have to try replacing the pot i suppose. Will update later tomorrow.


----------



## amb

Bad electrical contact/connection/solder joint?


----------



## sachu

Quote:


  Originally Posted by *amb* /img/forum/go_quote.gif 
_Bad electrical contact/connection/solder joint?_

 

I went through the solder points and couldn't spot any that were bad..Also The S22 had worked for well over 400 hours prior to this..which is what makes it quite puzzling.
 I will go over it again later when i rewire the pot.


----------



## Magsy

So, I've sat on my box of Beta 22 parts since late 2006, not quite sure why I never started but now is time!

 Four boards, one Sigma, a custom 120va shielded trafo, PRP, BG N/NX, Goldpoint attenuator etc.. I've placed 15 orders from 9 different suppliers, my BOM is $1700 so far and I don't have a chassis yet 
	

	
	
		
		

		
		
	


	




 This is an over-the-top all out spend as much as I can build, it is a fun hobby and I won't pretend I've chosen parts wisely but I didn't ever want to look at it and think about upgrading parts, so I've used flashy stuff from the off.
	

	
	
		
		

		
		
	


	




 Sigma went together very nicely and much to my suprise fired up first time, rock solid 30/-30 and appears to have no issues.

 I did one of the Beta 22 boards last night, first impressions are that it takes a bloody long time and I officially hate the ground plane which is so very hard to solder to. I have a Hakko and I think I can solder but the joints require a serious amount of heat and even then I redid a lot of them. I think I spent about 6 hours building. Drilling out the board to take M3 bolts isn't much fun and tapping all 20 heatsinks for M3 is a pain in the arse also 
	

	
	
		
		

		
		
	


	




 Anyway, after a lot of lead / nicotine inhalation and a very bad back, I stood back and plugged it in! Bingo, works right out of the box! All adjusted as per Amb's superb website and DC offset came to 0 with plenty of adjustment to spare.

 An easy build in many ways but the shear quantity of parts selection, unbagging, leg bending, orientation checking, matching and triple checking all adds up and it is quite an undertaking. I'm not actually looking forward to the other three boards 
	

	
	
		
		

		
		
	


	




 Kudos to those who build these for free, it is a lot of work and you must be nuts!


----------



## linuxworks

finally got my 3ch b22 working.

 I had a short in one of the boards to ground (from very close to the input, where 2 input fets have gates that connect). took me days to find it and in fact, I never did find it, I just worked around it (lol). I now have a 'greenwire' along one board that replaces the shorted trace. even after cleaning the board and defluxing many times, I could not find the micro short. (it was 2.5ohms to ground, if that matters).

 boy, this was a time consuming build! but its working now and I'm setting the bias now (waiting for the 10 minutes to expire so I can recheck the bias points again). I'll snap a pic or 2 of the problem area on my board. its not pretty but it works and sounds ok 
	

	
	
		
		

		
		
	


	




 when we build things, we sometimes forget that part of the time budget is to troubleshoot things that aren't even your own fault. I was sure I had a shorted glob of solder or a bad part somewhere, but when I unsoldered each node in that network and STILL could not find where the short was, I just gave up and worked around it. that costed me several days and so you need to allow for debug time even if you are very very careful about your board-work. "it may not be you", is what I'm saying 
	

	
	
		
		

		
		
	


	




 update: photos added:











 you can see the green wire (blue, really, but its called 'greenwire' when you make pcb repairs like this) in these 2 photos.


----------



## Pars

Nice builds guys. Man those BG Ns are massive overkill for that. It wouldn't surprise me if some of the 105 deg. rated recommended caps have lower ESR etc. as well. Looks pretty though 
	

	
	
		
		

		
		
	


	




 I like the PRPs also.


----------



## Magsy

Finished my last board at four am last night, I've hacked off my entire family by being awol the last few days but I'm done, all boards are built and passed initial setup, all go 0 offset.

 My arse hurts, my back is wrecked and I think I probably have some kind of lead poisoning; I'm not sure I ever want to take something on as involved as this again! 

 416 components and ~1500 solder joints done and I still have all the wiring to go 

 I am very very excited for the first audition later!!!!!


----------



## tintin47

Trying to order neutrik power connectors from newark. Newark for some reason states that they have 14 or 20 contacts, as seen here:Neutrik PowerCon (part no. 91F3454 if link doesn't work), but the linked datasheet from neutrik says they have three. The model numbers on newark and neutrik match up, but the part has different specs?

 Does anyone have an explanation for this? If this is the wrong model of connector, can someone link me to the right one?


----------



## digger945

Apparently, the Neutrik Powercon line is for 3 contact positions only.
 I don't know what your application is but the Neutrik website has much more info on many different connectors.
Neutrik - Connectors for audio, video, fiber optic and industry

 I think I would go with the manufacturers datasheet over the sellers description ;~)


----------



## Hottuna_

Alright, finally had some time to work on my B22 build (Amazing how work piled up just before the break).
 However, I have hit a snag with one of the boards.

 Would appreciate some troubleshooting help.

 LEDs light up and I can adjust voltage across R9 to 4.5 just fine.
 However I cannot measure anything across R34.

 A bit of checking voltages around and I found that the voltages across R10 and R11, R12 were out of whack:

 V_R9 = 4.49V
 V_R10 = 4.90V
 V_R11 = 7.9V
 V_R12 = 4.56V 

 Another thing not looking right are the voltage drops across D11 and D12
 V_D11 = 2.5V
 V_D12 = 0.8V

 Any ideas?


----------



## johnwmclean

Quote:


  Originally Posted by *tintin47* /img/forum/go_quote.gif 
_Trying to order neutrik power connectors from newark. Newark for some reason states that they have 14 or 20 contacts, as seen here:Neutrik PowerCon (part no. 91F3454 if link doesn't work), but the linked datasheet from neutrik says they have three. The model numbers on newark and neutrik match up, but the part has different specs?

 Does anyone have an explanation for this? If this is the wrong model of connector, can someone link me to the right one?_

 

Yep their 3 pole, have you considered Speakon connectors?


----------



## amb

Quote:


  Originally Posted by *Hottuna_* /img/forum/go_quote.gif 
_LEDs light up and I can adjust voltage across R9 to 4.5 just fine.
 However I cannot measure anything across R34.

 A bit of checking voltages around and I found that the voltages across R10 and R11, R12 were out of whack:

 V_R9 = 4.49V
 V_R10 = 4.90V
 V_R11 = 7.9V
 V_R12 = 4.56V_

 

Inspect your board carefully to make sure all polarized parts (zener diodes, CRDs, transistors, JFETs) are installed in the proper orientation. I suspect something might be backwards, in addition to the below:

  Quote:


 Another thing not looking right are the voltage drops across D11 and D12
 V_D11 = 2.5V
 V_D12 = 0.8V 
 

Are these the same type diodes and in the proper orientations? Check Q25, Q26, CR7 and CR8 to make sure they're mounted the right way. Note also that Q1-Q4 should not be installed accorfing to the silkscreen markings -- see the β22 website "Instructions" section.


----------



## Magsy

Weeehehe I'm done! Got the wiring finished at 4am and then one track turned into one album, got to bed at 5am 
	

	
	
		
		

		
			





 I think it is testament to Ti's superb design and work, the excellent website and forum contributions/threads that I put this together and everything worked first time. I have not had a _single_ problem. Thank you very very much. 

 The PSU gets very hot but the other boards are touchable, from what I've read this is normal but I may have to get an IR therm to keep an eye on it when inside a case.

 It looks totally insane, people have been questioning why I need something so big to power headphones and seeing it all on one board I tend to agree but as soon as you turn it on....
	

	
	
		
		

		
		
	


	




 It is very dynamic and you can get a punch in the side of the head like I've never had before. There is a strange feeling of light bass and then you hit a track with a massive almost sub-bass note and you realise it is all there just not overblown or thick. I have never heard bass go so low and it creates a great deep reverberation while remaining tight. Everything seems to move very fast, the rise and fall of notes is incredible. It is more open at the top than the M cubed and has a greater sense of space. 

 The only negative I can find is a touch of sibilance on some female vocals, it only seems to be present on heavily processed stuff, a good accoustic performance is fine so maybe it is source related.....or perhaps my all silver wiring is too much!

 Case work to follow, it is designed to drop into the chassis on the plexiglass base with just the input/output wiring needing triming but I'm too tired for now...


----------



## n_maher

You could easily justify dialing down the bias current so that your PS wouldn't run so hot.


----------



## linuxworks

yes, the boards should be touchable for a few seconds (at most). if you can touch the ps fins for more than 1 second, you must be wearing gloves at the time (lol).

 I once thought about using something cheaper for the b22, for the psu, but now that I see how much current the boards AND psu take (heat output) I'm glad I just stayed with the s22. the s22 isn't even that expensive, really. the trafo, THAT sucker is the expensive part of the PSU chain 
	

	
	
		
		

		
		
	


	




 my only complaint about the s22 is that its not current limited. that's by design, I understand; but if you have stuff that fails downstream, the s22 has no overcurrent sense or protection so it continues to pump energy even when things are blowing up down south 
	

	
	
		
		

		
		
	


	




 this causes more things to die than if the PSU had limiting.

 my guess is that for purism, limiting was conciously decided against. but I wish there was some throttle valve or way to set a max limit and still be 'cool with the audiophiles'


----------



## n_maher

Quote:


  Originally Posted by *linuxworks* /img/forum/go_quote.gif 
_my guess is that for purism, limiting was conciously decided against. but I wish there was some throttle valve or way to set a max limit and still be 'cool with the audiophiles' 
	

	
	
		
		

		
		
	


	


_

 

What's wrong with the fuse?


----------



## Magsy

Yea I can touch them for a second or two and I may well dial down the current later on. At the moment I have 55mv. Heat is going to be ok, I'll just cut more case over that side 
	

	
	
		
		

		
		
	


	




 I share your concern about the PSU but I wonder about the fuse. The docs / forums say use a 2 amp slow blow but this is on the primary side, that is equivalent to 480w over here in 240v land and seems a lot? Stuff would be toast way before that blew? 
 As I type I realise 2 amp was probably for a 120v AC source not 240v, so I should have a 1 amper..


----------



## linuxworks

you need a larger fuse due to the inrush current of such a large trafo (my guess).

 there's no soft start and so you need 'more fuse' to avoid false blows


----------



## Hottuna_

Quote:


  Originally Posted by *amb* /img/forum/go_quote.gif 
_Inspect your board carefully to make sure all polarized parts (zener diodes, CRDs, transistors, JFETs) are installed in the proper orientation. I suspect something might be backwards, in addition to the below:


 Are these the same type diodes and in the proper orientations? Check Q25, Q26, CR7 and CR8 to make sure they're mounted the right way. Note also that Q1-Q4 should not be installed accorfing to the silkscreen markings -- see the β22 website "Instructions" section._

 

Just did a pretty thorough check on all components against the parts list and also against my other boards that are working. 
 Everything seems to be in the correct locations and orientations. (Q1-Q4 placed according to site instructions)
 This is quite bewildering.

 Also reflowed pretty much every joint. Still no dice.


----------



## linuxworks

you may need to check the board, itself.

 it took me a long time but one problem I had with 1 board was a shorted pcb trace. 2 out of my 3 came out 100% perfect on the first try but that 3rd board had an internal short that I could never find. I narrowed down the network (set of nodes) that was shorted to ground but I could not easily see or find *where* it was. so I just worked around it with a greenwire. not elegant but it got me there.

 so, don't rule out board problems. its rare but it does happen. I've only run into this a few times but its not zero times and that's my point. this is the hard part about debugging hardware. sometimes its not enough to just put parts in the right places. sometimes, its not your fault but you still have to debug the whole system.


----------



## cfcubed

Quote:


  Originally Posted by *linuxworks* /img/forum/go_quote.gif 
_you may need to check the board, itself.
 <snip>it took me a long time but one problem I had with 1 board was a shorted pcb trace. <snip>
 so, don't rule out board problems. its rare but it does happen. I've only run into this a few times but its not zero times and that's my point._

 

Yes, indeed. I've not _that_ many build under my belt but have run into a pesky PCB fab error and it was under an installed part. But finding it was not too hard on an itty, bitty JISBOS board.


----------



## Hottuna_

Well.

 Day 3 now, still no idea...
 Gave it a nice one over with a magnifying glass. Did not find anything.
 Swapped out few transistors as well.
 Readings identical.

 Looks like i can go ahead with a 3 ch build or get another kit from Jeff.


----------



## linuxworks

if you have at least 1 board that works, use that as a 'live reference' and compare voltages and resistances to gnd and so on, between them. try to find the section that seems 'off'.

 I was about to call my bad board 'unsolvable' and just yank out the valuable parts and move them to a new board. I started to saw off (sharp knife) various sections of the bad trace or network but soon I realized even that was getting me nowhere. I knew this network had a short to gnd but could not find WHERE. so I just ran some parallel wires and 'worked around it'. in a small case, you can do that. I was semi lucky and that seems to be the only problem with that 'bad' board. the others were all fine from the get-go.

 at least having 1 good board gives you a live ref.

 and at worst case, maybe its worth moving the special or hard to get parts over. resistors can probably be ignored and you can get new ones of those. crd's are probably worth saving and all the transistors are, for sure.

 at some point you call it a day, with a bad board. but if you can locate the bad section, at least, then its worth throwing a bit more time at.


----------



## nattonrice

I have been in a very lost position once (actually now twice) before.

 I connected one probe to gnd and then, with the meter in continuity test mode, systematically (from one side to another) tested each solder point/node on the underside of the problem board.

 My meter only beeps in this mode when it is essentially a short.
 When ever it beeped I first checked if the trace that particular solder point connects to was shorted to ground by design or not (this is easy to verify using the schematic as you go).

 After hours and hours of trying all sorts of things (some my own ideas, some Ti's) it was this almost blind brute force method that nailed down the single trace that was causing the problem.
 This ended up only taking 10 min to fix (including the blind search).

 Edit: Linuxworks's cut and bypass trick is a very good idea if you can locate the trace but not the short.


----------



## Hottuna_

Alrighty, did the resistance to ground comparison with one of my other boards.
 Found the problem in the Q11, Q12, Q15, Q16 cluster.

 Pulled them all out and looked at the traces and the from R11 and R12 to the base of Q11 and Q12 were mis-etched under the components themselves. See attached pics.

 I dug out some old very very thing wire from back in the day when I had to do similar fixes. (though back then it was more my fault not picking up the error in protel before sending to fab)
 Soldered on the wire and fired it up.
 Works just fine.

 Thanks to everyone who gave suggestions and ofcourse linuxworks for giving me the idea for that test.


----------



## amb

If yiou could see the under-etched blotch, then it's easier to simply cut that blotch away with an x-acto knife rather than adding wires.


----------



## Hottuna_

Well in this case it was over-etched.
Attachment 24153

 Just finished biasing and zeroing DC offset.
 Still a fair bit of casework/assembly/wiring left to do.

 Can't wait to get it up and running 
	

	
	
		
		

		
			




 But I've had enough for today. Closing in on midnight here down under.


----------



## amb

Ah, ok. Instead of the long wires you could have just scraped a little bit of the soldermask away and tack-soldered a little resistor lead cutoff to bridge it. But anyway...


----------



## linuxworks

you found it and got it working! nice!!

 bet it feels REAL GOOD now (lol). the more 'sweat' you put into it, the more rewarding it is once it finally works.

 congrats


----------



## Magsy

Well done on that fix, I've been in that boat before and you start to lose the will to live but making it working is an amazing feeling! 
	

	
	
		
		

		
		
	


	




 Can somebody clarify how to connect a SE source please?

 If I understand the diagram correctly, I must short the input of two of the boards (the -) ones to ground but this must take place between the boards and the pot, not between the pot and the jacks? 
 Can I just bridge the input and gnd pads on the two boards?

 I guess I lose half the gain by doing this also?

 Thanks


----------



## amb

Quote:


  Originally Posted by *Magsy* /img/forum/go_quote.gif 
_Can somebody clarify how to connect a SE source please?_

 

Just like how you saw it in the diagram at the β22 website "Other options" section.

  Quote:


 If I understand the diagram correctly, I must short the input of two of the boards (the -) ones to ground but this must take place between the boards and the pot, not between the pot and the jacks? 
 

Correct, because you don't need a volume control on the "cold" amps when switched to unbalanced inputs. You only need those board to become referenced directly to ground.

  Quote:


 Can I just bridge the input and gnd pads on the two boards? 
 

Isn't that basically what the diagram does with the switch?

  Quote:


 I guess I lose half the gain by doing this also? 
 

Yes, but only if your unbalanced source outputs half the total output voltage swing compared to your balanced source.


----------



## hasanyuceer

Where can we find ß22 and sigma22 complete kits? (w/out chassis of course)

 I want to buy all kit and pcb's, and only solder them, then start to use...


----------



## nattonrice

Blind stuffing comes highly unrecommended.
 Casing that is not well thought out (or non-existent) is asking for hum and other problems.

 I believe Glass Jar Audio stocks pcb+component kits.

 Before diving into this you will want to read the threads here and especially the 3 threads at headwize FROM START TO FINISH.
 Most epic failures can be prevented that way.


----------



## hasanyuceer

Thanks nottonrice... I will look at Glass Jar Audio..

 I know it's like diving but i am not unfamiliar to pcbs and all these stuff. (Electronics Eng.) But i will listen your advice and read the threads...


----------



## linuxworks

do not build a b22 unless you are prepared to DEBUG it.

 this is not a heathkit and this is not just 'solder parts and it goes'. sometimes there are bad parts. sometimes there are bad boards. sometimes there are other things.

 do not be fooled that its just assembly work.

 don't let your ego assume that you can build this.

 that's all I have to say. I see a lot of bravado about 'I want to build the best!' but people FORGET that debugging is often a part of the build and most builders, sorry to say, are just not up to the task (being really honest, here).

 work your way up. start sensible. that's my suggestion.

 b22 is a final build not a FIRST BUILD.


----------



## hasanyuceer

My desire to get all parts in one time is because where I live. Its hard to find audiophile parts here. Only a missing capacitor loses me at least 10 days...

 This is why I am so on to finding all parts as kits..


----------



## linuxworks

I would suggest ordering extra parts, then. I've had to re-order and even getting the parts the same week for me is too much wait 
	

	
	
		
		

		
		
	


	




 order extras of the things that need matching and also the final transistors AND .47 resistors. order lots of those 
	

	
	
		
		

		
		
	


	




 just in case.

 no need for extra crd's but do order extra fets and transistors of all kinds.

 maybe extra caps (electros) in case you reverse some. I did (just 1 but it blew out a WHOLE SUB CHAIN of parts due to that!)

 again, can't say this enough: order extra parts since you are making 1 big shipment.


----------



## johnwmclean

Even before soldering any components a continuity check with the pcb matching back to the schematic would be advisable.


----------



## hasanyuceer

Thanks for advices, i am noting down them all...


----------



## Hottuna_

Well my balanced build is all wired up and making very awesome music.

 I was expecting a large improvement but was still blown away by it. My HD650 is singing like it has never sang before.
 I do not have any point of reference to compare it to other high end amps but all I can say is that it sounds absolutely incredible.

 Things that struck me immediately:
 Very impressive soundstage.
 The HD650 has strong bass, boomy at times but with this amp the bass it very controlled, iron-fisted control and it goes deeper than ever before.
 Increased impact/detail of the music. The HD650 by most accounts is a laid back/veiled phone but its certainly more lively now.
 I can listen to it at lower levels and not lose detail which is excellent for longer listening sessions.
 It does run rather hot, biased the B22 to 100mA to keep temps down but I reckon I will refrain from using it during the hotter days. (it is summer now in Australia and it can get pretty damn hot down here in Melbourne)

 I would like to express my thanks to johnwmclean for his advice and many tips that helped me along the way for both this B22 build and my earlier Buffalo32s build.
 AMB for having put in the time and effort designing and supporting the design.
 Linuxworks for suggesting what turned out to be the silver bullet in debugging my one dodgy board.
 And ofcourse the Head-fi community for causing much grief to my wallet!


----------



## johnwmclean

Thanks Hottuna_, welcome to the Beta22 club!


----------



## nattonrice

Even better welcome to the Aussie B22 club!
 There seem to be a fair few of us that built one =)


----------



## fishski13

Hottuna, 
 congrats! yes, it's a wonderful amp.

 i think there is 2 B22 owners here in Minnesota =).


----------



## qusp

hmmm i'm paused on the buy button for some PCBs, wont be ages till I collect all parts as I've recently blown some serious money on source and cans. i'm still undecided TBH even though I know the rep and have experienced the wonderful sound of the B22. reason i'm paused is I mostly listen to my JH13 even at home and my plan is to add discrete buffers to the transformer output of my new sabre (ackodac) and drive my cans directly as I have with my buff; but I really would like to build a B22


 so come on aussies; talk another one into the fold


----------



## Possede

I've had this built for a while, but have been enjoying it too much to take it apart and take pictures. I started this build in July 2009, and finished it mid December. It has definitely been a great learning experience as this was my first time attempting something of this magnitude. I have to take my hat off to Ti, as without him none of this would have been possible. And many thanks to everyone else who has chipped in along the way when I have stumbled into bother. I apologise for the following pictures but I am less than competent with a camera:





































 In total I spent around £850. I can now appreciate it when people say that this is an expensive project! The only annoying thing that cropped up was that the data sheet for the Neutrik NCJ6FI-V detailed the required holes as 3.2mm, so from that I ordered the front panel to have M3 countersunk holes to support the Neutrik connector. It was only when putting everything together that I realised that M3 screws are too large, so now I'm using M2 screws in a M3 countersunk cavity. 
	

	
	
		
		

		
		
	


	




 Apart from that everything went smoothly! Time to go back to listening...


----------



## adamus

looks f'ing great.

 Where are you based. I need me a listen of a b22


----------



## Possede

Quote:


  Originally Posted by *adamus* /img/forum/go_quote.gif 
_looks f'ing great.

 Where are you based. I need me a listen of a b22_

 

Cheers. I'm from Scotland, United Kingdom.


----------



## johnwmclean

Possédé, beautiful build - congrats.


----------



## nattonrice

Very nicely done!

 Only thing that may be of concern is the ventilation.
 The s22 box is most likely fine but the b22 may be operating very (!) hot.


----------



## johnwmclean

Quote:


  Originally Posted by *nattonrice* /img/forum/go_quote.gif 
_Very nicely done!

 Only thing that may be of concern is the ventilation.
 The s22 box is most likely fine but the b22 may be operating very (!) hot._

 

hehehe it’s a scottish Beta22 - I reckon it’d be fine


----------



## Possede

Thanks for the kind comments. 
	

	
	
		
		

		
		
	


	




 nattonrice, I have biased the quiescent current at ~100mA to try and bring the temperature down. The case does get warm, hopefully it doesn't overheat. I was wondering, does increasing/decreasing the quiescent current affect the sound quality?


----------



## amb

MOSFETs like to be biased heavily to sound their best, but on the β22, cascoding linearizes the effective transfer curve so it is not required to go crazy with biasing. That said, the higher the quiescent current, the more deeply in class A the amp operates in, which means that it would remain in class A even when asked to deliver a large swinging signal into a low impedance load.


----------



## linuxworks

latest take on my reconvert-a-case(tm) for my b22:






 I had some wooden end panels cut to slightly larger than the raw metal chassis dimensions. I'm going to see if I like this look or not. certainly better than *nothing* on the ends 
	

	
	
		
		

		
		
	


	




 some kind of hard wood at the lumberyard, then cut to size and beveled on the edges with a router. I took the boards home, gave them one coat of stain and attached them to the metal with wood screws thru holes in the edge of the metal frame.

 I have some smoked plexiglass for the top panel but it does not have vent holes cut yet. not sure I'll use the plexiglass or something else (metal perf screening, maybe?)

 also you'll have to forgive the rat shack knob 
	

	
	
		
		

		
		
	


	




 I have nothing that is of that size and all the smaller ones I have look worse on a box this box. need to get something 1.5" or even larger, and in black metal.


----------



## fishski13

Possede,
 i'll second Adamus and say that looks f'ing great. i love the simple aesthetic. congrats!!! enjoy the tunes!!!


----------



## fishski13

Adamus,
 the B22 is a wonderful amp, but a double-edged sword. the Bijou is a perfect tonic for poorly engineered/compressed recordings. i switch between the two amps frequently depending on what i'm listening to.


----------



## oneplustwo

Hey folks... looking for some help with a sigma22. I've made enough mistakes with various B22 boards now that I'm pretty good at fixing those on my own, but I just finished my first sigma that didn't work on the first try. Not sure where to start. All I can tell you is that I get no output, no smoke, no LED at power up. But I did verify I am getting the AC from the trafo to the board ok.

 Thanks is advance for the help!


----------



## fishski13

linuxworks,
 i was about to rip you for the knob choice but then read your last paragraph. seriously, keep the wood. also, check out the Kilo knobs at Digikey. looks f'ing great too!!!


----------



## Pars

Read and follow the *initial check* steps on amb's website. Follow these sequentially; don't jump around.

The &sigma;22 Regulated Power Supply

 If you get through the initial check and get the LED working, continue on in the troubleshooting section of that page, there are voltage points for several different output configurations listed on that page. That should get you started.


----------



## fishski13

Quote:


  Originally Posted by *oneplustwo* /img/forum/go_quote.gif 
_Hey folks... looking for some help with a sigma22. I've made enough mistakes with various B22 boards now that I'm pretty good at fixing those on my own, but I just finished my first sigma that didn't work on the first try. Not sure where to start. All I can tell you is that I get no output, no smoke, no LED at power up. But I did verify I am getting the AC from the trafo to the board ok.

 Thanks is advance for the help!_

 

do you have any measurements at operating points as outlined under "Initial Check"?


----------



## fishski13

Pars beat me to it.


----------



## oneplustwo

Yah, I don't get very far in the initial check section since my LED didn't light and I don't get any voltage at the output! So I was going to go through the voltage points but didn't know where to start. Is there a logic to start from the outside in, left to right, or other sequential order? I was scared to just start poking around since I didn't want it to just sit powered on for too long in case extended on time would lead to more bad stuff. 

  Quote:


  Originally Posted by *Pars* /img/forum/go_quote.gif 
_Read and follow the *initial check* steps on amb's website. Follow these sequentially; don't jump around.

The &sigma;22 Regulated Power Supply

 If you get through the initial check and get the LED working, continue on in the troubleshooting section of that page, there are voltage points for several different output configurations listed on that page. That should get you started._


----------



## linuxworks

Quote:


  Originally Posted by *fishski13* /img/forum/go_quote.gif 
_linuxworks,
 i was about to rip you for the knob choice but then read your last paragraph. seriously, keep the wood. also, check out the Kilo knobs at Digikey. looks f'ing great too!!!_

 

I may try a kilo at that size; there's only 1 that digikey carries that is at all large. may still not be big enough and it gets very pricey as you go up.

 maybe time to try partspipe or something on ebay. I just hate having to go to HK to get parts; I really do.


----------



## linuxworks

one thing about power supplies, don't short anything while testing it.. 
	

	
	
		
		

		
			





 should be obvious but sometimes its hard to test and look at the same time. what I will sometimes do is solder short wire-wrap wires to test points and use clip leads to grab onto those 'extension points'. you can work safer that way (as long as wire length doesn't affect things; and in this case it won't).

 then again, dont' short THOSE test leads if you grow a lot of them on the board at once 
	

	
	
		
		

		
		
	


	




 I soldered some test cutoff leads to the .47ohm r's on the b22 for bias checking just to make THAT job easier, too.


----------



## qusp

I do that too with power supplies; especially for adjusting shunt regulators and their CCS


----------



## dude_500

I just started having a problem with my amp... I was listening to a vinyl recording and at first thought it was just a messed up LP, heard screeching. But then I paused it and the screeching continued for a little while. Then I'd hit play again and it would start up again.

 I turned off my amp and the LED- instantly turned off and the LED+ turned off extremely slowly like there was no load on it at all. Q15 and Q16 on the sigma-22 were very hot after just a few minutes of use, much warmer than Q13 or 14.

 I have not turned it back on since to avoid further damage. Any suggestions?


----------



## Beefy

Sounds like you have developed a short somewhere, and it is drawing a lot of current. Would be a good plan to go through the whole procedure of checking wiring, checking for shorts to gnd, etc.


----------



## Pars

Quote:


  Originally Posted by *oneplustwo* /img/forum/go_quote.gif 
_Yah, I don't get very far in the initial check section since my LED didn't light and I don't get any voltage at the output! So I was going to go through the voltage points but didn't know where to start. Is there a logic to start from the outside in, left to right, or other sequential order? I was scared to just start poking around since I didn't want it to just sit powered on for too long in case extended on time would lead to more bad stuff._

 

Since the LED is powered off the rails, and since you have no rail voltage, might not be anything wrong there.

 The first thing I would do is go through every component, making sure it is the right part (particularly transistors) and that they are oriented properly. If that is fine, then with a schematic handy as well as the operating points, you probably want to start at the input and work towards the output until you find something that isn't right. Double check your transformer wiring as well.


----------



## UKToecutter

Hi all.
 Just ordered my boards from AMB.

 Can't wait !!!!!


----------



## UKToecutter

Oh, I forgot to ask.

 Did anybody use the ε27 board to mount their pot?

 Is it worth doing?


----------



## dude_500

Quote:


  Originally Posted by *UKToecutter* /img/forum/go_quote.gif 
_Oh, I forgot to ask.

 Did anybody use the ε27 board to mount their pot?

 Is it worth doing?_

 

I used it and it works very well, I think it's a great idea, especially if you need to do maintenance on it in the future where removing solder joints right on the pins could cause damage.

 I have since ordered the combo again for another build of a different amp... that will be my volume knob of choice unless I find something superior in the same price range.


----------



## oneplustwo

Quote:


  Originally Posted by *Pars* /img/forum/go_quote.gif 
_Since the LED is powered off the rails, and since you have no rail voltage, might not be anything wrong there.

 The first thing I would do is go through every component, making sure it is the right part (particularly transistors) and that they are oriented properly. If that is fine, then with a schematic handy as well as the operating points, you probably want to start at the input and work towards the output until you find something that isn't right. Double check your transformer wiring as well._

 

Thanks for the guidance Pars. I checked the trafo wiring and part orientation. Might be difficult to check that the parts are actually correct... dang things are so hard to read, but I'll give it a go.


----------



## UKToecutter

Quote:


  Originally Posted by *dude_500* /img/forum/go_quote.gif 
_I used it and it works very well, I think it's a great idea, especially if you need to do maintenance on it in the future where removing solder joints right on the pins could cause damage.

 I have since ordered the combo again for another build of a different amp... that will be my volume knob of choice unless I find something superior in the same price range._

 

Thanks dude_500.
 I'll add that to my next order


----------



## UKToecutter

Does anyone know who manufactures that braided cable sheething that people are using in their builds. Makes a real nice finish.

 Look at http://www.head-fi.org/forums/6291774-post2106.html

 2nd picture down shows what I mean. On the right hand side.......

 Very pretty


----------



## Possede

Hello UKToecutter, thanks for the kind comments. I got the braid from SMCS-UK Commonwealth Stamps on eBay. Very cheap and fast delivery. It's either the 3mm or 6mm.


----------



## UKToecutter

Thanks Possédé 

 I'm on it


----------



## jlefley

I'm starting to gather parts for a 4 ch balanced beta22/dual sigma 22 build and I'm wondering if there would be any noticeable effect on SQ or anything else if I used one of the s22 boards to power a Joshua Tree attenuator with two relays boards. I realize that the regulator on the JT relay driver board will get pretty hot due to the larger input voltage but apart from that would the ~400ma that the JT draws have any other noticeable effects on the amp?


----------



## IPodPJ

You could get a 3rd trafo and a cheaper low noise power supply.


----------



## jlefley

Quote:


  Originally Posted by *IPodPJ* /img/forum/go_quote.gif 
_You could get a 3rd trafo and a cheaper low noise power supply._

 

Considering the simple power supply that the JT relay driver board has integrated, it seems like it doesn't really an additional power supply with good regulation or low noise properties to supply the onboard regulator. I think it would be redundant to put an additional power supply in the box with the sigmas just to provide regulated power to the 5v regulator on the JT board located in the box containing the b22s. I'm just thinking that it would be an easy solution to draw power from one of the s22 that will be in place unless it will have any sort of adverse affects.


----------



## IPodPJ

Well I'm adding a third to mine to keep the audio channels completely free of any possible noise from the LEDs, relays, or motor drive on the attenuator. Just a suggestion. I know it isn't common, and I'm not sure if anyone's ever done it on their B22.


----------



## linuxworks

it would seem wise, if you can afford the space/etc, to have a separate power supply for digital control things. I'm going that way in my arduino builds and if you do have a bank of non-latching relays, you may want to have a pre/post setup for that. meaning, you can have preregulated voltage (before the 'logic' 5v regulator section) going to relays and then post-reg for the things that really need something a lot closer to 5v.

 many relays come in various voltages and so you could select your relays in the 'bank' to be a few volts higher than the 5v logic section needs and then feed the relays off of this pre-reg voltage.

 not the only way, but a nice stingy way to do it 
	

	
	
		
		

		
		
	


	




 same applies to motor-pots. some won't take more than 5v but I think I've had some that ran faster at 9v and didn't seem unhappy about it 
	

	
	
		
		

		
		
	


	




 so you could do the pre/post thing for motor pots, too. just be sure the pot can *take* more than 5v.

 I would not have control circuits going too close to audio paths and that also does include deriving b+ from the audio power supply rails. I do like the idea of a separate reg and trafo chain and if you get a custom trafo build (like from sumr) you can request another winding just for the digital control stuff. I was going to do that, myself, for an amp+controller project. if you can get an extra winding for almost-free (custom trafo with 1 more winding) do it! else you have to find space for a small 7v (etc) trafo for the 5v digital stuff.


----------



## linuxworks

Quote:


  Originally Posted by *UKToecutter* /img/forum/go_quote.gif 
_Does anyone know who manufactures that braided cable sheething that people are using in their builds. Makes a real nice finish._

 

is that tech-flex that you're talking about? the blue stuff that I use, for example:






 I used some blue for some runs and some black for the b22 amp boards to the motherboard. red shrink tubing just cause that's what I had on hand at the time 
	

	
	
		
		

		
		
	


	




 is this what you're referring to? you can buy it in many colors and use whatever color heat-shrink you want. you can pick a theme and run power with one color and line-in with another and line-out with another! or not 
	

	
	
		
		

		
		
	


	







 its not braid and not shielded, just a plastic expanding web-like thing that collects wires into tight groupings. and when you cut this stuff to length it frays and so you *have* to do the heatshrink tubing thing or it will look really unfinished and sloppy.


----------



## jlefley

Yeah the more I think about it and based on the replies I'll probably just get an additional transformer and put together either a TREAD or sigma25 to provide the 5v.


----------



## Beefy

Quote:


  Originally Posted by *jlefley* /img/forum/go_quote.gif 
_Yeah the more I think about it and based on the replies I'll probably just get an additional transformer and put together either a TREAD or sigma25 to provide the 5v._

 

The JT controller has an onboard voltage rectifier and voltage regulator. Why do you feel the need to feed it DC?


----------



## linuxworks

just a thought: but do you want to design your 'infrastructure' (ps and wiring) based on some products or make it more generic? the JT has onboard reg and stuff but others may not. if you plan for it in the infrastructure you have more upgrade options available to you later on. since the chassis is a big part of the cost, it might make sense to plan for extra PS lines 'just in case'.

 heck, I'd want an extra 5 and an extra 12/-12 or something like that in case I need extra audio rails


----------



## jlefley

Quote:


  Originally Posted by *Beefy* /img/forum/go_quote.gif 
_The JT controller has an onboard voltage rectifier and voltage regulator. Why do you feel the need to feed it DC?_

 

I would think that it would not be a good idea to send ac into the enclosure housings the b22s, where the attenuator relay driver board will be located. (I am planning on placing the amp boards and power supplies in separate enclosures)


----------



## Beefy

For a transformer sized for the JT, say 5-10VA, the effect will be negligible. But I see your point.


----------



## linuxworks

one thing I was considering - what do you guys think? in a setup where you feed ac into the b22 box (so the s22 is inside the same box as the b22), you have 60v p-p in ac form that you *could* tap into and step this down to 7v (to allow for drop to get to the target 5v). you won't be drawing that much from that 60v rail (both sides of the 30v rails) and so if you assume a US current of 120vac, you could take a trafo that is rated at 2x your target and when running it at 1/2 input you'd get your target (5v) out. would that work? I think so, but what do you guys think?

 it would keep the wiring simpler (for my setup, at least) having *just* the 30, 0, 30 vac wires come in and then break that 60v diff down into a control voltage for my digital stuff.

 comments on that idea?


----------



## Beefy

Quote:


  Originally Posted by *linuxworks* /img/forum/go_quote.gif 
_comments on that idea?_

 

Only that a 5-10VA transformer at the correct secondary voltage is surely going to be a crapload easier


----------



## linuxworks

Quote:


  Originally Posted by *Beefy* /img/forum/go_quote.gif 
_Only that a 5-10VA transformer at the correct secondary voltage is surely going to be a crapload easier 
	

	
	
		
		

		
		
	


	


_

 

what I was hoping for was to simplify things. if I have to carry the 30/0/30 AC from the PS box to the amp box, that's fine. that's 3 wires and its easy on the connector and the cable bundle. then if I can derive the control voltage, while things are still in AC, down to 5v and put a very small trafo off in the corner of the amp box, that seems like a win to me. even more if you needed a local 12/-12 set of rails. again, running the big old 30/0/30 AND a 5 AND a pair of 12's thru umbilical? no thanks! that is clumsy. I'd rather send the 'bulk' (dual 30) thru and derive the rest. if possible. you don't like this idea?


----------



## amb

Aside from what others have already posted, if you use one of the two σ22s to power the JT (and assuming that the JT would indeed draw 400mA), then that σ22 will run significantly hotter than the other one, and you'll need to account for the extra current requirement into your choice of transformer. Also, since the JT needs only a single supply rail, and the σ22 is a dual-rail regulator, it would create current draw asymmetry in two ways -- between the positive and negative rails on one σ22, and between the two σ22s. Not that this is inherently a bad problem, but it just seems out-of-whack in an otherwise beautifully balanced architecture.


----------



## linuxworks

that would be another reason why I'd want to straddle the 2 ac lines and steal power from that with my mini step-down trafo idea. you are keeping things 'balanced' that way (both rails get equally 'hit' for the lower control voltage). I would not want to tap into just one of the sides; that would ruin the symmetry.


----------



## Beefy

Quote:


  Originally Posted by *linuxworks* /img/forum/go_quote.gif 
_I'd rather send the 'bulk' (dual 30) thru and derive the rest. if possible. you don't like this idea?_

 

No, not really. I would rather run a second umbilical.


----------



## linuxworks

I guess we differ in approaches, then 
	

	
	
		
		

		
		
	


	




 2 cords from box to box seems unprofessional to me; and I'd like to keep it to 1 semi-thin cord instead of 1 big 'garden hose' or even 2 cords.

 I'll have to try it to see. but is there anything technically wrong with using a 120/14 v trafo and powering at 1/2 so that it gets 60 in and 7 out? I think that's fine (?).


----------



## Pars

How about using something like this as the connector?
Digi-Key - 670-1133-ND (Manufacturer - SRCN2A16-7S)
 7 x #16 contacts rated at 10A, you could run both the 30-0-30Vac and your 7V or whatever on it. Reasonably priced and well made.


----------



## linuxworks

Quote:


  Originally Posted by *Pars* /img/forum/go_quote.gif 
_How about using something like this as the connector?
Digi-Key - 670-1133-ND (Manufacturer - SRCN2A16-7S)
 7 x #16 contacts rated at 10A, you could run both the 30-0-30Vac and your 7V or whatever on it. Reasonably priced and well made._

 

cool! added to my cart along with its mate 
	

	
	
		
		

		
		
	


	




 have not seen/used that one before. sure, I'll give it a try.

 but still, I do have to question if its better to have local trafos in the amp box (off in a corner, literally) and reduce the complexity and thickness of the box-to-box wire? in fact, you could still use the same connector and just parallel the key rail voltages (in this case, both, lol) on the pins, making the connector effectively 'thicker, electrically'.

 taking the devil's advocate on myself (lol) one advantage of putting both the 'big' and 'control' trafos in the same remote box would be that you could power switch the big one on/off (via SSR on the 110vac side) and still leave a constant 5v for control. that would be a very nice and clean way to power off the remote 'floor box'; you'd have a control wire from the amp to the PSU box (that's 1 wire) and 2 wires from the PSU to the amp for 5v/gnd, for controller use. the controller would send a logic 0/1 over that control wire and the PSU would SSR-control, on or off, the big 30/30 trafo. and by keeping the 5v control voltage always on, the unit can fully be controlled by the 'non-floor' box 
	

	
	
		
		

		
		
	


	




 it can even pre/post mute things since it will know about the 30/30 trafo coming on/offline. things like that.

 maybe I should just put them both in the same PSU box and run a thicker umb. cable. just seems less elegant to me, though, overall.


----------



## pila405

Does the B22 hiss? From HD800 to very sensitive phones like Denons.


----------



## m1abrams

Quote:


  Originally Posted by *pila405* /img/forum/go_quote.gif 
_Does the B22 hiss? From HD800 to very sensitive phones like Denons._

 

I do not have one, but would think that the only reason a B22 would hiss is if it was improperly built. I have a M^3 and it is dead silent even with sensitive IEMs. I would expect the B22 to be as quiet as the M^3 if not more.


----------



## amb

There is no such things as a noiseless amp. The trick is to build it with an appropriate amount of gain for the type of headphones you'll be using it with. Too much gain and the noise floor will become audible, too little gain and you won't be able to get loud enough with the volume control maxed. Since headphones span a wide range of impedances and sensitivities (K1000s to IEMs at both extremes), it's almost impossible to have one gain setting that works well with all of them. Throw in differing sources with different output levels and things get even more complicated. But, usually, a gain of 5 is a good compromise and allows the amp to work with a wide range of sources and headphones.


----------



## pila405

On what gain will you recommend for using the HD800 & K701 with Gamma2?


----------



## wuaffiliate

Quote:


  Originally Posted by *Tedro* /img/forum/go_quote.gif 
_Sorry, Camera phone picture:





_

 

Badass i love how that looks, i'm definitely going to make my first desktop amp with plexi.


----------



## IPodPJ

Ti, on my 4-ch B22 build I am using a gain of 5 which gives an effective gain of 10 per channel, correct? I'm thinking it might be too much. With the HD800 @ 300 ohms and a 4.8V out from my source, the amp will put out 3W (or was it 6W, I don't remember what Steve said). The headphones only handle 1/2W. However, because I'm using a current output DAC, we are implementing the passive I/V resistors in the amp chassis. They will have a dipswitch so I can select from 3 different resistor values, giving me either 1.2V, 2.4V, or 4.8V. With 1.2V, the amp will give the HD800 480mW, and at 2.4V it will yield 2W I think.

 So the question is should I leave the gain where it is? It seems to be the most common setting for the balanced Beta22. Or should I do away with the lower I/V resistor values and lower the gain? I'd like to be able to drive more demanding (less sensitive) headphones if the need arises, and I may not always be using the current output DAC. However the HD800 are my one and only headphone now and I have no intention of changing them anytime soon. My system is built around them.

 Thanks.


----------



## amb

Gain of 5 is good. Maybe 8.


----------



## IPodPJ

Don't you think 8 would be too much? And does the gain of 5 yield a gain of 10 per channel? Or are you saying we should do 2.5 per board, if that's even possible?


----------



## ShinyFalcon

At 300 and 62 ohms, 5x is probably fine.

 I'm seeing stacked film capacitors in some PSU's, and have been wondering what makes them special. In the σ11/σ22's case, they are C14/C14 & C15 respectively and are used as compensation caps for Q14. In the LCDPS, they're used before the rectifier bridge.


----------



## amb

Sorry IpodPJ, I was answering pila405's question and our posts crossed. He asked about using a γ2 with β22. Since γ2 is an unbalanced source with 1.4Vrms output at 0dBFS, an unbalanced β22 with gain 5 or 8 is good for HD800.

 As for your amp, what source are you planning on using it with and what's its output level at 0dBFS (balanced)?


----------



## IPodPJ

Quote:


  Originally Posted by *amb* /img/forum/go_quote.gif 
_Sorry IpodPJ, I was answering pila405's question and our posts crossed. He asked about using a γ2 with β22. Since γ2 is an unbalanced source with 1.4Vrms output at 0dBFS, an unbalanced β22 with gain 5 or 8 is good for HD800.

 As for your amp, what source are you planning on using it with and what's its output level at 0dBFS (balanced)?_

 

I apologize too. I got some of my numbers mixed up. The source is the Reference One or Reference Seven and it has an output of 5V via XLR, but I am not using the XLR outputs. We are implementing our own passive I/V conversion without the 0db buffer (which we have tested in a cable and it sounds great). The current output of the DAC (4.8mA, 2.4mA from hot to ground, 2.4mA from cold to ground) will run into a circuit inside the amp with a choice of 3 I/V resistor values that will yield 1.2V (600Ohm, 300Ohm per + and -), 2.4V (1.2kOhm, 600Ohm per + and -) and 4.8V (2.4kOhm, 1.2kOhm per + and -). With the current gain setting of 5 per board, 1.2V in will output 480mW to a 300 ohm headphone.

 The volume would be maxed out to get full power. I guess this is ideal for the headphones, but shouldn't there be some headroom in there? And I'd rather have less gain with a higher resistor value than more gain with a lower resistor value. The less noise the better.

 The boards have already been assembled with a gain of 5. But if they had to be changed they could be.


----------



## amb

Well, I guess you'll just have to give it a try to see.


----------



## IPodPJ

Quote:


  Originally Posted by *amb* /img/forum/go_quote.gif 
_Well, I guess you'll just have to give it a try to see._

 

Well, sure, that's ideal but the problem would be shipping back a 30+ pound chassis for modification. 
	

	
	
		
		

		
		
	


	




 Not cheap.

 But I'm still wanting to know if a gain of 5 on a 4-ch means you'll be getting a gain of 10 per channel.


----------



## johnwmclean

IPodPJ, I’m using a balanced Buffalo at 4V output, my balanced β22 is set to a gain of 2 (effective 4). For the HD800 this is perfect for me, most of my listening is around the 11.00 - 12.00 o’clock position on my DACT, my lowest output recording would be around 2.30 - 3.00 o’clock. I’m a fairly loud listener btw, and I’ve have never run out of steam when it come’s to volume hope that helps somewhat.


----------



## IPodPJ

Hi John. Yes, that is very helpful. Thank you. Is it possible to do a gain of 3?


----------



## ShinyFalcon

Yes, following the convention (R4 / R3) + 1 for the left and right channels. As for stability on gain 3x, I don't know.


----------



## NumLock

So I would like to try to build one for myself. So all I need is the B22 and S22 kits + cases + connectors(headphones/rca/xlr)? Is that it? Sounds fairly easy. I work in a electronics lab so I have all the tools. I could even custom design and order PCB here but AMB has all the PCB needed right?


----------



## oneplustwo

that's about it... you can go to glassjaraudio.com and it's even easier! Jeff can be busy sometimes so it might not be quick... but his kits do make it super convenient.

 you need to think about some things like how many channels, what size trafos, (gain), and things like that too.


----------



## IPodPJ

I can't change the gain. I forgot about one major discrepancy. We are adding a 4th input and it will be single ended, and will work with the balanced outputs. If I use a 2V source with a gain of 2 it won't be nearly enough. Looks like 5 is it.


----------



## amb

I have not tested and determined the appropriate compensation cap values to use for gain of 3. While you could try and interpolate between the values for gain 2 and gain 5, I suggest staying with the tried and true gain settings. The difference between gain of 2 and 3 (or between 4 and 8 balanced) is only 3.5dB.


----------



## NumLock

Quote:


  Originally Posted by *oneplustwo* /img/forum/go_quote.gif 
_you need to think about some things like how many channels, what size trafos, (gain), and things like that too._

 

I am all new to this so I have no idea what I need or want. I was thinking of getting a LD MKVII. So something similar, balanced, xlr/rca inputs, ingle ended and balanced headphone jacks.

 The 2 phones I plan to buy first are the Beyer DT8800 600ohm and HD600. Any suggestions on which way to go? I don't know how many channels I need or tarfos, gain, etc.


----------



## amb

NumLock, please read the β22 and σ22 websites, as well as the related discussions about them here and at headwize.com. It's a lot of information but that's the nature of this kind of project.


----------



## NumLock

Thanks AMB, I am reading it right now. Looks like I will need 4 channels/boards. I will do some more research and also build my own DAC first before attempting the B22. This is exciting but also depressing since I won't have a working amp anytime soon. 
 Thanks.


----------



## linuxworks

build a small amp, first. you can use that immediately. then build a small dac. you can use them both immediately 
	

	
	
		
		

		
			





 THEN work on the longer range projects.


----------



## oneplustwo

what linuxworks said! the B22 is a complex project that is certainly worth the effort but doing one (or two or three!) simpler projects first will serve you well. plus, it will give you an appreciation for how good the B22 really is as you'll have a frame of reference.


----------



## Magsy

I have HD650 (and I don't know how that compares to the HD800) but I had deep reservations in using a gain of 2x (4x overall). 
 However, now at over 100 hours I'm glad to say I haven't hit a single track when I don't have enough volume. I have been at full volume several times but usually around 2-3o clock. My source is 4v balanced.

 When I ran a single ended passive I/V TDA1543 Dac (roughly 1.2v) in there was almost enough but occasionally it ran a little short. I do like it very loud tho and someobody else would be fine. (Using the balanced output but two boards input to gnd)


----------



## IPodPJ

Quote:


  Originally Posted by *amb* /img/forum/go_quote.gif 
_I have not tested and determined the appropriate compensation cap values to use for gain of 3. While you could try and interpolate between the values for gain 2 and gain 5, I suggest staying with the tried and true gain settings. The difference between gain of 2 and 3 (or between 4 and 8 balanced) is only 3.5dB._

 

Do you mean "(or between 4 and 6 balanced)" ?


----------



## amb

Yes, typo.


----------



## pila405

AMB - Is it possible to build B22 w/o ventilation holes on the top - only on the bottom/back?

 Will the aluminium chassis do the work?

 This is how it meant to be:


----------



## nattonrice

You will answer that your self if you went to his website store.
 You can add it up your self.


----------



## oneplustwo

Ok... some of you may remember I toasted a B22 by making the mistake of not isolating the speaker jacks. Oops! Anyway, I fixed the boards and they all test fine as far as the initial setup goes. But when I hook everything up and power up, at first I get nothing and then a second later, a loud screech (this is through headphones... I disconnected the speaker outputs entirely.) When I move the stepped attenuator through it's range, the sound remains for the first 3 positions, then goes away for the next 6, and then comes back entirely at the last step. This happens with an input plugged in and without. Is it possible my stepped attenuator is toast as well? (The power supply tests fine as well BTW.)


----------



## Rooford

Hi,

 I had a mishap with my 3 channel B22. The problem is with the ground channel. After hooking up probes to R9 and powering on, I saw a couple of sparks by the probe and powered down. Looking at the board I nipped/scrapped the board coating and probably shorted the left side of R9 to the ground plane. I should be more careful 
	

	
	
		
		

		
		
	


	




 I checked the diodes, it looks like CR7 is toast (nothing visible but fails the diode check on my multi-meter. Q25 measures differently to the other boards, I've been measuring between the base-emitter base-collector using the diode check on my multimeter. Q23 seems a little inconsistent measuring between the gate/drain/source when comparing to the other boards.

 The other pnp/npn transistors seem OK, they pass the diode check when measuring between base-emitter, base collector. 

 Does anyone have any advice checking MOSFETS and JFETS?

 The resistances between the gates/drain/sources are consistent with the other two boards. Other diodes on the ground channel board check out. 

 I've been listening with basic two channels, so I have two working boards to use as reference. Sounds great with just two channels by the way!

 Before I order new parts I wanted to check if there are better ways of determining if the MOSFETS/JFETS are OK preferably in circuit. I've not powered up the ground channel since the mishap.

 If the board will take too much re-work it might be worth starting over. 

 Thank in advance for any help anyone can provide.

 James


----------



## nattonrice

I had the same thing happen multiple times (solder mask hole under R9 from a bubble) on the same board before I realized what was going on.
 Replace D11 and Q25 and it should all be fine.


----------



## oneplustwo

Rooford - Like natto, I've done the same thing a few times. For me, it's been Q25 every time (or the corresponding one on the other side).

 If you need to order them, I'd go ahead and get a few for spares (for both sides.)


----------



## linuxworks

my rec, fwiw, replace the .47ohm R's as a matter of course if you replace the mosfets. I've had to, many times myself. sometimes the resistor LOOKED ok but when I replaced it things went back to working again. on the power supply, as well!

 I keep a spare bunch of the .47's and also the mosfets. I've also learned to solder wire wrap wire to test points (powered down!) and avoid probes in live circuits. that always screwed me over and so I went with temp tack-on wires to do test point measurements. then power down, unsolder test wire and move to next. not elegant but I can't 'manage' probes with 100% accuracy, either 
	

	
	
		
		

		
			





 oh, and in terms of parts to order: don't order extra crd's unless that's your last option. they're pricey and they tend not to blow (so I'm told).

 order extra transistors (they are not too expensive) and I have not had to order extras of the matched quads; only the transistors that are 'near' the final mosfets are the ones that I've had go bad on me.

 clean the board well (alcohol and canned air duster) and that mostly helps you SEE if there are other zapped areas that need to be cleaned up, as shorts.


----------



## amb

You can't measure CRDs like a diode using your DMM. They are not actually diodes.


----------



## oneplustwo

Argh! Ok, second beta question for the day. This is on my balanced rig which I've finally gotten a chance to work on. It's 4 channel with a Twisted Pear joshua tree attenuator. 

 The XLR jacks are wired to the two JT boards. +/- of right XLR to one board, +/- of left XLR to the other board. Of course, the corresponding outputs feed the beta boards. The beta outputs are wired to combination XLR/TRS jacks. So, the left jack has pins 2 and 3 wired to the left 2 boards AND ring from the left + board, tip from the right + board, and is grounded to the PSU. And the right jack pins 2 and 3 wired to the right 2 boards AND ring from the left - board, tip from the right - board, and is grounded to the PSU. Does that make sense?

 While listening with my balanced headphones, I get one channel coming in nicely... although at less volume than I would have expected (might be just that I need more gain.) When listening with single ended headphones, I get that same channel coming in through my left and right ears from both combo jacks. 

 I switched the source from left to right (Buffalo 32S verified to be working correctly) and the same thing happens except it's the other channel coming in in mono.

 Any ideas on what might be wrong? It feels like I have confounding results... like I should only have one side coming in when connected single ended. I reflowed all the joints on the attenuator board feeding the side that doesn't come through when listening balanced. Now I'm not sure what to check... maybe I'll measure the resistance at the in and out terminals of the JT boards to make sure they're both working correctly?


----------



## tintin47

A couple questions. I am trying to choose LEDs for my beta build. I am using amber, in the 592 nm range. I found this one: HLMP-EL35-TW0DD at Newark. Does a T-1 3/4 size bulb have lead spacing of .2 inches? 

 The bulb is rated at 7200 mcd, which is very bright, but will it be bright enough running at 7ma? 

 Last, where should I connect the LED wires for my bulgin power switch if I am using the board LED slot already? I plan on using zener diodes to drop the voltage down to 12V, but where is the best place to attach the wires?


----------



## ShaneP

From the sheet linked off the newark page you should expect half light output with half current input (10ma probably around 1.85v forward). Lead spacing appears to be .100 in.


----------



## luvdunhill

I'm working down a list of boards that have destructed from the single ended jack shorting. I have one board that's being particularly stubborn. All four MOSFETs were bad, as well as R32 (and maybe R28, I don't remember but I replaced it). R29 and R33 were fine. After replacing all the MOSFETs, the PSU comes up and I get +-30V rails. However, I cannot get any current through the output stage. Input stage is fine (remember, this was a working board before).

 So, I was looking for a list of operating points for the b22, but I cannot seem to find it. I've taken a few measurements I'd like to compare (voltages are measured across the given device and no polarity is given):

 1.5V R28
 1.07V R29
 0V R32
 0V R33
 3.2V R23
 3.35V R24
 50mV R25
 48mV R26
 1.12V D12
 2.33V D11
 3.9V R14
 3.77V R15

 There were a few traces that had to be repaired, so don't assume the board is perfect. I did double check these things, but you know, I could have missed something. Also, remember this was a previously working board. Nothing is just jumping out at me (maybe Q18?) :/

 Thanks!


----------



## oneplustwo

luvdunhill - here's the operating points:


----------



## luvdunhill

cool!

 found it, it indeed was the Q17-Q17 in the Vas


----------



## amb

oneplustwo, how about a diagram showing how everything is connected?
 tintin47, you can tap the LED power from the σ22 V+ and V- output terminals, and solder the zeners inline (and shrink wrapped) to the Bulgin switch LED terminals.


----------



## Rooford

Hi,

 Thanks for the advice, I replaced Q25 and the board passed the initial setup checks 
	

	
	
		
		

		
		
	


	




 Snap on the screeching in three channel configuration, with apple earbuds and the volume turned down, trying with other headphones I don't get screeching. 

 Could the amp screeching be oscillation, and would low impedance buds be more susceptible to screeching/oscillation?

 Final note: Very impressed with the B22, it sounds subtly smoother than the M3 I built, M3 has AD8610 op-amps. I think there's a clearer sonic distinction between the different headphones I've tried, which I guess is good indication of it's transparency. 

 Thanks again for the advice and to Ti for designing a great amp!


----------



## fishski13

Quote:


  Originally Posted by *Rooford* /img/forum/go_quote.gif 
_Hi,

 Thanks for the advice, I replaced Q25 and the board passed the initial setup checks 
	

	
	
		
		

		
		
	


	




 Snap on the screeching in three channel configuration, with apple earbuds and the volume turned down, trying with other headphones I don't get screeching. 

 Could the amp screeching be oscillation, and would low impedance buds be more susceptible to screeching/oscillation?

 Final note: Very impressed with the B22, it sounds subtly smoother than the M3 I built, M3 has AD8610 op-amps. I think there's a clearer sonic distinction between the different headphones I've tried, which I guess is good indication of it's transparency. 

 Thanks again for the advice and to Ti for designing a great amp!_

 

i don't think the B22 would oscillate with HPs as long as your DC offset is 0. with speakers, you may need a Zobel on the speaker outs.


----------



## amb

Some headphone loads may be complex enough to require a zobel network as well. It won't hurt to put one on anyway.


----------



## oneplustwo

For question #1: Could be oscillation... I was using my cheapo ear buds actually. I can try my grados although they're low impedance as well. Not sure what else it would be (other than the stepped attenuator) if the PSU and all three boards test out correctly.

 For question #2 (the balanced rig), here's a sketch of the wiring. I tied the two JTA boards' grounds together... not sure if that matters or not. (Note TRS are three separate lugs on the combo jack.)


----------



## amb

One mistake I see is that you have the right channel output wired to the Tip and left channel to the Ring. That's backwards, but should only result in a reversal of left and right channels, not the symptoms you describe. I hope the picture reflects how you actually wired everything up accurately. You should double check.

 Also, In this scheme, one of your TRS jacks will be out of phase relative to the other one. If you believe in the need for absolute phase correctness then one of them would be wrong. If not, then no biggie.

 Thirdly, I hope that the Sleeve connection goes to the sigma22's G terminal directly, not riding on the G wire from the amp boards back to the PSU.


----------



## oneplustwo

Quote:


  Originally Posted by *amb* /img/forum/go_quote.gif 
_Some headphone loads may be complex enough to require a zobel network as well. It won't hurt to put one on anyway._

 

Well, I tried it with the Grados and it works fine! Might be because one of the board's DC offset was only able to be reduced to 5mV and that in combination with my in ear phones (Ety's in my sig) made it oscillate?

  Quote:


  Originally Posted by *amb* /img/forum/go_quote.gif 
_One mistake I see is that you have the right channel output wired to the Tip and left channel to the Ring. That's backwards, but should only result in a reversal of left and right channels, not the symptoms you describe. I hope the picture reflects how you actually wired everything up accurately. You should double check.

 Also, In this scheme, one of your TRS jacks will be out of phase relative to the other one. If you believe in the need for absolute phase correctness then one of them would be wrong. If not, then no biggie._

 

I'll check the wiring again tomorrow. It wouldn't be the first time I double/triple checked something and found a mistake on the fourth (or later) check.

 For the TRS jacks, what would be the proper way to maintain phase? + from right and - from left for both combo jacks? I'll probably leave it as I'm not a stickler for phase correctness per se, but I would like to know so I can do it right the next time.

 The ground does indeed go back to the PSU case and a sigma ground terminal on it's own wire. I have an 8-connector umbilical so I'm using one of the two slots not used by the 2 sigmas.


----------



## Hottuna_

Looking at oneplustwo's drawing, a question popped into my mind.
 For single ended outputs from a 4 channel 2 sigma22 build where one sigma powers L+,L- and the other R+,R-.

 Where does the sleeve of the TRS connector get connected to? Does it connect to whichever sigma22 or do the two sigmas need to be shorted at ground?

 Or do the sigma22s have to be configured to power L+,R+ and L-,R- respecitvely and the sleeve of the TRS connector connected to the associated sigma's ground.


----------



## ShinyFalcon

It shouldn't matter which σ22 you use for TRS's ground.


----------



## Beefy

Quote:


  Originally Posted by *ShinyFalcon* /img/forum/go_quote.gif 
_It shouldn't matter which σ22 you use for TRS's ground._

 

I think it would if they are powered from separate transformers?


----------



## amb

It shouldn't matter. The grounds come together at the input jacks (and interconnect cable) anyway. As long as you don't let the higher current ground return from the headphones "ride" on the signal ground reference wires from the boards to the PSU, then all should be well.


----------



## amb

Quote:


  Originally Posted by *oneplustwo* /img/forum/go_quote.gif 
_Well, I tried it with the Grados and it works fine! Might be because one of the board's DC offset was only able to be reduced to 5mV and that in combination with my in ear phones (Ety's in my sig) made it oscillate?_

 

It probably has nothing to do with DC offset. As I said, some headphones (and its cable) present enough impedance complexities that may cause the amp to oscillate, so add the zobel network.

  Quote:


 For the TRS jacks, what would be the proper way to maintain phase? + from right and - from left for both combo jacks? I'll probably leave it as I'm not a stickler for phase correctness per se, but I would like to know so I can do it right the next time. 
 

No. L+ -> tip, R+ -> ring on both TRS jacks will give you correct phase.


----------



## Beefy

Quote:


  Originally Posted by *amb* /img/forum/go_quote.gif 
_It shouldn't matter. The grounds come together at the input jacks (and interconnect cable) anyway. As long as you don't let the higher current ground return from the headphones "ride" on the signal ground reference wires from the boards to the PSU, then all should be well._

 

Ah, gotcha.


----------



## tintin47

So the 100uF and 470uF caps for my sigma 22 are 50V instead of 63V. Is that going to be a problem or will the PS run normally?


----------



## amb

It's fine for +/-30V output.


----------



## tintin47

Wow. That was fast. Thanks very much.


----------



## oneplustwo

My joshua tree attenuator is being fed with 30V from the sigma. It's only supposed to take 7-24 but I've been doing it for short stints as I test out the amp. What's the easiest way to dial the voltage down to the acceptable range? Can I just put a resistor in line with the wiring? Or is a zener diode a better idea?


----------



## Beefy

Quote:


  Originally Posted by *oneplustwo* /img/forum/go_quote.gif 
_It's only supposed to take 7-24 but I've been doing it for short stints as I test out the amp._

 

The JT is meant to take 7-24V*AC*. Do it _properly_ and get a separate transformer.


----------



## ShinyFalcon

If the relay board is anything like the TREAD the relay board should accept DC as well; the bridge and cap won't be doing much. If you have parts lying around I suppose lots of diodes in series (σ22 -> diodes -> Tree AC input) will work fine, but a nicer solution will indeed be a separate σ24. Remember that the tree only needs 5VDC to work.


----------



## oneplustwo

Yes, I know... someone else had asked the TPA guys and they said it wouldn't matter. So instead of adding another trafo and another umbilical, I figured this would work fine.


----------



## Beefy

Quote:


  Originally Posted by *ShinyFalcon* /img/forum/go_quote.gif 
_If the relay board is anything like the TREAD the relay board should accept DC as well; the bridge and cap won't be doing much. If you have parts lying around I suppose lots of diodes in series (σ22 -> diodes -> Tree AC input) will work fine, but a nicer solution will indeed be a separate σ24. Remember that the tree only needs 5VDC to work._

 

Yeah, I appreciate that, but to use the 30VDC would unnecessarily increase current draw on one rail of the S22 and cause unnecessary heat production on the JT regulator. It is a poor solution.

  Quote:


  Originally Posted by *oneplustwo* /img/forum/go_quote.gif 
_Yes, I know... someone else had asked the TPA guys and they said it wouldn't matter. So instead of adding another trafo and another umbilical, I figured this would work fine._

 

There's a big difference between something working 'fine' and doing something properly.


----------



## oneplustwo

Point taken. I can't seem to find any little toroidal trafos. I guess I'll just do the sigma24 thing unless someone has a small cheap chassis mount option that would work.

 UPDATE: I figured out the problem. Turns out one of the joshua tree attenuator boards was not working because the ribbon cable was not pierced all the way through at the connector. Finally listening to my Senns at their "full" potential. 
	

	
	
		
		

		
			





 Now that I'm going to go ahead and get the little trafo added and need the "spare" wires in the umbilical, I think I'm just going to not use SE headphones with it for the time being. Besides... why use my single ended grado SR80s when I can use my balanced Senn HD650s!


----------



## Pars

Question on CRDs. I bought some 1N5314s from a guy on diyaudio. They are marked KSI 1N5314. I tested a couple of them with my DMM in series (mA) with a 9V battery and was getting ~6.5mA thru these, which is a bit high. Any problem with using these in a sigma22 I am building? I assume you can test these in this manner also?


----------



## luvdunhill

Quote:


  Originally Posted by *Pars* /img/forum/go_quote.gif 
_Question on CRDs. I bought some 1N5314s from a guy on diyaudio. They are marked KSI 1N5314. I tested a couple of them with my DMM in series (mA) with a 9V battery and was getting ~6.5mA thru these, which is a bit high. Any problem with using these in a sigma22 I am building? I assume you can test these in this manner also?_

 

you should know by now, amb has a diagram for everything!


----------



## Pars

Yeah, I know, lazy 
	

	
	
		
		

		
		
	


	




 That's basically how I tested them just using 9V battery cuz... it was handy. Ammeter was on the other side, but shouldn't make a difference. These apparently are Knox Semiconductor (never heard of them).


----------



## amb

I use 1N5xxx series made by Central Semiconductors and they are usually pretty good. Never tried Knox, so can't comment on those.

 At any rate, the σ22 will work just fine even when the CRD is that far off. In this particular application it's not the absolute accuracy that matters. As long as it's working as a reasonable CCS, then all is well.


----------



## Bina

HI, I'm thinking about building Beta 22 for my JH13.

 Can you say me, how much is 2 Channel beta (this is for single ended right?)? Only price for parts for desks in beta, I will use power supply build by one of czech builder.

 Thanks for response.


----------



## luvdunhill

how much gain are you planning to configure the boards with?


----------



## linuxworks

b22 for iems???


 boggle!

 are iems ever hard to drive? I wasn't under that impression.

 why the b22 for such easy phones?


----------



## IPodPJ

With a sensitivity of 119dB @ 1mW and an impedance of 28 ohms, if you used a stepped attenuator the first notch might be too much volume. Your probably best using a potentiometer and the lowest gain setting of 2, unless you can go even lower. That's probably the most sensitive headphone/IEM in existence. Even the JH-16 is less, at 118dB.


----------



## Bina

It looks from specification, but in real, thesy need more volume than any other IEM I owned, excluding ER-4S. I dont know if this helps, but for example on Benchmark DAC 1, with bulid in amp, I set volume on something like 9 clock.


----------



## luvdunhill

Quote:


  Originally Posted by *IPodPJ* /img/forum/go_quote.gif 
_Your probably best using a potentiometer_

 

I would say pretty confidentially that would be your second worst option. I'd consider a custom stepped attenuator or a DVC solution myself.


----------



## tintin47

^ yeah. I would pick the resistors for a custom stepper. Either way the beta is way overkill and unnecessary.


----------



## linuxworks

there's your concensus, a speaker-grade amp is just NOT needed (or even really wanted) to drive iems. it does not matter how much the iem's cost - they simply do not have enough mass to need anything like a b22 to drive them. you'd be defeating the purpose of a powerful amp if you 'gain it down' too much via gain and input atten.

 the b22 is wrong for your app. any portable amp is fine (pimeta, mini3, etc). I would not even go to a 'home' level amp, since the portables are more than good enough for iems.

 this should not be about ego or money. it should be about matching equip based on gain, impedance, power levels and need. iems don't need this kind of amp.


----------



## digger945

Quote:


  Originally Posted by *tintin47* /img/forum/go_quote.gif 
_^ yeah. I would pick the resistors for a custom stepper. Either way the beta is way overkill and unnecessary._

 

 Quote:


  Originally Posted by *linuxworks* /img/forum/go_quote.gif 
_there's your concensus, a speaker-grade amp is just NOT needed (or even really wanted) to drive iems. it does not matter how much the iem's cost - they simply do not have enough mass to need anything like a b22 to drive them. you'd be defeating the purpose of a powerful amp if you 'gain it down' too much via gain and input atten.

 the b22 is wrong for your app. any portable amp is fine (pimeta, mini3, etc). I would not even go to a 'home' level amp, since the portables are more than good enough for iems.

 this should not be about ego or money. it should be about matching equip based on gain, impedance, power levels and need. iems don't need this kind of amp._

 

What about the unique circuit of the Beta? 
 What about the sound?
 Ego, money, gain, impedance, power and need aside, would anything else sound the same? 
	

	
	
		
		

		
		
	


	





  Quote:


  Originally Posted by *luvdunhill* /img/forum/go_quote.gif 
_I would say pretty confidentially that would be your second worst option. I'd consider a custom stepped attenuator or a DVC solution myself._

 

How about a TVC or Slagleformer?


----------



## linuxworks

Quote:


  Originally Posted by *digger945* /img/forum/go_quote.gif 
_What about the unique circuit of the Beta? 
 What about the sound?
 Ego, money, gain, impedance, power and need aside, would anything else sound the same? 
	

	
	
		
		

		
		
	


	


_

 

this is my view, fwiw, but my take on the b22 is that its a great amp for driving *loads*. true hard-to-drive loads; often ones that need decent voltage swing due to the load being high-z.

 iem's are not high-z and are the easiest thing to drive.

 the m3 is even lower in noise than the b22 (according to amb's specs). I believe this, too; my m3 sounds slightly quieter. for iems, you want THAT!

 sorry, but its just funny to imagine a humvee being used to carry bubble wrap across your backyard 
	

	
	
		
		

		
		
	


	




 it just seems that silly to me, to use a heavy duty amp to drive loads that are trivial and need no serious voltage swing.


----------



## oneplustwo

I think this is a funny debate. 99% of the population would laugh at us for amplifying headphones in the first place. I for one never even knew such a thing existed before I caught the bug myself not too long ago. So it amuses me to see 99% of us playing down the idea of using a B22 to drive IEMs.

 To use linuxworks analogy, if a b22 for IEMs is like a Humvee carrying bubble wrap, perhaps a b22 for headphones like Senn HD650s is like a Humvee carrying a case of bubble wrap. Who's to say where the line should be drawn? Certainly, a Humvee carrying a load of full sized people can also be argued as excessive.

 In any case, I would say go ahead and try a beta. If you enjoy the sound, then that's what matters. Every one else can offer guidance and perspective but ultimately, it's only your own personal enjoyment that matters. Worst case scenario, you sell it off and add that to your own experience. Isn't that what these hobbies are about to some degree?


----------



## Hottuna_

Got a question for oneplustwo.
 How hot does the reg on your JT get running it from your sigma22.
 I am pondering getting a balanced JT for my B22 and may have problems shoehorning another trafo into the dual sigma22 case.
 I guess i only need a tiny transformer for it. Will have to look around for options.
 My plain jane 23 step attenuator just does not give me the degree of volume control i would like.


----------



## Magsy

I've done it with a wallwart before due to lack of space, I didnt like the idea at the time but now I do. I power the attenuator and AC relays via it and there is some peace of mind knowing there isn't 240v constantly flowing in something I made! 
	

	
	
		
		

		
			





 As a side note I have a really good range and granularity with a Goldpoint 50k attenuator, infact I haven't once become stuck between steps or wished for more range. I'm really quite suprised and when I started building I was willing to accept some quirks with it but there are none. About the same price as the JT and a ton less complex, the clicking of relays is _annoying_


----------



## oneplustwo

Hottuna - I haven't run it very long since I know that it's not supposed to take that much voltage. But it does get quite hot in the short time I do run it. The sigma24 board that amb has along with the specified trafo is a nice small easy solution. I may just go to radio shack and get a small chassis mount trafo and be done with it.

 Magsy, did you just plug in a wallwart and feed the wire through a separate hole? Or did you tear apart a wallwart and scavenge the trafo from it to feed something?

 As a side note, the JT from TPA is pretty cool. Lots of steps! The only thing I still have to get used to is all the clicking as the relays turn on and off.


----------



## Bina

If we get out of question about amping IEMs, can anybody please answer on my original question? 
  Quote:


  Originally Posted by *Bína* /img/forum/go_quote.gif 
_Can you say me, how much is 2 Channel beta (this is for single ended right?)? Only price for parts for desks in beta, I will use power supply build by one of czech builder.

 Thanks for response._


----------



## luvdunhill

Quote:


  Originally Posted by *Bína* /img/forum/go_quote.gif 
_Can you say me, how much is 2 Channel beta (this is for single ended right?)? Only price for parts for desks in beta, I will use power supply build by one of czech builder._

 

what's a desk exactly?


----------



## oneplustwo

I'm assuming "desks" = "boards?" The glass jar audio kits are good proxies. Jeff has one beta board listed as $92.29 so a two channel kit sans power supply would be $200 or so depending on shipping/paypal fees, etc. (Enclosure and ancillaries would be additional of course.)


----------



## Bina

Thank you.


----------



## EugeneK

Just got mine done. 30 minutes ago.


----------



## El_Doug

Quote:


  Originally Posted by *EugeneK* /img/forum/go_quote.gif 
_Just got mine done. 30 minutes ago._

 

Congrats!


----------



## oneplustwo

And?! Pictures? Listening impressions?


----------



## EugeneK

My camera is out of action for a little bit, this is from my cellphone. :/

 I don't think I'll be a very good judge of the amp. lolz. I believe I'll be biased. XD


----------



## fishski13

Quote:


  Originally Posted by *EugeneK* /img/forum/go_quote.gif 
_Just got mine done. 30 minutes ago._

 

congrats and enjoy 
	

	
	
		
		

		
		
	


	




.


----------



## EugeneK

Quote:


  Originally Posted by *fishski13* /img/forum/go_quote.gif 
_congrats and enjoy 
	

	
	
		
		

		
		
	


	




._

 

Thanks! ^.^


----------



## tintin47

whoops. Misread some of the specs.


----------



## UKToecutter

20mm 2A slow blow.
 You sort of answered the question yourself.

 Or have I missed the point?


----------



## Pars

I don't think you need to be concerned with the breaking capacity, at least if it is above the fuse rating. See Fuse (electrical) - Wikipedia, the free encyclopedia

 Any of the 250V 2A 5x20mm fuses at Newark will be fine (assuming this is the rating specified on amb's website). Not sure whether you want fast blow or slow blow (I would guess slow?)


----------



## Beefy

My very rough rule of thumb is whatever your total transformer load is rated at, double it, and use slow blow.


----------



## tintin47

^^Yeah. I just realized that. Its been a long week.


----------



## luvdunhill

where would you guys suggest starting to troubleshoot a board that I cannot zero the offset? The output stage and input stage are biased properly. With the pot in the center I'm getting 84mV offset. At all the way counterclockwise I get 23mV offset. R9-R12 are at 4.5V. Output bias is at 120mA across R34 and 119mA across R35. Just looking for a place to start checking I guess.


----------



## naamanf

Quote:


  Originally Posted by *luvdunhill* /img/forum/go_quote.gif 
_where would you guys suggest starting to troubleshoot a board that I cannot zero the offset? The output stage and input stage are biased properly. With the pot in the center I'm getting 84mV offset. At all the way counterclockwise I get 23mV offset. R9-R12 are at 4.5V. Output bias is at 120mA across R34 and 119mA across R35. Just looking for a place to start checking I guess._

 

Stupid question but did you check out the notes an AMBs B22 page? Looks like the easiest thing to try is using a lower value resistor in R13 and see if that gets you closer.


----------



## oneplustwo

From Amb's page:

 The input JFETs are matched within acceptable limits, but the N-channel and P-channel devices are installed in a manner such that their deviation from perfect match becomes additive. In this event you can try swapping the order of Q1 and Q2, but keep Q3 and Q4 where they are. Alternatively swap Q3 and Q4, but leave Q1 and Q2 as-is. Then power-up and re-check the DC offset and see if it could be trimmed down to near zero. 

 The input JFETs may not be matched closely enough. If this is the case, you can try hand-matching additional JFETs for better Idss match and replace Q1 through Q4 with the closest quad you could find. 

 You may increase the DC offset adjustment trimpot range. One way to do this is to reduce the value of R13. You can try going as low as 5KΩ. Note that if this is being done to a left or right channel board, then the other channel should also be similarly modified because this modification will also cause a small change in overall voltage gain. 

 You can also increase the DC offset adjustment range by modifying the D3 and D4 diodes such that they are each two 1N4148 diodes in series.


----------



## fishski13

two 1N4148 in-series worked for me and i didn't need to rip out the boards to do this either.


----------



## luvdunhill

hm. This board originally worked fine, Nate built it. It then went up in smoke. I then repaired the output stage, and while I was at it upped the gain. I would think the problem would not be as simple as lowering R13, and having to change it on three board boards would be a PITA at this point. I'm going to check D3 and D4 and go from there. Trying to get this board fixed for a meet tomorrow :/

 edit: okay, trying the 1n4148 in series...


----------



## Fitz

Quote:


  Originally Posted by *luvdunhill* /img/forum/go_quote.gif 
_hm. This board originally worked fine, Nate built it. It then went up in smoke. I then repaired the output stage, and while I was at it upped the gain. I would think the problem would not be as simple as lowering R13, and having to change it on three board boards would be a PITA at this point. I'm going to check D3 and D4 and go from there. Trying to get this board fixed for a meet tomorrow :/

 edit: okay, trying the 1n4148 in series..._

 

I do hope you guys it worked out. I guess Steve shouldn't have built the chassis with that wood from trees growing on that ancient burial site, huh?


----------



## luvdunhill

Quote:


  Originally Posted by *Fitz* /img/forum/go_quote.gif 
_I do hope you guys it worked out. I guess Steve shouldn't have built the chassis with that wood from trees growing on that ancient burial site, huh?_

 

garlic coated silver cables seemed to have fixed that part. Oh, and the series diodes fixed the other part. 

 Is it bad that the gain is 16 and I still want more volume with my modded LCD-1? I guess I might have to get one of those new fangled high output sources sometime soon...


----------



## amb

When the gain is increased, so may the DC offset, because a portion of that comes from the input stage and is amplified by the gain. What was previously possible to null with the trimpot might no longer be possible (out of adjustment range). The fix is to try one or more of the solutions outlined at the β22 website.


----------



## UKToecutter

Does anyone have the sigma22 and beta22 graphics for a front panel I'm doing?

 Thanks


----------



## amb

Search the "Let's build krmathis a beta22" thread, I posted a ZIP of the FPE files. And read the README file in there.


----------



## UKToecutter

Thanks Ti.


----------



## UKToecutter

Damn you Ti!!!
 I just spent the best part of 90 minutes reading that thread before I found your zip file.

 Wow, what a generous endevour.

 You guys are real class. Thumbs up to you all.

 Andy


----------



## swt61

Naaman and group, Thanks bunches for your help! We did in fact get the amp running beautifully due to your advice.

 Fitz, the burial ground was actually and old wild west bordello, so the trees were just a bit sassy. After a séance where we paid homage to Miss Kitty, everything became lighter, and the MOSFETs emitted a lovely Blue glow for about 10 seconds, then the music of the gods played, and angels with harps appeared overhead.

 Either that or Marc spiked my Pepsi.


----------



## luvdunhill

Quote:


  Originally Posted by *swt61* /img/forum/go_quote.gif 
_We did in fact get the amp running beautifully due to your advice._

 

It was still pretty beautiful when it wasn't running


----------



## fishski13

yes, very pretty. is that cherry wood? i'm glad the the extra diode in series worked for you - much easier that replacing R13 with boards mounted.


----------



## EugeneK

here's a proper pic!


----------



## digger945

Very nice Eugene. Where did ya get the hanger that's holding the 800s?


----------



## EugeneK

Those are from Sennheiser. You'll find them if you do a google search for "Sennheiser HH-10", HH stands for headphone holder. XD


----------



## fishski13

Quote:


  Originally Posted by *EugeneK* /img/forum/go_quote.gif 
_Those are from Sennheiser. You'll find them if you do a google search for "Sennheiser HH-10", HH stands for headphone holder. XD_

 

thanks!


----------



## linuxworks

no one has the hh10 in stock, though. looks useful. I'd like to get one, myself


----------



## linuxworks

Quote:


  Originally Posted by *luvdunhill* /img/forum/go_quote.gif 
_It was still pretty beautiful when it wasn't running 
	

	
	
		
		

		
		
	


	







_

 

I LOVE that look!

 the routed out wood is great; I am going to try that, myself.

 (any bay area woodworkers want to lend a hand on my box build??)


----------



## Beefy

Quote:


  Originally Posted by *linuxworks* /img/forum/go_quote.gif 
_no one has the hh10 in stock, though. looks useful. I'd like to get one, myself 
	

	
	
		
		

		
		
	


	


_

 

There is also the Koss HoldaPhone.


----------



## digger945

Quote:


  Originally Posted by *Beefy* /img/forum/go_quote.gif 
_There is also the Koss HoldaPhone._

 

oooo. And very attractively priced I might add. Thanks there Beefman. I shall have to try this one.


----------



## Beefy

Quote:


  Originally Posted by *digger945* /img/forum/go_quote.gif 
_oooo. And very attractively priced I might add. Thanks there Beefman. I shall have to try this one._

 

Koss KSH1 Hold-a-Phone Stereophone Hook, Black - eBay (item 220543731607 end time Feb-19-10 08:51:41 PST)

 Would it be too bold of me to propose another mini group buy? 
	

	
	
		
		

		
		
	


	




 Curse these stupid companies that won't ship internationally......


----------



## digger945

Quote:


  Originally Posted by *Beefy* /img/forum/go_quote.gif 
_[
 Would it be too bold of me to propose another mini group buy? 
	

	
	
		
		

		
		
	


	


_

 

Why certainly not.

  Quote:


 Curse these stupid companies that won't ship internationally...... 
 

Vee hav vays of deeeling wiv these types


----------



## oneplustwo

Quote:


  Originally Posted by *linuxworks* /img/forum/go_quote.gif 
_I LOVE that look!

 (any bay area woodworkers want to lend a hand on my box build??) 
	

	
	
		
		

		
		
	


	


_

 

I'd be happy to help... let me know what you're looking for.


----------



## pila405

Guys, can I build balanced b22 with only one o22? And what are the differences between using 1 o22 or 2? [Will be used with pair of HD800 so the gain will probably be 5]

 @linuxworks - http://global.ebay.com/Senn_heiser_H...082869997/item

http://www.headphone.com/accessories...one-holder.php

*@EugeneK * - Where did you buy the chassis? What model is it? And from where the front panel?


----------



## deathg0d

eugenek, i am planning to get hd800 as well and i have a similar setup as yours so what are you thoughts?


----------



## oneplustwo

You certainly can. It just won't be quite as "dual mono" which many of the hard core people here would prefer. But I'm not sure anyone would be able to tell the difference frankly. With my own, I used a single sigma for a while before my second sigma was in working order and I personally didn't notice a difference myself FWIW. One thing to consider, if you'll be powering speakers, it might be good to split the load between 2 sigmas. Also, make sure you size your trafo(s) accordingly.

 By gain of 5, I assume you mean a combined gain of 10? That should be fine.


----------



## Beefy

The concern with having two power supplies for a balanced build isn't for sound quality, or any ideal of your amp being dual mono. It is for heat management on the MOSFETs on the S22. Four boards suck a lot of current, and if your unregulated voltage is high that means a LOT of heat will be generated.

 A single S22 powering four boards should probably use larger than default heatsinks, and be _very_ well ventilated.


----------



## pila405

There are some cases / enclosures with heat sinks on the sides, can you recommend me on some good enclosures to do the task? 
 It doesn't have to look good, just to be built properly and made off aluminum.


----------



## oneplustwo

these are a bit pricey, but look quite nice:


----------



## pila405

But its HUGE! Is there something like that just about half the width?

 There are some enclosures which you can attach the heat sniks on the sides to the MOSFET. Do you know what I am talking about?

 Look on the photo gallery of the b22 on AMB's site. The one with the red front panel [meant to be used with AKG K1000] - The seconed one after Ti's b22.


----------



## oneplustwo

I don't think it's that much bigger. Were you looking at this one?

 If you're doing a three channel and sigma in one case, that's going to be comfortable.

 EDIT: Now that I think about it, you're probably doing a 2 channel using one board for each side? In which case, this is kinda big.


----------



## pila405

But the b22 is gonna be in different chassis...I need a enclosure which is half as wide as what you offered. But thank you very much, it is exactly the style I wanted.


----------



## EugeneK

Quote:


  Originally Posted by *deathg0d* /img/forum/go_quote.gif 
_eugenek, i am planning to get hd800 as well and i have a similar setup as yours so what are you thoughts?_

 

I love it. ^.^ B22 + HD800 is more detailed than Auditor + HD800


----------



## Magsy

I've got mine, 4 boards, 1 psu and 120va trafo in a square of 310x310mm but it is stupidly tight. Those cases just look big, a balanced B22 is BIG!

 My single psu is ok, it is pretty hot tho but I've been burning it in for 20 nights for 8 hours a night, flat out. Totally fine!


----------



## pila405

But I want the supply to be in different enclosure...


----------



## dazzer1975

got the backplane boards ordered the beta boards and psu boards and the parts available on ambs shop thus far.

 still deciding wether to go 2 channel active ground or fully balanced. Going balanced would require an upgrade of my source too, but to diy a beta 22 and not go the whole hog seems a bit silly lol

 gotta do some more reading to check out my options before I buy any more parts etc but looking forward to it all.

 printed off all the releveant build info bookmarked a few threads here and on headwize so should be ready to go for the summer time when I plan to tackle it.


----------



## linuxworks

Quote:


  Originally Posted by *dazzer1975* /img/forum/go_quote.gif 
_still deciding wether to go 2 channel active ground or fully balanced. Going balanced would require an upgrade of my source too, but to diy a beta 22 and not go the whole hog seems a bit silly lol_

 

strongly disagree.

 balanced is hype for most consumers. its about ego more than anything.

 I'll take the opposite view and say that balanced is 'a bit silly' in this context. I may bring my 2ch b22 and 3ch b22 with me to the next meet. I challenge anyone to do a DBT and tell me which was which. I doubt anyone could.

 I wish ego would not enter into 'building the biggest' amp. this is not the reason to build 'big amps' (sigh).


----------



## m1abrams

NOTE: I have not built or heard any beta22

 I agree with linuxworks that going balanced is probably not going to make much of a difference for most headphone users. One reason that would make me build a balanced beta22 is if I planned on using it for speaker duty where the extra power maybe needed.


----------



## linuxworks

I've been using my 2ch b22 for speaker use (8" tannoy 2way pbm8's) and it seems to fill the room with volume (and bass, too!) before I even get to '11' on my volume control (lol). typical size bedroom, not large living room, though.

 I'd go b24 before I'd go balanced on a b22 for spkr use. balanced b22 is VERY expensive and it seems like the b24 is the better choice if you truly are going to drive 'hard' (large) spkrs.

 it took me a long long time to even 'concede' to do a 3ch b22 
	

	
	
		
		

		
			





 and I did it because the backplane was 'there' and easy to use. to be honest, I never heard any diff on the 3ch version. once you are 'very good' being better does not make the sound any better; only makes your wallet lighter and your stereo rack heavier


----------



## m1abrams

Quote:


  Originally Posted by *linuxworks* /img/forum/go_quote.gif 
_I've been using my 2ch b22 for speaker use (8" tannoy 2way pbm8's) and it seems to fill the room with volume (and bass, too!) before I even get to '11' on my volume control (lol). typical size bedroom, not large living room, though.

 I'd go b24 before I'd go balanced on a b22 for spkr use. balanced b22 is VERY expensive and it seems like the b24 is the better choice if you truly are going to drive 'hard' (large) spkrs.

 it took me a long long time to even 'concede' to do a 3ch b22 
	

	
	
		
		

		
			





 and I did it because the backplane was 'there' and easy to use. to be honest, I never heard any diff on the 3ch version. once you are 'very good' being better does not make the sound any better; only makes your wallet lighter and your stereo rack heavier 
	

	
	
		
		

		
		
	


	


_

 

Ah but the b24 requires a preamp no? balanced b22 would make a great preamp


----------



## Magsy

Quote:


  Originally Posted by *linuxworks* /img/forum/go_quote.gif 
_I've been using my 2ch b22 for speaker use (8" tannoy 2way pbm8's) and it seems to fill the room with volume (and bass, too!) before I even get to '11' on my volume control (lol). typical size bedroom, not large living room, though.

 I'd go b24 before I'd go balanced on a b22 for spkr use. balanced b22 is VERY expensive and it seems like the b24 is the better choice if you truly are going to drive 'hard' (large) spkrs.

 it took me a long long time to even 'concede' to do a 3ch b22 
	

	
	
		
		

		
		
	


	




 and I did it because the backplane was 'there' and easy to use. to be honest, I never heard any diff on the 3ch version. once you are 'very good' being better does not make the sound any better; only makes your wallet lighter and your stereo rack heavier 
	

	
	
		
		

		
		
	


	


_

 

Maybe look at it from the source side? Most of the seriously good DAC's are balanced and if they have an SE output it has usually been neutured by only using half the signal or summed via opamp.
 In some cases you even have a 'discrete output stage' only to find that they got lazy and stuck an opamp in for the SE output.


----------



## dazzer1975

Quote:


  Originally Posted by *linuxworks* /img/forum/go_quote.gif 
_strongly disagree.

 balanced is hype for most consumers. its about ego more than anything.

 I'll take the opposite view and say that balanced is 'a bit silly' in this context. I may bring my 2ch b22 and 3ch b22 with me to the next meet. I challenge anyone to do a DBT and tell me which was which. I doubt anyone could.

 I wish ego would not enter into 'building the biggest' amp. this is not the reason to build 'big amps' (sigh)._

 

ego? We both could probably spend all day posting links to threads containing posts from well respected long standing members of the community decrying how much better balanced rigs are than single ended.

 Having not built my beta 22 yet, I can only go off the fact that the consensus seems to be that balanced sounds better.

 ego? What man.


----------



## linuxworks

I've only built 2 b22 boxes but having experienced the extreme overkill that even 1 board gives per driver, I just cannot see using 2 of them per driver. sorry but that seems like ego to me.


----------



## NumLock

Hey guys just wondering what would be a tube rival to the Beta22? I still plan on building a B22 but funds are low right now. I plan on have a B22 and some tube amp just to have the best of both worlds.


----------



## dazzer1975

Quote:


  Originally Posted by *linuxworks* /img/forum/go_quote.gif 
_I've only built 2 b22 boxes but having experienced the extreme overkill that even 1 board gives per driver, I just cannot see using 2 of them per driver. sorry but that seems like ego to me._

 

Ive no idea how you can state that everyone who owns a beta22 in balanced config do so as a result of ego.


----------



## Anonanimal

When you consider how amazingly powerful a 3-channel B22 really is, I'd also lean more toward the idea that building the balanced version is more of a "because I could" or, of course "just for fun". Whether or not it has anything to do with ego, I don't really have an opinion... This is, of course, coming from someone who has not done extensive listening to balanced setups, so I have no gauge of how much better/different it can sound.


----------



## tintin47

Quote:


  Originally Posted by *NumLock* /img/forum/go_quote.gif 
_Hey guys just wondering what would be a tube rival to the Beta22? I still plan on building a B22 but funds are low right now. I plan on have a B22 and some tube amp just to have the best of both worlds._

 

Tube hybrid would be something like a balanced EHHA or the Stacker II if/when that project comes out into the open. Pure tube I would check headwize.


----------



## tintin47

Quote:


  Originally Posted by *Anonanimal* /img/forum/go_quote.gif 
_When you consider how amazingly powerful a 3-channel B22 really is, I'd also lean more toward the idea that building the balanced version is more of a "because I could" or, of course "just for fun". Whether or not it has anything to do with ego, I don't really have an opinion... This is, of course, coming from someone who has not done extensive listening to balanced setups, so I have no gauge of how much better/different it can sound. 
	

	
	
		
		

		
		
	


	


_

 

Or it is "because I wanted balanced phones" or "because I have a k1000". The beta 22 is generally overkill anyway, but there is something to be said for never worrying whether your amp will be up to the task.


----------



## Kabeer

Quote:


  Originally Posted by *tintin47* /img/forum/go_quote.gif 
_Tube hybrid would be something like a balanced EHHA or the Stacker II if/when that project comes out into the open. Pure tube I would check headwize._

 

I think the stackerII will only be commercial not DIY release now...


----------



## linuxworks

Quote:


  Originally Posted by *tintin47* /img/forum/go_quote.gif 
_ there is something to be said for never worrying whether your amp will be up to the task._

 

this, I agree with 
	

	
	
		
		

		
		
	


	




 that's what prompted me to build the b22 in the first place.

 perhaps what I'm saying is that once you reach some threshold, throwing 'more' at it does not help. that's my experience and even 1 board of b22 is way beyond the point of sensibility (to be honest). you *know* its doing its job and doing it well, just feel those heatsinks and see how much effort they spend 'standing still' (lol).

 one does not need double that. imo. but I suppose ymmv (standard disc)


----------



## Anonanimal

Quote:


  Originally Posted by *tintin47* /img/forum/go_quote.gif 
_The beta 22 is generally overkill anyway, but there is something to be said for never worrying whether your amp will be up to the task._

 

X2! This was also my reason.


----------



## swt61

Quote:


  Originally Posted by *linuxworks* /img/forum/go_quote.gif 
_I've only built 2 b22 boxes but having experienced the extreme overkill that even 1 board gives per driver, I just cannot see using 2 of them per driver. sorry but that seems like ego to me._

 

I'm compensating for a small p3nis.


----------



## Beefy

I do it to meet chicks.


----------



## johnwmclean

For one extra board and 2 extra channels on your pot. Why not? Overkill’s never more simple and doable.


----------



## ting.mike

Well it gives me the bragging rights that I have the same set up that johnwmclean has.


----------



## jezz

"Overkill" is a relative term I think. I define it as the amount of time or money one is willing to spend to ensure performance. My opinion comes from the semiconductor market, these days at AMD/ATI. The discrete graphics market is dominated by mainstream cards basically, and the ultra-high-end cards are used by a select few, which I liken a bit to the high-end amp market. You can get whatever you want .

 Original intent of posting: I'm gonna build me a 3ch β22. Eventually. Still trying to pick out a chassis or figure out what I'm going to do to a NABU. I don't have access to a shop these days; does anyone have any tips regarding either ventilating a NABU or a chassis of similar milling ease? Frankly, I don't care much how it looks as I don't tend to stare intently at my amp while listening to music, and I'm capable enough with a circular saw to make a fair looking wooden front panel.


----------



## keyid

Can a single e22 w/ 100va power four b22 boards to drive Senn 600/650?


----------



## oneplustwo

keyid - this was covered just a few posts ago. short answer, yes. but you need to be careful of heat management.


----------



## amb

If by "e22" you mean σ22, the answer is yes. The σ22 PSU was designed to power up to four β22 boards serving only headphone duty. That said, the σ22 MOSFETs will run quite hot in this configuration so be sure to ventilate the case well, and use larger heatsinks if possible.

 EDIT: oneplustwo beat me to it. I love it... now that there is enough β22/σ22 expertise in the community I could rely on more of you to support each other!


----------



## oneplustwo

HAHAHA! I have a long way to go before I am able to balance out the "takes" with any "gives" I may be able to contribute. And of course, I still have a lot to learn. But that's why I'm in this... to learn!


----------



## UKToecutter

I wish my boards would get here.

 I'm aching to make a start


----------



## deerinheadlights

I am having difficulties getting my b22 into a case. It has been two months of listening enjoyment.
	

	
	
		
		

		
		
	


	




 I was unable to zero the DC offset on the right and left channel boards so I swapped either Q1 and Q2 or Q3 and Q4. Afterward the the DC offset zeroed out.
 A few days after completing the boards I may have shorted the output jack to the volume pot. This resulted in a blown fuse. Replaced a bad Q23 on the ground channel board. Ran initial setup again. Amp sounds great.

 But I started worrying after reading about about what happens when R9 sparks during the initial setup. The same thing happened with my ground board. A diode check revealed... Q25 on the ground board was bad. Q2 on the s22 was bad.
 For all other BJTs the diode check with a fluke 12b showed .56-.65 on the BJTs. When reversing the polarity the diode check showed 0L on one leg and 1.2-2.0 on the other leg. So I compared each measurement of each component to the same component of the other boards and they were all in the same 1.0-2.0 range for one leg and 0L on the other leg. A diode check of the newly installed components before power up yielded... Q25 measures .59 one way and 1.06 and 1.27 with polarity reversed. Q2 measures .65 and .65 one way and 1.995 and 0L (started at 2.33 and after a few seconds read 0L) the other way.
 Measured resistance of R32, R28, R34, R35, R33, R29, Q23, Q21, Q22, Q24, Q17, and Q18. The MOSFETs and the JFETs are not shorted. The resistors are measuring correct. The .47 ohm resistors show .5 ohms.

 There are some voltages that are look very wrong for all 3 of the b22 boards.
 Voltages around VR1 area, R13, R20, R21, R22, VR2 area seem to be the most off.
Sigma22 Voltages
Beta 22 Ground channel voltages
Beta 22 Left Channel voltages
Beta 22 Right Channel voltages

 There is a hum at approximately 1-3 o'clock on the alps 50K volume pot. The hum is present when connected to an ipod, d10 or gamma1/2++ powered by s11. Plugging in the USB or touching the USB cable to the gamma1/2++ case will kill the hum.

 Also the right channel board heatsinks feel quite a bit hotter than the ground and left channel.


----------



## amb

dearinheadlights, all your voltages look reasonable. If your amp is uncased then there is no "chassis ground" and I am not surprised that there is hum. I wouldn't worry about it until you get it all cased up and wired according to the β22 website "Wiring & ground" section.


----------



## ShinyFalcon

I don't think I seen this mentioned, but is the σ11 capable of outputting inverted voltage (-24V) after replacing the N-channel MOSFETs with P-channels?


----------



## amb

Quote:


  Originally Posted by *ShinyFalcon* /img/forum/go_quote.gif 
_I don't think I seen this mentioned, but is the σ11 capable of outputting inverted voltage (-24V) after replacing the N-channel MOSFETs with P-channels?_

 

No, that won't work, but you could simply call the V+ output "ground" and then V- would be "negative"...


----------



## UKToecutter

Quote:


  Originally Posted by *amb* /img/forum/go_quote.gif 
_No, that won't work, but you could simply call the V+ output "ground" and then V- would be "negative"... 
	

	
	
		
		

		
		
	


	


_

 

Making sure that your PS Ground and signal ground are isolated (of course)


----------



## LeMat

2 quick questions for helping me moving forward on this project :

*1. Casing *: I see the vast majority of people having built a b22 encased it into a square edged enclosure. Assuming I'd like something with curved edge, like these exemples :
RE77
 W-8
326S

 Where could I get such case ? I'm aware that high-end audio companies have the ressources to machine their own fancy faceplate but audio-gd seem to use a quarter cylinder to round-up the corner. 

*2. Toroid :* I received a 120VA 30+30 toroid transfo. After a test, unloaded, its output is 35,6 VAC. Shouldn't it be more closer to 30 ? or do I received a 36+36 ??

 tx


----------



## jezz

Quote:


  Originally Posted by *LeMat* /img/forum/go_quote.gif 
_*2. Toroid :* I received a 120VA 30+30 toroid transfo. After a test, unloaded, its output is 35,6 VAC. Shouldn't it be more closer to 30 ? or do I received a 36+36 ??_

 

No, your transformer is fine. The ratings of a transformer refer to their loaded voltage. The unloaded voltage of transformers is often designed to be higher than their quoted voltages because the windings in the transformer have resistance and thus the currents through the primaries and secondaries will drop a little voltage.


----------



## LeMat

Quote:


  Originally Posted by *jezz* /img/forum/go_quote.gif 
_No, your transformer is fine. The ratings of a transformer refer to their loaded voltage. The unloaded voltage of transformers is often designed to be higher than their quoted voltages because the windings in the transformer have resistance and thus the currents through the primaries and secondaries will drop a little voltage._

 

Glad to hear that ! I know it's usually higher than specified but I wasn't expecting it to be that much. 
 So I'll be able to connect it to my s22 tonight and see how it goes. 
 Thanks

 Any suggestion regarding the enclosure ?


----------



## MoodySteve

LeMat, I am not sure if they make any that are the right size for a ß22 (most seem to be more 'compact') but MiniSemi will soon be selling cases with curved edges/corners on their website.

High end enclosure chassis available soon at Minisemi.com - diyAudio


----------



## LeMat

Quote:


  Originally Posted by *MoodySteve* /img/forum/go_quote.gif 
_LeMat, I am not sure if they make any that are the right size for a ß22 (most seem to be more 'compact') but MiniSemi will soon be selling cases with curved edges/corners on their website.

High end enclosure chassis available soon at Minisemi.com - diyAudio_

 

Thanks. It starts to look like what I want. I don't know whether they'll do custom size but a chance, they are in Montreal... me too


----------



## scottder

My first project, CMOY of course. Friend is teaching me and another person how to solder. We're going to start with a simple LED light board to learn the basics, then move on to the CMOY.

 My Aoyue 936 arrived yesterday (still shopping for a multimeter) along with a set of 'helping hands' and a spool of solder.

 I can't wait!

 Scott

 Opps sorry misread what the thread was about, my bad!


----------



## LeMat

Quote:


  Originally Posted by *LeMat* /img/forum/go_quote.gif 
_Glad to hear that ! I know it's usually higher than specified but I wasn't expecting it to be that much. 
 So I'll be able to connect it to my s22 tonight and see how it goes. 
 Thanks

 ..._

 

So it's now connected and it worked !! slighty low but ok : 29.28v


----------



## Fitz

I got these parts sitting around and unsure what to do with them... should I build a beta22, or a really bitchin' toaster oven?


----------



## swt61

Quote:


  Originally Posted by *Fitz* /img/forum/go_quote.gif 
_I got these parts sitting around and unsure what to do with them... should I build a beta22, or a really bitchin' toaster oven?_

 

Hmmm, would that be called a Bagel22? 
	

	
	
		
		

		
		
	


	




 This is one to keep an eye on! I happen to know a bit about this build, and it's going to be a stunner. No real surprise though with Fitz at the helm.


----------



## Fitz

Mmm, Bagel22, I like the sound of that.


----------



## jlefley

Making some progress:


























 I have since added the MOSFETs to the S22 in the pictures and both boards are working well. I'm still waiting on some capacitors for the B22 boards but I should have those done within a week or two.


----------



## johnwmclean

Quote:


  Originally Posted by *Fitz* /img/forum/go_quote.gif 
_I got these parts sitting around and unsure what to do with them... should I build a beta22, or a really bitchin' toaster oven?




_

 

How are you going to be attaching the FETs to those sinks, without running into potential oscillation problems? I’m curious as I’ve got a build progressing where I’ve gone down a custom sink path...


----------



## Fitz

Quote:


  Originally Posted by *johnwmclean* /img/forum/go_quote.gif 
_How are you going to be attaching the FETs to those sinks, without running into potential oscillation problems? I’m curious as I’ve got a build progressing where I’ve gone down a custom sink path... 
	

	
	
		
		

		
		
	


	


_

 

The amp boards will mount directly to the heatsinks with standoffs, and the mosfets will be soldered underneath the board. Lead length will be essentially the same as it would with on-board heatsinks, so it doesn't introduce any oscillation problems. In the case of the power supply, I'll just go the typical angle-bracket route.


----------



## jantze

Quote:


  Originally Posted by *LeMat* /img/forum/go_quote.gif 
_*1. Casing *: I see the vast majority of people having built a b22 encased it into a square edged enclosure. Assuming I'd like something with curved edge, like these exemples :
RE77
 W-8
326S

 Where could I get such case ? I'm aware that high-end audio companies have the ressources to machine their own fancy faceplate but audio-gd seem to use a quarter cylinder to round-up the corner. _

 

How about Hexateq case?






 Here is one nice build using that case: Picasa Web Albums - Vincent - Multichannel UCD


----------



## aloksatoor

how about a few htpc cases? silverstone lian li makes good ones and you can easily remove the cooling fans et all


----------



## LeMat

Quote:


  Originally Posted by *jantze* /img/forum/go_quote.gif 
_How about Hexateq case?






 Here is one nice build using that case: Picasa Web Albums - Vincent - Multichannel UCD_

 

Looks good ! but I must say it's a bit big and I wanted something black. 
 Thing is I'm building a b22 with the transfo in its own enclosure. I would have to change my plan and have it back in the box. Sure I have a shielded transfo but most of the people here recommend me to keep it separated. Purist approach 
	

	
	
		
		

		
		
	


	




 Regarding the htpc case, never thought at it... definitely a path to explore.


----------



## LeMat

Quote:


  Originally Posted by *aloksatoor* /img/forum/go_quote.gif 
_how about a few htpc cases? silverstone lian li makes good ones and you can easily remove the cooling fans et all_

 

Do you think it would be possible to customize the faceplate ? I don't have the equipment to drill hole and so on... I intended relying on front panel express... unless I could find in my area some manufacturer with a CNC machine kind enough to accomodate a particular...


----------



## jantze

Quote:


  Originally Posted by *LeMat* /img/forum/go_quote.gif 
_Regarding the htpc case, never thought at it... definitely a path to explore._

 

Check out HFX cases.











HFX - Home


----------



## LeMat

wow these one are good looking !! Still big enough to make a standalone unit but damn sleek look. 
 Quite expensive though (+/- 430 euros)
 I also notice no vent holes.... 

 Thanks for this one !


----------



## UKToecutter

My Galaxy cases arrived yesterday (so my wife tells me).
 She said "what the hell have you been buying from Italy" LOL

 Can't wait to get home and see


----------



## linuxworks

Quote:


  Originally Posted by *Fitz* /img/forum/go_quote.gif 
_I got these parts sitting around and unsure what to do with them... should I build a beta22, or a really bitchin' toaster oven?_

 

I just don't understand; WHY is it that people are so hung up on either/or situations??

 its not either/or.

 it can be BOTH. just plan for some wide heat vents in case you like your bread^Wtoast cut thicker.



 (lol....)


----------



## Fitz

Quote:


  Originally Posted by *linuxworks* /img/forum/go_quote.gif 
_I just don't understand; WHY is it that people are so hung up on either/or situations??

 its not either/or.

 it can be BOTH. just plan for some wide heat vents in case you like your bread^Wtoast cut thicker.



 (lol....)_

 

But does the kind of bread you toast affect the sound? I mean, it won't make the sound become empty and lifeless if I happen to put in some white bread, will it?


----------



## linuxworks

that's just a new frontier for 'tuning'. I have no idea which bread would be the best. I'm willing to help develop/debug though. would be a good thing, early in the morning, I think.


----------



## naamanf

Quote:


  Originally Posted by *Fitz* /img/forum/go_quote.gif 
_But does the kind of bread you toast affect the sound? I mean, it won't make the sound become empty and lifeless if I happen to put in some white bread, will it?_

 

Only if you eat the bread right away. If you toast it slowly for the next 2000 hours and let us know how it changes every 15 minutes it should be fine. Also make sure you cryo treat your toaster and only use the purest silver/nichrome element.


----------



## wink

Fitz said:-
 I got these parts sitting around and unsure what to do with them... .

 Give 'em to me. It'll be a good start to a 6 Channel B22 I want to build.


----------



## linuxworks

Quote:


  Originally Posted by *naamanf* /img/forum/go_quote.gif 
_Only if you eat the bread right away. If you toast it slowly for the next 2000 hours and let us know how it changes every 15 minutes it should be fine._

 

slow? I'm not sure I agree.

 go tandoori style. hot and fast.


----------



## tintin47

Just finished. Finally. Tested perfectly and they're all cased up and glowing. Will post pics soon.


----------



## El_Doug

Quote:


  Originally Posted by *tintin47* /img/forum/go_quote.gif 
_Just finished. Finally. Tested perfectly and they're all cased up and glowing. Will post pics soon._

 

congratulations!


----------



## Anonanimal

Congrats, tintin! Eagerly awaiting pics and impressions.


----------



## tintin47

Took a couple of quick pics with my cell phone. This thing dwarfs my dorm room. It doesn't look right, but oh well. The whole thing is made from 3/16" scrap aluminum that I rescued from the shop at school. It was a little beat up, and has some dings that I couldn't sand out, but that adds character. The finish is just 600 grit with an orbital sander. It is fit to within .005", for the hell of it, and is held together with aluminum L-bracket at the corners. 

 I have a Valab stepper, and amphenol jacks, with a neutrik powercon umbilical. The switch is a bulgin latching model, and is connected to a relay. 

 The amp is 3 channel, not balanced even though it has a 4pin xlr jack. I just used xlr to negate the short problems with TRS and 4 pin so I don't have to recable my phones again or make new cables if I go balanced.

 I will post better pics when I can borrow someones camera.


----------



## oneplustwo

Looks good! Isn't scrap metal great?! I don't have access to a shop anymore, but the scrap cut offs from the local metal shop for my B24 was relatively cheap.


----------



## tintin47

^Yeah. It's crazy that I was able to find 4 16x12" plates basically in the garbage.

 The amp sounds great so far. It gets surprisingly toasty. I am really happy to be done, both because I have the amp and because I have reclaimed my room from all of the components, soldering irons, etc.


----------



## Anonanimal

tintin- Great looking beta! I love the bare aluminum- man I miss having my university's machine shop at my disposal...


----------



## RedLeader

I'm extremely curious about how to do this build, but to do it cheaply. If you could do this with 2 boards, a regulated wallwart and some cheap pre-fab cases, or a simple wooden build, I wonder what it would end up costing. I noticed the kits for a single board are around $100, has anyone managed to do it cheaper by buying pieces from mouser or elsewhere? About how much was the cost per board?

 Seems like you could likely make a hell of an amp for under $300


----------



## m1abrams

I would not skimp on the psu on a build like this. If need to go that cheap better to build a different design.


----------



## Anonanimal

RedLeader, I'm fairly certain that someone did a low-cost build and posted it in this very thread. Search around a bit and you'll probably find it.


----------



## RedLeader

Quote:


  Originally Posted by *m1abrams* /img/forum/go_quote.gif 
_I would not skimp on the psu on a build like this. If need to go that cheap better to build a different design._

 

Don't need to, just curious how well it would work, compared to other DIY amps at the same parts cost.


----------



## tintin47

I think that cfcubed did a budget beta 22 for around $350. I could not tell the difference between it and a 3ch b22 o22 during a meet, whatever that says. 

 That said, I don't really understand the idea of skimping on this amp. If you need a great cheap amp, build a CK2III. If you want no holds barred amping insanity, go with a beta. If you want NHBAI, you don't skimp on parts, IMO


----------



## RedLeader

Quote:


  Originally Posted by *tintin47* /img/forum/go_quote.gif 
_That said, I don't really understand the idea of skimping on this amp. If you need a great cheap amp, build a CK2III. If you want no holds barred amping insanity, go with a beta. If you want NHBAI, you don't skimp on parts, IMO_

 

Fair enough, but one of the things I love about DIY is that you're free to scale projects up and down as you see fit. You can trick out a CMOY or scale back a beta22, IMO it depends not on your budget (though of course that's a consideration) but more on what you can do with a design. I'm of the mind to start simple and scale up from there. I know most people would decide on exactly what they want, build it and be done with it. I'd likely start off with a skeleton build and add on to it if I felt I liked the way it worked/sounded. And if I don't, I sell the amp as a cheap design and move on to something else. I suppose it's the curse of the endless tinkerer.


----------



## oneplustwo

I did my first beta as a three channel in a cookie tin (see my sig). Sounded great. To answer your question, I think the glassjar audio kits are going to be about the same as building your own kit via Mouser. Unless you plan on building a bunch of them, the kits are the way to go. Especially since you don't need to source from amb AND mouser AND digikey AND whoever else.

 The other thing to consider is that you need to be concerned about trafo hum with this amp. Not to say you couldn't do it cheaply, but it is something to consider when thinking about your enclosure. Shielded trafos are another option if you want a single enclosure.

 I'm in the process of building a 2 channel in a wooden enclosure with a shielded trafo. This is probably about as cheap and simple as I would go personally. It will cost me about $400 in parts (2 betas, 1 sigma, shielded trafo, ancillaries) and nothing in the enclosure since I'll basically be using scrap wood from other projects. I expect the result to be a great "bang for the buck" contender.


----------



## linuxworks

Quote:


  Originally Posted by *RedLeader* /img/forum/go_quote.gif 
_I'm extremely curious about how to do this build, but to do it cheaply._

 

omit an expensive case and re-work a throw away case. I never 'finished' this case but got it up to the point where it held things reliably and safely, it kept wiring away from sensitive parts and when the top was off (which was always, lol) it gave all the cooling I needed. not everyone's style but it was dead silent, with the PSU being a 'floor box' of some other nondescript kind (just a trafo running 30/30 ac down its longish wire to this box)







 the trafo box is super simple:






 that thing sits on the floor and is remotely switched on/off so, in fact, it can go behind some shelf or book case or something and disappear. disappear sonically, too, as any physical hum from the windings (there is some) also goes away when you 'floor box it' 
	

	
	
		
		

		
		
	


	




 style wise, its ugly; the 2 box thing. its extra parts and extra hassle but it also does have some advantages. remoting the trafo does solve a lot of problems very cost effectively. and you can re-use some metal chassis for the b22, keep it to 2ch and save a lot. b22 in 2ch mode is still a very 'worthy' amp and building it on the cheap is not a bad idea at all.


----------



## cfcubed

Quote:


  Originally Posted by *tintin47* /img/forum/go_quote.gif 
_I think that cfcubed did a budget beta 22 for around $350. I could not tell the difference between it and a 3ch b22 o22 during a meet, whatever that says._

 

Others that tried it felt the same... I _think_ it says that it'd take critical listening in a quiet environment w/good equipment to try to detect a difference vs full/real 3-ch builds. Of course it could be that y'all were being nice saying such things
	

	
	
		
		

		
		
	


	



 My 2c about it:
I'd not do one-case build w/o nice shielded transfo & lots of room to sep it+o22 from amp proper, so "real/full" build would likely = 2-case build for me. And that costs. Using wallwarts yielded _most_ of the advantages of a 2-case build.
that said, I'd use a bit bigger case next time to get some sep between PS & amp boards. Also consider the lower-noise fixed regs talked about in another thread here (like MC7924CTG / MC7824CTG?). Perhaps build off simplistic tracking +/- design from datasheets (e.g w/TIP42A, etc).
BUT think considering nice M³ build instead of all this business could be great way to go if nice <= $350 USD SS amp is desired.
 Quote:


  Originally Posted by *tintin47* /img/forum/go_quote.gif 
_That said, I don't really understand the idea of skimping on this amp._

 

It's to save $$$ of course
	

	
	
		
		

		
		
	


	




 Best bang-for-the-buck & all that. (Edit: Perhaps linuxworks said this better)
 In my mind, if you go o22 then you should go good toroidal transfo & 2-case build & that adds cost & complication. 
 We all pick our points on the cost/perceived-benefit curve.

*Edit: Note also that I had two spare 24VAC WWs around that I'd gotten cheaply & they wanted something to do.
 Also, the simple +/- 24VDC PS in my budget build generates little heat. Stock ventillation in HB-350 case top, w/some bottom/back holes, is quite enough.*


----------



## RedLeader

Quote:


  Originally Posted by *cfcubed* /img/forum/go_quote.gif 
_[*]BUT think considering nice M³ build instead of all this business could be great way to go if nice <= $350 USD SS amp is desired._

 

Very valid point, and one I am considering as well, as that design looks like an interesting one. I'm not sure its quite as flexible and "tinker-friendly" but you could do some fun stuff with it. 

 Part of this is prompted by my desire to get another set of K340 as I have some more ideas about what to do to them this time. And as I have found out, they are probably the most difficult cans to drive properly that I have ever come across. The only amp that I've heard that did justice to them was a $3000 custom monstrosity by McAllister audio, and for several very good reasons that's not an avenue I can attack. Given the stupid level of difficulty in driving those cans, I don't want to too heavily invest in time/money going one way when I won't be completely happy with it.


----------



## luvdunhill

Quote:


  Originally Posted by *RedLeader* /img/forum/go_quote.gif 
_I'm not sure its quite as flexible and "tinker-friendly" but you could do some fun stuff with it_

 

A M3 is much more "tinker-friendly" than a beta22. Note how many warnings amb issues on "don't change these parts, don't change these values, don't allow long wires to this, or keep leads as short a possible on that" on a beta22 compared to the M3 design.


----------



## tintin47

So how hot is too hot for the inside of the cases in terms of temp? I don't have a thermo couple right now but I'd like to know a ballpark temp that is too high for when I do. 

 My amp gets quite toasty, but it has plenty of ventilation directly over the heat sinks as well as on the sides, and it looks like more ventilation in terms of surface area than most other betas.


----------



## luvdunhill

Quote:


  Originally Posted by *tintin47* /img/forum/go_quote.gif 
_So how hot is too hot for the inside of the cases in terms of temp? I don't have a thermo couple right now but I'd like to know a ballpark temp that is too high for when I do_

 

One generally accepted value is that the heat sinks shouldn't exceed 60C. A good way to check this is to put your hand on the heat sinks, and if you have to pull it away in three seconds, you're right about on target. In other words, shut the lid, wait 1 hour, open the lid and stick your hand on the heat sink and start counting.


----------



## johnwmclean

Quote:


  Originally Posted by *luvdunhill* /img/forum/go_quote.gif 
_One generally accepted value is that the heat sinks shouldn't exceed 60C. A good way to check this is to put your hand on the heat sinks, and if you have to pull it away in three seconds, you're right about on target. In other words, shut the lid, wait 1 hour, open the lid and stick your hand on the heat sink and start counting._

 

Pain threshold accountability?


----------



## cfcubed

NP test scale


----------



## luvdunhill

Quote:


  Originally Posted by *cfcubed* /img/forum/go_quote.gif 
_NP test scale




_

 

I didn't want to invoke the almighty name in case amb had another opinion, but yes indeed you caught the reference quite well


----------



## cfcubed

Trying to build up a full 4-ch b22 & have run into a snag on one of the boards. I try not to call for help, but would appreciate some direction here.

 During setup cannot get board to *maintain* > 1.8mv across R34/R35 (R9/R11 = 4.5v, R10/R12 = 4.8v).

 As I've an identical perfectly working board, I moved VR2 on the problem board up a few turns - close to where VR2 is set on the working one. 
 Problem board starts out exactly as all my other b22 boards do - like 80mv settling to 60mv BUT then falls to 1.8mv (all within about 3 secs).

 What I've tried:
3X review of all parts & orientation. Full check of board top & bottom w/magnifier. Full reflow of all joints, wash & more visual checks.
Compared resistances of top exposed leads to gnd, V-, V+ to working board. Allowing caps to equally charge between the boards, measurements are comparable between them... IOW don't think there are any unintended opens or shorts..
Since Q25/Q26 come up a lot here, pulled tested & replaced them.
My guess is a temperamental/bad part... In the old days I would have reached for Freon spray & tried that on the semis. 
 About to embark on checking live Vs but it'd be great if I knew where to focus my efforts.


----------



## amb

cfcubed, what you describe does sound like a thermal-related issue with a certain part. A cold spray here and there sounds like a good idea. At any rate, also check R25-R27, Q17/Q18 and the 0.47 ohm output resistors. With power on, measure the DC voltage across the wire jumpers at R30 and R31 as you turn the VR2 trimmer clockwise, that voltage should increase. Don't let it go much over 7V without also checking the voltage drop across R34/R35 to make sure you don't overbias the MOSFETs. If that voltage does increase to 7V without a problem, then the problem is isolated to the output stage alone, otherwise, it could be Q17/Q18 and surrounding parts or further upstream.


----------



## cfcubed

Thanks a bunch amb... I'll give your suggestions a go this weekend.
 Hopefully I can pick up some sort of cold spray @ a decent elec store nearby as well.


----------



## LeMat

Finally finished my 3 boards B22... fired up... 2 boards working perfectly but the ground channel .. quite the opposite. Leds are on, r9 is 4.5v but i have 0mv across R34... damned ! 
 If there is something obvious coming to your mind, please share ! Otherwise, what's the better way to debbug it / narrow down the possible issue ?


----------



## amb

LeMat, tried looking back at past posts in this very thread?


----------



## cfcubed

Quote:


  Originally Posted by *amb* /img/forum/go_quote.gif 
_..check R25-R27, Q17/Q18 and the 0.47 ohm output resistors. 
 ..wire jumpers at R30 and R31 as you turn the VR2 trimmer clockwise, 
 .. If that voltage does increase to 7V without a problem
 ..otherwise, it could be Q17/Q18 and surrounding parts or further upstream._

 

Could not find bad part using cold spray (well, upside-down RS dust-off - same thing)
 R25-27 & 0.47R resistors checked out fine (w/a little variance for being in-circuit)
 R30 - R31 Vdiff starts @ 8v within 4 secs drops to 2.5v & VR2 will not raise it.
 Replaced Q17,Q18,Q12 & Q16 w/known good spares

 All my actions to date on the board have not changed its behavior.

 The "worst" variance in operating Vs for this board is on the right side (Q22/Q24), * most notably V @ Q22 gate drops from 3.3v all the way to 0V.*
 Seems something is dragging down the whole line on schem from Q16 collector -> Q22 gate to 0v after 4 secs or so.


----------



## amb

cfcubed, check the rail voltages on both sides of Q25 and Q26 before and after your 4 second interval to see if the supply rails are still where they should be.


----------



## cfcubed

Rails are holding fine:
 Q25 coll=24v,base=22.5v,emit=22v...Q26 coll=-24v,base=-23.4v,emit=-22.6v
 with +/- 24v PS after 3 mins (PS running cold/little draw)... As a reality check swapped in working board & all is still fine w/it & PS is not cold powering it (expected draw)

 Note: I've a yet-to-be-build b22 kit I can pillage for parts if we want to try things


----------



## amb

There has to be a bad part somewhere that only goes bad when powered up for a short moment. Time to do more exhaustive voltage measurements and compare to the operating points PDF file found at the β22 website's "initial setup" section, under the "Troubleshooting" heading. Maybe that will help identify what's going on.


----------



## oneplustwo

What's the best way to install a zobel network for headphones? My thought is that it would be easiest to just go from the positive and negative tabs of the headphone jack to the ground tab. Of course, with speaker posts, it's straight forward, but I'm wondering if folks have had good luck with a particular method installing for headphone jacks. (This is for the beta that I had problems with oscillating with very low impedance headphones.)


----------



## amb

Directly on the headphone jack would be best, but depending on the model of jack you have, it may or may not be easy to do.


----------



## simwells

Looking into building one of these once I finish my Gamma2, I'm somewhat confused as to the actual advantage of the active ground version over just the two board design. Would be for headphone useage and I don't want to go as far as a balanced unit. Also am I right in thinking I need a sigma22 per beta22 board?


----------



## oneplustwo

No... one sigma is enough for 2, 3 or 4 beta boards. Usually, people use 2 sigmas for 4 in order to distribute the load and manage heat. But 2 or 3 board setups typically use 1 sigma. At least for headphone use.

 As for the advantage of an active ground, some people say it's significantly better than a 2 channel, others not. You can search for previous discussions on this topic, but IMHO, the decision is probably based on things like budget, enclosure size, etc as much as your belief on the merits of active ground.


----------



## DemonicAngelz

Hi guys. I've read this thread all the way from post #1 to #2384 and I'm seriously contemplating building a two board b22 with a s22. I've built the pimeta a couple of cmoy and the mini3 from amb. However I am relatively lousy at troubleshooting if any problems pop up. I am willing to learn of course. Time is not an issue, have lots of time to spare from now till october.

 I intend to upgrade by building another set of 2 board b22 and s22 running balanced out to my hd650. Doing this way because i'm not totally confident that I can fix up one, if I happen to give up half way it wouldn't be too expensive either. 

 Do you guys think this is a good idea for me to start off or should I hold off till I have more experience?


----------



## oneplustwo

It's doable. The B22 is not an easy build, but there's lots of help on the board (which I've taken full advantage of myself). One thought is to go ahead and buy the parts for your 2 channel + sigma and then build the sigma first. The sigma is a bit more straight forward and will give you a sense for whether or not you feel comfortable continuing on with the beta boards or if you would prefer to stop, tackle another project or two first, and then continue on.

 I would also recommend taking your time, reading the pages on Amb's site multiple times, and focusing especially on the wiring/ground sections. I've already blown up one set of boards by missing one important detail (not isolating speaker posts... strangely, it was my third beta build... first two went flawlessly.)

 One thing to consider in your plan... if you do go balanced using the existing 2 channel you had already built, keep in mind your effective gain will double unless you redo the existing boards for a lesser gain.


----------



## johnwmclean

DemonicAngelz, sounds like a good plan, you’d be fine. But do the research, read AMB’s website carefully, a process of elimination is the key, ie ensure all components are installed correctly and you lower the chances of ever having to do any troubleshooting.
 The Headwize threads are a valuable source of information, read them, I found following the problems other people had with their builds helped. Good Luck.


----------



## DemonicAngelz

Quote:


  Originally Posted by *oneplustwo* /img/forum/go_quote.gif 
_It's doable. The B22 is not an easy build, but there's lots of help on the board (which I've taken full advantage of myself). One thought is to go ahead and buy the parts for your 2 channel + sigma and then build the sigma first. The sigma is a bit more straight forward and will give you a sense for whether or not you feel comfortable continuing on with the beta boards or if you would prefer to stop, tackle another project or two first, and then continue on.

 I would also recommend taking your time, reading the pages on Amb's site multiple times, and focusing especially on the wiring/ground sections. I've already blown up one set of boards by missing one important detail (not isolating speaker posts... strangely, it was my third beta build... first two went flawlessly.)

 One thing to consider in your plan... if you do go balanced using the existing 2 channel you had already built, keep in mind your effective gain will double unless you redo the existing boards for a lesser gain._

 

I intend on printing the whole b22 amb site out and study it carefully, highlighting important parts. 

 As for the gain, i'm ordering two boards with gain of 5. If I upgrade i'll just get two more with gain of 5, totalling at 10. I figure this is not too bad considering I have 600ohm dt880 to drive too. 

 The main thing i'm not comfortable with is the s22. Its the first time i'm working live voltage. Scared that I may electrocute myself!


----------



## UKToecutter

Quote:


  Originally Posted by *DemonicAngelz* /img/forum/go_quote.gif 
_I intend on printing the whole b22 amb site out and study it carefully, highlighting important parts. 

 As for the gain, i'm ordering two boards with gain of 5. If I upgrade i'll just get two more with gain of 5, totalling at 10. I figure this is not too bad considering I have 600ohm dt880 to drive too. 

 The main thing i'm not comfortable with is the s22. Its the first time i'm working live voltage. Scared that I may electrocute myself!_

 

You might try soldering the components without the mains plug in....


----------



## oneplustwo

I was nervous about live voltages as well which is probably healthy actually. But it's not so bad as long as you use normal safety measures. But like I said, a healthy respect for it is good for you.

 Gain plan sounds reasonable.


----------



## UKToecutter

After a number of 'healthy belts', I too have a healthy respect for mains voltage.
 Especially the 240V we have in the UK.


----------



## LeMat

It was my first build and I've been trough the whole process without too much pain. My s22 and 2 b22 boards are working perfectly... but while I wanted to avoid trouble shooting, I'll have to do it since my ground channel board is not working properly. The Q25 even blew up big time !
 I'll update this post with the picture which worth a look 
	

	
	
		
		

		
		
	


	




 DemonicAngelz, you can do it... just do your homework


----------



## tintin47

Quote:


  Originally Posted by *DemonicAngelz* /img/forum/go_quote.gif 
_The main thing i'm not comfortable with is the s22. Its the first time i'm working live voltage. Scared that I may electrocute myself!_

 

Working with mains voltage is really just about respect. As long as you respect that you _can_ be electrocuted you'll be fine. There isn't a ton of risk as long as you are careful with wiring. If wired correctly, testing the thing takes 30 seconds. In my whole build, I had the case of the sigma open with the power on for about 5 minutes. 

 Just know when the power is on and don't go near the mains.


----------



## UKToecutter

Quote:


  Originally Posted by *tintin47* /img/forum/go_quote.gif 
_Working with mains voltage is really just about respect. As long as you respect that you can be electrocuted you'll be fine. There isn't a ton of risk as long as you are careful with wiring. If wired correctly, testing the thing takes 30 seconds. In my whole build, I had the case of the sigma open with the power on for about 5 minutes. 

 Just know when the power is on and don't go near the mains._

 

Oh, and make sure that the electrolytics are discharged as well.
 It might not kill you but, boy it hurts!!!


----------



## DemonicAngelz

I would like to ask one more thing. 

 What are the advantages and disadvantages of using one 100VA s22 to power 4x B22 boards versus two 50VA s22 to power two sets of 2x B22 boards.

 I'm kinda on budget and using one s22 saves me quite a bit if it does not compromise on sound.


----------



## johnwmclean

DemonicAngelz, using 2 σ22 is better for heat dissipation. One σ22 is good for headphones, alternatively use larger sinks on the one σ22.

 Further reading:
http://gilmore2.chem.northwestern.ed...num=3&tid=6525


----------



## linuxworks

I'm reboxing my b22 (happens every springtime, this being the first) and I'm now wondering, should the speakers use the 3rd channel as a common ground or should they use the input-ground as their ground?

 I have the 3ch backplane board and that has a molex connector on the edge (4 cond) marked for speakers. their ground is the 3rd channel out (the unity gain amp's out).

 the last 2 b22's I did had speakers *not* burdening that 3rd channel. and my speaker/phones A/B switch was easy since I only had to switch 2 wires (DPDT). the phones ground was always tied to the 3rd channel-out and the speaker grounds were tied directly (very directly) to spare PSU ground screw terminals.

 this build, I want to use relays instead of a mechanical DPDT switch; but I wonder if its really worth having the speakers on the ground-channel or not. what do you experts say? should speaker-mode be a 2ch mode when *in* speaker mode and then go to 3ch mode when its a *phones* mode amp? in fact, power to the 3rd channel can be dropped (a heavy DPDT relay) in speaker mode and that 'donates' more of the psu over to the remaining 2 boards.

 comments on that kind of config?


----------



## amb

You could go either way.

 If you skip the ground channel for speakers, then the speakers' "-" binding posts should be wired directly to the σ22 PSU "G" terminals. Do not wire them to the β22 board's signal ground. The small-signal ground reference should not "ride" on the same wire as the high current return from the speakers.

 On the ε22 backplane board, the speaker "-" pads are wired to the ground channel output. The reason for this is because I do not assume that it would be feasible to run wires to the PSU (the builder may have an external σ22, and only has 3P connectors for V+, V- and signal ground). Using the ground channel avoids having to run those separate ground wires, but does put additional load on the ground channel amp. Since ε22 has no provisions for offboard heatsinking, it should only be used as a light-duty speaker amp anyway.

 Oh and btw, you should not turn off the ground amp's power by switching it on the DC rails. The σ22 does not take kindly to this sort of thing -- there are warnings on the σ22 website.


----------



## linuxworks

Quote:


  Originally Posted by *amb* /img/forum/go_quote.gif 
_
 If you skip the ground channel for speakers, then the speakers' "-" binding posts should be wired directly to the σ22 PSU "G" terminals. Do not wire them to the β22 board's signal ground. The small-signal ground reference should not "ride" on the same wire as the high current return from the speakers._

 

check. I forgot to mention that I have the luxury of having the s22 inside the same chassis and so it was an obvious choice to pick a pair of ground terminals from there and leave the backplane's ground alone.

  Quote:


 Oh and btw, you should not turn off the ground amp's power by switching it on the DC rails. The σ22 does not take kindly to this sort of thing -- there are warnings on the σ22 website. 
 

that would not be live, of course! what I had in mind was a controlled power down style change-over. it would be the equivalent of turning off the amp, waiting about 10 seconds for things to bleed (the stones actually wrote a song about that, I think) then plugging or unplugging that last cable on the backplane board; the one that connects the b22 gnd channel to, well, everything. I've done that almost daily, in fact. I power the whole amp down, wait a bit (for all the leds to go off and then a bit more), then either yank that last cable or insert it (if I'm going with phones). been doing that for a few months, now 
	

	
	
		
		

		
		
	


	




 I just simply want to automate the whole thing.

 but it was more about: since speakers tend not to be as high a resolution device as headphones, would they truly benefit from '3rd channel isolation' or would the energy available in a single s22 be better used to keep 2 b22 modules warm instead of 3? that was my whole reason for this complicated change-over.

 if there's a compelling case to continue to drive speakers from a 3rd channel config then I guess I'll try that; but it seems a lot harder to drive speakers and adding a 3rd channel may not work for this. works great for phones but I just wonder if its optimal for spkr use?


----------



## amb

A powered-on and idling ground amp will add less than 200mA of load to the PSU, depending on how heavily you biased it. That's not too much in the grand scheme of things, I'm not sure it's worth the hassle to shut it off, especially with the complicated scheme you describe. I also would not plug/unplug the Molex connectors too much. They are good connectors, but are not designed for that kind of use.


----------



## linuxworks

really, just 200ma for the gnd channel, if its not in use? ok, that's small enough to just leave on, I guess.

 but I can still use a DPDT to switch the 2 non-gnd connections between the front phones jack and the rear spkr 2 + jacks, right? then the 2 rear - speaker jacks go to the 3rd amp channel (always) and the phones gnd wire also goes to the 3rd amp channel (always). no need for 3 poles in my spkr/phones relay, right?


----------



## LeMat

Quote:


  Originally Posted by *LeMat* /img/forum/go_quote.gif 
_Finally finished my 3 boards B22... fired up... 2 boards working perfectly but the ground channel .. quite the opposite. Leds are on, r9 is 4.5v but i have 0mv across R34... damned ! 
 If there is something obvious coming to your mind, please share ! Otherwise, what's the better way to debbug it / narrow down the possible issue ?_

 

 Quote:


  Originally Posted by *amb* /img/forum/go_quote.gif 
_LeMat, tried looking back at past posts in this very thread? 
	

	
	
		
		

		
			



_

 

I didn't have the time to browse 3100 posts so I sticked to the schematic and did some tests.. Oddly one of the Mosfet wasn't working properly and after replacement, miracle.., my last board works ! In the process I've lost Q25 which blew up for I don't know what reason. 
 I found it quite rewarding to solve the problem by myself 
	

	
	
		
		

		
		
	


	



 Now i have to order a BJT550 to enjoy my amp ! A chance I also realized i messed up when ordering a part for the e12 (wrong dpdt relay).. I didn't want to pay 8$ of shipping for 0,02$ part !


----------



## oneplustwo

LeMat - I can mail you a couple 550's if you want. PM me your address.


----------



## amb

Quote:


  Originally Posted by *linuxworks* /img/forum/go_quote.gif 
_but I can still use a DPDT to switch the 2 non-gnd connections between the front phones jack and the rear spkr 2 + jacks, right?_

 

Yes.

  Quote:


 then the 2 rear - speaker jacks go to the 3rd amp channel (always) 
 

If you want the ground channel amp to source/sink the return current, then yes. Otherwise, these go to the PSU 'G'.

  Quote:


 and the phones gnd wire also goes to the 3rd amp channel (always). no need for 3 poles in my spkr/phones relay, right? 
 

Yes. A DPDT switch is all you need, either way.


----------



## dude_500

Over the last few weeks I've noticed a quiet hiss that lasts for maybe a tenth of a second and occurs every few seconds (not at a constant rate, seemingly random in occurrence and exact sound). It doesn't occur all the time, sometimes it does it a lot, usually not at all, sometimes just a little. It is volume knob related and when the volume is at zero it's totally silent, and at max the noise is very loud. At listening volumes it's quite quiet but definitely there. Does this mean it's outside of the volume knob? Even with source unplugged it does it and I don't understand how the wire from the knob to the RCA jacks could do this. I didn't change anything, It's just started doing it recently.


----------



## Kitarist

So guys is this amp worth the price?


----------



## johnwmclean

Quote:


  Originally Posted by *dude_500* /img/forum/go_quote.gif 
_Over the last few weeks I've noticed a quiet hiss that lasts for maybe a tenth of a second and occurs every few seconds (not at a constant rate, seemingly random in occurrence and exact sound). It doesn't occur all the time, sometimes it does it a lot, usually not at all, sometimes just a little. It is volume knob related and when the volume is at zero it's totally silent, and at max the noise is very loud. At listening volumes it's quite quiet but definitely there. Does this mean it's outside of the volume knob? Even with source unplugged it does it and I don't understand how the wire from the knob to the RCA jacks could do this. I didn't change anything, It's just started doing it recently._

 

Sounds like a minor joint has become cold, I’d check around the pot especially the ground wiring, make sure all joints are secure. Give each wire a good tug and make sure each connection has a good contact. The hiss is from both channels?


----------



## dude_500

Quote:


  Originally Posted by *johnwmclean* /img/forum/go_quote.gif 
_Sounds like a minor joint has become cold, I’d check around the pot especially the ground wiring, make sure all joints are secure. Give each wire a good tug and make sure each connection has a good contact. The hiss is from both channels?_

 

Seems a tad louder in the left side but it's in both. I'll run over the solder joints and report back if I'm still having problems


----------



## amb

Maybe cell phone interference?


----------



## DemonicAngelz

Hey guys, i've got a random thought. I have read that the beta 22 runs real hot. So, is it possible to add a fan in the casing, such as what little dot do to the mkvi+?


----------



## johnwmclean

Quote:


  Originally Posted by *DemonicAngelz* /img/forum/go_quote.gif 
_Hey guys, i've got a random thought. I have read that the beta 22 runs real hot. So, is it possible to add a fan in the casing, such as what little dot do to the mkvi+?_

 

Sure it runs hot it’s heavily biased class A, but properly ventilated and cased this is not a problem, unlike the LD MKVI which is not and needs a silly fan IMO.


----------



## jh4db536

that is at approx 140mA on the output stage...it was connected for about 30 minutes to see how much the everything drifts. I would say that the b22 is pretty sensitive to temperature it takes about a good 20 minutes to warm up and stabilize. the input stage and output stage readings are all over the place until it warms up fully.

 has anyone Water cooled their b22 yet? i think they make mosfet copper water jackets that could span across a mosfet quad.

 seeing how sensitive to temps the JFETS are, i noticed that people orient their b22 boards across or in line from each other #O #O #O #O (each Jfet is close to a hot heatsink except the first or last). that would mean 3 JFET quads are hot and 1 is cold is that optimal? 
 maybe oriented like this #O O# #O O# you would have all equally warm quads. # represents the hot heat sinks and O are the JFET side


----------



## amb

I wouldn't worry about equalizing the temps around the input JFETs across the boards. As long as the temperature gradient between Q1/Q2 and Q3/Q4 is minimal (and they should be due to the close proximity), all would be well.

 Btw, the #O O# #O O# arrangment that you mention is how many people have built their balanced β22s. including the group-build β22 (see pics in the β22 website gallery) .


----------



## boinger

I was moving my setup into a more permanent case and doing some rewiring / testing... 

 long story short there was a loose wire and the v+ from the sigma shorted to the signal ground on the beta i believe i am not 100% sure thats what happened but judging from the wires positioning and my glancing looks i think thats what i saw... 

 the sigma wont power up now... so just wondering if any have had this happen before so i dont have to start testing each thing any help would be appreciated....

 thanks


----------



## amb

boinger, "won't power up" isn't very much info...


----------



## luvdunhill

Quote:


  Originally Posted by *boinger* /img/forum/go_quote.gif 
_the sigma wont power up now... so just wondering if any have had this happen before so i dont have to start testing each thing any help would be appreciated...._

 

I've had this exact same symptom before. I had my power supply plugged into a power strip, but the power strip itself wasn't turned on. Perhaps I correctly guessed what your problem is?


----------



## Fitz

Quote:


  Originally Posted by *luvdunhill* /img/forum/go_quote.gif 
_I've had this exact same symptom before. I had my power supply plugged into a power strip, but the power strip itself wasn't turned on. Perhaps I correctly guessed what your problem is?_

 

But what did you have to do to fix it??


----------



## luvdunhill

Quote:


  Originally Posted by *Fitz* /img/forum/go_quote.gif 
_But what did you have to do to fix it??_

 

I replaced the MOSFETs. Then it worked fine.


----------



## boinger

Quote:


  Originally Posted by *amb* /img/forum/go_quote.gif 
_boinger, "won't power up" isn't very much info..._

 

well i heard a loud pop when the v+ line from my sigma power supply shorted to the signal ground (input) on one of the beta boards 

 so im sure something blew out in the sigma cause it will no longer give me any voltage readings... you think it could be the mosfets ?


----------



## johnwmclean

Fuse?


----------



## oneplustwo

in my experience, it's either the mosfets or one or more of the transistors. might want to check the 0.47Ohm resistors as well.


----------



## boinger

ok thanks will do


 Edit: 

  Quote:


  Originally Posted by *johnwmclean* /img/forum/go_quote.gif 
_Fuse?_

 


 no its not the fuse cause my other sigma (from the same mains) is working fine


----------



## pistolsnipe

just starting in on a beta 22 build, so im sure you guys will hear more from me haha

 i want to build a balanced b22, with each board having a gain of 8. 

 ive looked around on the amb site and searched a bit here, but couldn't find the answer to this question.

 what are the trade-offs in choosing the output voltage of the sigma 22? i would rather have stable than performance, so is 24 volts a better choice than 30?


----------



## amb

+/-30V rails will give you more output voltage swing capability before clipping than +/-24V, and will cause the MOSFETs to run a bit hotter given the same quiescent current settings. There is no difference in "stability", at least not in the established definition of the term with respect to amplifiers.


----------



## luvdunhill

Quote:


  Originally Posted by *amb* /img/forum/go_quote.gif 
_+/-30V rails will give you more output voltage swing capability before clipping than +/-24V, and will cause the MOSFETs to run a bit hotter given the same quiescent current settings. There is no difference in "stability", at least not in the established definition of the term with respect to amplifiers._

 

Ti:

 what's your opinion on how much current and voltage swing is really necessary to drive the more mainstream headphones (i.e. leave out the various outliers with special needs) to reasonable levels?


----------



## amb

Depending on the headphone, of course, since there is a 10+:1 impedance range and varying sensitivities, it's hard to pin down what "mainstream headphones" are. Anyway, a couple hundred mAs and 20Vp-p should be enough for most. But, "enough" is a qualitative description. Just like 100 hp/100 lb.ft of torque is "enough" for a car to get the job done...


----------



## fault151

Hi guys, I finally got round to taking some pics of my B22 amp. It has taken me over a year to get to this point and I thought i'd share my hard work with you all. First of all, a *[size=x-large]MASSIVE[/size]* thank you to everyone who has helped me with this project especially, Ti (AMB LAbs), MR Majestic, and johnwmclean. I would not have been able to do it without your help and patience! 
	

	
	
		
		

		
		
	


	




 The amp sounds bloody amazing, really happy with it. Its safe to say its not the easiest amp I have ever built, there is a lot that can go wrong (and did go wrong!) but got there in the end. I will be adding some more pics for those interested on the post pics thread (I didn't want to clutter this thread too much).


----------



## digger945

That is indeed Refined. Great pics of a very nice looking amp.


----------



## nattonrice

Very sexy!
 I love the layout =)


----------



## fault151

Cheers guys, i tried to go balanced/symmetrical all the way even in the layout.


----------



## amb

fault151, even though the journey was a bumpy one but the result looks fabulous. Congratulations!


----------



## fault151

Quote:


  Originally Posted by *amb* /img/forum/go_quote.gif 
_fault151, even though the journey was a bumpy one but the result looks fabulous. Congratulations! 
	

	
	
		
		

		
		
	


	


_

 

Thank you Ti, really appreciate it! 

 Yeh its not been an easy one. I have learned a lot though, which is good. Plus i have ended up with something I'm really happy with soundwise, which is great!

 It has been said many of times, but the the amp is amazing You really have done a great job of the design!


----------



## askforwhy

Beautiful amp!!
 Congratulations, fault151.


----------



## askforwhy

Uh, I think something is wrong with my Sigma22s.
 Today I decided to reflow all the joints in my Beta22 and Sigma22 because I think there are some cold joints compromising the performance(I am so lame..).
 When I carefully finished reflowing my four Sigma22s, I checked the output voltage, two of them are working correctly, 29.8V~or so, but the other two measured 44.8V~!
 It is really weird, I checked everything twice, and all of them had been working for half a year without a problem. I guess something is wrong with my cranky DMM or I heated something too long during reflowing, possibly the zener diode?
 Thanks for your input.

 edit:
 forgot to say, I didn't find anything unusual with the two Sigma22s, nothing is getting hot, even the LEDs are as bright as others. I will find another DMM tomorrow and check again.


----------



## linuxworks

when you worked on your power supply, DID YOU DISCHARGE THE CAPS, first?

 very important....


----------



## Anonanimal

@ fault151- That is a beautiful build!! Congratulations on completing the job and enjoy!


----------



## boinger

fault id love to know where you did your case work from... im looking to go for something a bit better myself right now its very very very basic.


----------



## fault151

Cheers guys! really, really appreciate the nice comments! 
	

	
	
		
		

		
		
	


	




 The case was from Hifi 2000 and I designed the panels and then had them made at Front Panel Express on 6mm panels.


----------



## UKToecutter

Quote:


  Originally Posted by *fault151* /img/forum/go_quote.gif 
_Cheers guys! really, really appreciate the nice comments! 
	

	
	
		
		

		
		
	


	




 The case was from Hifi 2000 and I designed the panels and then had them made at Front Panel Express on 6mm panels._

 

I'd love a copy of your fpd files................


----------



## Oberst Oswald

I just ordered my parts from GJA for a 3-channel (2x gain for Denon D-7000) with 80 va S-22. Hopefully everything will go well so I won't be a pest to you guys. I have enough amps but I want to build something... a hard decision because I want to do them all. EHHA or a Bijou were my other choices on this go around.


----------



## Magsy

Quote:


  Originally Posted by *fault151* /img/forum/go_quote.gif 
_Cheers guys! really, really appreciate the nice comments! 
	

	
	
		
		

		
		
	


	




 The case was from Hifi 2000 and I designed the panels and then had them made at Front Panel Express on 6mm panels._

 

Awesome build, very neat and tidy, you should be proud
	

	
	
		
		

		
		
	


	




 Did you have FPE cut the acrylic around the knob? Are they accurate enough so that you can make for example a 40mm hole in the alu and have them cut a 40mm diameter plastic 'filler' and they end up a tight push fit? or did you acheive that some other way?

 Thanks!


----------



## fault151

Quote:


  Originally Posted by *Magsy* /img/forum/go_quote.gif 
_Awesome build, very neat and tidy, you should be proud
	

	
	
		
		

		
		
	


	




 Did you have FPE cut the acrylic around the knob? Are they accurate enough so that you can make for example a 40mm hole in the alu and have them cut a 40mm diameter plastic 'filler' and they end up a tight push fit? or did you acheive that some other way?

 Thanks!_

 

Yeh they are very accurate, but you still need to give it some space to slide in to the metal. I think i made mine 1 mm smaller and then tweaked it to fit. The fit is tight, but id much rather do it slowly and manually to make sure. I only had to sand it down a little bit. It was harder for me as i wanted to counter sink the volume knob in to the plastic, which was then countersunk in to the metal panel. So a lot of measuring and fiddling about to get it to fit. It took me a long time to get my panels the way you see them. I measured things, printed it out and tested it against components, then re measured and so on...


----------



## UKToecutter

Quote:


  Originally Posted by *fault151* /img/forum/go_quote.gif 
_Yeh they are very accurate, but you still need to give it some space to slide in to the metal. I think i made mine 1 mm smaller and then tweaked it to fit. The fit is tight, but id much rather do it slowly and manually to make sure. I only had to sand it down a little bit. It was harder for me as i wanted to counter sink the volume knob in to the plastic, which was then countersunk in to the metal panel. So a lot of measuring and fiddling about to get it to fit. It took me a long time to get my panels the way you see them. I measured things, printed it out and tested it against components, then re measured and so on..._

 

I'm struggling to find out how to do the screen printing on the rear panels.
 I've got all the engrave options.
 Did they engrave the rear panels?
 If so, how do you specify a colour fill?

 Andy


----------



## fault151

It should say something along the lines of 'infill colour' in the properties panel. That is if you are using Front panel designer.


----------



## Beefy

Under File -> Frontpanel Properties you have to make sure 'In-fill engravings' is ticked. It is at the bottom left

 Then if you right click -> Properties on each individual text label you can select the in-fill colour on the bottom right.

 Be careful, because the cost adds up very quickly!


----------



## tintin47

Quote:


  Originally Posted by *Oberst Oswald* /img/forum/go_quote.gif 
_I just ordered my parts from GJA for a 3-channel (2x gain for Denon D-7000) with 80 va S-22. Hopefully everything will go well so I won't be a pest to you guys. I have enough amps but I want to build something... a hard decision because I want to do them all. EHHA or a Bijou were my other choices on this go around._

 

Were I you, I would consider getting sockets for the gain resistors so that you can change it easily if 2x turns out to be too low. It might work for your denons, but if you ever get a less efficient pair of phones you'll probably be all the way near the end of your pot.


----------



## UKToecutter

Yep, Got it
 Thanks guys.

 Fault. Where did you get the acrylic disk from?


----------



## m1abrams

Quote:


  Originally Posted by *Beefy* /img/forum/go_quote.gif 
_Under File -> Frontpanel Properties you have to make sure 'In-fill engravings' is ticked. It is at the bottom left

 Then if you right click -> Properties on each individual text label you can select the in-fill colour on the bottom right.

 Be careful, because the cost adds up very quickly! 
	

	
	
		
		

		
			



_

 

Yes they do. To keep costs down and use infill try to keep it to just 1 color.


----------



## fault151

Quote:


  Originally Posted by *UKToecutter* /img/forum/go_quote.gif 
_Yep, Got it
 Thanks guys.

 Fault. Where did you get the acrylic disk from?_

 

You can't just buy it as it is, you need to tell the guys at FPE what you want. Ie design it as you want in the program, then tell them in the 'notes on production' to use acrylic/perspex instead of metal.

 It will all depend on what size you need it and the shape.


----------



## Pars

Very nice job on the amp Fault!


----------



## UKToecutter

Yeah it really is a super job.

 Well done!


----------



## fault151

Cheers guys, I appreciate it! It's been fun and I kind of wish I was still working on it. Ah well on to the next build (my valve output buffalo 2 dac).


----------



## johnwmclean

fault151, man that’s some build congrats! What volume knob is that?


----------



## fault151

You mean the one on the jaycar? If so it's from world audio designs. If you mean my b22 , I had that custom made. Thanks for the nice comments! :0)


----------



## UKToecutter

fault.

 Where did you get the headphone image for your front panel from?


----------



## fault151

I drew it myself in adobe illustrator then converted it for use with fpe.


----------



## UKToecutter

You guys are just tooooo clever for me.

 This Front Panel Designer programme is like a black art!!!!

 Time to call my 'arty farty' brother-in-law


----------



## fault151

It's just practice. I found it hard to use 
 at first, but when you get the hang of it, it's easy. The worst bit by far is the measuring!


----------



## m1abrams

Quote:


  Originally Posted by *fault151* /img/forum/go_quote.gif 
_It's just practice. I found it hard to use 
 at first, but when you get the hang of it, it's easy. The worst bit by far is the measuring!_

 

I find the worst part is clicking "Buy" since I am always worried I missed something or measured something incorrectly.


----------



## fault151

Yeh I know what you mean, I was paranoid for two weeks that i measured wrong. I just kept measuring it over and over. Think I checked it 4 times just to be sure!


----------



## Magsy

Thanks for the info, I was thinking it was probably safest to do the final fit myself but I'm a bit lazy 
	

	
	
		
		

		
			





 I've used FPE program a lot, I've never actually had anything made but I have used it for design for a long time. I found printing it onto transparent sheets or giant sticky labels was handy!


----------



## UKToecutter

Funnily enough I'm OK with the measuring up.

 The DXF files that you can download for the Galaxy cases are quite good and easy to follow (for the fixing holes and panel sizes).
 Also, the component suppliers have good datasheet support for all the chassis parts.

 I got the 'official' s22 and b22 logos from a post Ti made in this or another thread.

 I too am paranoid about clicking 'buy' as I have no idea how much I'll be charged for the 'extras' (i.e. the acrylic disc and the panel thickness).

 Still, brother-in-law is here in the morning so I should be able to get it done tomorrow.


----------



## fault151

It should calculate it for you before u buy so you will know the exact price. Good luck with it!


----------



## m1abrams

Quote:


  Originally Posted by *fault151* /img/forum/go_quote.gif 
_It should calculate it for you before u buy so you will know the exact price. Good luck with it!_

 

No it does not include extras that you add in the comments, like any thickness greater than 4mm, etc.


----------



## UKToecutter

Yes, That's what I meant.

 So far the PS case is going to cost me about $90.00

 The case itself was less than €20........


----------



## UKToecutter

Doh, that sounds silly.
 I meant the front and rear panels are going to cost about $90


----------



## Beefy

Quote:


  Originally Posted by *UKToecutter* /img/forum/go_quote.gif 
_Doh, that sounds silly.
 I meant the front and rear panels are going to cost about $90_

 

Each? Or for both? Sounds pretty reasonable to me.

 The front panel alone for my Exstata clocked in at a wallet crushing $114. Cavities and threaded holes on the back of the panel are a killer


----------



## fault151

Quote:


  Originally Posted by *Beefy* /img/forum/go_quote.gif 
_Each? Or for both? Sounds pretty reasonable to me.

 The front panel alone for my Exstata clocked in at a wallet crushing $114. Cavities and threaded holes on the back of the panel are a killer 
	

	
	
		
		

		
		
	


	


_

 

I can't remember exactly how much mine cost to make, but it wasn't cheap at all. I had 4 panels made, two on 6mm thick aluminium and one perspex 4mm thick disk.

 It was all the countersinking of parts that cost the most!


----------



## UKToecutter

fault

 My B-I-L has drawn me a nice headphone in Illustrator.
 How did you manage to export to a hpgl file?
 It does not seem to be a save or export option.


----------



## fault151

Quote:


  Originally Posted by *UKToecutter* /img/forum/go_quote.gif 
_fault

 My B-I-L has drawn me a nice headphone in Illustrator.
 How did you manage to export to a hpgl file?
 It does not seem to be a save or export option._

 

I got a mate to do it for me as i didn't have any programs which use hpgl files. I know Corel draw does, if you have that? If you haven't got the program maybe someone on here could do it for you?

 Its only a case of saving it. Id do it for you if i had a program that does it.


----------



## Magsy

Use CorelDraw or send it to me and I'll do it. (Any format thats a vector please i a n @ m a g s y . n e t )

 I had an issue with FPE though in as much as they charge you for the HPGL you import, so if you import a huge 1000px X 1000px HPGL and then scale it back to say 20%, they bloody charge for the big imported size. I had this confirmed via email because my logo was costing 400 euro


----------



## UKToecutter

Magsy

 Thanks for the offer.
 I'm in the middle of downloading the Corel suite trial.

 I'll let you know if I can't do it


----------



## Magsy

Cool!

 File > Export > PLT - HPGL.

 When the HPGL export box pops up asking for options you can leave them all default but for better quality you might want to change the 'pen width' to match the engraving tool in FPD (0.2mm?) 
 Also if you have a fill not just an outline, you are going to need to fiddle on the last tab with crosshatching to simulate a fill. If you crosshatch too much it costs a fortune, so you need to balance the spacing to get a complete fill with the minimal amount of strokes. 
 If the logo is tiny this probably doesn't matter but I've been making a big one, 100x50mm. 

 A HPGL is just a series of lines for the machine to plot, so by its nature you cannot just 'fill' a blank area with color, it has to make each stroke to create a fill, each stroke costs time on the machine=money...


----------



## askforwhy

Quote:


  Originally Posted by *linuxworks* /img/forum/go_quote.gif 
_when you worked on your power supply, DID YOU DISCHARGE THE CAPS, first?

 very important...._

 

Yes, I think I am aware of that.
	

	
	
		
		

		
		
	


	




 Today I swapped the zener diodes, and I used another DMM to check again, no good.
	

	
	
		
		

		
		
	


	



 Uh, I am completely lost now, I may check those BJTs later.


----------



## linuxworks

well, not to insult, but I've zapped a few caps when I forgot to discharge them. so its easy for people to forget 
	

	
	
		
		

		
		
	


	




 I did, more than once!

 as a matter of course, I simply replace all MOSFETS and .47ohm r's. 

 I don't even bother checking the .47 r's. I just replace them.


----------



## luvdunhill

Quote:


  Originally Posted by *amb* /img/forum/go_quote.gif 
_Anyway, a couple hundred mAs and 20Vp-p should be enough for most_

 

cool, this is pretty much what I found this weekend 
	

	
	
		
		

		
			





 In fact, I settled on 14vrms number, so that's pretty funny. 

 Perhaps you might run into the fruits of my labors this upcoming weekend!


----------



## digger945

Quote:


  Originally Posted by *fault151* /img/forum/go_quote.gif 
_ Ah well on to the next build (my valve output buffalo 2 dac)._

 

Now that sounds like a project that I would be very interested to see. I bet that would go very nicely with your Beta 22.


----------



## jtostenr

Quote:


  Originally Posted by *fault151* /img/forum/go_quote.gif 
_Hi guys, I finally got round to taking some pics of my B22 amp. It has taken me over a year to get to this point and I thought i'd share my hard work with you all. First of all, a *[size=x-large]MASSIVE[/size]* thank you to everyone who has helped me with this project especially, Ti (AMB LAbs), MR Majestic, and johnwmclean. I would not have been able to do it without your help and patience! 
	

	
	
		
		

		
		
	


	




 The amp sounds bloody amazing, really happy with it. Its safe to say its not the easiest amp I have ever built, there is a lot that can go wrong (and did go wrong!) but got there in the end. I will be adding some more pics for those interested on the post pics thread (I didn't want to clutter this thread too much). _

 

Very nice build Fault151. I am working on a build similar to yours, and have so many questions lol.....I will just stick with a few for now 
	

	
	
		
		

		
		
	


	




 Looks like you are using the Speakon 8-pole connectors for the umbilical as far as I can tell. What cable did you use? I found some 8 conductor shielded cable for $1.65/ft so I might give that a shot.

 Would you mind spelling out what you have running through the umbilical? I figure 3 wires per S22 and a couple of trafos, but not sure what else. Did you run a TRS ground return wire?

 Thanks,
 Jeff


----------



## oneplustwo

Not sure what fault151 used, but I got a per-terminated 8 wire speakon cable from ebay for a pretty good price. Not sure if the connectors are "official" Neutrik parts but they seem to work just fine and the build quality is good. And the cable is really beefy. The overall diameter is about 3/4" but still nice and flexible.

 For my balanced beta, I have 6 wires for 2 sigmas and 2 wires for a trafo that feeds my joshua tree attenuator. If you plan on running two beta boards for a 2 channel output, you should run a ground return wire as you mention. I do not have mine setup to run anything but balanced so I did not bother.


----------



## fault151

Quote:


  Originally Posted by *digger945* /img/forum/go_quote.gif 
_Now that sounds like a project that I would be very interested to see. I bet that would go very nicely with your Beta 22._

 

cool, ill post up some pics when i have something to show. I found the buffalo 24 sounded great with a B22 so if that is anything to go by, the new buffalo 2 and ivy 3 should be really nice sounding!


----------



## fault151

Quote:


  Originally Posted by *jtostenr* /img/forum/go_quote.gif 
_Very nice build Fault151. I am working on a build similar to yours, and have so many questions lol.....I will just stick with a few for now 
	

	
	
		
		

		
		
	


	




 Looks like you are using the Speakon 8-pole connectors for the umbilical as far as I can tell. What cable did you use? I found some 8 conductor shielded cable for $1.65/ft so I might give that a shot.

 Would you mind spelling out what you have running through the umbilical? I figure 3 wires per S22 and a couple of trafos, but not sure what else. Did you run a TRS ground return wire?

 Thanks,
 Jeff_

 

Hi, for the umbilical chord, I used two sets of 4core wires. I don't think its anything particularly special, just good quality copper wire. I went for some thick 1.5 mm wire.

 If i remember correctly i wired up all my connections and was left with 2 spare. Sou out of two neutrik connectors i had 14 wires running from the psu to the amp. Yes i also hooked up the ground return on both psu's.

 I wouldn't have needed to use so many wires if i didn't use the bulgin switches to switch my speaker/headphone board and the balanced/unbalanced otto board.

 Hope that helps.


----------



## fault151

Heres a pic of my umbilical chords without the nice expandable braiding. 
	

	
	
		
		

		
		
	


	




 I'm using 8pole Neutrik speakons.


----------



## jtostenr

Thanks, that helps alot


----------



## jlefley

I have a question regarding the group build Beta22/Sigma22 that hopefully amb can answer. I am considering placing the boards in a similar configuration with the edge of the board opposite of the heat sinks overlapping the edge of another board so they share the same mounting holes on that edge to save some space. 

 I am wondering what kind of connector was used for the input on the bottom board. I can see from the pictures that a keyed .1" 2 position Molex KK header was used on the top board but unless some pretty tall standoffs are used to space the boards, that same header would not work on the bottom board because of the clearance between the two PCBs. The pictures of the group build amp don't really show the details of the connector and I would still like to have a detachable connection for all 4 boards rather than soldering the wires directly. I thought about a right angle KK header but the standoffs supporting the top board would prevent this from working. Any insight or suggestions would be great. Thanks


----------



## amb

jlefley, I don't really remember what I did, and you're right that the photos don't show this detail because it's obscured by the top board. I may have installed right-angle Molex KKs on the bottom side of those boards, or I may have used Molex .062" inline connectors instead.


----------



## oneplustwo

Although it's not nearly as clean, you can just solder the wires directly to the pad. That's what I did with my build as I didn't even think about other options.


----------



## amb

It's not just about "clean". Having connectors means that you could remove the whole board for servicing without desoldering any wires. With these complex builds, you'll appreciate the convenience.


----------



## n_maher

Quote:


  Originally Posted by *amb* /img/forum/go_quote.gif 
_It's not just about "clean". Having connectors means that you could remove the whole board for servicing without desoldering any wires. With these complex builds, you'll appreciate the convenience._

 

There is great wisdom in this post, ignore it at your peril.


----------



## fault151

I have to admit, I'd prefer to solder direct to the board, however I had a few issue with the boards during my build and it was such a pain I'm the ass trying to service it. I ended up unsoldering them and using connections instead. It made it 1 step toward being less painful when servicing the board. :0)


----------



## linuxworks

I'll sometimes go overboard on offboard connectors (lol) but I consider making something 'serviceable' an ART form. to be strived for.

 fwiw


----------



## Anonanimal

Agreed. I went out of my way to make sure that everything running to and from my Beta boards was through a connector of sorts. Saved me a *lot* of time and headaches in the end.


----------



## oneplustwo

My wires go to the joshua tree with screw terminal blocks so the boards are still serviceable. But for sure, i would have preferred a connector.


----------



## Beefy

I prefer screw terminals myself. Not nearly as fast or easy as a connector, but in my humble experience they are much more robust over the long term.


----------



## UKToecutter

Quick question for Ti....

 I'm building a 3 board active ground b22 on the e22 backplane and I'm trying to work out how many contacts I'll need on the cable harness from the s22.
 The s22 has 4 sets of +G- connectors and and additional 2 x G
 The e22 appears to have 1 connector block for + G -

 What is the recommended method of interconnecting.


----------



## UKToecutter

Ah.....

 Forget that last post.
 I found the info on the b2 wiring page


----------



## pompon

We are 3 friends building our B22 + Sigma 22.

 Any suggestions for solder ? Is-it good idea to take silver like (Wonder or Cardas Quad) ?
 For internal wiring any suggestions ?
 For XLR plugs and volume controls ?


----------



## linuxworks

regular solder is fine. more important than 'type' of wire is wire *routing* and placement. that will affect your SQ far more than boutique wire.

 look at the backplane for ideas on how to route the wiring to keep noise down. that's your biggest win on the build.


----------



## oneplustwo

another thought on solder is to get something relatively thin. if it's too thick, it will be difficult to get good joints consistently. i personally agree with linuxworks on the type though... I've just used the thin radio shack stuff myself. The 63/37 stuff seems to work just fine.

 Any XLR plugs are fine. Neutrik ones are pretty standard around here. As for volume controls, the Alps pot is very popular. DACT attentuators and Valab (from ebay) have also seen plenty of use with good results.


----------



## tintin47

Quote:


  Originally Posted by *Beefy* /img/forum/go_quote.gif 
_I prefer screw terminals myself. Not nearly as fast or easy as a connector, but in my humble experience they are much more robust over the long term._

 

I tend to agree, as I have had never ending difficulties with the molex-type connectors that Ti recommends, but I decided to go for it once more for my beta and they have worked beautifully. Don't know quite what changed though.


----------



## tintin47

Quote:


  Originally Posted by *pompon* /img/forum/go_quote.gif 
_We are 3 friends building our B22 + Sigma 22.

 Any suggestions for solder ? Is-it good idea to take silver like (Wonder or Cardas Quad) ?
 For internal wiring any suggestions ?
 For XLR plugs and volume controls ?_

 

Silver solder is a bad idea unless you have a good iron, and even then it is more difficult to work with. I would stay away from it and just use thin radioshack solder.

 Internal wiring, I would use teflon coated wire. It is easier to work with IME and you don't have to worry about melting the insulation with a stray iron.

 For XLRs, I like the Amphenol female plugs I got, but neutrik are probably almost identical. They were about $5 at mouser. 

 Volume control, I like the Valab stepper, which I used on my beta. If you are looking for a pot, the Noble AP-25 from Michael Percy is supposed to be good for the money. You could also look at the TKD pots available from parts connexion.


----------



## Magsy

The Cardas Quad solder (no silver) is so nice to use that I 'waste' it doing any soldering job, on the car, round the house etc. It melts at such a low point that its useability is the best I have seen. I buy it for that reason alone, imo nothing is quite as easy to work with.


----------



## johnwmclean

I have a question regarding a psu build I’m in the midst of http://www.head-fi.org/forums/f6/diy...s-like-471094/ I would like to add an auxiliary AC output, for future amps that might need stuff like momentary switches a Joshua Tree Attenuator etc.
 I’d like a default transformer to cover this, I’m thinking 30VA 2 x 12V would be a good starting point. What do you think?


----------



## oneplustwo

As it turns out, I just added a small trafo to my own B22 PSU to power the JTA. Do you think you'll need 30VA? That seems like a lot for the ancillary stuff you'd likely want to add. I guess if the size is small and it's not too expensive, there's no downside. Just something to think about.


----------



## amb

You should know what you're planning to power, so you could choose the transformer voltage and current ratings appropriately. You need sufficient VA rating to do the job, but no more. Too much voltage and the regulator will have to dissipate a lot of heat, too much current rating means a larger transformer, which costs more, uses up more space, and emits more magnetic interference.


----------



## johnwmclean

Thanks oneplustwo and amb I guess I need to do more thinking...


----------



## bizkid

I'm currently planning my ß22 build, for the case i already decided on the hifi 2000 Pesante dissipante since i plan to use the amp in my 19" studio rack. I'm not entirely sure how much height is sufficient (3U, 4U or even 2U?) to not build up too much heat. I'll leave 1U between devices in my rack so there should be enough room for heat to escape once it get's out of the case.


----------



## tintin47

I am not sure how big 1U is, but 3.5-4" or 9-10cm would be sufficient. Most people's builds are in that range.


----------



## n_maher

1U is approximately 1.75" (44.45mm). It's short for 1 rack unit.

19-inch rack - Wikipedia, the free encyclopedia


----------



## pistolsnipe

i have been looking into this and i was wondering what wire gauges are minimum for the following runs:

 e22 to each amp board (3 power lines)

 e22 to each amp board (signal lines)

 sigma 22 to e22


 i have some decent 28 awg upocc silver i would like to use for signal, and some 24-26 awg spc i would like to use for power between the e22 and each b22, but 26 awg might be cutting it close from this table


American Wire Gauge table and AWG Electrical Current Load Limits with skin depth frequencies

 earlier someone said that an idle ground board runs something like 200 milliamps?

 how much can i expect a b22 board with a gain of 8 to need for current?


----------



## UKToecutter

Hmmm...

 I believe I read that Ti recommended 16 or 18 guage for power interconnects.


----------



## Lil' Knight

Quote:


  Originally Posted by *tintin47* /img/forum/go_quote.gif 
_I am not sure how big 1U is, but 3.5-4" or 9-10cm would be sufficient. Most people's builds are in that range._

 

Hmmm... I'm wondering if 3.5" height could fit a e24 and 3 boards?


----------



## oneplustwo

^ depends on your heat sinks and standoffs, but yes, 3.5" should be plenty for the e24 and three boards.


----------



## pistolsnipe

Quote:


  Originally Posted by *UKToecutter* /img/forum/go_quote.gif 
_Hmmm...

 I believe I read that Ti recommended 16 or 18 guage for power interconnects._

 

i believe that that was the gauge recommendation for an umbilical cord from the sigma 22 to the backplane, but i would imagine that the power requirements from the backplane to each board would be less...

 also, haven't heard a recommendation for signal gauge


----------



## Lil' Knight

Quote:


  Originally Posted by *oneplustwo* /img/forum/go_quote.gif 
_^ depends on your heat sinks and standoffs, but yes, 3.5" should be plenty for the e24 and three boards._

 

Cool beans. I hate huge cases.


----------



## tintin47

Quote:


  Originally Posted by *Lil' Knight* /img/forum/go_quote.gif 
_Hmmm... I'm wondering if 3.5" height could fit a e24 and 3 boards?_

 

Yes. The inside of my amp is 2.68" and it fits 1/2 " spacers, the backlplane, 3/8" spacers and the board and 1.5" heatsinks with about .3" to spare.


----------



## Lil' Knight

Sweet. I'm looking at some Context Engineering cases which all have 3.5" height.


----------



## Lil' Knight

Quote:


  Originally Posted by *pistolsnipe* /img/forum/go_quote.gif 
_
 also, haven't heard a recommendation for signal gauge_

 

HeadWize: View Post [DIY Workshop » β22: A discrete, cascoded, fully complementary, pure class A amplifier]


----------



## pistolsnipe

Quote:


  Originally Posted by *Lil' Knight* /img/forum/go_quote.gif 
_HeadWize: View Post [DIY Workshop » β22: A discrete, cascoded, fully complementary, pure class A amplifier]_

 

thanks for the link!


----------



## Lil' Knight

No problem.

 I'm wondering what everybody's opinions are about the R27 and DACT. I've never tried any stepped attenuator before so I have no idea how it 'feel'. Does it worth the difference in price (>$100)? I'm trying to limit the budget for a 3-channel + 1 o22 build below $1k.


----------



## nattonrice

I had never used a SA before I got the quad channel for my b22.
 I think it is a very nice movement and the lack of channel imbalance is great =)

 You can "tune" the feel of the steps by using different sized knobs.


----------



## johnwmclean

Quote:


  Originally Posted by *nattonrice* /img/forum/go_quote.gif 
_You can "tune" the feel of the steps by using different sized knobs._

 


 Good Point! The knob makes a big difference to the action, the weight as well as the diameter alters the feel. The best result I’ve had so far is by using an actual DACT knob.


----------



## Lil' Knight

I'm not sure if the DACT has enough steps for me. I tried to look for the RK40 but no success so far. Might be I'll just go with the TKD 2511.


----------



## Magsy

I had my reservations about the limited number of steps but I have genuinely not even thought about it since I have built the amp. It really is a non issue, I don't ever find myself between steps or wishing for more granularity.

 I plug the HD650 in and I'm using 50%-85% range and when I plug the SA5000 in I'm using 30%-60% range. 

 I have a gain of 2 but 4 effective because I'm balanced, also have a 4v source.

 With a big knob the steps feel awesome and subtle, with a smaller knob it just feels tight and very high precision....choose your poison!


----------



## jh4db536

have you considered using the TPA JTA? you get 128 steps. the disadvantage is the extra space that it takes up and complexity.


----------



## oneplustwo

The JTA also make a pretty loud clicking when changing volumes. Doesn't really create any problems, but it is something to know.


----------



## Lil' Knight

Quote:


  Originally Posted by *jh4db536* /img/forum/go_quote.gif 
_have you considered using the TPA JTA? you get 128 steps. the disadvantage is the extra space that it takes up and complexity._

 

I did but after weighing up the pros and cons, I'd simply go with a 'classic' pot.

 I have a custom made knob which weighs ~500g


----------



## linuxworks

you can always add a relay module later on, even in series with the amp. simply turn the volume pot all the way up and its -mostly- out of the circuit, then.


----------



## Lil' Knight

Anybody knows the tightest case that can fit the e22 and 1.5" heatshink?
 I really like the ATI case but looks like they are out of business now


----------



## jtostenr

Quote:


  Originally Posted by *linuxworks* /img/forum/go_quote.gif 
_I did exactly that - to parallel the input wires with some outputs that go to my sub.

 in fact, I go thru a 2nd vol control so that I can remotely control sub volume.

 you may want a LP filter or band split (hp/lp) or just use the one in the sub.

 but yes, a passthru has good use for subwoofers.

 passthru is just a y-cable, folks 
	

	
	
		
		

		
		
	


	


_

 

Just wanted to clear something up w.r.t. loop-outs, preamp outs and subwoofers. I'd rather not have to hack my B22 apart later to fix the loop-out/preamp-out. 

 So if I understand this correctly, the standard definitions are:

 loop out = no amplification, no volume control
 preamp out = with amplification and volume control

 Which makes me wonder, if I *do not* want a separate volume control for my sub, then I must connect it to the preamp out. However, is this signal too hot for a powered sub?


----------



## tintin47

^^Your custom knob weighs 500g, as in 1.1lbs? Even if it were made out of steel, it would have to be stupidly large, like 6 cm in diameter. Why would you want something that big?


----------



## UKToecutter

Gee,

 That's a big knob


----------



## quattro98

A powered sub should take line-level inputs, the same as the amplifier for your main speakers, so the pre-amp outputs should be fine.

  Quote:


  Originally Posted by *jtostenr* /img/forum/go_quote.gif 
_Just wanted to clear something up w.r.t. loop-outs, preamp outs and subwoofers. I'd rather not have to hack my B22 apart later to fix the loop-out/preamp-out. 

 So if I understand this correctly, the standard definitions are:

 loop out = no amplification, no volume control
 preamp out = with amplification and volume control

 Which makes me wonder, if I *do not* want a separate volume control for my sub, then I must connect it to the preamp out. However, is this signal too hot for a powered sub?_


----------



## Lil' Knight

Quote:


  Originally Posted by *tintin47* /img/forum/go_quote.gif 
_^^Your custom knob weighs 500g, as in 1.1lbs? Even if it were made out of steel, it would have to be stupidly large, like 6 cm in diameter. Why would you want something that big?_

 

It's only 40mm x 40mm. Not really big but damn heavy. And yes, it's made of solid steel.


----------



## pistolsnipe

hey, i've been looking into a chassis for my build as of late, and this one doesn't quite fit my bill (looking for 3 inch tall max), but it seems pretty awesome and is dirt cheap, so i thought i would share my find

Metal Project Boxes

 (top link)


----------



## askforwhy

Quote:


  Originally Posted by *linuxworks* /img/forum/go_quote.gif 
_well, not to insult, but I've zapped a few caps when I forgot to discharge them. so its easy for people to forget 
	

	
	
		
		

		
		
	


	




 I did, more than once!

 as a matter of course, I simply replace all MOSFETS and .47ohm r's. 

 I don't even bother checking the .47 r's. I just replace them._

 






You're welcome, linuxworks.
 Well I've replaced several MOSFETs. Because the Q2 in my Sigma22s was dead and I didn't find out at first, I just kept buring MOSFETs after I replaced them.
 I also checked one of my Beta22s is failure right before I powered up. One zener diode was blown and the MOSFETs were dead.
 Now everything is fine and I stll have a long way fighting against the hum nosie. Guess I will replace the trafos next step.


----------



## dude_500

Quote:


  Originally Posted by *dude_500* /img/forum/go_quote.gif 
_Over the last few weeks I've noticed a quiet hiss that lasts for maybe a tenth of a second and occurs every few seconds (not at a constant rate, seemingly random in occurrence and exact sound). It doesn't occur all the time, sometimes it does it a lot, usually not at all, sometimes just a little. It is volume knob related and when the volume is at zero it's totally silent, and at max the noise is very loud. At listening volumes it's quite quiet but definitely there. Does this mean it's outside of the volume knob? Even with source unplugged it does it and I don't understand how the wire from the knob to the RCA jacks could do this. I didn't change anything, It's just started doing it recently._

 

I haven't had much time to troubleshoot this over the last few weeks so I've kind of just left it, and it slowly has been getting worse. Before today, it would just happen randomly, usually during late afternoon at a similar time. As of today, it started becoming periodic (~1 short click per second), and it is doing it constantly now, has been all day. It is also getting louder. Right now it interferes with listening.

 It's identical in both channels so I don't think it's a solder joint in the volume knob. Also it is still fully volume knob dependent and cuts out with no volume. Continues with source unplugged from the amp. It is not dependent on the placement of the amp within my room or even house.

 Any ideas here? I'm stumped since it's volume knob dependent.


----------



## amb

Cell phone interference?
 Or some other interference from elsewhere?
 The fact that it's silent when the volume is down means that it's not coming from the amp's electronics. It's from some external source.


----------



## dude_500

Is it possible to get some sort of feedback RF loop coming out of the amp electronics back to the input? The fact that it happens equally in both channels at the same level and period in various rooms of my house seems to rule out external interference. Does it without cellphones nearby.


----------



## digger945

The only other thing that I can think of would be a problem with grounding within the amp, especially between the attenuator and boards. Turning the volume down and noticing that it seems to get quieter or go away doesn't necessarily mean the problem isn't there, it could mean that it isn't amplified enough to hear.
 To suggest an RF problem means that something would have to be oscillating. Do you have a scope(I can't remember?) You might be able to pick up some AC with a DMM.
 Does it sound like a 60Hz tone? Tried moving the PS around? 
 I'm not sure if you could be getting some trash from the wall outlet. I suppose moving the amp to another location might rule out some possible things.


----------



## Anonanimal

I'd try things like unplugging any wireless routers, etc. to see if you can eliminate it- as those signals will permeate mostly your entire house and possibly create the non room-specific symptoms that you're seeing.

 Or maybe try taking it w/ you to a friend's house or work or something and see if the problem "follows" you. That might help you narrow it down more rapidly. Good luck!


----------



## dude_500

Tried unplugging wireless devices, no effect.

 I earthed the ground of the amp and it got significantly quieter (though still existent). The problem is, after I then turned it off and solidly attached the earth ground and turned it back on, the positive rail of the power supply promptly burned out. Is this normal when earthed?

 I do have a scope and will look at the output after I repair the power supply.

 It's not 60hz, it's a short pop every second


----------



## digger945

I wasn't referring to earth ground, but the daisy chain or star grounding of the inputs/attenuator/boards, but having a good earth ground is not a bad idea for more than one reason. What you're experiencing doesn't sound like that is the problem though, and given the interval you're getting the popping noise I doubt that a scope will do anything to help. A steady ~1 second interval sounds like a device doing a check or update, like a modem or cell phone or cordless phone perhaps. I've had similar problems with USB at times that would never be consistent, but you've made it clear that it persists even with no input to the amp.


----------



## pistolsnipe

hey, i am looking for 1.5 inch heatsinks on mouser without pins (so i can thread and screw them down.) i have found everything else but those. amb specefies them as Aavid-Thermalloy 529802B00000, but i cant seem to find them. has anyone found these from mouser?


----------



## UKToecutter

I think I got mine from digikey.....

  Quote:


  Originally Posted by *pistolsnipe* /img/forum/go_quote.gif 
_hey, i am looking for 1.5 inch heatsinks on mouser without pins (so i can thread and screw them down.) i have found everything else but those. amb specefies them as Aavid-Thermalloy 529802B00000, but i cant seem to find them. has anyone found these from mouser?_


----------



## oneplustwo

Not sure if you have a reason to prefer those or not, but personally, I found the ones with pins much more straight forward. No threading and no fear of over tightening. And I didn't see myself needing to remove the heatsinks ever. Just my $0.02.


----------



## quattro98

You can buy them directly from the AMB store.

AMB audio shop

  Quote:


  Originally Posted by *pistolsnipe* /img/forum/go_quote.gif 
_hey, i am looking for 1.5 inch heatsinks on mouser without pins (so i can thread and screw them down.) i have found everything else but those. amb specefies them as Aavid-Thermalloy 529802B00000, but i cant seem to find them. has anyone found these from mouser?_


----------



## digger945

Quote:


  Originally Posted by *pistolsnipe* /img/forum/go_quote.gif 
_hey, i am looking for 1.5 inch heatsinks on mouser without pins (so i can thread and screw them down.) i have found everything else but those. amb specefies them as Aavid-Thermalloy 529802B00000, but i cant seem to find them. has anyone found these from mouser?_

 

 Quote:


  Originally Posted by *UKToecutter* /img/forum/go_quote.gif 
_I think I got mine from digikey....._

 

http://dkc3.digikey.com/PDF/US2010/P2477.pdf<<<Figure 17.

Digi-Key - HS276-ND (Manufacturer - 529802B00000)


----------



## pistolsnipe

Quote:


  Originally Posted by *oneplustwo* /img/forum/go_quote.gif 
_Not sure if you have a reason to prefer those or not, but personally, I found the ones with pins much more straight forward. No threading and no fear of over tightening. And I didn't see myself needing to remove the heatsinks ever. Just my $0.02._

 

yeah i would totally agree with you, however i already have some that are tap/screw mount, so i would like to make them all match


  Quote:


  Originally Posted by *quattro98* /img/forum/go_quote.gif 
_You can buy them directly from the AMB store.

AMB audio shop_

 

 Quote:


  Originally Posted by *digger945* /img/forum/go_quote.gif 
_http://dkc3.digikey.com/PDF/US2010/P2477.pdf<<<Figure 17.

Digi-Key - HS276-ND (Manufacturer - 529802B00000)_

 


 yeah, i was hoping to find them at mouser to avoid extra shipping, however i will probably end up getting them there, sucks because mouser has 1 and 1.75 inch but no 1.5 inch (at least that i can find) but i do appreciate the input


----------



## digger945

Quote:


  Originally Posted by *pistolsnipe* /img/forum/go_quote.gif 
_yeah i would totally agree with you, however i already have some that are tap/screw mount, so i would like to make them all match







 yeah, i was hoping to find them at mouser to avoid extra shipping, however i will probably end up getting them there, sucks because mouser has 1 and 1.75 inch but no 1.5 inch (at least that i can find) but i do appreciate the input_

 

529802B02500G Aavid Thermalloy Heatsinks
 They have pins. If you search HF you can find how others have removed the pins and tapped them, but for the trouble you might be better off ordering from Digikey.


----------



## Anonanimal

Quote:


  Originally Posted by *dude_500* /img/forum/go_quote.gif 
_Tried unplugging wireless devices, no effect.

 I earthed the ground of the amp and it got significantly quieter (though still existent). The problem is, after I then turned it off and solidly attached the earth ground and turned it back on, the positive rail of the power supply promptly burned out. Is this normal when earthed?

 I do have a scope and will look at the output after I repair the power supply.

 It's not 60hz, it's a short pop every second_

 

Which ground did you tie to earth? How many boards did you use in your Beta?

 If it's an active ground (3ch+) and you tied the output to earth ground I can see that causing problems. Either that or I'm not 100% understanding what you tested.


----------



## LeMat

Thanks to oneplustwo who sent me a spare BJ550, I've been able to finish and listen to my B22 ! While still not encased, it's working perfectly. The sound is really different from by WA2... much more dynamic and with a huge soundstage. It's on the bright side, making my HF2 quite sibilent but it's maybe because of my silver interconnect.
 Still, I have an issue with my ALPS blue velvet... Basically it's not working, or only on the first 10%, then after it has no effect on the volume. Any idea what could cause that ? 
	

	
	
		
		

		
			





 Don't tempt me with a DACT....


----------



## linuxworks

I suspect you don't have it grounded at the end of the pot. a series R might act like that with a 'floating' shunt part of it


----------



## LeMat

Quote:


  Originally Posted by *linuxworks* /img/forum/go_quote.gif 
_I suspect you don't have it grounded at the end of the pot. a series R might act like that with a 'floating' shunt part of it 
	

	
	
		
		

		
		
	


	


_

 

indeed the end of the pot is not grounded (the amp is "breadboard style" for now).... but I don't really understand why it affects its behavior like this. I'll try and let you know ! Thanks


----------



## amb

dude_500, maybe posting some clear pics of the guts of your amp would help.


----------



## dude_500

Quote:


  Originally Posted by *Anonanimal* /img/forum/go_quote.gif 
_Which ground did you tie to earth? How many boards did you use in your Beta?

 If it's an active ground (3ch+) and you tied the output to earth ground I can see that causing problems. Either that or I'm not 100% understanding what you tested._

 

It's 2-board non-active ground. I just earthed one of the ground terminals on the sigma-22, which previously earth was nowhere at all in the amp wiring as someone suggested to me a while back.

 It's quiet today, although I think I just heard one little pop. 

 Here are a few picts. It is not in a case, I rarely get around to enclosing my projects in a reasonable time frame. It's been just like this since I built it last July though and I've not had this problem until a few weeks ago.


----------



## amb

dude_500, an uncased amp might pick up all kinds of junk in the airwaves. Earthing the power supply ground on an uncased amp is also not a useful exercise. You should really put everything into a metal case and follow the "wiring & ground" instructions. You may find that's all is necessary to fix the problem. I don't know why this noise only seems to have occurred recently, maybe there is a strong interference from outside your own house.

 Oh btw, those green mylar caps you have on the σ22 are sub-optimal. These are used for high frequency compensation in the design, and should have good high-frequency performance. Unfortunately, those green mylar caps are inductive and do not work well in this application. I don't _think_ this is the source of your noise problem, but who knows, I would recommend replacing them with non-inductive film or multilayer ceramic caps.


----------



## dude_500

Quote:


  Originally Posted by *amb* /img/forum/go_quote.gif 
_dude_500, an uncased amp might pick up all kinds of junk in the airwaves. Earthing the power supply ground on an uncased amp is also not a useful exercise. You should really put everything into a metal case and follow the "wiring & ground" instructions. You may find that's all is necessary to fix the problem. I don't know why this noise only seems to have occurred recently, maybe there is a strong interference from outside your own house.

 Oh btw, those green mylar caps you have on the σ22 are sub-optimal. These are used for high frequency compensation in the design, and should have good high-frequency performance. Unfortunately, those green mylar caps are inductive and do not work well in this application. I don't think this is the source of your noise problem, but who knows, I would recommend replacing them with non-inductive film or multilayer ceramic caps._

 

I'll case it up soon and replace those caps and see if the problem persists. I'd need to case it before heading off to college next year anyways, so may as well get it done now.


----------



## digger945

Do you listen to the amp with the tower it's sitting on powered up?
 I don't see a PS in the computer where one should be so I'm guessing it's just a table atm(been there done that
	

	
	
		
		

		
		
	


	




)


----------



## dude_500

Quote:


  Originally Posted by *digger945* /img/forum/go_quote.gif 
_Do you listen to the amp with the tower it's sitting on powered up?
 I don't see a PS in the computer where one should be so I'm guessing it's just a table atm(been there done that
	

	
	
		
		

		
		
	


	




)_

 

No, it hasn't been on for many years, I have more scrap computer cases than tables in my room


----------



## UKToecutter

hmmm....

 I got the exact same mylar caps on my s22.

 They were listed on a bom that someone posted.

 Oh well. I'd better change mine too.


----------



## Fitz

Quote:


  Originally Posted by *amb* /img/forum/go_quote.gif 
_Oh btw, those green mylar caps you have on the σ22 are sub-optimal. These are used for high frequency compensation in the design, and should have good high-frequency performance. Unfortunately, those green mylar caps are inductive and do not work well in this application. I don't think this is the source of your noise problem, but who knows, I would recommend replacing them with non-inductive film or multilayer ceramic caps._

 

It would probably be a good idea to take them (Xicon PF) off the parts list on the σ22 page then, otherwise people are likely to keep using them.


----------



## amb

I didn't realize the Xicon PF was those green mylars, I don't remember why I added them to the parts list. Anyway, they are obsolete anyway, and now removed from the BOM.


----------



## Fitz

Mouser still has some of the higher tolerance versions of the Xicon PF, plus the Xicon PEI which seems to be the current equivalent. I only know what they are because I ordered some a while back trying to avoid making a separate order at Digikey just for those caps.


----------



## nattonrice

AMB, I found that everything was obsolete (for c14/15) except for the one from digikey.


----------



## pompon

For a B22 balanced (4 board) with dual sigma 22 ... We want cable inside with silver wire.
 (that include, volume control and 1 input)
 What would be the required length of cable about? 5 foot, 10 foot, 25 foots?

 Silver cable is pretty expansive ... it's why I ask!


----------



## Lil' Knight

25 feet? Your cases must be huge.
 Just try to keep the signal wiring as short as possible.


----------



## linuxworks

I would not use fancy 'silver' wire. its certainly not needed and since regular wire is known to work (and work well) why not try that first before assuming you need 'upgraded' wire?


----------



## Beefy

Quote:


  Originally Posted by *linuxworks* /img/forum/go_quote.gif 
_I would not use fancy 'silver' wire. its certainly not needed and since regular wire is known to work (and work well) why not try that first before assuming you need 'upgraded' wire?_

 

pompon believes in audible differences between power cables. Enough said


----------



## mhamel

So, I'm getting close to embarking on a Beta22 adventure. 

 I've been reading and researching for a few weeks now... have made it all the way through this thread, 2-1/2 of the Headwize threads, Amb's Web site (multiple times) and a bunch of other assorted threads.

 I've been going back-and-forth on whether to go with a 3-channel active ground build, or just go all out and build a balanced amp. I'm leaning heavily towards the 3-channel active ground config.

 I've got what may be a stupid question about power supply configuration, but I'm going to go ahead and ask it just the same. Heh

 I'm thinking of building the PSU with dual Sigma22 PSU boards, to spread the thermal load out, and to minimize future work if I decide I eventually want to upgrade to a 4-channel balanced config.

 I know I could run 2 of the amp boards from one PSU board and the 3rd from the 2nd PSU board, but with the thought of keeping the power and thermal loading as even as possible, can the o22 outputs be run together in parallel?

 Thanks,
 -Mike


----------



## oneplustwo

My opinion.... size the enclosure, plan the layout and jacks (get an 8 pin speakon jack or something similar) for two sigmas and trafos but only install one. Then, if you go balanced later, it will be easy to add another sigma.


----------



## johnwmclean

Quote:


  Originally Posted by *mhamel* /img/forum/go_quote.gif 
_I know I could run 2 of the amp boards from one PSU board and the 3rd from the 2nd PSU board, but with the thought of keeping the power and thermal loading as even as possible, can the o22 outputs be run together in parallel?_

 

 Quote:


  Originally Posted by *amb* /img/forum/go_quote.gif 
_Also, *never* parallel the outputs of two σ22s. One σ22 will "see" the output of the other, which will appear as a short circuit and the two will fight. You'll have some blown parts as a result._


----------



## nattonrice

In addition to the suggestion above, I would also layout, cut vents and xlr jack holes, and drill mounting holes for a 4 board build.
 That way when/if you make the decision to change to a balanced build it is as simple as dropping in the 4th board and wire.
 ... well you also need to make a handful of parts changes to the 3rd board but that will be trivial.


----------



## amb

You cannot parallel the outputs of two σ22s (or, for that matter, most regulators). One will "look" like a dead short to another due to its low output impedance, and the two will "fight" and both will likely be damaged.


----------



## mhamel

John/Amb - Thanks... sorry, I must have missed the discussion about parallel along the way... lots of info to digest.

 I'm thinking I'll take oneplustwo's advice, build up the dual PSU and just use one side for now, that way at least that part of it is done and available for a later upgrade.

 Thanks,
 -Mike


----------



## oneplustwo

Another thought... depending on the likelihood of going balanced, you might consider going with a 2 channel at first. If a 4 channel is inevitable, this would make your life easier especially if you don't have to change the gain of the existing boards. (Remember, your effective gain will double once you go balanced.) This would also give you the opportunity to think about a truly mono-mono setup where you could have one sigma PSU and one 2 channel beta enclosure for the left and another for the right. I've never actually seen that done (for good reason I think) but for your situation where you could potentially build half a balanced beta at a time, that could work. Plus, if you decide 2 channels is good, you won't have these large enclosures with wasted space. Just a thought.


----------



## aloksatoor

The volume control on a dual mono would be complex at best. You either need 2 knobs or you need a digital attenuator controlled by a single knob or buttons. It works for power amps since we have a preamp to control the volume.


----------



## mhamel

Yes, I think a monoblock design with 4 chassis wouldn't work that well for a headphone amp. Whichever config I end up with, I'm going to keep it to a single PSU chassis and single amp chassis, but try to lay everything out so that upgrading later on won't be that bad, if I decide to go that route.

 I've been playing around with panel designs and enclosure layouts just to get some idea of how feasible it would be, and I think I have something that would work... using Neutrik D-series jacks for the RCA inputs and headphone outputs, that way if I decide to go balanced, replacing those with the same series XLR jacks will be trivial.

 The Ecomate power connectors come in a 6-contact version, so I'll plan on using that from the start, with a 6-conductor umbilical, and that keeps me covered later as well.

 As far as gain goes, from what I've read, I think I'd need to change if I upgrade. I'm going to be ordering D7000s in the next few weeks, which would need lower gain, but will also be using the amp with 250 ohm DT-990s. I've settled on a gain of 5 for the unbalanced config, but if I go balanced, I'm thinking I'd need to drop that to a gain of 2 per board to account for doubling. Still, though, as long as I'm careful with the boards, swapping out the gain parts shouldn't be too bad after the fact.

 I'm still deciding on which way to go for volume control. I've got some email out to TKD about their stepped attenuator - according to their data sheet, it doesn't come in a 50K version, and it's rated at "0-15KHz frequency" - I wasn't sure if that had any effect on using it for this, though from everything else I've read, it seems to be a good choice. If they don't have it in 50K, though, I need to decide on an alternate. They've got 10K, 20K and 100K listed in the data sheet.

 Another potential downside - no quad version of the TKD. So if I upgrade, it also means a change of volume control, so I need to think about that for the layout as well.

 Still time for decisions, though.. I'm not rushing into anything... I want to make sure I plan this out well before I start.

 -Mike


----------



## oneplustwo

If you plan on having the balanced amp run unbalanced, you'll need the ground to go back to the sigma PSU. So you'd need the 8 pole ecomate if they have one to accommodate this. I used an 8 pole speakon from Neutrik which is awesome. I got a matching preterminated cable from ebay for super cheap too.


----------



## aloksatoor

Im on the lookout also for an 8 conductor cable can you point me to the ebay seller?


----------



## FallenAngel

Uhm... 8 cables, sleeve in nylon?


----------



## oneplustwo

Here you go.


----------



## aloksatoor

Thanks!!


----------



## NumLock

About to start ordering parts. One question though. If I can get all the caps and resistors for free, how much would I save if I buy the boards, heat sinks, etc, over the glass jar kit?


----------



## Pars

Quote:


  Originally Posted by *Beefy* /img/forum/go_quote.gif 
_pompon believes in audible differences between power cables. Enough said 
	

	
	
		
		

		
			



_

 

It will be interesting to see if pompon hears differences between his silver cable and a standard power cable with this. It is my premise that differences in power cables can be attributed to the quality of the PSU (or lack thereof).


----------



## ezzieyguywuf

I built my first cmoy last summer and plan on building a starving student next week. I've seen "beta 22" talked about, and seen a few finished builds in the "show off your builds" thread, but never really looked into it. I've taken a look at their website though, and lemme tell you, I've been drawn in. I mean, multiple inputs, multiple outputs, and a bunch of "discrete" crap I don't even understand? I build my own power supply?

 This sounds like the ULTIMATE DIY project. Mark me down as "thinking about doing it". As soon as I graduate and get a job, I'm in.


----------



## pompon

Quote:


  Originally Posted by *Pars* /img/forum/go_quote.gif 
_It will be interesting to see if pompon hears differences between his silver cable and a standard power cable with this. It is my premise that differences in power cables can be attributed to the quality of the PSU (or lack thereof)._

 

I am not doing a powercable ... I just want to know what is the lenght I need to wire a B22 balanced.


----------



## nattonrice

Length of what? Umbilical between the PSU and AMP?
 Check the wiring and ground section of the b22 website for what AMB considers the longest length before causing problems.


----------



## m1abrams

Quote:


  Originally Posted by *pompon* /img/forum/go_quote.gif 
_I am not doing a powercable ... I just want to know what is the lenght I need to wire a B22 balanced._

 

We can not answer that question for you. You need to layout your boards in the case figure where you are going to have your connectors and measure.


----------



## mhamel

Just a note for anyone thinking of picking up a TKD attenuator for a build, and follow-up to my earlier comments about them.

 I had written them asking if there was a 50K part available as it wasn't in the data sheet. Very friendly response, got back to me within a day. They will do custom builds with about a 30-45 day turnaround. No problems on a 50K, and they'll even do a 4-gang for balanced.

 Far from cheap, but through the US distributor they sent me to, pricing works out to be a bit less for a custom 4-gang attenuator, including shipping, than it would be to buy 2 x stereo controls from Percy Audio + shipping.

 -Mike


----------



## SoapSeller

Hi,
 Lately I've noticed some power-off thump in one side with my ~2 years old balanced b22.
 I'm not sure if this is a new thing for the amp or something that was always there. 
 (I've upgraded my headphones to HD800 recently)

 I've rechecked all the voltages and for DC offset and everything seems in order.
 Any idea where to look next?


----------



## amb

Does it thump with the volume set to minimum when you power off? The thump could be from the source if the volume is up. A β22/σ22 should emit almost no thump on power up or down.


----------



## SoapSeller

yes, it does...

 I'm using TP Joshua Tree for volume control, and I have no idea how it behave on power-off.


----------



## linuxworks

if there is a thump on turn on/off then something is not 'symmetrical'. one of the design goals (as I understand it) is to BE symmetrical so that things are 'even' at turn on and off times.

 maybe some component has drifted over time, throwing off the careful internal balance? or a solder connection started showing some resistance?


----------



## pistolsnipe

hey guys, just got around to testing my first sigma 22, and i am already ready to start onto the questions hah. i built the board for 30 volts, but i am getting +and- 22.03

 would definately appreciate any help, i have triple checked all the values on the pars list, and they are correct as far as i could tell.



 here are all the values i could easily get to 

 cr2 8.28
 cr3 25.15
 cr4 25.11
 r1 46.01
 r2 46.52

 after bridge rectifiers : 46.5

 i can possibly post hirez pics later tonight, thanks a lot guys!


----------



## amb

With the power off and all capacitors discharged, measure the resistance of your R8 and R10. Are these what you expect?
 With power on, measure the voltage across D5. What is it?


----------



## pistolsnipe

first of all, thanks for the assistance, and you're awesome brainchild.

 the voltage across d5 is 8.86, i am assuming that is supposed to be 12... looks like i ordered the wrong part

 resistances are correct, 10k and 6.81 k

 here is a pic







 edit:replaced with 12 volt unit and everything is now happy, thanks ti!


----------



## Lil' Knight

What's the polar for LED on the S22? I didn't see any - mark.


----------



## amb

The LED cathode (negative) pin is toward the negative bank of the board.


----------



## ivanrocks321

almost done with my two board beta. im looking for decent pot is the Dale 23 Step Attenuator 50K good choice? and is this 1/4 jack good choice also Neutrik NJ3FP6C-BAG 1/4" Female Chass? I can spend more if its really worth the extra cash.


----------



## oneplustwo

I actually don't like the locking ones. If you trip over the wire, everything comes tumbling down... would rather the plug just come out. Plus, it takes two hands to remove the plug. Also, they're harder to mount and wire. I like these.

 Work great, simple, easy to use, and cheap!


----------



## rhester

What gauge wiring is being used on b22 builds for power? Especially on the e22 backplane feeding the b22 boards?


----------



## oneplustwo

I've used 16 and 18 gauge on my builds. Stranded is easier to work with. My umbilical for my balanced beta uses 14 gauge. That seems a bit over-overkill but it came as part of my speakon assembly.


----------



## tintin47

Quote:


  Originally Posted by *ivanrocks321* /img/forum/go_quote.gif 
_almost done with my two board beta. im looking for decent pot is the Dale 23 Step Attenuator 50K good choice? and is this 1/4 jack good choice also Neutrik NJ3FP6C-BAG 1/4" Female Chass? I can spend more if its really worth the extra cash._

 

If you are using a 1/4" jack, make sure that you read the notes on R34-35 on amb.org to make sure you don't burn up any parts.


----------



## johnwmclean

As there is no device matching category for the σ22 on the AMB site, I assume this is not as critical as with the β22 and not a prerequisite. Does this mean components are acceptable so long as they operate within there specified tolerances?

 Another query...
 I received an order from Farnell today, IRF9Z34N are different in appearance to the pieces I’ve received from GJA in the past, the data spec is exactly as per AMB’s parts list. Here is a pic:



 The two arched notches that are usually seen near the screw hole are straight, and the text is smaller and more defined, it does have the International Rectifier logo though, any ideas? These are intended for my σ22.


----------



## amb

International Rectifier has multiple production facilities in different countries, and they may use different suppliers for their TO-220 package basis. It wouldn't be unusual for a batch to look different than another. I've seen other variations in the past.


----------



## johnwmclean

Thanks Ti!


----------



## nattonrice

Quote:


  Originally Posted by *johnwmclean* /img/forum/go_quote.gif 
_As there is no device matching category for the σ22 on the AMB site, I assume this is not as critical as with the β22 and not a prerequisite. Does this mean components are acceptable so long as they operate within there specified tolerances?._

 

Check the parts list for the s22 under "Transistors"


----------



## johnwmclean

Oh dear, I blame my old eyes. Thanks Tom.


----------



## MrMajestic2

Ok guys, I need some pointers in the right direction. I have a B22 board that measures 4.5V on R9, but around 3.5V on R10, R11 and R12. Any ideas where I should start looking? Everything looks like its soldered into the right place.


----------



## johnwmclean

Quote:


  Originally Posted by *MrMajestic2* /img/forum/go_quote.gif 
_Ok guys, I need some pointers in the right direction. I have a B22 board that measures 4.5V on R9, but around 3.5V on R10, R11 and R12. Any ideas where I should start looking? Everything looks like its soldered into the right place._

 

You might have to dig into the troubleshooting pdf and do some voltage measurements.


----------



## MrMajestic2

Quote:


  Originally Posted by *johnwmclean* /img/forum/go_quote.gif 
_You might have to dig into the troubleshooting pdf and do some voltage measurements._

 

I figured that much, I just don't know where the most logical place is to start.


----------



## quattro98

I started this a few years ago & then was too busy to finish it. Recently, I decided it was time to get it completed. This is my first true DIY project (although I have plenty of experience soldering & using a multimeter). I'm excited by how well it turned out.

 The chassis is from ATI Research. I sent them files for the face plates & they did the machining & provided the knobs. Unfortunately, I understand they're no longer in business. The left-most knob is a headphone-preamp-out switch, the middle one is the volume control, & the right-most knob is for the input selector. Originally, the left-most knob was meant for a Tangent crossfeed circuit, but I decided to omit it, but I already had the faceplate machined for the 3rd control, so I added the switch. It comes in handy to disconnect the front panel jacks when changing headphones without powering off the amp.

 I would like to thank Ti Kan (AMB), Jeff Rossel (Glassjar), Arthon (ATI), & all of the contributors at Headwize & Head-Fi. I was able to find answers to all of my questions in the various support threads which made this possible.

 The amp sounds amazing & I'm sure it will make a great pre-amp if I want to use it to setup a 2 channel system.


----------



## Lil' Knight

Quote:


  Originally Posted by *Magsy* /img/forum/go_quote.gif 
_Finished my last board at four am last night...





_

 

I'm wondering what are the caps he used instead of the Wimas?
 And what are the resistors in the R34,R35?


----------



## Beefy

Quote:


  Originally Posted by *quattro98* /img/forum/go_quote.gif 
_I started this a few years ago & then was too busy to finish it. Recently, I decided it was time to get it completed. This is my first true DIY project (although I have plenty of experience soldering & using a multimeter). I'm excited by how well it turned out._

 

It's gorgeous. Really like it 
	

	
	
		
		

		
		
	


	




 Do the heatsinks stay cool enough? Doesn't look like there is a lot of room for airflow.


----------



## quattro98

Quote:


  Originally Posted by *Beefy* /img/forum/go_quote.gif 
_It's gorgeous. Really like it 
	

	
	
		
		

		
		
	


	




 Do the heatsinks stay cool enough? Doesn't look like there is a lot of room for airflow._

 

Thanks. The amp seems OK (it's biased to 120 mA), but the power supply does run warmer than I'd like. The case for the amp has slots on both the base & the lid, while the power supply case only has slots on the lid. I might drill holes in the base of the power supply to allow for more ventilation.


----------



## johnwmclean

Quote:


  Originally Posted by *MrMajestic2* /img/forum/go_quote.gif 
_I figured that much, I just don't know where the most logical place is to start._

 

A 1 volt discrepancy may be simply the tolerances of the CRD’s, does the rest of the board test ok?


----------



## fishski13

quattro98,
 very sexy. where did you source the knobs?


----------



## quattro98

They're from ATI, who also supplied the chassis.

  Quote:


  Originally Posted by *fishski13* /img/forum/go_quote.gif 
_quattro98,
 very sexy. where did you source the knobs?_


----------



## amb

Quote:


  Originally Posted by *MrMajestic2* /img/forum/go_quote.gif 
_Ok guys, I need some pointers in the right direction. I have a B22 board that measures 4.5V on R9, but around 3.5V on R10, R11 and R12. Any ideas where I should start looking? Everything looks like its soldered into the right place._

 

A bad JFET in the Q1-Q4 quad? This should not have anything to do with the CRDs.


----------



## fishski13

Quote:


  Originally Posted by *quattro98* /img/forum/go_quote.gif 
_They're from ATI, who also supplied the chassis._

 

damn.


----------



## MrMajestic2

Quote:


  Originally Posted by *amb* /img/forum/go_quote.gif 
_A bad JFET in the Q1-Q4 quad? This should not have anything to do with the CRDs._

 

Ok, thanks. I know where to start now.


----------



## MrMajestic2

Quote:


  Originally Posted by *johnwmclean* /img/forum/go_quote.gif 
_A 1 volt discrepancy may be simply the tolerances of the CRD’s, does the rest of the board test ok?_

 

Actually it doesn't. R34 measures around 100mv at VR2s minimum position. So the only way that goes when adjusting is up, so something else must be wrong too.


----------



## MrMajestic2

Oh great, now I have problems with another board. R9 adjusting to around 4.5V at the maximum range of VR1 and then dropping past 4 volts and downwards. R34 is measuring zero 
	

	
	
		
		

		
		
	


	




 I have gone over both problem boards with a magnifying glass and finding no obvious mistakes.


----------



## swt61

Very nice quattro98!

 Here are a few pics of my own β22. It's a four channel, with dual σ22s in a separate enclosure. There were many hands involved with this project...luvdunhill, N_Maher & fierce_freak. The Top unit is a fully balanced TPA Darwin source selector with six balanced inputs, two balanced outputs and a balanced loop out. The cases were built by me, and are figured Black Cherry w/a five coat, modified Tung Oil finish.


----------



## quattro98

Thanks! Those are amazing. I like how everything matches perfectly.

  Quote:


  Originally Posted by *swt61* /img/forum/go_quote.gif 
_Very nice quattro98!

 Here are a few pics of my own β22. It's a four channel, with dual σ22s in a separate enclosure. There were many hands involved with this project...luvdunhill, N_Maher & fierce_freak. The Top unit is a fully balanced TPA Darwin source selector with six balanced inputs, two balanced outputs and a balanced loop out. The cases were built by me, and are figured Black Cherry w/a five coat, modified Tung Oil finish._


----------



## MrMajestic2

Quote:


  Originally Posted by *swt61* /img/forum/go_quote.gif 
_Very nice quattro98!

 Here are a few pics of my own β22. It's a four channel, with dual σ22s in a separate enclosure. There were many hands involved with this project...luvdunhill, N_Maher & fierce_freak. The Top unit is a fully balanced TPA Darwin source selector with six balanced inputs, two balanced outputs and a balanced loop out. The cases were built by me, and are figured Black Cherry w/a five coat, modified Tung Oil finish._

 

Nice work, really impressive.


----------



## JamesL

Would someone do me the favor of a quick sanity check for the transformer?
  Quote:


  Originally Posted by *s22 lower limit* 
_Lowest wall voltage I'm likely to see = 110v 
 Rated voltage with 1A draw @ 120v = 24.3v
 maximum forward voltage (d1+d2) = 0.975v *2

 (24.3v * 110/120 * root2) - 1.95v = 29.6vdc unregulated_

 

I plan on setting it to regulate at 25v and if I did the calculations correctly, ~1.8w dissipated per s22 mosfet, and ~2.7w per b22's cascode mosfets (under normal conditions).


----------



## amb

The heat dissipation numbers are all comfortable as long as your case will be ventilated. But whether any of these numbers are realistic or not depends on the load behavior of your transformer.


----------



## JamesL

The load behavior is specified on the datasheet and is factored into my calculations, but I do not know for certain until I test it.

 The top of my case will be well ventilated but it is a rather small chassis, so I am trying be less wasteful; keeping the transformers output close to b22's operating voltage but without compromising regulation.

 What is the total diode drop? My understanding is <~2v per rail, but I wasn't sure.


----------



## amb

Quote:


  Originally Posted by *JamesL* /img/forum/go_quote.gif 
_What is the total diode drop? My understanding is <~2v per rail, but I wasn't sure._

 

Depends on the diode you use. You can look at the datasheet and check the Vf spec, and multiply by 2 to get a rough estimation for a full-wave bridge.


----------



## jtostenr

I've managed to get 3 out of 4 B22 boards up and running, but the last one is giving me trouble. I installed LED+ backwards, but it won't light up even after I fixed it.

 Pics and measurements here:
AMB Laboratories DIY Audio &bull; View topic - no LED+ on B22 board

 Jeff


----------



## amb

Quote:


  Originally Posted by *jtostenr* /img/forum/go_quote.gif 
_I've managed to get 3 out of 4 B22 boards up and running, but the last one is giving me trouble. I installed LED+ backwards, but it won't light up even after I fixed it.

 Pics and measurements here:
AMB Laboratories DIY Audio &bull; View topic - no LED+ on B22 board

 Jeff_

 

Replied there.


----------



## jh4db536

IT"S ALIVE











 Note nothing is pinned down yet. I think i am going to keep the B22 boards oriented that way. The Sigma22 i may move it farther back

 well i know it works. Still got a long way to go. I figured i might as well test it to make sure it works before i decide to go all out on the CNC work in the upcoming months. got all the DC offset to zero. 4.5v through the input stage, and set VR2 down to 55mV

 I don't really know how it sounds yet i only tried 1 side at a time. There was a very slight hum (barely audible), but i think it is from the transformer (right next to everything) and probably the very messy job i did of clipping everything together for the bench test.

 My transformer definitely hums audibly if i put my head near it. The trafo itself gets about 140F on my temp gun with the lowered Qcurrent. I lowered the Qcurrent/vDrop down to 55mV per board and the temps are much better on the Sigma22 and B22 Mosfets.

 i cant wait to listen to it. i have my XLRs with the zobels soldered to the back. I am ready.


----------



## tintin47

I am having a strange issue with my beta right now. Over time, while I am listening, the right volume sort of dies away and eventually disappears completely. I have isolated the amp as the cause by unplugging/changing everything else in the chain, but the amp tests perfectly on all channels. I havent been able to isolate any bad wiring, but wiring would seem to cause intermittent issues. 

 What could be causing this? Any ideas on what I should be looking for. The PS tests perfectly as well.


----------



## amb

tintin47, it does seem like bad wiring/contact. Use your DMM and start checking the continuity between the input jacks and the volume pot, and from the pot to the amp boards, and from the amp outputs to the headphone jack contacts.

 Also, check your interconnect cables and try a different source and a pair of headphones to see if the problem is external to the amp.


----------



## Anonanimal

tintin47- you may want to also go over the amp board for that channel and check all of your solder joints. Perhaps as the amplifier heats up over time (while cased up) something gets warm enough to shift a little.


----------



## tintin47

Will do. I absolutely know the problem is confined to the amp. It has happened on multiple headphones with multiple interconnects and two sources. I think that anonanimal may be on to something with the idea it is heat-related. I will just start going over the whole thing when I have some time.

 This only started happening after I took it to the boston meet. Most likely I just havent found the jostled wire yet.


----------



## LeMat

I'm currently finalizing my build before ordering the enclosure but I'm encountering some difficulties with the use of my momentary switch (shurter illuminated).
 Things are getting fuzzy on how to wire this thing. I do have built an e24 but it seems to require its own toroid (that I forgot to order....). Start to be cumbersome having an e24+relay+toroid just to make my switch work, no ? 
 On the other side, on the Krmathis build, the team has used what appears to be an AC relay directly connected to the switch. 
 Basically, what's the "simplest" way to connect this kind of switch ? I'm aiming at having a very compact case so space matters 
	

	
	
		
		

		
		
	


	



 Sometime I feel dumb dumb... I managed to build up the amp and PSU without a glitch but am blocking on the switch.... 
 Thanks


----------



## jlefley

If you want to use a momentary switch, the e24 circuit is required. The e24 takes a single pulse from the momentary switch and then holds the relay open or closed until it receives another pulse from the switch. The e24 circuit does require transformed AC however the s24 from AMB allows the usage of a very compact EI-30 transformer to power the e24. The s24 board is the same size as the e24.

 In the group build, a latching switch was used and subsequently the e24 circuit was not required. The push button switch "stays in" when it is pushed, providing a constant current to the relay coil, keeping the power supply on. Pushing the button again returns it to its original position and shuts off the relay.

 Using a latching push button switch is somewhat simpler because it doesn't require the e24 driver circuit and the associated transformer. However if you already built an e24 and you have the momentary push button, you just need a small transformer. The s24 board and components are fairly inexpensive so its actually not that much more complicated to use the e24 and the s24 and e24 can stack for a compact footprint. Both options do require the use of a relay.


----------



## LeMat

Thanks for your explanations and for pointing me toward the s24... seems to be the most compact solution for me. I won't change my switch for a latching one since it already cost me some $$. I'll gonna waste some more money with shipping fees for pretty cheap components but I start to get use to it since I started this project. Hopefully the end is near !


----------



## Lil' Knight

Working on my S22. After measuring the G/V+ and G/V-, I only get +-28.3V. Is it OK to measure like this? My S22 is built for +-30V.


----------



## Beefy

Quote:


  Originally Posted by *Lil' Knight* /img/forum/go_quote.gif 
_Working on my S22. After measuring the G/V+ and G/V-, I only get +-28.3V. Is it OK to measure like this? My S22 is built for +-30V._

 

Measure the voltage across D5. What do you get?

 If it is less than the 'proper' 12V due to the tolerance of the Zener, then the output will be different accordingly.


----------



## n_maher

Quote:


  Originally Posted by *Beefy* /img/forum/go_quote.gif 
_Measure the voltage across D5. What do you get?

 If it is less than the 'proper' 12V due to the tolerance of the Zener, then the output will be different accordingly._

 

Don't forget that R8 and R10 also play a roll here and if their values are different it will affect the output voltage as well.

  Quote:


  Originally Posted by *amb.org* 
_When R8 is 10KΩ and R10 is 6.81KΩ, the gain is 2.5. With a 12V zener diode as D5, then the positive rail output voltage is 30V. The negative rail will automatically invert and track the positive rail so its output is -30V._


----------



## LeMat

Quote:


  Originally Posted by *Lil' Knight* /img/forum/go_quote.gif 
_Working on my S22. After measuring the G/V+ and G/V-, I only get +-28.3V. Is it OK to measure like this? My S22 is built for +-30V._

 

Should'nt have any consequences since the b22 has a good tolerance (anything between 24 and 30v as far as I remember)


----------



## Beefy

Quote:


  Originally Posted by *n_maher* /img/forum/go_quote.gif 
_Don't forget that R8 and R10 also play a roll here and if their values are different it will affect the output voltage as well._

 

Oh sure. But I would like to think that most people would stick to the default values, and use 1% resistors that they check before installing. The tolerance of the zener is 5%, and rarely checked.


----------



## n_maher

Quote:


  Originally Posted by *Beefy* /img/forum/go_quote.gif 
_Oh sure. But I would like to think that most people would stick to the default values, and use 1% resistors that they check before installing. The tolerance of the zener is 5%, and rarely checked._

 

True enough, but even using the "stock" values you'd never see an actual 30V. The stock gain is actually 2.47 so if you actually had a 12V zener you'd get 29.6Vout. Adjust that 12V down 5% to 11.4V and you get 28.16 so it seems like Lil' is well withing the range of tolerances. I know that I had a heck of a time getting exactly 5V (spec req'd +/- .1V) out of the 11's that I built as SB3 power supplies.

 All that said, unless I was building a beta22 to power speakers I wouldn't bother with anything more than +/-24V.


----------



## johnwmclean

Quote:


  Originally Posted by *Beefy* /img/forum/go_quote.gif 
_Oh sure. But I would like to think that most people would stick to the default values, and use 1% resistors that they check before installing. The tolerance of the zener is 5%, and rarely checked._

 

How do you check the a zener’s voltage?


----------



## Lil' Knight

Quote:


  Originally Posted by *johnwmclean* /img/forum/go_quote.gif 
_How do you check the a zener’s voltage?_

 

I have the same question 
	

	
	
		
		

		
			





 So like Nate said, I guess +-28.3v is just fine since mine is only a 2-channel and doesn't have speaker outputs.


----------



## n_maher

Quote:


  Originally Posted by *johnwmclean* /img/forum/go_quote.gif 
_How do you check the a zener’s voltage?_

 

Zener Diode Testing

 In order to dial in my SB3 power supply I just bought 30 or so and simply inserted each one into the SB11 which measuring the output voltage. You could also simply measure R8 and R10 and use the measured output voltage to calculate the zener value.


----------



## johnwmclean

Quote:


  Originally Posted by *n_maher* /img/forum/go_quote.gif 
_Zener Diode Testing

 In order to dial in my SB3 power supply I just bought 30 or so and simply inserted each one into the SB11 which measuring the output voltage. You could also simply measure R8 and R10 and use the measured output voltage to calculate the zener value._

 

I had a similar experience last night with my s11, trying to get 12.6V output. I managed 12.58V 
	

	
	
		
		

		
		
	


	




.
 I installed the zener without R10 took the output reading, I was able to calculate the value for R10 that way.

 Thank’s for the link nate!


----------



## aloksatoor

same here last night I powered on the tube heater s11 and got a 6.2 was aiming for a 6.3....


----------



## Beefy

Quote:


  Originally Posted by *Lil' Knight* /img/forum/go_quote.gif 
_I have the same question 
	

	
	
		
		

		
		
	


	


_

 

For you testing it now in-circuit, you literally measure across the diode. One multimeter probe at each end of the zener. You'll likely find it is ~11.5V.


----------



## Lil' Knight

Thanks. I used the stock parts from GlassJar. Just double check all again and still get +-28.3V. Looks like I'm settled with this then.


----------



## Beefy

So did you actually measure the zener voltage?


----------



## Lil' Knight

Yep. It's ~11.46v.


----------



## Beefy

Yep, spot on. No worries at all


----------



## jh4db536

So i am finally listening to my 4 board b22; it put a big smile on my face and i am not easily impressed. Source is a balanced/Dual mono Opus DAC (no output stage). The only time i ever heard a B22 (active ground) was at CJ2009 when i went to TK's table for a very brief time. That's when i became set on building my own.

 I love it. It is dead quiet even with my hack job mock up since i havent cut my faceplate or backpanels, all the AC wires are unshielded because i havent installed my umbilical yet. No hiss no transformer hum.

 Every note hits with Massive weight and control especially bass, yet it still has a balanced tone and a little laid back. I would say the bass is right up there compared to my Apache, which i think is the best i've heard so far. Sound signature is definitely different, the RSA being VERY Airy, expansive, yet powerful at the same time. The Beta22 sounds heavy, fast at the same time and quite intimate, not exactly extremely neutral compared to my experience with Dynalo/Gilmore/Headamp amps.

 This is reflective of the Opus Dac which has a very rich and heavy sound signature compared to my DAC1. The B22 just amplifies and refines/tightens up that characteristic.

 Another thing i don't regret is using the TPA JT attenuator. 128 steps is superior to 24 steps. I cant stand the DACT unit, as nice as it is, in my apache. It doesnt have enough settings.


----------



## m11a1

Quick question: I'm planning to building a 6-channel B22, what's available as for the attenuator?


----------



## johnwmclean

Quote:


  Originally Posted by *m11a1* /img/forum/go_quote.gif 
_Quick question: I'm planning to building a 6-channel B22, what's available as for the attenuator?_

 

m11a1, a 4 channel attenuator should do the trick


----------



## m11a1

Quote:


  Originally Posted by *johnwmclean* /img/forum/go_quote.gif 
_m11a1, a 4 channel attenuator should do the trick 
	

	
	
		
		

		
		
	


	


_

 

Much Obliged, John 
	

	
	
		
		

		
		
	


	




 One more question though, my intended custom volume knob is roughly 2 inches in diameter and of 2 inches in depth, which potentiometer is suitable for this kind of knob?


----------



## nattonrice

You should start by measuring the shaft size of the knob otherwise we can't help you.


----------



## m11a1

Quote:


  Originally Posted by *nattonrice* /img/forum/go_quote.gif 
_You should start by measuring the shaft size of the knob otherwise we can't help you._

 

It's custom like I just said. The diameter of the shaft is customizable. I just need to find the right potentiometer that can handle that big of a knob.


----------



## MrMajestic2

Quote:


  Originally Posted by *m11a1* /img/forum/go_quote.gif 
_It's custom like I just said. The diameter of the shaft is customizable. I just need to find the right potentiometer that can handle that big of a knob._

 

Most attenuators have a 6mm shaft and most will have no problem accommodating your large knob. Man, that last part sounded so wrong


----------



## nattonrice

Oh right. The way you said it I thought you already had it made.

 Anything would be fine and (as above) most have a 6mm shaft.
 Only thing to keep in mind is that on stepped attenuators (like the dact) the steps will feel softer/looser with larger knobs.


----------



## LeMat

I've spent sometime this week end listening to my bare B22... still an incredible sound, especially with the HF2. 
 But one thing I noticed is its ability to play the radio antenna... Many told me to be careful with EMI while I was building it but it's freakin true. 
 I can create hum noise only by approaching my hand to the input wire (from pot to board)... is it normal to be that sensible ?? 
 Even without playing with the input cable, I always have a slight background noise. (FYI the PSU is shielded)
 RCA inputs to pot is wired with a shielded cable so I don't have this problem. 
 I really hope the problem will be solved once I'll use an enclosure.
 Do you guys use shielded wires throughout your build ?


----------



## amb

Yes, a proper enclosure should fix this problem. You should make sure your pot's body is making contact with the case metal. This is all shown in the β22 website "Wiring & ground" section.


----------



## Anonanimal

LeMat- I did use shielded wire on the input side on my build, but not the output. Though I did not do much listening before I cased it up, I have not had an issue with this type of noise. As amb mentioned, the enclosure should help you out quite a bit.


----------



## LeMat

Thanks for your answers
 My pot's body is already connected to the signal ground but I have some remaining noise. 
 We'll see how when everything will be cased up. Worse case, I'll swap to shielded cable and add mu-metal sheet. Nothing too tricky here. 
 I should order cases this week. Can't wait because I know what to expect...pure sound !


----------



## fishski13

Quote:


  Originally Posted by *LeMat* /img/forum/go_quote.gif 
_Thanks for your answers
 My pot's body is already connected to the signal ground but I have some remaining noise. 
 We'll see how when everything will be cased up. Worse case, I'll swap to shielded cable and add mu-metal sheet. Nothing too tricky here. 
 I should order cases this week. Can't wait because I know what to expect...pure sound !_

 

if it's any reassurance, i used mostly wood for my 2 chassis, and other than the TX, didn't shield any wiring. it's dead quiet. please post pics when finished!


----------



## MrMajestic2

Quote:


  Originally Posted by *MrMajestic2* 
_Ok guys, I need some pointers in the right direction. I have a B22 board that measures 4.5V on R9, but around 3.5V on R10, R11 and R12. Any ideas where I should start looking? Everything looks like its soldered into the right place._

 

 Quote:


  Originally Posted by *amb* /img/forum/go_quote.gif 
_A bad JFET in the Q1-Q4 quad? This should not have anything to do with the CRDs._

 

Ok, I swapped out the quads, but the problem is still the same. R9 = 4.5V and R10, R11 and R12 are ~3.5V. R34 is still ~100mV at VR2s minimum position. Should I try changing the Mosfets?


----------



## amb

MrMajestic2, before randomly replacing MOSFETs, you should first check the parts that are closer to the problem area. Use the BJT sanity check tutorial I posted to test your BC550C and BC560C transistors first. Also check to make sure all the 12V zeners are not shorted, and actually have about 12V across them while powered up.


----------



## MrMajestic2

Quote:


  Originally Posted by *amb* /img/forum/go_quote.gif 
_MrMajestic2, before randomly replacing MOSFETs, you should first check the parts that are closer to the problem area. Use the BJT sanity check tutorial I posted to test your BC550C and BC560C transistors first. Also check to make sure all the 12V zeners are not shorted, and actually have about 12V across them while powered up._

 


 The BC550 and BC560s seem to pass the test. Compared to a working board they measure the same when doing the "sanity check". The zeners also measure the same as on a working board.

 I'm a little concerned that the R34 measures very high even when VR2 is on the lowest position. That's why I wanted to try to swap out the Mosfets.


----------



## amb

MrMajestic2, also make sure all trimpots are the correct values, and oriented properly. If you populated a wrong value VR2 trimpot it could cause excessive output quiescent current.

 Measure the MOSFETs for shorts if you suspect they are bad. Also, make sure you didn't install the wrong MOSFETs -- Q21/Q23 = IRFZ24N, Q22/Q24 = IRF9Z34N. Pay attention that you didn't put an IR_*L*_Z24N in place of the IRFZ24N.


----------



## MrMajestic2

Quote:


  Originally Posted by *amb* /img/forum/go_quote.gif 
_Pay attention that you didn't put an IR*L*Z24N in place of the IRFZ24N._

 

If I did, I'll be sure to visit Mr. Rossel and insert a faulty B22 board up his rear end 
	

	
	
		
		

		
			





 Could faulty Mosfets result in the wrong voltage across R10, R11 and R12?


----------



## amb

Quote:


  Originally Posted by *MrMajestic2* /img/forum/go_quote.gif 
_Could faulty Mosfets result in the wrong voltage across R10, R11 and R12?_

 

Possibly, but a misadjusted DC offset could also do it, as is a number of other things. This amp's topology is such that everything "hangs in balance" when everything is working properly. One thing wrong and it could set everything askew.


----------



## MrMajestic2

Quote:


  Originally Posted by *amb* /img/forum/go_quote.gif 
_MrMajestic2, also make sure all trimpots are the correct values, and oriented properly. If you populated a wrong value VR2 trimpot it could cause excessive output quiescent current.

 Measure the MOSFETs for shorts if you suspect they are bad. Also, make sure you didn't install the wrong MOSFETs -- Q21/Q23 = IRFZ24N, Q22/Q24 = IRF9Z34N. Pay attention that you didn't put an IR*L*Z24N in place of the IRFZ24N._

 

All VRs are the correct value and oriented correctly. I swapped out Q22 after I measured it. R34 measures around ~80mV lowest as opposed to ~100mV before. The R10-R12 measurement remains the same though.


----------



## MrMajestic2

Quote:


  Originally Posted by *MrMajestic2* /img/forum/go_quote.gif 
_R9 adjusting to around 4.5V at the maximum range of VR1 and then dropping past 4 volts and downwards. R34 is measuring zero 
	

	
	
		
		

		
		
	


	


_

 

Solved this one. C10 was mounted incorrectly. I still have the other board to fix though.


----------



## TheShaman

Would you guys say that a 3-channel (active ground) B22 would be better than a dual mono 2-channel version (= featuring two Sigma22s and separate transformers)?

 I'm thinking that some of the benefits attributed to active ground (channel separation / crosstalk related) are often associated with going dual-mono as well. Plus, the latter solution, although more expensive, offers a cleaner upgrade path to a dual-mono balanced B22 when budget allows.


----------



## oneplustwo

Quote:


  Originally Posted by *TheShaman* /img/forum/go_quote.gif 
_Would you guys say that a 3-channel (active ground) B22 would be better than a dual mono 2-channel version (= featuring two Sigma22s and separate transformers)?

 I'm thinking that some of the benefits attributed to active ground (channel separation / crosstalk related) are often associated with going dual-mono as well. Plus, the latter solution, although more expensive, offers a cleaner upgrade path to a dual-mono balanced B22 when budget allows. 
	

	
	
		
		

		
		
	


	


_

 

If you were going to go balanced eventually, then the 2 channel is the way to go. I would probably not bother with going dual mono... just save room in the enclosure and in your umbilical for a second sigma if you do go balanced later. That being said, my personal opinion is that the three channel is really very good and now that I've built all three configurations, I believe that the gap from the three to the four channel is much less than the gap from the two to the three channel. Just my own opinion. No data to back it up. And keep in mind, the two channel in itself is already good. So we're talking about a pretty small "gap" in absolute terms.

 I would probably build the three channel now with room for an extra board and an extra PSU. Changing the active ground channel to a "normal" board isn't that difficult. The bigger issue you may have is what gain to choose.


----------



## TheShaman

Thanks for the input!
 My headphone rig only has SE sources atm and I haven't recabled my AKGs.
 I won't go balanced until I upgrade my Buffalo 32S DAC (perhaps with the newer version) and move it from my main rig to my headphone rig.


----------



## MrMajestic2

Since I needed a break from troubleshooting the B22 board I've been writing about I started on another set of boards needing repairs. These two had been shorted using an XLR to RCA adapter by the user. So, R34 and R35 were smoked, even giving an imprint in the soldermask 
	

	
	
		
		

		
		
	


	




 So I swapped those out and the MOSFETs. Both boards lights up and one of them tests correctly. Th other one however is a different story. R9 and her mates give me 0V. SO poking around with the multimeter on the diodes first I came across a weird phenomenon. When doing a diode test on D11 the LED lights up, hmm. And of course, it doesn't pass the diode test. CR7 gives me 0.35V which on the working board is around 0.54V. So, could this be why I get 0V on R9? By the way, these boards where fully functional before the short circuit, so all components are mounted correctly.


----------



## amb

MrMajestic2, your Q25 is probably blown. That would definitely cause the R9 measurement to fail.


----------



## MrMajestic2

Quote:


  Originally Posted by *amb* /img/forum/go_quote.gif 
_MrMajestic2, your Q25 is probably blown. That would definitely cause the R9 measurement to fail._

 

Right on the money, thanks 
	

	
	
		
		

		
		
	


	




 Board is up and running. Tomorrow, back to the board that god forgot


----------



## K3cT

OK, this question is primarily addressed to builders not located in the US. 

 Where do you guys usually source your transformers for Sigma22 since they are not easily available at the big 4? I'm looking for a 220V, 80VA, +/- 30V specifically and the closest match I can find is this BLOCK transformer at Farnell #1419561 but it's at 100VA... Anyone have any experience using that brand before? 

 I've also been exchanging E-mails with Mr. Summer of SumR but the international shipping cost from Canada is quite staggering.


----------



## UKToecutter

try Power Transformers and Power Converters From Avel Lindberg 2002 Ltd.


----------



## UKToecutter

Incidently.
 They have a minimum order value of £30 so it's more economical to buy 3 of at £11.20 each +VAT +Del.
 I don't know where you are, so I have no idea how much delivery will be to you.

 Andy


----------



## johnwmclean

K3cT, Richard’s transformers are still relatively cheap, if it was not for the shipping cost.
 I have two spare Avel Lindbergs (Y23605’s 100VA +/30V)... Let me know!

 Edit: shoot me a pm...


----------



## johnwmclean

OOps


----------



## K3cT

@UKToecutter 
 I'm located straight in the heart of Asia in Jakarta, Indonesia. Thanks for the site, I'm going to ask whether they ship internationally or not. 
	

	
	
		
		

		
			





 @johnwmclean
 You've got a PM. Thanks for your help also, John.


----------



## kunalraiker

Quote:


  Originally Posted by *fault151* /img/forum/go_quote.gif 
_Hi guys, I finally got round to taking some pics of my B22 amp. It has taken me over a year to get to this point and I thought i'd share my hard work with you all. First of all, a *[size=x-large]MASSIVE[/size]* thank you to everyone who has helped me with this project especially, Ti (AMB LAbs), MR Majestic, and johnwmclean. I would not have been able to do it without your help and patience! 
	

	
	
		
		

		
		
	


	




 The amp sounds bloody amazing, really happy with it. Its safe to say its not the easiest amp I have ever built, there is a lot that can go wrong (and did go wrong!) but got there in the end. I will be adding some more pics for those interested on the post pics thread (I didn't want to clutter this thread too much). 





























_

 

That is one nice amp, such neat work mate
	

	
	
		
		

		
		
	


	




,i'am stunned with the way you've done it.
 what did it cost you, also who designed your case.


----------



## fault151

Hi, thanks for the nice comments. I designed the panels and had them made at FPE. The chassis was from HIFI 2000.

 I'm not sure exactly how much it all cost me, but i can tell you it wasn't cheap! I tried to build the best i could.


----------



## LeMat

IMPRESSIVE work here !!! Congrats

 Quick question on the e24 power switch circuit. 
 I finished mine but something is bugging me. I have to keep the button pressed for nearly 2sec then release to power on the amp. 
 On the other side, to power it off, it's immediate.
 Any idea on how I can make it more responsive ?

 Thanks !


----------



## cAsE sEnSiTiVe

Fault...

 That is one gorgeous β22. Congrats on the build!


----------



## Iniamyen

Fault151, as if my build didn't already look like crap, you had to add salt to the wound 
	

	
	
		
		

		
		
	


	




 Definitely one of the sexiest builds out there...


----------



## amb

Quote:


  Originally Posted by *LeMat* /img/forum/go_quote.gif 
_Quick question on the e24 power switch circuit. 
 I finished mine but something is bugging me. I have to keep the button pressed for nearly 2sec then release to power on the amp. 
 On the other side, to power it off, it's immediate.
 Any idea on how I can make it more responsive ?_

 

It shouldn't behave that way... Did you use the correct value Rs and Cs?


----------



## johnwmclean

Just thought I’d check this out before disaster... 
 With a dual σ22 psu can I connect both the ground outputs together to form part of a star ground scheme within another chassis?


----------



## aloksatoor

Would that be really an isolated dual mono supply then? I think not though I might be wrong


----------



## johnwmclean

Well no aloksatoor it won’t a “pure” dual mono in the true sense of the meaning. But I need to wire *two* σ22’s to a single star ground scheme.
 Here is a schematic I’m following for reference.


----------



## amb

johnwmclean, the diagram above shows only one σ22, but if you are building a variation that uses two σ22s (one per two amp boards), then yes, you can connect their respective G pads to a common star ground point (see my β24 PSU wiring scheme below as an example). My diagram shows the G on the "input" side of the σ22s being used for star-grounding, but you could do it on the "output side" just as well. They are all connected to the board's ground plane.

 The V+ and V- outputs from the two σ22s cannot be tied together, but I hope that's obvious.


----------



## johnwmclean

Thanks AMB, that is what I assumed - glad to get confirmation. I knew connecting the -V and +V outputs from two supplies = fireworks.


----------



## LeMat

Quote:


  Originally Posted by *amb* /img/forum/go_quote.gif 
_It shouldn't behave that way... Did you use the correct value Rs and Cs?_

 

Yes, I followed carefully the instruction.
 The only variation is the s24 which output is 17.3v instead of 12v (due to stronger line voltage)
 I also omitted K1, Q1, D2 and R4 since I didn't use the thermal probe.


----------



## amb

LeMat, check the values of R1, R2, R5, R6 and C3. Measure the resistors with your DMM, and read what the marking on the capacitor says.

 Even if the label on the Digi-key or Mouser baggie says what you think it should be, they may have packed the wrong part in it.


----------



## LeMat

Quote:


  Originally Posted by *amb* /img/forum/go_quote.gif 
_LeMat, check the values of R1, R2, R5, R6 and C3. Measure the resistors with your DMM, and read what the marking on the capacitor says.

 Even if the label on the Digi-key or Mouser baggie says what you think it should be, they may have packed the wrong part in it._

 

Sounds like a wise advice... I agree there should be a component with the wrong value somewhere in this circuit. 
 Thanks


----------



## LeMat

So, here are the possible variations :
 - C2 = 17.1 uf... almost twice more than recommended
 - R3 is not a miniature resistor but has a the right value (DMM read 2.162 k) and wattage rating. 

 Values you requested are ;
 R1= 469.9 k
 R2= 2.205 M
 R5= 327.3 k
 R6= 9.93 k
 C3= 337 uf


----------



## amb

LeMat, hopefully your C3 isn't really 337uF. It should be 0.33uF.


----------



## LeMat

Quote:


  Originally Posted by *amb* /img/forum/go_quote.gif 
_LeMat, hopefully your C3 isn't really 337uF. It should be 0.33uF. 
	

	
	
		
		

		
		
	


	


_

 

Ooops I made a typo, my mistake 
	

	
	
		
		

		
		
	


	




 C3 is 337nf hence 0.33uf.


----------



## amb

Ok, did you measure the capacitance?  Or was that from a marking on the cap?


----------



## LeMat

Quote: 





amb said:


> Ok, did you measure the capacitance?  Or was that from a marking on the cap?


 

 Everything I mentionned was measured with my DMM.
  Couln't it be C2 since it's the only value to be "off" ?
  tx


----------



## amb

Quote: 





lemat said:


> Everything I mentionned was measured with my DMM.
> Couln't it be C2 since it's the only value to be "off" ?
> tx


 

 C2 is a power supply rail decoupling cap and its capacitance is not critical.
  Given what you've reported so far I don't know why it's behaving like it does.  Are the transistors and MOSFET what's listed in the parts list?


----------



## LeMat

Quote: 





amb said:


> C2 is a power supply rail decoupling cap and its capacitance is not critical.
> Given what you've reported so far I don't know why it's behaving like it does.  Are the transistors and MOSFET what's listed in the parts list?


 

 I didn't double check but I see no reason why I would have used something different. Picking the wrong piece is not really probable since I ordered only what I needed (hence not re-using spare component I may have).
  Thinking about the behavior, it's like something is slowing down the capacitor charging. Since I have to keep the button pressed for a longer time, it means something takes more time to be charged up.
  I have a couple of things to order at mouser so I'll order some extra components to swap with the one I used in this circuit and we will see... maybe one is faulty (even though the value is ok).
   
  Speaking of order, any idea where I could get nice feet for my build ? Flat cylinder.. I've only found very cheap rubber feet or overpriced spilke... 
  An example : http://www.musicdirect.com/products/images.php?i=-1&p=73991&h=86554
   
  Thanks for all !


----------



## JamesL

Quote: 





lemat said:


> Speaking of order, any idea where I could get nice feet for my build ? Flat cylinder.. I've only found very cheap rubber feet or overpriced spilke...
> An example : http://www.musicdirect.com/products/images.php?i=-1&p=73991&h=86554


 

 A few PC-mod stores carry those type of feet..
for example
  I know I've seen them around other places as well but can't seem to find them


----------



## LeMat

Quote: 





jamesl said:


> A few PC-mod stores carry those type of feet..
> for example
> I know I've seen them around other places as well but can't seem to find them


 
   
  I never think to Pc-mod shops.... but it makes sense ! 
  Your example is bang on what I'm looking for.

 Thanks !


----------



## ekano

I'm about to build a 4-channel B22 with the o22 power supply, and I have a question..
   
  What fuse should I use in the Sigma? I'll be using a 100VA transformer and the mains voltage here in Sweden is 230 VAC.


----------



## LeMat

Quote: 





ekano said:


> I'm about to build a 4-channel B22 with the o22 power supply, and I have a question..
> 
> What fuse should I use in the Sigma? I'll be using a 100VA transformer and the mains voltage here in Sweden is 230 VAC.


 

 Someone correct me if I'm wrong but it should be a : 3A slow blow fuse


----------



## ekano

Quote: 





lemat said:


> Someone correct me if I'm wrong but it should be a : 3A slow blow fuse


 
  Thank you!


----------



## amb

For 230VAC mains you should use 1/2 the fuse rating as you would for 115VAC.  If you are using a single 100VA transformer, I would use a 1A slow blow.


----------



## Nada

Quote: 





fault151 said:


> Hi guys, I finally got round to taking some pics of my B22 amp. It has taken me over a year to get to this point and I thought i'd share my hard work with you all. First of all, a *[size=x-large]MASSIVE[/size]* thank you to everyone who has helped me with this project especially, Ti (AMB LAbs), MR Majestic, and johnwmclean. I would not have been able to do it without your help and patience!
> 
> 
> 
> ...


 






 wow, thats art


----------



## alamakazam

where can I purchase a backpane?


----------



## MisterX

The for sale section maybe?


----------



## Lil' Knight

Quote: 





alamakazam said:


> where can I purchase a backpane?


 

 You might want to take a look at the group buy at amb's forum.


----------



## alamakazam

Quote: 





lil' knight said:


> You might want to take a look at the group buy at amb's forum.


 

 cool thanks dude
   
  for the rest
   
  http://www.amb.org/forum/group-buys-f29/interest-check-epsilon22-backplane-board-for-3-channel-beta22-t114.html?sid=c6a925623e2bbfd1f095774a50048757


----------



## MrMajestic2

Ok, so now I have more problems with my build  I got a new fourth board in working order, it measures correctly, but it the heatsinks get so hot Im afraid to run it for any longer than a minute. None of my other boards get remotely hot with 56mV, but the fourth is burning. I havent dared plugging anything it yet to listen to it. Any ideas why this board is hot and not the others?


----------



## amb

The heat dissipation is simply the quiescent current through the MOSFET multiplied by the voltage across it.  Since the voltage is fixed, then that leaves only the current that's the sole factor.  Simple Ohm's Law.  If you set the quiescent current the same as the other boards, then it should produce the same amount of heat.
   
  Now, that assumes a well-behaved amp that's quiet at idle so the quiescent current is all DC.  It doesn't take into any account possible oscillations or noise.  Do you have the inputs shorted when doing the initial setup?  Do you have the correct value capacitors for C1-C5, and are they all mounted in the correct holes?


----------



## MrMajestic2

Quote: 





amb said:


> The heat dissipation is simply the quiescent current through the MOSFET multiplied by the voltage across it.  Since the voltage is fixed, then that leaves only the current that's the sole factor.  Simple Ohm's Law.  If you set the quiescent current the same as the other boards, then it should produce the same amount of heat.
> 
> Now, that assumes a well-behaved amp that's quiet at idle so the quiescent current is all DC.  It doesn't take into any account possible oscillations or noise.  Do you have the inputs shorted when doing the initial setup?  Do you have the correct value capacitors for C1-C5, and are they all mounted in the correct holes?


 

 Inputs are shorted and C1-C5 looks correct. I will reflow and check again.


----------



## CafeNoir

Hi,
   
  I have a small issue with my one-chassis 3-channel B22 that I can't figure out: It doesn't seem to have optimally low crosstalk.
   
  I have made two experiments:
   
  1) I disconnected one rca input  (let us say left) from the cd player, and disconnected the opposite output at the end connection of my HD-650 (where the headphone cable is connected to the cans), therefore the only sound I hear is theoretically crosstalk in the remaining channel. The result of this is I hear music playing at a low level, but subjectively at least three times louder than my reference SPL Auditor (ruling my aftermarket headphone cable inherent crosstalk out of the equation).
  The importance of crosstalk increases when the volume is set higher. I would roughly say it is around -70dB.
   
  2) Believing the most obvious source of crosstalk would be proximity of right and left input/output wires, I remade the wiring to place them resonably remote from each other. But it didn't change the situation.
  Second possible source of crosstalk: the stepped attenuator. For this, I disconnected the left output wire of the attenuator - therefore the input pad of the left board is connected to nothing. The result: still the same amount of crosstalk, plus additional noise ("free air" noise from the disconnected wire?) at high volume level.
   
  So now I am a bit puzzled. The only remaining causes of crosstalk are logically contamination between the boards themselves (unlikely) and contamination of the signal ground wiring ( input and ground wires are supended above the heatsinks, touching them lightly, could it be it?). The output wires to the jack are below the boards and resonably remote from one another, so I don't think they are in cause. So would you have any suggestion? Is there another source of crosstalk I have not been thinking about?
   
  Sorry for the long post, but I love my Beta so much I want it to be perfect.


----------



## amb

Cafenoir, your method of testing for crosstalk is questionable.  If you simply unplug one channel's input and let it float, it will act as an antenna and pick up noise/crosstalk from the other channel.  This is not a realistic use situation.  In real life, each channel's input would be driven from a low-impedance source (rather than float).


----------



## cfcubed

On the subject of crosstalk, but not directly relating the last 2 posts, I've been learning the +s & -s of using shielded cabling for low-/line-level inputs.  Perhaps better for another thread & matter more for builds w/PS in same enclosure as amp.
   
  In builds like those in my sig using shielded input cabling _seems _to have quieted down/made the background "blacker".  But, not surprisingly, using multiconductor shielded cable allowed crosstalk amongst the conductors.  So going forward I'll be leaning toward single conductor shielded cable for this application FWIW.


----------



## fault151

Quote: 





nada said:


> wow, thats art


 
   
   
  Thanks :0) glad you like it. Took me long enough to build!!!


----------



## yuk228

del


----------



## Blasto_Brandino

*looks at fault151's amp* 
 I have so much learning to do, it isn't even funny, 
 Anyway I'm interested in building a 3 channel, but I'm going to have to do some learning first, now other then the tech school classes I'm going to take, does anyone have a good starter amp or project they suggest?


----------



## chum_2000_uk

Quote: 





blasto_brandino said:


> *looks at fault151's amp*
> I have so much learning to do, it isn't even funny,
> Anyway I'm interested in building a 3 channel, but I'm going to have to do some learning first, now other then the tech school classes I'm going to take, does anyone have a good starter amp or project they suggest?


 
   
  Yep. A year ago I had never even used a soldering iron. Started an EE course as I fancied a change in direction career wise. Obviously I've done a bit of soldering and theory in the course, but I have found I have learnt the most by building amps. There is a lot of people who can help here, and plenty of other sources online too. I started by practicing my soldering skills with a bit of empty radioshack board and cheapo resistors. Then I went and ordered the stuff to build a little CMOY. You learn so much by building a CMOY, particularly if you use a mint tin - you not only learn soldering and basic circuit stuff but also a bit of casework too. Plus if it doesn't work right away, you will learn some fault finding too. I'd suggest if your first attempt doesn't go according to plan, try again until it does - particularly making it neat case wise, e.g. nice clean drill holes for the jacks and volume pot. Obviously you want the thing to work as well, but I wouldn't pay _too_ much attention to how neat the soldering is - CMOYs do tend to look a bit untidy underneath imo due to the board that people tend to use (radioshack multipurpose PC board generally). Your soldering will become neater with subsequent builds, and I found soldering PCBs so much easier to keep neat than the r-shack PC board. Just always visually inspect very closely to ensure you haven't got any solder bridges, or possibly bad solder joints and you'll be fine. The best advice I can think of is TAKE YOUR TIME. Ignore people who say they can make a CMOY or whatever in X amount of hours from start to finish. I'd rather spend a few days, or however long it takes to do it slow and methodically so that it works first time than spend ages pulling my hair out and asking people for help when I can't figure out why it's not working.
   
  After I built a CMOY, I built a fully modded Jaycar. As fault151 and many others will no doubt tell you, this is a seriously good little single ended amp. Mine is very similar to fault's, apart from the fact I used an Audio-GD PSU rather than a Jaycar one. Fault151 did give me some help and advice on some of it, along with some of the other guys on here who are very knowledgeable about them - in particular Sennsay, who I have become good friends with. He helped me enormously, particularly because I had decided I wanted to make a fully modded one right off the bat, rather than fussing around making a standard one and then adding to it. He has built three of them in total I believe! I'm listening to the amp right now, and it sounds wonderful! My HD650's have never sounded better.
   
  When building the Jaycar, I learnt so much about how to solder neatly and compactly. I also learnt a lot about various other aspects, but I am no means any authority about how the circuit actually works. Some background about how and why components work in the circuit does help here and there though, but you tend to pick that up as you read about the assembly etc. The great thing about the Jaycar is that it comes with full instructions on assembly anyway, and that in combination with the tons of info from members here and at the rock grotto forums, it's a suitably challenging but ultimately do-able build. I enjoyed it immensely, from start to finish, and apart from a few small hiccups (silly little mistakes on my part) the amp worked first time. Again this is probably due to the fact that I really took my time over it, and checked and re-checked everything over and over, especially when wiring the power supply to the amp board.
   
  I was quite lucky with drilling the front and back panels of my case, the college I'm doing my EE course at has lots of industrial equipment like pillar drills and so on. So I got that done there. In future though I think there is a good chance I will send my panels to somewhere like Front Panel Express as they will do a much more professional job, for example at college I wasn't able to recess the volume knob, and the panels did get ever so slightly scratched. Overall I am delighted with the way the amp turned out!


----------



## LeMat

Very simple question which may be useful for the other beginners out there. How do you fix the pcb onto the bottom plate of an enclosure ? I guess it's screwed but I made a test with male-female spaceoff on a spare piece of aluminium I had and it seems the hole need to be threaded. How do you do that ?
  Otherwise, I guess I can make a hole and use a screw with a female spaceoff.
  As you can see, I'm really reaching the end of my project 
  tx


----------



## El_Doug

the easiest method is to just spread huge quantities of hot glue all over the bottom of the enclosure, and then quickly put the PCBs in place before the glue cools
   
  alternatively, a tap can be used to thread the holes once youve drilled them   then you can put in the spacers with ease


----------



## m_Lowry

Just use a threaded hex standoff. Mouser stocks these.
   
  http://www.keyelco.com/pdfs/M55p63.pdf


----------



## LeMat

Quote: 





m_lowry said:


> Just use a threaded hex standoff. Mouser stocks these.
> 
> http://www.keyelco.com/pdfs/M55p63.pdf


 

 I know, I just didn't really know how to screw these standoff into an aluminium panel. If the hole is not threaded, it ends up very loose. I guess I'll have to find one of these tap bit.


----------



## ShinyFalcon

How about lock washers? I ordered some that comes with the 4880-SG heatsink isolating kits (they can be ordered separate, I don't remember their number), and I'm thinking they'll work fine, preventing the screws from loosening over time.


----------



## Medel

Quote:


lemat said:


> I know, I just didn't really know how to screw these standoff into an aluminium panel. If the hole is not threaded, it ends up very loose. I guess I'll have to find one of these tap bit.


   
  You make a clean hole through the aluminum. A screw goes from one side of the panel, through the hole, and into the standoff. Should be able to crank it down pretty hard since it's steel/brass on the standoff and screw and an aluminum panel. If you're worried about it being loose you can locktite or lock washer it. (If you need something fast to try, there's always http://www.radioshack.com/product/index.jsp?productId=2102848 )


----------



## n_maher

Quote: 





el_doug said:


> the easiest method is to just spread huge quantities of hot glue all over the bottom of the enclosure, and then quickly put the PCBs in place before the glue cools


 

 This is some of the worst advice I've seen on this forum, ever.
   
  I use standoffs and loctite everything.


----------



## wquiles

+1
   
  Specially considering the item being built is a high quality audio amplifier.
  
  Quote: 





n_maher said:


> This is some of the worst advice I've seen on this forum, ever.


----------



## El_Doug

I sure hope no one took it seriously!!! 
  
  Quote: 





n_maher said:


> This is some of the worst advice I've seen on this forum, ever.
> 
> I use standoffs and loctite everything.


----------



## johnwmclean

Quote: 





el_doug said:


> I sure hope no one took it seriously!!!


----------



## yossi126

In a few weeks I'll be buying an active ground and boards from Glass Jar. What gain will be optimal for LCD-2?


----------



## El_Doug

Though I have not used an LCD-2 via a 3-channel B22, I'd imagine a gain of 5 should be more than sufficient - you could probably get away with a gain of 2 with ease (thats the way i'd go)
  
  Quote: 





yossi126 said:


> In a few weeks I'll be buying an active ground and boards from Glass Jar. What gain will be optimal for LCD-2?


----------



## yossi126

Thanks


----------



## chronomitch

Hi guys.
   
  I have been planning a Beta22 build for some time now. I started researching the project about four months ago and have been slowly amassing the required knowledge and parts for the build. As I still need to finish a few other non-electronic projects first, it will still probably be a few more months before I actually start building a Beta22. However, I have a few questions in the meantime.
   
  My plan for casing is to use one or two of these: http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=370262841221. It is basically a Par Metal 20-16124.
   
  If I use only one case, I know I will require a shielded transformer to prevent RF interference from messing with the audio circuits. As I understand it, the use of a ground loop breaker will prevent the AC power ground and the signal ground from mixing. Still, will this one-boxed setup have any effect on audio quality? I know a two-boxed setup is heavily recommended, but I would rather like to go for a more compact, single case setup. In other words, given the necessary precautions (shielded transformer and ground loop breaker), will there be any difference in audio quality between a one-boxed setup and a two-boxed setup?
   
  Secondly, if I decide to go with a two-box setup, would it still be a good idea to use a shielded transformer? The reason I ask is that these cases are made out of aluminum, and I am under the impression that aluminum serves as a far poorer RF shield than steel does. Keep in mind that I will be stacking these boxes one on top of another.


----------



## johnwmclean

[size=medium][size=13.0px]I haven’t heard or read about any kind of audio degradation from a one box build, only the inherent issues you’ve pointed out.
 I use two par metal cases stacked, the psu has 2 unshielded 50VA transformers and I’ve had no noise, hum or RF issues, but of course there’s no insurance.
 If it was me I’d put the transformer in a small box away from the amp and psu, that way you could still have the convenience of one box on display and the transformer tucked away out of sight.[/size][/size]


----------



## chronomitch

johnwmclean said:


> [size=medium]I haven’t heard or read about any kind of audio degradation from a one box build, only the inherent issues you’ve pointed out.
> I use two par metal cases stacked, the psu has 2 unshielded 50VA transformers and I’ve had no noise, hum or RF issues, but of course there’s no insurance.
> If it was me I’d put the transformer in a small box away from the amp and psu, that way you could still have the convenience of one box on display and the transformer tucked away out of sight.[/size]


 
   
  Thanks for the info. I have considered the small transformer box option, but I want to have some uniformity in the casing and use a nice power switch (epsilon 24 & Bulgin switch), so I'm either going to use a single box for everything or one box for the transformer, sigma 22, and power switch circuitry and another box for the beta 22 boards.


----------



## johnwmclean

In that case, if your chassis is aluminum then yes it’s definitely a good idea to use a shielded transformer in a two box build.


----------



## mgrewe

I have been told that I will need about 20 feet of 18 awg wire for the power runs and about 20 feet of 22 awg wire for everything else.  Will this change now that I am using an epsilon 22 backplate?
   
  By the way I am housing only my transformer in a separate chassis and my omega 22 board and three beta 22 boards are in a separate chassis.
   
  Thanks


----------



## johnwmclean

[size=12.0px]mgrewe, look at option 2 on AMB’s website under wiring and ground.

 20 foot will be over considering your using an ε22 backplane board which saves internal wiring, you could use the remainder for another project?

 omega 22? I think you need do a little reading. Good Luck. [/size]


----------



## dude_500

I recently built an enclosure for my beta-22 so I wanted to verify adjustments to make sure my output stage current wasn't so high that anything would burn up since it seemed to be running pretty hot in there. I got to checking the DC offset on my meter and the meter reads somewhere between 250V and meter-out-of-range (1kv). Obviously this can't be accurate, must be some sort of oscillations fooling the meter? The volume knob is zeroed so the inputs are grounded. Any thought what is going on? I don't have access to a scope at the moment so I can't just use that to set the dc offset. This is a nice Velleman meter, not sure why it's acting up in this manner.


----------



## amb

Quote: 





dude_500 said:


> I recently built an enclosure for my beta-22 so I wanted to verify adjustments to make sure my output stage current wasn't so high that anything would burn up since it seemed to be running pretty hot in there. I got to checking the DC offset on my meter and the meter reads somewhere between 250V and meter-out-of-range (1kv). Obviously this can't be accurate, must be some sort of oscillations fooling the meter? The volume knob is zeroed so the inputs are grounded. Any thought what is going on? I don't have access to a scope at the moment so I can't just use that to set the dc offset. This is a nice Velleman meter, not sure why it's acting up in this manner.


 
  Clearly that's not possible as there is not that much voltage in the amp.  Is that supposed to be mV instead of V?
  You can sanity-check your meter by measuring a battery.


----------



## dude_500

Agreed it's not possible... just checked, the meter is in auto-scaling mode, tested it on the main rails and it reads +-28V properly, then in that same mode hook it up to either channel's output and it reads >1kv with overload signal.


----------



## amb

Quote: 





dude_500 said:


> Agreed it's not possible... just checked, the meter is in auto-scaling mode, tested it on the main rails and it reads +-28V properly, then in that same mode hook it up to either channel's output and it reads >1kv with overload signal.


 

 Does it do that on all channels?  Or only on one of the boards?  Maybe there is indeed an oscillation that's confusing the meter.


----------



## chronomitch

I have two Goldpoint stepped attenuators that I am planning to wire in series for my beta22 volume control. They are rated as 10k, so I'm guessing doing this will result in an overall 20k resistance. This should still be fine, right?
   
  I will be using the amplifier with a number of different sources, so I want to have a good amount of play in the volume control. In other words, I plan to use one control just to get the volume in a decent range and the other for fine tuning.


----------



## amb

Quote: 





chronomitch said:


> I have two Goldpoint stepped attenuators that I am planning to wire in series for my beta22 volume control. They are rated as 10k, so I'm guessing doing this will result in an overall 20k resistance. This should still be fine, right?
> 
> I will be using the amplifier with a number of different sources, so I want to have a good amount of play in the volume control. In other words, I plan to use one control just to get the volume in a decent range and the other for fine tuning.


 
  Please post a diagram of exactly how you could wire the two attenuators.  "Series connection" could be interpreted in one of two ways -- literally stacked, or cascaded (one after another).  The equivalent resistance of the combination is not the same between the two, and the adjustment range also differs.


----------



## chronomitch

They would be cascaded. In other words, the output of each channel from the first attenuator would be fed into the inputs of the second attenuator.
   
  I am building a three channel beta22, and these are stereo attenuators.


----------



## amb

Quote: 





chronomitch said:


> They would be cascaded. In other words, the output of each channel from the first attenuator would be fed into the inputs of the second attenuator.
> 
> I am building a three channel beta22, and these are stereo attenuators.


 

 OK, in this case the total resistance of the two would be 10K when the first one is in the minimum position, or 5K when both are max.  Also, the two will each have the same (large) adjustment range down to "-∞" dB


----------



## chronomitch

Quote: 





amb said:


> OK, in this case the total resistance of the two would be 10K when the first one is in the minimum position, or 5K when both are max.  Also, the two will each have the same (large) adjustment range down to "-∞" dB


 

 Thanks. I take it that when you say they will have the same (large) adjustment simply means that wiring the attenuators in this way will not make the volume steps any smaller.


----------



## dude_500

Quote: 





amb said:


> Does it do that on all channels?  Or only on one of the boards?  Maybe there is indeed an oscillation that's confusing the meter.


 

 It did it on all channels... solve the problem by putting a 100 ohm resistor between the output and ground and probing the drop across that, not sure why it mattered but it fixed it, I guess that was able to lower whatever no-load oscillations were occuring


----------



## amb

Quote: 





chronomitch said:


> Thanks. I take it that when you say they will have the same (large) adjustment simply means that wiring the attenuators in this way will not make the volume steps any smaller.


 

 When either one is at maximum setting, the other one would work like a "normal" one-attenuator setup.  But if one is set lower, then the other one has less range to "work with" so to speak.  I am not sure if that's what you have in mind, but neither one would be a "fine adjustment".
  
  Quote: 





dude_500 said:


> It did it on all channels... solve the problem by putting a 100 ohm resistor between the output and ground and probing the drop across that, not sure why it mattered but it fixed it, I guess that was able to lower whatever no-load oscillations were occuring


 

 What are you using as the output wiring from the board to the jack (or are you probing on the board itself)?  What wiring is on your meter's probe leads?  Maybe there is significant capacitance or inductance.


----------



## chronomitch

Quote: 





amb said:


> When either one is at maximum setting, the other one would work like a "normal" one-attenuator setup.  But if one is set lower, then the other one has less range to "work with" so to speak.  I am not sure if that's what you have in mind, but neither one would be a "fine adjustment".


 

 I understand. What I'm going for here is a variable pre-attenuation circuit. I thought the easiest way to do that would be to just add a second attenuator. I suppose I could simply just add in resistors as described at http://www.goldpt.com/mods.html, but I will be using several different sources which will have various output levels. In other words, I need the pre-attenuation to be variable.
   
  I have seen some interesting designs which involve mounting attenuators on the input jacks of amplifiers, but I thought I could get the same effect by putting in another attenuator in the volume control section.


----------



## amb

A diagram would be helpful here.  The cascaded pots you described is the first arrangement in the illustration below, and both pots could attenuate down to -∞ dB.
   
  I added a second, alternative configuration.  In this setup the first pot will have only up to -6dB of attenuation (assuming the same value pots), while the second one can attenuate down to -∞ dB.


----------



## chronomitch

Quote: 





amb said:


> A diagram would be helpful here.  The cascaded pots you described is the first arrangement in the illustration below, and both pots could attenuate down to -∞ dB.
> 
> I added a second, alternative configuration.  In this setup the first pot will have only up to -6dB of attenuation (assuming the same value pots), while the second one can attenuate down to -∞ dB.


 

 I'm planning on using the setup in the first illustration. The main problem I am trying to combat here is that the beginning attenuation steps of most stepped volume attenuators are too large, especially when running with a hot source. I tend to like listening to music at lower volume levels, so it is difficult for me to find a good step (it is either too soft or too loud). This problem is further complicated due to the fact that I want to use multiple sources which will run at different output levels.
   
  If I use a second attenuator, I can start it at the maximum volume level (i.e. no attenuation), and then back it down a notch or two. Since the upper steps of the attenuator are smaller, this will allow me to get to the right volume level. In other words, I will be able to attenuate the volume in smaller decibel steps.


----------



## dude_500

Quote: 





amb said:


> What are you using as the output wiring from the board to the jack (or are you probing on the board itself)?  What wiring is on your meter's probe leads?  Maybe there is significant capacitance or inductance.


 

 The hookup wire in the amp to the jack is about 8" of generic copper hookup wire, I think 18 gauge. Regardless, I'm testing it right at the board with generic multimeter probes. I've never had issues with this meter, not sure what's up with it... but regardless I got the problem solved with the 100ohm loading


----------



## amb

chronomitch, as I said, the top attenuator in the second diagram only has a 6dB range, so each "step" will have very fine adjustment.  You use the bottom attenuator to set a basic volume, then fine tune using the top one.


----------



## chronomitch

Quote: 





amb said:


> chronomitch, as I said, the top attenuator in the second diagram only has a 6dB range, so each "step" will have very fine adjustment.  You use the bottom attenuator to set a basic volume, then fine tune using the top one.


 

 Unfortunately, I doubt 6dB will be enough. My current M3 amp uses a gain of 5, and even with some Rothwell in-line RCA attenuators (-6dB), I usually don't move the stepped attenuator much past 9 o'clock.


----------



## Beefy

Quote: 





chronomitch said:


> I have two Goldpoint stepped attenuators that I am planning to wire in series for my beta22 volume control. They are rated as 10k, so I'm guessing doing this will result in an overall 20k resistance. This should still be fine, right?
> 
> I will be using the amplifier with a number of different sources, so I want to have a good amount of play in the volume control. In other words, I plan to use one control just to get the volume in a decent range and the other for fine tuning.


 


 A possible alternative......
   
  Set up the attenuators as per AMB's second picture, with both attenuators in series. But instead of two 10k models, use a 50k as the first attenuator and a 5k or 10k as the second. With a 5k as the second attenuator you can get ~21dB of range from the first attenuator, with a 10k you could get ~15dB.


----------



## digger945

why not just use the first attenuator as a 2 wire shunt. That would give you the ability to kill as much signal as you like, with no added resistance directly between input and the second attenuator. I'm sure some of them would overlap, but that's 529 possible combinations(ignoring the zero positions)


----------



## Beefy

I can imagine that it would get confusing trying to use it that way. If you have two set up such that the first in series is fine control, and the second is coarse, it is much easier to understand how to get a good level.


----------



## chronomitch

Ok. I'm pretty confused by this point, so I'm taking AMB's suggestion and providing some pictures. Please note that I only have two GoldPoint attenuators, and they are both 10k.
   
  This is a diagram of the inputs/outputs of the attenuators and the epsilon 22 board with no wiring. Only one channel (right) is shown.

   
  This next picture shows how I am planning to wire the attenuators. As I understand it, this should allow both attenuators to attenuate down to negative infinity.

   
  And yes, I know my drawing skills are crappy.


----------



## digger945

The way amb described would probably work best, as the way I put it would halve your effective overall max value to 5k if you're using 2 of the 10k attenuators.
  Do let us know how it works out for you. Below is a diagram to explain what I had in mind. It would give the ability to shunt a lot of the signal to ground, but I don't think it would work very good.
  Each click to turn the volume down on the first pot will alter the input impedance of the amp.

   
  Edited to reflect amb's correction in post #2773 below.


----------



## amb

Quote: 





> Originally Posted by *chronomitch* /img/forum/go_quote.gif
> 
> This is a diagram of the inputs/outputs of the attenuators and the epsilon 22 board with no wiring. Only one channel (right) is shown.


 

 Your ε22 volume pot connector pin assignment does not match the board.

  
  Quote: 





digger945 said:


> The way amb described would probably work best, as the way I put it would halve your effective overall max value to 5k if you're using 2 of the 10k attenuators.
> Do let us know how it works out for you. Below is a diagram to explain what I had in mind. It would give the ability to shunt a lot of the signal to ground, but I don't think it would work very good.
> Each click to turn the volume down on the first pot will alter the input impedance of the amp.


 
   
  This scheme will short circuit the source's output to ground when the first attenuator is turned down to minimum.  Not a good thing!  Also, that first attenuator shunts the signal to ground, but its effect is completely determined by the output impedance of the source.  If the source has very low output impedance (e.g., a few ohms), then most of the adjustment range of the first attenuator will have little or no effect until the first (minimum) click or two.


----------



## chronomitch

Quote: 





amb said:


> Your ε22 volume pot connector pin assignment does not match the board.


 

 I know. I just did it from memory.


----------



## digger945

Quote: 





amb said:


> This scheme will short circuit the source's output to ground when the first attenuator is turned down to minimum.  Not a good thing!


 


 Whoops. I fixed it.
   
  I tried to just change the url link thing, if that's possible, so that quoted posts would reflect the changes, but it didn't work. I'm not even sure it's possible.


----------



## amb

digger945, the added R fixes the short-to-ground problem, but the other issue of dependency on source output impedance still stands, and the adjustment range is actually made worse by the added R.


----------



## digger945

Yea I kinda new that adding the resistor would make the shunt even less effective. It(the whole thing) was just an adjustable idea for a fixed solution... so to speak. I see now how the lower(and fluctuating with adjustment) impedance would maybe not be a good idea for a source/pre.


----------



## chronomitch

I'm making progress on my build. So far, the power button boards and power supply are finished, and they work perfectly. The only problem I had was an ID10T problem when I was hooking up the power button.
   
  Note to self: B stands for button, not Blue LED.



   
  I'm still waiting for the Beta 22 kits to arrive from Glass Jar Audio, so I'm going to work on the various panel connections next.


----------



## MrNobody

Hi, I am planning on building a balanced 4-board β22. I had no experience on building an amp. Other than 4-board of β22 and 2 boards of σ22, case, volume control and plugs, what else do I need? How is the wirings done in a balanced 4-board β22? Do I need a pair of ε22 board? What about the heatsinks? Can anyone enlighten me on this and the important points to take note of if I were to build it? Is there any step by step guide available? Thanks for your help guys.


----------



## m1abrams

Quote: 





mrnobody said:


> Hi, I am planning on building a balanced 4-board β22. I had no experience on building an amp. Where can the ground/left/right channel amplifier module be bought from. Other than 4-board of β22 and 2 boards of σ22, case, volume control and plugs, what else do I need? How is the wirings done in a balanced 4-board β22? What about the heatsinks? Can anyone enlighten me on this and the important points to take note of if I were to build it? Is there any step by step guide available? Thanks for your help guys.


 

 I do not want to sound mean, however I think you are in over your head.  B22 is one of the more complex builds you can do, and doing a balanced just adds more complexity.  The answer to your questions are detailed on amb site. 
   
  I would strongly recommend you build a few other easier projects before you jump into building a balanced B22.  You may think that you want to save money by jumping straight to the B22 but chances are if you do that you will waste much more money in mistakes than you would ever spend on several smaller projects.


----------



## m1abrams

Please get some insulated quick connects for your high voltage AC lines.  They are cheap and easy to find at the local hardware store and can save you from a very life costly mistake.  If you can not find insulated ones then just cover the connectors with some heat shrink.
  Quote: 





chronomitch said:


> I'm making progress on my build. So far, the power button boards and power supply are finished, and they work perfectly. The only problem I had was an ID10T problem when I was hooking up the power button.
> 
> Note to self: B stands for button, not Blue LED.
> 
> ...


----------



## MrNobody

Quote: 





m1abrams said:


> I do not want to sound mean, however I think you are in over your head.  B22 is one of the more complex builds you can do, and doing a balanced just adds more complexity.  The answer to your questions are detailed on amb site.
> 
> I would strongly recommend you build a few other easier projects before you jump into building a balanced B22.  You may think that you want to save money by jumping straight to the B22 but chances are if you do that you will waste much more money in mistakes than you would ever spend on several smaller projects.


 
  Thanks for your reply. What project would you recommend me to start of with?


----------



## chronomitch

Quote: 





m1abrams said:


> Please get some insulated quick connects for your high voltage AC lines.  They are cheap and easy to find at the local hardware store and can save you from a very life costly mistake.  If you can not find insulated ones then just cover the connectors with some heat shrink.


 

 That's my plan. I just have it setup like that temporarily. I will be working on the rest of the panel connections soon, and I will rewire the AC socket and switch then.


----------



## Lil' Knight

Quote:  





> Is there any step by step guide available?


 
  I seriously doubt there's any.


----------



## K3cT

Quote: 





mrnobody said:


> Thanks for your reply. What project would you recommend me to start of with?


 
   
  If you can solder, I would suggest MMM and its companion Sigma11 power supply.


----------



## MrNobody

k3ct said:


> If you can solder, I would suggest MMM and its companion Sigma11 power supply.









 How much will I be looking for if I were to build that? 500usd?


----------



## FallenAngel

Depends on casework and opamp choices (I personally really like AD825 for the M^3).  You can fit an M^3 and Sigma11 into $350 with an inexpensive case, if you plan things well.
  
  Quote: 





mrnobody said:


> How much will I be looking for if I were to build that? 500usd?


----------



## deandake

I am in the process of building an Opus DAC. As soon as I finish this I will be moving on to my Beta and Sigma. I have the DIY itch and I feel the need to scratch it.


----------



## chronomitch

Quote: 





deandake said:


> I am in the process of building an Opus DAC. As soon as I finish this I will be moving on to my Beta and Sigma. I have the DIY itch and I feel the need to scratch it.


 

 May I ask why you decided to build an Opus rather than a Buffalo II DAC? I'm curious because I was considering building a Buffalo II after I finish my Beta 22.


----------



## deandake

I chose it for three reasons. One is it's cost. I have always loved music and now that I have weened myself away from mp3's I have decided to make myself some nice components to listen to music. That said, this is all new to me. The cost to get into the Opus dac is much more palatable to me at this point in my newly found interest in high fidelity equipment. The second reason was all the rave reviews on the units. Not just here at Head-Fi but all over the web. Third reason would be that I can purchase the Opus pieces at a time. Three Opus boards, the psu and a usb interface. Oh yeah, and the enclosures. Still haven't figured out what I am going to use. I think wood and have some metal fabricated for the ends top and bottom. Keeping the build modular keeps me from taking a big hit in the pocket book.
  Considering I am just starting down this road I don't even have a good iron yet. That is about $100 to add to the project.


----------



## jdkJake

deandake said:


> Considering I am just starting down this road I don't even have a good iron yet. That is about $100 to add to the project.








 Do you have a Fry's in the neighborhood? They always have a good price on the Hakko 936.

 http://www.frys.com/product/454489?site=sr:SEARCH:MAIN_RSLT_PG


----------



## deandake

That is exactly the Iron I plan to purchase. $74 right now. I knew you guys would be informitive but didn't realize how supportive this group is. Thanks guys


----------



## jdkJake

Excellent iron. Especially at that price. You will not be disappointed.


----------



## aloksatoor

yep Also one thing i cannot live without it the cleaning gauze which frys sells (hakko brand) , looks like metallic wool but works wonders for cleaning solder much better than provided pad http://www.frys.com/product/1563515?site=sr:SEARCH:MAIN_RSLT_PG


----------



## deandake

That stuff looks awesome. Back when I did electronics repair they didn't have that.  My local Fry's doesn't have it. gonna try another one before ordering it.


----------



## wquiles

Once I tried using these metal sponges, I stopped using the pads altogether.  The metal sponge works AWESOME!


----------



## bridge8989

hey guys i ran into some problems with the ground plane board.  when i adjust vr1 to get the voltage across R9 to 4.5V im getting ~5.5V on R10/R12 and ~7.5V across R11. The heatsinks warms up pretty fast compared to the other 2 boards which are working properly.  anyone have any suggestions?


----------



## ShinyFalcon

Is your VR2 is all the way counterclockwise? Is your DC offset at zero? Can you measure the resistance between the two pins of VR2 (that are not connected)?


----------



## bridge8989

yea VR2 is fully CCW; all three of the pins are connected to the board, ~2 ohms between pin1/2 and ~470ohms  between pin2/3 on VR2.  is dc offset between output and ground? i tried adjusting it with VR3 but the pot maxes out @ .13V DC.


----------



## deathg0d

Quote: 





bridge8989 said:


> yea VR2 is fully CCW; all three of the pins are connected to the board, ~2 ohms between pin1/2 and ~470ohms  between pin2/3 on VR2.  is dc offset between output and ground? i tried adjusting it with VR3 but the pot maxes out @ .13V DC.


 

 Hi I encountered a almost similar problem like yours some time back, which was, no matter how i adjusted and checked and troubleshooted, the readings just cannot be achieved, i even replaced parts as suggested and suspected to be faulty and still the readings are not correct, everytime, i power up the board, the readings just went haywire and in a couple of minutes i see smoke coming out from one of the mosfet (i have replaced and checked countless of times on everything from soldering to components etc)
   
  finally, i realised the cost of buying replacement parts and time i spent on troubleshooting came almost equivalent to getting a new single board kit set and populate it again, thus i choose the easy way out i guess and ordered a single board kit from gj and now i am a happy man with everything running great. i could be wrong but i personally guess there could be something wrong with the board itself since i have checked on everything else, so if you have checked and is pretty sure everything were done correctly, then try getting a new board or a new single board kit.


----------



## chronomitch

Well, I finally finishing stuffing the boards and wiring everything up, but now I have problems with the initial setup.
   
  Without any of the Beta 22 boards connected, I get approximately 29 volts (positive and negative) from the Sigma 22. However, when I connect the first Beta 22 board (haven't tried the other two), the voltage is about 20 volts (positive and negative) and slowly climbs as time goes on (about 0.1 volts every few seconds). What's more, the heat sinks on the Beta 22 board get REALLY hot (too hot to touch).


----------



## digger945

Assuming that the heatsinks on the sigmas are cool with nothing connected, you should then double check the amp boards as per the Beta 22 website. It's hard to believe that the sigmas would drop that much voltage without a fuse blowing, or something being very wrong, like a part somewhere taking up smoking.


----------



## jackmccabe

Hi, I am planning on building a beta22 but I am currently trying to decide what gain I should get.
  I am going to go balanced and I am wondering whether a gain of 5 (effectively 10) would be too high for either the grado rs1's or the ultrason hfi-780's.
  Thanks


----------



## ShinyFalcon

2x gain is more than enough for those two. What attenuator do you plan on using?


----------



## chronomitch

Quote: 





digger945 said:


> Assuming that the heatsinks on the sigmas are cool with nothing connected, you should then double check the amp boards as per the Beta 22 website. It's hard to believe that the sigmas would drop that much voltage without a fuse blowing, or something being very wrong, like a part somewhere taking up smoking.


 

 The heatsinks on the Sigma 22 are cool with nothing connected.

 I didn't notice any smoke for the first Beta 22 board, but I did notice a smell. Perhaps something was burning? I went ahead and tried hooking up another channel and I had the same problem: really hot heat sinks, low positive and negative rail voltages, and a strange smell. This time though, I also noticed a small amount of smoke. Unfortunately, though, I couldn't tell what part it was coming from.
   
  How sensitive are Q1-Q4 to heat? When I was soldering the boards, I noticed I had put those parts in wrong at first, as per the Beta 22 instructions, and had to desolder them. I wonder if I gave them too much heat when I was trying to remove them.


----------



## fishski13

Quote: 





chronomitch said:


> The heatsinks on the Sigma 22 are cool with nothing connected.
> 
> I didn't notice any smoke for the first Beta 22 board, but I did notice a smell. Perhaps something was burning? I went ahead and tried hooking up another channel and I had the same problem: really hot heat sinks, low positive and negative rail voltages, and a strange smell. This time though, I also noticed a small amount of smoke. Unfortunately, though, I couldn't tell what part it was coming from.
> 
> How sensitive are Q1-Q4 to heat? When I was soldering the boards, I noticed I had put those parts in wrong at first, as per the Beta 22 instructions, and had to desolder them. I wonder if I gave them too much heat when I was trying to remove them.


 
  you need to double check the component values and ohm out the B22 boards.  you're drawing way too much current and have a short and/or dead components.  i would post questions to over at http://www.amb.org/forum/.  Ti is at BAF in S.F. today and may not be able the reply right away.


----------



## jackmccabe

Oh yeah whoops I forgot to mention I am planning on purchasing a pair of akg k1000 and I have recently purchased a pair of k340's that's why I was looking at such high gain.
  Also I have not decided on an attenuator yet but I am willing to spend a fair amount.
  Thanks for your reply


----------



## deathg0d

Quote: 





chronomitch said:


> The heatsinks on the Sigma 22 are cool with nothing connected.
> 
> I didn't notice any smoke for the first Beta 22 board, but I did notice a smell. Perhaps something was burning? I went ahead and tried hooking up another channel and I had the same problem: really hot heat sinks, low positive and negative rail voltages, and a strange smell. This time though, I also noticed a small amount of smoke. Unfortunately, though, I couldn't tell what part it was coming from.
> 
> How sensitive are Q1-Q4 to heat? When I was soldering the boards, I noticed I had put those parts in wrong at first, as per the Beta 22 instructions, and had to desolder them. I wonder if I gave them too much heat when I was trying to remove them.


 
  components usually can take the heat of the soldering iron rod unless you delibrately hold them too long for it to burn, thus from normal soldering and desoldering, it cant cause damages.
  if you are unable to find out or determine which part is wrong. this will be a pretty silly sugguestion but i used it myself on my bad board. just let a single board runs on slightly longer till you can notice which component is giving out smoke but you really gotta be quick and have sharp eyes.


----------



## qusp

hahahaha...thats awesome!!


----------



## wink

Quote: 





> if you are unable to find out or determine which part is wrong. this will be a pretty silly sugguestion but i used it myself on my bad board. just let a single board runs on slightly longer till you can notice which component is giving out smoke but you really gotta be quick and have sharp eyes.


 
   
  That's what's called the old smoke test.......
   
  SMOKIN"


----------



## chronomitch

deathg0d said:


> components usually can take the heat of the soldering iron rod unless you delibrately hold them too long for it to burn, thus from normal soldering and desoldering, it cant cause damages.
> if you are unable to find out or determine which part is wrong. this will be a pretty silly sugguestion but i used it myself on my bad board. just let a single board runs on slightly longer till you can notice which component is giving out smoke but you really gotta be quick and have sharp eyes.


 
   
  Unfortunately, the smoke that I did see at first was very small, and now I don't see any more after turning on the power. I am really afraid I am going to do some major damage to other parts if I leave the power on too long due to the ridiculous amount of heat coming from the heatsinks.
   
  OK. This may be a stupid question, but I will ask anyway. Are the pads for mounting the on-board heat sinks isolated? I assumed they were, so I mounted the mosfets to the heat sinks without any isolation pads. I am using Glass Jar Audio kits, which provide small metal cylinders already mounted in the heat sink mounting holes (presumably for easy mounting to the Beta 22 boards). As such, I simply soldered these metal shafts to the aforementioned heat sink mounting pads. I figured it would be the simplest way to mount them. Everything I read on the AMB website seems to indicate this is OK.


----------



## deathg0d

Quote: 





chronomitch said:


> Unfortunately, the smoke that I did see at first was very small, and now I don't see any more after turning on the power. I am really afraid I am going to do some major damage to other parts if I leave the power on too long due to the ridiculous amount of heat coming from the heatsinks.
> 
> OK. This may be a stupid question, but I will ask anyway. Are the pads for mounting the on-board heat sinks isolated? I assumed they were, so I mounted the mosfets to the heat sinks without any isolation pads. I am using Glass Jar Audio kits, which provide small metal cylinders already mounted in the heat sink mounting holes (presumably for easy mounting to the Beta 22 boards). As such, I simply soldered these metal shafts to the aforementioned heat sink mounting pads. I figured it would be the simplest way to mount them. Everything I read on the AMB website seems to indicate this is OK.


 

 I sorry but i am not very clear on what you are trying to describe on the mosfets mounting. all i can say is that, the mosfets are screwed onto the heatsink together with the 'coolant' pad (sorry i forgot the name) inbetween them to help heat transfer. also, heatsink are usually very hot, for my case, all my heatsinks are so hot that i usually cant touch them more than a minute with my finger after they have been running for 30 mins.
   
  so i guess somehwere on your solderings could have went wrong which is why you cant get the readings. maybe you should start looking from the psu that all readings are correct then to start looking on each boards.


----------



## ShinyFalcon

It's safer to have isolation pads installed. The pads to mount the heatsinks to the β22 board should be isolated.


----------



## sachu

That's just irresponsible. Rather than saying, its fine..go ahead..use the heatsink insulators and you may save your skin when you go poking around in there. Always be safe and err on the side of caution. Will only take you another 5 mins to mount the insulators and 5$.


----------



## jdkJake

The pads also provide for thermal conduction (assuming you did not use any form of thermal paste). You get far better heat transfer along with electrical isolation.


----------



## Anonanimal

Quote:  





> Are the pads for mounting the on-board heat sinks isolated? I assumed they were, so I mounted the mosfets to the heat sinks without any isolation pads. I am using Glass Jar Audio kits, which provide small metal cylinders already mounted in the heat sink mounting holes (presumably for easy mounting to the Beta 22 boards). As such, I simply soldered these metal shafts to the aforementioned heat sink mounting pads. I figured it would be the simplest way to mount them. Everything I read on the AMB website seems to indicate this is OK.


 

 The pads are isolated.  When in doubt, break out the multi-meter!  What you need to worry about, and amb describes this very clearly on the site (for the others saying this is taboo), is if the heat sinks are in very close proximity to the enclosure when installed.  If so, then there is potential for them to short to the chassis (and therefore each other), which would then be a problem.  I wouldn't say it's irresponsible by any means to leave those out if you know what you're doing, but I do agree that it's always good to err on the side of caution if you're not sure. 
	

	
	
		
		

		
			




   
  Edit: Directly from the Instructions page on the site.
  Quote: 





> Since each MOSFET's mounting tab is internally connected to the drain pin, it will carry live voltages and should not be shorted to the chassis, ground or other parts of the circuit. If your onboard heatsinks will be in close proximity to the top metal cover when the board is installed in your chassis case, then you should mount the MOSFETs to the heatsinks using TO-220 mounting kits. If you use offboard heatsinks, then TO-220 mounting kits are also required. Otherwise, you may mount the MOSFETs directly to the heatsinks using #4-40 or M3 machine screws and hex nuts, after applying some heatsink thermal paste to the mating surfaces.


----------



## chronomitch

anonanimal said:


> The pads are isolated.  When in doubt, break out the multi-meter!  What you need to worry about, and amb describes this very clearly on the site (for the others saying this is taboo), is if the heat sinks are in very close proximity to the enclosure when installed.  If so, then there is potential for them to short to the chassis (and therefore each other), which would then be a problem.  I wouldn't say it's irresponsible by any means to leave those out if you know what you're doing, but I do agree that it's always good to err on the side of caution if you're not sure.
> 
> 
> 
> ...


 
   

 [size=medium]Thanks for the info guys, but what I was really referring to were the screw holes which connect the heatsinks to the PCB, not the mosfets to the heatsinks. As per the instructions on the AMB website, I did not use isolation pads between the heatsinks and the mosfets because the heatsinks were not going to touch anything else. What I was worried about instead, was that soldering the heatsinks to the PCB using the screw holes would connect all of the heatsinks together, and, in turn, the drain pins of all of the mosfets.
   
  I will start measuring some voltages across resistors tonight to see if I can find anything abnormal and report back.​[/size]


----------



## Anonanimal

Quote: 





chronomitch said:


> Thanks for the info guys, but what I was really referring to were the screw holes which connect the heatsinks to the PCB, not the mosfets to the heatsinks.​


 
   
  That's what I was referring to as well in my very first sentence.  Sorry for any confusion, but I was in fact answering your original question.  I was simply expanding on my answer with the other info because some of the previous posts suggested you had done something horribly wrong by leaving out the thermal pads.
   
  Of course if you want to be sure, the quickest way to check is still w/ a multimeter.  Just set your multimeter to ohms mode and check between the MOSFET mounting holes and the heat sink mounting hole pads.


----------



## chronomitch

anonanimal said:


> That's what I was referring to as well in my very first sentence.  Sorry for any confusion, but I was in fact answering your original question.  I was simply expanding on my answer with the other info because some of the previous posts suggested you had done something horribly wrong by leaving out the thermal pads.
> 
> Of course if you want to be sure, the quickest way to check is still w/ a multimeter.  Just set your multimeter to ohms mode and check between the MOSFET mounting holes and the heat sink mounting hole pads.


 

 I took your advice about using a multimeter and confirmed that there were no issues regarding the heat sink and mosfet mountings. I haven't had a chance yet to investigate the main problem yet, but hopefully I will have sometime in the next few days.
   
  I did have time to take a hard look at the soldering work on the underside of the board. I previously cleaned the boards really well using some 99% isopropyl alcohol. Unfortunately, I did not see any obvious problems. There were no solder bridges between contacts, and all the joints looked like they were fine.


----------



## Anonanimal

Good to hear that there are no issues there.  Check out the Troubleshooting section of the Initial Setup page on amb's site for a good start on what to check.
   
  Other than that, one of the first things I'd check is the orientation of your trimpots.  I've seen a number of blown boards on the forums here that occurred from trimpots installed upside down.


----------



## K3cT

I thought you could buy the TO-220 thermal and electrical isolation package from Mouser and that was what I did for each and every heatsink in my Beta22.


----------



## Anonanimal

Quote: 





k3ct said:


> I thought you could buy the TO-220 thermal and electrical isolation package from Mouser and that was what I did for each and every heatsink in my Beta22.


 

 You can (and I did as well).  What I was stressing earlier is that they are definitely not required, though some were giving Chrono the idea that they were.  Either way, that wasn't his problem so we can move on.


----------



## chronomitch

It appears I put in the trim pots in backwards, as Anonanimal guessed. I had assumed that the marking on the board should have matched up with the arrow symbol on the trim pot, but it seems that marking was referring to the position of the control screw. I verified my mistake by checking the trim pot data sheet and Beta 22 schematic.
   
  I guess the question now is what parts are likely to have blown as a result.


----------



## amb

Quote: 





chronomitch said:


> It appears I put in the trim pots in backwards, as Anonanimal guessed. I had assumed that the marking on the board should have matched up with the arrow symbol on the trim pot, but it seems that marking was referring to the position of the control screw. I verified my mistake by checking the trim pot data sheet and Beta 22 schematic.
> 
> I guess the question now is what parts are likely to have blown as a result.


 

 Check output MOSFETs for shorts and R34/R35 for correct resistance.


----------



## SP Wild

Hi,  I just wanted to ask those that purchased a Glass Jar Audio kit whether or not some of the important components are matched as recommended by AMB?
   
  Also a general question regarding the B22.  I have this desire to have a remote control input and source selection, the easiest implementation I thought would be to bypass all attenuation on the B22 and use it as a headphone "power amplifier" and using a high quality (possibly Audio GD Phoenix) pre-amp as the control center and using its remote source switching and volume knob.  Is this feasible or would it be self defeating in the pursuit for "perfection"?  The absolute best speaker setups seem to always have an active preamp ahead of the power amplifier.


----------



## amb

Quote: 





sp wild said:


> Also a general question regarding the B22.  I have this desire to have a remote control input and source selection, the easiest implementation I thought would be to bypass all attenuation on the B22 and use it as a headphone "power amplifier" and using a high quality (possibly Audio GD Phoenix) pre-amp as the control center and using its remote source switching and volume knob.  Is this feasible or would it be self defeating in the pursuit for "perfection"?  The absolute best speaker setups seem to always have an active preamp ahead of the power amplifier.


 
   
  Sounds like you're looking for the upcoming LCDuino-1 + δ1 + δ2, if you're willing to wait a little time for their release.
  An example implementation is my new α10 buffer preamp, except you'd be using β22s instead of JISBOS.  Discussions about the α10 are found here.


----------



## matthewh133

^ wow. Awesome.


----------



## cfcubed

From my comm & b22 kit buying from Jeff, he matched the "important" devices to match & did not match the "less important" devices to match. 
  Don't remember specifics from amb's "Which devices to match", but you can communicate/confirm/request things to be sure.
  May take Jeff a couple days to reply but I've always been happy w/my dealings w/him.
  
  Quote: 





sp wild said:


> Hi,  I just wanted to ask those that purchased a Glass Jar Audio kit whether or not some of the important components are matched as recommended by AMB?


----------



## FallenAngel

Ti... you are an evil man!  I now absolutely have to build that!


----------



## aloksatoor

haha X2 on that....
  
  Quote: 





fallenangel said:


> Ti... you are an evil man!  I now absolutely have to build that!


----------



## chronomitch

Guess what? I de-soldered the trim pots for all of the boards and put them in the right way, and everything works now! 
	

	
	
		
		

		
		
	


	




 Everything checked out during the initial setup.
   
  Now I cannot stop listening to it. The music just flows effortlessly. 
	

	
	
		
		

		
		
	


	



   
  I want to give a big shout out and thank you to AMB for designing such an awesome piece of equipment. Also, thanks to everybody who helped me out in this thread, especially Anonanimal for suggesting I check the orientation of the trim pots.
   
  Here are a few pictures:
   


   
  I decided to go ahead and use the two stepped attenuator volume control I discussed a few pages back. It turns out it works really well. I use the one on the right as pre-attenuator to allow the left attenuator to get in the 12 o'clock range. I can then use the left attenuator to adjust the volume in two decibel steps. If I had just used one attenuator, even the current gain of 5x would have made it very difficult to control the volume (i.e. normal volume would be reached at 7 or 8 o'clock.


----------



## adamus

what a strange fix. it shouldnt matter which way the trimpots are installed... it only alters the direction of adjustment, not the total adjustment as pin two is the wiper. Something else must have happened, maybe a bad joint or something?>


----------



## amb

Quote: 





adamus said:


> what a strange fix. it shouldnt matter which way the trimpots are installed... it only alters the direction of adjustment, not the total adjustment as pin two is the wiper. Something else must have happened, maybe a bad joint or something?>


 

 When VR1 and VR2 are mounted backwards, their direction of adjustment is indeed also reversed.  If you then follow the β22 website initial setup procedure and pre-set those trimpots fully-counterclockwise before powering up, you've just set them up for _maximum bias_.  On a β22 this means a lot of current is going to flow through the stages, and the output MOSFETs are going to get really hot in no time.


----------



## Anonanimal

Great to hear that it's up and running!  Enjoy your new amp- over a year after building mine I rarely go a day without listening to it...


----------



## Fitz

Quote: 





amb said:


> When VR1 and VR2 are mounted backwards, their direction of adjustment is indeed also reversed.  If you then follow the β22 website initial setup procedure and pre-set those trimpots fully-counterclockwise before powering up, you've just set them up for _maximum bias_.  On a β22 this means a lot of current is going to flow through the stages, and the output MOSFETs are going to get really hot in no time.


 

  
  I've got a better one for trimpot screwups. I put the wrong trimpot in the VR1 spot, and after I noticed it and got it desoldered so I could put the right one in instead, I went and put the _same_ one right back in. I felt pretty dumb that day.


----------



## fishski13

Quote: 





fitz said:


> I've got a better one for trimpot screwups. I put the wrong trimpot in the VR1 spot, and after I noticed it and got it desoldered so I could put the right one in instead, I went and put the _same_ one right back in. I felt pretty dumb that day.


 

 who said solder fumes make you smarter?  i know the feeling 
	

	
	
		
		

		
		
	


	




.


----------



## amb

Quote: 





fallenangel said:


> Ti... you are an evil man!  I now absolutely have to build that!


 

 Quote:


aloksatoor said:


> haha X2 on that....


 

 Sorry about the off-topic post, but if you're interested in building the α10 buffer preamp, please follow (and subscribe to) the α10 thread and JISBOS group-buy.  Momentum is gathering on that front.


----------



## aloksatoor

subscribed


----------



## turgonml

I can't seem to find the CR1, CR2: 2.2mA or 2.4mA current regulator diode on Digikey (needed for the σ22. I've found almost every single part I need from digikey and AMB and I don't really want to pay an extra 20 euro shipping to get it from Mouser.
   
  Thanks in advance.


----------



## jackmccabe

Hi, what is the lowest gain you would recommend to go with a pair of k1000's.
  This is because I also have a pair of grado rs1's, so I would like to be able to use both of them without one be very quiet and the other very loud.
  thanks


----------



## johnwmclean

Quote: 





jackmccabe said:


> Hi, what is the lowest gain you would recommend to go with a pair of k1000's.
> This is because I also have a pair of grado rs1's, so I would like to be able to use both of them without one be very quiet and the other very loud.
> thanks


 

 Balanced or Single Ended.


----------



## jackmccabe

I will be building it balance sorry forgot to say.
  Thanks


----------



## amb

Quote: 





jackmccabe said:


> Hi, what is the lowest gain you would recommend to go with a pair of k1000's.
> This is because I also have a pair of grado rs1's, so I would like to be able to use both of them without one be very quiet and the other very loud.
> thanks


 

 It's going to be difficult to make one gain setting work well for both of those headphones because they're such extreme opposites.  K1000 is super inefficient and needs high gain to achieve good SPLs, but such an amp would have too much gain for the Grado.  A switchable input attenuator might be useful to equalize the volume (I posted about this before, search for it), but it's not a cure-all.


----------



## amb

Quote: 





turgonml said:


> I can't seem to find the CR1, CR2: 2.2mA or 2.4mA current regulator diode on Digikey (needed for the σ22. I've found almost every single part I need from digikey and AMB and I don't really want to pay an extra 20 euro shipping to get it from Mouser.
> 
> Thanks in advance.


 


  PM me and I could help you out.


----------



## GMF2010

Can anyone confirm that they are able to use a gain of 6 balanced (3 single ended) with Denon D7000s without producing hiss?
   
  My amp is currently set to a gain of 4 balanced, but my other headphones (LCD-2) leave me needing just a few more clicks on the DACT with lower recordings. If someone who has tried balanced D7000 with a gain of 6 could comment, I would really appreciate it.
   
  P.S. My DAC is a Buffalo 32 with an output of 2V RMS.
   
  Thanks,
   
  Greg


----------



## FallenAngel

Hiss is not just about gain - it's also about how close your PSU is to the boards and Low-Z wiring after pot.


----------



## jcx

There are some things that can be determined from the specs alone:  LCD-2  50 Ohm 91 dB/mW vs D7000 25 Ohm 108 dB/mW
   
  looks like the numbers say the Dennon are ~ 20 dB/V more sensitive - thats a lot - definitely where you should consider output attenuation- "Hiss Buster" or output Xfmr
   
  the Headroom impedance graph is pretty flat though so the series R of a power resistive divider shouldn't introduce much coloration
   
  a 20:5:20 Ohm balanced divider's output Z would be low enough that the D7000 impedance bump would give inaudible frequency response difference compared to "0" Ohm drive
   
  I would just string together 9x 5 Ohm 1/2 W or or bigger 1% metal film resistors for each chan divider - they could be inside the B22 with a switch or built into a external box ( probably not just the connector headshell though because they will be wasting a few W)
   
   
  also if you're using a Ivy III with the Buffalo Dac then a Volumite will give better S/N with the Dac straight in to the B22 than any volume pot setting down to nearly 20 dB attenuation (assuming 10K attenuator - higher Ohm attenuators will be even noisier)
   
   
  in fact the D7000 would probably be fine straight from the Ivy


----------



## GMF2010

Quote: 





fallenangel said:


> Hiss is not just about gain - it's also about how close your PSU is to the boards and Low-Z wiring after pot.


 


 With respect to the PSU's proximity to the boards, I should be fine. The S22 (x2) are in their own par-metal case, and while I do have the B22's case stacked on top of it, there is an additional inch of separation provided by the isolation feet I have. I'm not sure if an inch is negligible or not, regardless...


----------



## jcx

Hiss is "white" noise from active devices and resistor thermal noise - in the b22 the volume attenuator resistance noise at intermediate settings will be larger than the B22 input fet noise - many sources will have higher noise than the b22
   
  Hum is power line fundamental - often ground loops and xmfr leakage magnetic coupling
   
  Buzz is power line frequency harmonics from cap input ps rectified current spikes - can be magnetically coupled from poor wire routing or may be "ground contamination" from poor ground wiring topology
   
   
  if you don't hear any of these with the LCD-2 then you wouldn't with the D7000 and the 20 dB output attenuator
   
   
  since this is the DIY forum you could diagnose these problems with a decent soundcard by looking at the noise fft (RMAA)


----------



## LeMat

Since I got very important information and help in this thread, I thought some may be curious to see how winded up my first DIY experience... a Beta22.
  I could't say I haven't been advised to start with a smaller project, and I won't say it's been easy, but it finally went ok. Actually it's selecting and shopping parts in so many different web-store/boutique that I've found difficult. Designing the case has been also very time consuming. All things considered, I really loved the experience ! Now I have some fine tuning to do but it already sounds really great.
   
http://www.head-fi.org/forum/thread/85561/post-pics-of-your-builds/7710#post_7214853


----------



## chronomitch

Nice build, LeMat. What did you use for the cases? The volume knob looks like a GoldPoint, but how did you fashion the lighted ring?


----------



## LeMat

Quote: 





chronomitch said:


> Nice build, LeMat. What did you use for the cases? The volume knob looks like a GoldPoint, but how did you fashion the lighted ring?


 

 Cases are from Hifi2000. Took a while to get these, with very little communication, but it's very well made, and perfectly packaged (each plate is wrapped into thermo-plastic)
   
  Volume knob and attenuator are indeed from goldpoint.
   
  Lighted ring "how to " has been very well explained here : http://www.head-fi.org/forum/thread/85561/post-pics-of-your-builds/7710#post_7207929
   
  Only difference, I used only one disc of frosted perspex.
  Holes are sized so I can "plug-in" 5mm LED.


----------



## MrMajestic2

I have a persistent problem guys. I had a board before that didn't measure correctly on R10, R11 and R12. They measured 1 volt lower than R9. So I gave up and got a prebuilt board thinking I would save some time and effort. Sure enough, the board works, but looks horrible and nothing even remotely like the other boards I have. So I bit the bullet and bought a new set from Jeff Rossel and lo and behold, that board has the same problem as my first one  Any ideas would be most helpful since I cant really find anything obviously wrong with the boards.


----------



## sphinxvc

I was pondering building a 2CH Beta to start out with and then eventually making it a 4CH in the future - what gain is optimal?  (The gain is locked and unchangeable, correct?)


----------



## chronomitch

sphinxvc said:


> I was pondering building a 2CH Beta to start out with and then eventually making it a 4CH in the future - what gain is optimal?  (The gain is locked and unchangeable, correct?)


 
  I built a 3-channel Beta 22 with a gain of 5 for the boards, and it is more than loud enough for anything I have tried it with (HD800, HD650, LCD-2). Remember that when you go balanced, the gain is doubled. So if you use a gain of 5 for each board, using them in a balanced configuration would yield an effective gain of 10.
   
  It's not the end of the world if you need to change the gain of your boards, as you only need to change two resistors (R3, R4) and four capacitors (C2-C5).


----------



## Lil' Knight

Gain 2 is more than enough for all my headphones.


----------



## Oberst Oswald

Group-buy: ε22 backplane board for 3-channel β22   
  In case anyone is interested there is a group buy going on the AMB site
   
  http://www.amb.org/forum/interest-check-round-2-epsilon22-backplane-board-for-3-ch-beta22-t1493.html


----------



## amb

Quote: 





oberst oswald said:


> Group-buy: ε22 backplane board for 3-channel β22
> In case anyone is interested there is a group buy going on the AMB site
> 
> http://www.amb.org/forum/interest-check-round-2-epsilon22-backplane-board-for-3-ch-beta22-t1493.html


 

 The link is here: Group buy: ε22 backplane board for 3-ch β22 (round 2)
  The sign-up phase will end this coming Monday January 9, 2012.


----------



## joeyjojo

My first post of many in this thread - hi all and thanks in advance for any help! We'll start with a hopefully relatively easy one...
   
  Quote: 





amb said:


> Quote:
> 
> 
> Originally Posted by *johnwmclean* /img/forum/go_quote.gif
> ...


 

  
  I am planing to build a beta22 with balanced functionality for use with a Cambridge Audio DACMagic, which says it puts out 4.2 V rms when balanced (2.1 V unbalanced). Yes, rms. This is going to be too much even for gain 2, no? Primary headphones are HD650s.


----------



## bcg27

Well if you are doing balanced (4 board) then a gain of 2 on each board turns into a gain of 4. I would say that is a bit high with such a hot source. A single ended with gain of 2 would probably be fine though. If you are set on building a balanced amp, I would spend the money on a good stepped attenuator, or better yet build amb's delta 1 attenuator. This will give you excellent channel balance even at high levels of attenuation that you will need.


----------



## joeyjojo

Thanks bcg27. Do we think a good 50k attenuator would do the job in this case?


----------



## bcg27

The value of the attenuator is not too important. Anything from 10k to 100k would be fine probably. I have used 25k in most of my builds. Like I said though I would build amb's delta1 if you can swing it for the excellent channel matching and other features.


----------



## luke99

What's an estimate of the bulid cost for a stereo B22 and power supplies?


----------



## joeyjojo

Quote: 





luke99 said:


> What's an estimate of the bulid cost for a stereo B22 and power supplies?


 


  $300 from glassjaraudio for two boards and power supply, plus enclosure and other bits and bobs (at least $700 I'd guess, with some nice extras).


----------



## bcg27

Probably $5-600 for a bare minimum build


----------



## joeyjojo

Quote: 





bcg27 said:


> Probably $5-600 for a bare minimum build


 

 Yep this is better (I was allowing for a larger attenuator)


----------



## joeyjojo

Almost ready to make my mouser order and I'm looking for a few recommendations. Mouser part numbers preferably.
   
  First, LEDs. Which ones are people using for the boards? And what would be a good choice for a panel mounted indicator LED? For the latter, what's a good way to mount them? It seems you can buy little plastic holders for this function.
   
  Second, switches. I need switches for three purposes:
  1. Switch between transformer primaries and power entry model to select between 115 and 230V. Obviously needs rating for the higher voltage, not sure what kind of current (perhaps 80/115 = 0.7A ? But inrush is higher I suppose?). Doing two transformers so needs to be 4PDT.
  2. Power switch, also between power and primary (aside: it doesn't matter if it's on the live or netural line, does it?). Same ratings I assume. Simple switch (SPST).
  3. Source select switch. Sits in signal path (quality). 2x DPDT preferably, or 1x 4PDT.
   
  Third, mounting hardware. What are people using? 
   
  Fourth, I'm looking at this power entry module (Mouser 631-FN282B-6-06). It's cheaper than the non-medical grade ones for some reason, OK to use?
   
  Thanks very much


----------



## Beefy

Quote: 





joeyjojo said:


> Fourth, I'm looking at this power entry module (Mouser 631-FN282B-6-06). It's cheaper than the non-medical grade ones for some reason, OK to use?


 

 I used that exact module in my Buffalo DAC build. No problems at all.


----------



## Pars

For voltage selection, they make a number of power entry modules that provide this function. Digikey seems to list more of them than Mouser does, but I may have missed them. Search for :voltage selector: on Digikey, then select the power entry modules. You can probably find the same at Farnell, etc. in the UK.


----------



## joeyjojo

Excellent, thanks very much. I'm now thinking this one: 592-PM0SXSSXB, which has connections for dual primary transformers, standard filter, 10A rating and shielding. It's ideal.
   
  So, still to figure out are the LEDs, individual power switches (2xSPST for dual s22s), source selection switch (2x DPDT), and mounting hardware.
   
  Power switch: 540-CRE22F2PBBNE ? What the hell is quick connect? As opposed to soldering...
   
  Also, how about this as a source select 633-GW22LHP ? It takes .100 molex by the look of it, which is nice.
   
  Edit: damn the power switch is minimum order size 810 :/


----------



## bcg27

LED's are extremely unimportant. You don't even need them actually. Any color is fine, just calculate the appropriate resistor you need from the led forward voltage drop and your power supply rails and you are done. 
   
  Quick connect means you use things like this: http://www.mcmaster.com/#lug-terminals/=fyouvv
   
  Switches are one of the things that makes your build unique. Pick something with an appropriate rating that you like the look and form factor of. That's about all there is to it.


----------



## luke99

Its quite an expensive amp, is it so much better than the M3?


----------



## K3cT

Yes, IMHO.


----------



## MrMajestic2

Quote: 





k3ct said:


> Yes, IMHO.


 


  +1 on that


----------



## Magsy

The law of diminishing returns sets in, I threw everything at mine, I don't think I could have spent more on the build and I love it, it is great and wouldn't replace it, if you can afford to do it right, do it.... :]
   
  However, it started a chain reaction, previously I had M3 and EMU0404, once at the B22 I had to buy new DAC, then new 'phones and a lot of tweaks until I was as happy. It was a bit like a last 15% thing, M3 was 85% and the B22 brought the last 15% (for a lot of money)
   
  I suppose what I am saying is that don't expect miracles, nor it to be your last purchase and given my experience with an all Blackgate N'd, PRP, balanced, Goldpoint attenuated monster I can't imagine a two board B22 is miles ahead of an M3. As always, the more transparent the equipment the worse the music gets, I still enjoy the M3 at times for the warmth


----------



## joeyjojo

Quote: 





amb said:


> If you're using a source that is "too hot", then you might want to add an input attenuator at the amp. Here is a schematic of a switchable attenuator. It is drawn for an unbalanced (2 or 3 channel) amp, for a 4-channel balanced amp you'll need to double everything for the negative signal, and use either a 4PDT switch, or two DPDT switches.
> 
> 
> 
> ...


 

 Ti, what's this? With the switch one way it shorts the resistor and sees the signal, with the switch the other way it sees ground...?


----------



## Pars

With the switch in the position as shown in the figure, the input goes directly to the pot (no attenuation). With the switch flipped, input goes through Ra and then to the pot with Rb in parallel to the pot... i.e., a voltage divider. Attenuated.


----------



## Avro_Arrow

In other words...it's a "mute" switch...


----------



## joeyjojo

Thanks Pars, I was being thick.


----------



## beerguy0

Reading through these threads has convinced me to build a Beta 22. I need to let my wallet recover from my latest headphone binge (MiniMAX, GrubDAC, and Denon D5000 headphones, all in the span of a month.) I'm probably going to do the 3 board active ground, with separate enclosures for the amp and power supply. (I actually have a Sigma 22 kit on order to replace a blown power supply on one of my other amps, so that will be good practice.)
   
  I started sketching out some case ideas. I have access to a pretty insane (in a good way) machine shop at work, which will make the case work easier. I'll probably have to wait until Fall to order the board sets, but I'm going to get the BOM started and get some parts together for the case and wiring. In the mean time I plan to do a lot of reading (I'm about 1/2 way through this thread, and have spent some time at Headwize as well.


----------



## jcx

I still can't see how "3-channel" ever gained popularity over dual mono - there's simply no comparison - "3-channel" is wrong on nearly all counts that are claimed as tech advantages


----------



## johnwmclean

jcx - have you substantiated your convictions from any formal testing, both objective and subjective?
   
  Otherwise...


----------



## beerguy0

Quote: 





jcx said:


> I still can't see how "3-channel" ever gained popularity over dual mono - there's simply no comparison - "3-channel" is wrong on nearly all counts that are claimed as tech advantages


 
   

 Please enlighten us.


----------



## jcx

from the popcorn icon I doubt you're truly interested in following the intellectual argument - if so I suggest forum search
   
  Ti had to concede my TRS common gnd crosstalk argument when he finally did the measurement properly - on the headphone side of the connector - the milliOhms of common gnd jack/plug contact resistance totally obscures his published crosstalk numbers (measured on the amp board)
   
  NwAvguy/RocketScientist has measured the flaws I point out in arguing against "3-channel" gnd - admittedly with "lessor" amps than the B22
   
  if you are serious about "gnd contamination" then 4-pin "balanced" headphone cable termination is the only choice
   
  add dual mono PS and the only common point is the source signal gnd connection
   
  keeping TRS with its compromises you can replace the 3rd board with a few $ of Cu roof flashing for a uOhm technical gnd - and the Cu won't have distortion (which doesn't cancel - another false "3-channel" claim)


----------



## rds

It seems that 3 channel will have some benefits in terms of cancellation of amplifier noise


----------



## cfcubed

Non-technical, subjective opinion from having compared my 2-ch (not dual-mono) vs. 4-chl/balanced β22 builds (+ comparing the 2-ch to 3-ch in meet settings) - think most would be hard-pressed to _hear_ a difference amongst the topologies.  Especially when not doing proper A/B/Xing. 
   
  For my 2-ch vs 4-ch comparison I feed them w/same source, used a 1/4" -> XLR adapter on the 2-ch so was able to almost instantly switch the same headphones between them.  Won't say I didn't perceive the slightest difference but not confident I could pick each out reliably even w/proper A/B/Xing.  YMMV and others w/better ears, the best source + source material could fare differently.
   
  With the cost/complexities involved IMO build 2-ch for unbalanced, 4-ch for balanced.


----------



## jcx

I quite agree that my expectation is the the differences in good builds are likely inaudible with B22 - so "3-channel" is a waste of time and resources
   
  and most of the technical claims justifying "3-channel" simply wrong on engineering principles
   
   
  the PSRR (power supply rejection ratio - how much of a change in power supply V show up in the amp output) argument could be partially true, other system noises are worse with "3-channel" - you are adding a whole amp between signal gnd and your headphone's gnd - in "3-channel" the "output gnd" amp has added noise, distortion in series with your headphones
   
  the B22 circuit uses a number of design techniques to give it unusually high PSRR, combined with half decent regulated supplies there is no reason to think PSRR performance needs improving


----------



## beerguy0

Quote: 





jcx said:


> from the popcorn icon I doubt you're truly interested in following the intellectual argument - if so I suggest forum search
> 
> Ti had to concede my TRS common gnd crosstalk argument when he finally did the measurement properly - on the headphone side of the connector - the milliOhms of common gnd jack/plug contact resistance totally obscures his published crosstalk numbers (measured on the amp board)
> 
> ...


 
   

 I apologize for my sarcasm, but I don't follow this forum regularly, and when I see a statement like yours, with no proof offered, I tend to be skeptical. I'll search the forum for your posts so I can further understand the technical side.
   
  I have no intention of going to a balanced system at this time, so I may well just do a two-board version. I like your suggestion for replacing the 3rd board with copper - I happen to have a slab of .09" thick copper, about the size of the amp boards. I'll just slap that in the case along with the amp boards.


----------



## cfcubed

Quote: 





beerguy0 said:


> <snip> I may well just do a two-board version.* I like your suggestion for replacing the 3rd board with copper *- I happen to have a slab of .09" thick copper, about the size of the amp boards. I'll just slap that in the case along with the amp boards.


 
   
  Now maybe someone can enlighten me how a slab of copper a few inches long for ground would make much difference given the headphone cable's "ground" lead gauge & length (and proximity to L&R hot leads).  Would think using heavier gauge ground wire (e.g. 18 -> 14) than the PS's +/- and L&R channel wire should suffice, but I guess everything is some sort of compromise


----------



## beerguy0

Quote: 





cfcubed said:


> Now maybe someone can enlighten me how a slab of copper a few inches long for ground would make much difference given the headphone cable's "ground" lead gauge & length (and proximity to L&R hot leads).  Would think using heavier gauge ground wire (e.g. 18 -> 14) than the PS's +/- and L&R channel wire should suffice, but I guess everything is some sort of compromise


 
   

 If I understand jcx's theory, the idea is to have a low impedance ground (low capacitance, low inductance, low resistance). Wire has inductance, capacitance, and resistance, while a sheet of copper has less of all three.


----------



## Fickle-Friend

can someone recommend a builder as I'm in the market for a Balanced β22/Dual σ22. Thanks


----------



## jc9394

Check out my signature, not sure Corey have time to build one for you or not but his work is one of the best.


----------



## c12mech

I am starting mine next week. It will be a fully balanced build to go with the Buffalo 3 that I am working on now. Still undecided on the attenuator though. It will either be a Goldpoint, DACT, Khozmo, or δ1. The plan is to use Plitron transformers, PRP resistors, and Nichicon FG caps. Hopefully it will all come together in the next two months.


----------



## haejuk

I am going to start a fairly minimal Beta 22 build soon.  I am having trouble finding enclosures that are not way too big for a 2 channel build.  What are some enclosure options for a 2 channel build?  I will be using another of the same enclosure for the Sigma 22 if it is the right size.  Does anyone have any suggestions?  I also have no idea how people get their front/rear panels machined.  Do people just have really good skills with front panel express?


----------



## MisterX

Quote: 





> What are some enclosure options for a 2 channel build?


 
   
  A couple options off the top of my head are:
   
http://www.par-metal.com/product-ttp-20series.php
http://www.modushop.biz/ecommerce/cat153_l2.php?n=1
   
  There are other options listed on the Beta 22 parts list page IIRC.
   
   
   
  Quote: 





> Do people just have really good skills with front panel express?


 
   
  Their software is very easy to learn... give it some time.


----------



## haejuk

Looks like the par-metal ones already have vents in them, that is a huge plus.  I guess that when working with front panel express (it is pretty easy, I am just worried about making the holes the right dimension) I can find the mounting specs (hole size, spacing, etc) in the datasheet for the part I am looking to mount?


----------



## MisterX

Yep, the datasheet is where they usually hide that information but it never hurts to double check the parts with your calipers.


----------



## haejuk

What do people use for punching holes in the bottom of a case in order to mount the PCBs?  I am totally comfortable with soldering (not as much so with measuring, probably going to read around before I ask anything about that), but I am totally clueless on casework.  Is it prohibitively expensive to have Par-Metal punch all the holes I need when I order from them?
   
  I haven't actually started my build yet due to budgetary setbacks, but I want to know how to do things so I know what tools I need.


----------



## cfcubed

You should use search & try to find some build threads around here (not necessarily just for this project)... IIRC there are some good ones around, showing tools, techniques, etc.
   
  I think many use a good hand drill or drill press (w/center-punch, masking tape) to make their PCB standoff holes, etc.  The expense of proper, fancy professional-looking casework (machined cases, FPE endplates, etc) is higher than doing those manually.  But it does take some skill, planning, tools & practice to get decent looking results using a raw case & manual "machining".
   
  For warm/hot projects one thing that's hard to manage manually & have it come out nice is enclosure ventilation.  I had to resort to some greenlee punch hackery to get adequate ventilation in my budget 2-ch beta22 build:
   

   
  Note: I've since asked the ebay seller of this case to offer one w/more top panel ventilation & he has - search "*Metal Cabinet Project Box HB-350-1*" - you could use one of those cases for the PS & one for the AMP box of a 2-ch build.  They're once example of a low-cost serviceable case if you wanted to try to go the manual route.   I'm planning to pick some of those cases up once I clear the decks of my in-progress projects


----------



## jcx

don't necessarily need holes for PCB mounting to chassis http://www.richco-inc.com/products/circuit-board-hardware/97-circuit-board-hardware-catalog.html?PartNum=&country=RICHCOUSA&grpcode=A1680
   
  search: self adhesive pcb standoff


----------



## jdkJake

jcx said:


> don't necessarily need holes for PCB mounting to chassis http://www.richco-inc.com/products/circuit-board-hardware/97-circuit-board-hardware-catalog.html?PartNum=&country=RICHCOUSA&grpcode=A1680
> 
> search: self adhesive pcb standoff




Nice concept. That much is for sure.

How does the adhesive stand up under prolonged exposure to heat? Or is that not an issue as it will generally be used on the underside of a board?


----------



## haejuk

I had seen those adhesive stand-offs before.  I am just not sure how well they will stand up to shipping, as I will be moving to the other side of the world in the foreseeable future.  My main concern is all the heatsinks on these boards may be too heavy if a case ends up sideways in a box or something.
   
  cfcubed, thanks for the tips.  I will search around more and check out those enclosures.  I was thinking of going with Par-Metal 20 series as they already have more than adequate ventilation.  They are just a little large for a 2 channel build, but I can deal with that.


----------



## haejuk

If I use an aluminum case for my Sigma22 and one for my Beta22 with the B22 stacked on top of the S22, will an unshielded transformer cause any hum in my B22?  I have read that aluminum is a totally useless an as EMI shield.  I was going to stack 2 Par-Metal 20 series cases on top of eachother, even though they are way bigger than what I need for a 2 channel build.  Will I have problems without a shielded toroid?


----------



## MrMajestic2

Quote: 





haejuk said:


> If I use an aluminum case for my Sigma22 and one for my Beta22 with the B22 stacked on top of the S22, will an unshielded transformer cause any hum in my B22?  I have read that aluminum is a totally useless an as EMI shield.  I was going to stack 2 Par-Metal 20 series cases on top of eachother, even though they are way bigger than what I need for a 2 channel build.  Will I have problems without a shielded toroid?


 
   
  I've built one B22/S22 combo with four transformers in it and I didn't hear any hum.


----------



## mechgamer123

Can anyone answer my noobie question? How much would all of the parts for 3 boards cost?


----------



## jcx

I realize its hard for newcomers to judge but 3-channel really is a unfortunate local to head-fi fad - not technically justified - you can have an excellent amp with just 2 amp boards
   
http://www.glassjaraudio.com/product.sc?productId=5 is one kit source
   
  for further cost savings you can buy open frame linear supplies pre-built for less than sigma22 kit prices, near the cost of new parts alone if you shop aggressively unless you find surplus/remaindered/used parts
   
   
  the biggest step up in "quality" - in many of the parameters that are claimed to motivate "3-channel" construction - is "dual mono" - separate, isolated power supplies for each channel - but to get full advantage requires 4-pin "balanced" connectors/headphone cabling


----------



## OJNeg

Quote: 





mechgamer123 said:


> Can anyone answer my noobie question? How much would all of the parts for 3 boards cost?


 
   
  I think you could get the beta22 boards (w/components) for ~$100 each. The sigma22 board (w/components) would cost another $100. Add in the step-down transformer, heatsinks, case, case components, internal wiring, power and transfer cables, and shipping and....I'm not sure where that leaves you. My educated guess would be <$500 if you're lucky. Can anyone give a more concrete number for a frugal-ish 2 channel build? I'm actually quite interested myself.
   
  Quote: 





jcx said:


> I realize its hard for newcomers to judge but 3-channel really is a unfortunate local to head-fi fad - not technically justified - you can have an excellent amp with just 2 amp boards
> 
> http://www.glassjaraudio.com/product.sc?productId=5 is one kit source
> 
> ...


 
   
  Link? Or are they just out there?


----------



## jcx

http://www.mouser.com/catalog/catalogusd/645/2174.pdf  [size=xx-small]HAA24-0.6-A+-G[/size] dual 24 V @0.4 A is a fine size for most headphones/2 board Beta22 - more V "needed" only for a few insensitive exotics


----------



## haejuk

I have all the parts for my boards, but before I start I am planning everything out so I don't end up with a mess on my hands.
  So, I am back with a few questions about parts for the S22.  I would like some suggestions as to what are some attractive power switches that are rated up to 250V (I will be adding a voltage selector).
   
  I have found this one on my own so far:
http://www.mouser.com/ProductDetail/Schurter/124166211120000/?qs=VO2%2fVXZcKR0q6Y2q9v1PLg%3d%3d
   
  I was wondering if there are other good looking ones out there, preferably in black, rated for 250V.  Also, is this one safe to hook up to the power mains as a power switch?  Any suggestions would be helpful.
   
  I also need suggestions for IEC power connectors (fuse?), and I found a voltage selector which should work with the transformer I have (series-parallel).  If anyone is interested, I plan to use this voltage selector:
http://www.mouser.com/ProductDetail/Schurter/00334504/?qs=j1qng3XoT%2fnBgzwr5nRvnQ%3d%3d
   
  I found the connectors I will use for the umbilical cable on p. 103 of this thread, but don't know what cable to use for it.
   
  Finding the proper parts for the B22 is much easier as I understand that end better.  But I would like some suggestions for internal wiring wire (especially sheilded wire to wire to the pot on the front).
   
  Thanks as always.


----------



## MrMajestic2

Quote: 





haejuk said:


> I have all the parts for my boards, but before I start I am planning everything out so I don't end up with a mess on my hands.
> So, I am back with a few questions about parts for the S22.  I would like some suggestions as to what are some attractive power switches that are rated up to 250V (I will be adding a voltage selector).
> 
> I have found this one on my own so far:
> ...


 
  Do not use the switch in your link because its a momentary switch. You will cut the power as soon as you let go.


----------



## haejuk

That does make sense.  I was wondering why it only had 3 contact points.  I guess I am back to the start for the power switch search.


----------



## joeyjojo

Quote: 





mechgamer123 said:


> Can anyone answer my noobie question? How much would all of the parts for 3 boards cost?


 
   
  Including various import taxes in the UK I paid £78.21 per board a few months ago. $100/board is a very good estimate.
   
  The same calculation for a sigma22 is £62.25.
   
  jcx - are you saying 2x beta22 + 2x sigma22 is better or worse than 3x beta22 + 1x sigma22? The cost difference is small (£280.92 vs. £296.88) and if dual mono was better don't you think AMB's own beta22 would be of this design?
   
  I'm interested because I currently have a passive ground build but have parts left over for 4 b22 channels and/or 1 s22. I don't believe adding any of them will produce an audible difference. I suspect Ti Kan uses a 3 channel because it gives him a sense of satisfaction when he imagines the currents cancelling on the supply rails


----------



## cfcubed

Think your queries WRT topologies is well-covered ground here & suggest searching instead of re-hashing the discussion.
  You can search for jcx's posts in particular to locate the various discussions/posts for this.
   
  After building, owning, comparing and/or hearing all but a dual-mono beta22 build (e.g. 4-ch, 3-ch, 2-ch w/sigma22, 2-ch w/simple LM-series regulation), IMO it's difficult to _hear_ differences amongst them.  Probably because of the superior design, PSRR, etc of beta22.  I've even built/sold a nice 4-ch build & kept my "budget" beta22 after directly comparing them w/same source & cans and not being able to reliably discern a difference between them (w/my hearing & music - all caveats apply).
  Quote: 





joeyjojo said:


> jcx - are you saying 2x beta22 + 2x sigma22 is better or worse than 3x beta22 + 1x sigma22?


----------



## joeyjojo

Thanks cfcubed, your experiences back up what I expected on the audible differences between these configurations - they are probably too small to justify $100+ expense, if they're audible at all.
   
  The theoretical benefits are very real (current cancellation on supply rails with 3/4 channel primarily) but using such a config in real life is I think more for the satisfaction of knowing than anything else. This is why jcx calls it a "fad" I think.
   
  I haven't searched through jcx's posts, but he seems to be saying that dual mono is somewhere between passive ground and active ground. I was just pointing out that the difference in price between dual mono and active ground is actually very small (5%) so not doing active ground and using 2 sigma22s is not justified by price. If one did as he suggests and gets a cheaper power supply that probably changes things.
   
  To say using three B22 boards "is not technically justified" is simply false however (this has been done to death). However it probably is mainly for the warm feeling when you imagine those quiescent power rails. This is why AMB says that 2 channels is a world class amplifier, 3 is the icing on the cake (but for a 33% cost hike).


----------



## OJNeg

Let me get this straight. The dual mono design assumes you have a PS board for every amp board correct? This would mean 2 beta boards and 2 sigma boards. A fully balanced build means you would have 4 beta boards and 2 sigma boards, correct?


----------



## cfcubed

Quote: 





ojneg said:


> Let me get this straight. The dual mono design assumes you have a PS board for every amp board correct? This would mean 2 beta boards and 2 sigma boards.


 
  Yes if choosing to use the "customary"/"default" PS to power them (σ22).
  Quote: 





ojneg said:


> A fully balanced build means you would have 4 beta boards and 2 sigma boards, correct?


 
  That's one option but a single σ22 will power a 4-ch / balanced β22 for headphone duty.


----------



## OJNeg

Quote: 





cfcubed said:


> Yes if choosing to use the "customary"/"default" PS to power them (σ22).
> That's one option but a single σ22 will power a 4-ch / balanced β22 for headphone duty.


 

 Doesn't a truly balanced design have to run off of separate power supplies?


----------



## jcx

"dual mono" completely isolated amplifiers for L,R channels With 4-pin "balanced" headphone connector/cabling separating R,L driver wiring completely cures any "cross contamination", common gnd coupling issues between the channels - R,L channel load currents never "mix"
  the signal gnds are usually still connected in the source, so mains-sec leakage current can still flow in the signal gnd path - use split bobbin ps xmfr with lower parasitic C than toroids, heavy shield braid coax for signal IC, or balanced input with pin 1 gnd carrying the leakage current
   
  "true balanced" has a few interpretations - bridged output "4-board" B22 doesn't meet the strictest definition but gives some of the advantages - common mode rejection happens but eats into dynamic range if the Vcm is at all large, and in Class A the bridged amps do draw ~constant current from the ps
   
  'balanced" doesn't really say anything about number of power supplies - some versions of balanced/bridged amps mitigate some power supply effects so a "balanced" design may give some of the advantages of multiple isolated supplies
   
  a "balanced" amp with bridged output "bypasses" common gnd impedance issues by not having load current flowing in the gnd
   
  a "true balanced" input amp even with a single ended output, even single supply for both channels, can reject common gnd impedance error signals by virtue of its input signal common mode rejection - if it is wired correctly
  each input signal diff receiver should translate the signal input for that channel to the gnd/return terminal of the headphone driver for the same channel
   
   
  with its output cascode, filtered input circuitry giving ridiculously good PSRR I really don't think the B22 "needs" the cancellation of ps load current variation at the price of doubling the load - you could easily lose more to the effects of the heavier load
   
   
  and as mentioned above, well executed B22 projects 2,3,4 board, 1,2,4 power supplies all can be excellent, differences can be made inaudibly small in most home listening situations


----------



## joeyjojo

Thanks jcx.
   
  Quote: 





jcx said:


> the signal gnds are usually still connected in the source, so mains-sec leakage current can still flow in the signal gnd path - use split bobbin ps xmfr with lower parasitic C than toroids, heavy shield braid coax for signal IC, or balanced input with pin 1 gnd carrying the leakage current


 
   
  Can you please explain this bit? Which transformers are you talking about?


----------



## amb

haejuk said:


> That does make sense.  I was wondering why it only had 3 contact points.  I guess I am back to the start for the power switch search.




You can use a normally-open momentary switch as a "trigger" for the ε24 power switch driver circuit, which then uses a relay to switch the power. With the ε24, the momentary switch can have low voltage and current ratings because it doesn't "see" the AC line. The relay must have contacts rated for the desired voltage and current.


----------



## haejuk

Thanks Ti.  I had found the e24, but I don't really want another board and another transformer in my build.  I am not super experienced at wiring stuff up and the voltage selector is already giving me a headache.  So I have just decided to go with a simple DPST switch for my power.
   
  I do have to say that the e24 with the pcb for its transformer would make a really cool addition to any project and I can't rule out adding it in after I finish if I can wrap my head around how to wire it in with a voltage selector.


----------



## jcx

Quote: 





joeyjojo said:


> Thanks jcx.
> 
> 
> Can you please explain this bit? Which transformers are you talking about?


 
  I was talking about the power supply transformers, different construction changes how well they couple or isolate from the wall power higher frequency noise - determines how much leakage current your system has in these parasitic gnd loops
   
  to see part of the reasoning used in "gnd contamination" analysis see http://www.diyaudio.com/forums/diyaudio-com-articles/163575-audio-component-grounding-interconnection.html - referenced on AMB's site too
   
  power entry line filter modules also add capacitive line leakage currents which the the signal gnd system has to carry - in single ended inupt amps always use the lowest resistance braid/shield RCA coax
   
   
  "true balanced" input requires additional circuitry to make a differential signal receiver that rejects common mode V - audio input signal transformers are simple, pricey for better performance "full audio" bandwidth, low low frequency distortion
  with the "balanced" B22 just using 4 boards with all the same positive gain any common mode V is amplified by that gain, eats into signal output dynamic range, but does reduce common mode output heard in the headphone drivers to the fraction of the gain resistor tolerance/mismatch


----------



## haejuk

I got some parts for my Beta22 over the past week, but I have a question about locking TRS jacks.  I got a switchcraft locking TRS jack, and tried plugging something into it.  It doesn't really seem to lock.  In fact it takes less force to pull the plug out than the non-locking TRS jacks on my current amps (I am not pushing the unlocking mechanism at all).  Did I get a defective jack or do I need a special connector to get it to lock?  I know this isn't the perfect place to ask, but I figure anyone looking here might have some experience with this.
   
  Edit: Resolved on another forum.  Apparently "locking" TRS jacks may not lock super well sometime, so I ordered a replacement just in case.


----------



## haejuk

I just finished populating all my boards!  I am going to start casework this weekend.  When they are mostly cased up I will start all of the initial checks on them.  I am just waiting on my mini-grabber adapters so that I don't accidentally short anything.


----------



## DefQon

Is it easy to convert a 2 channel passive ground based b22 to a 3 channel active ground or even a balanced setup? (Excluding the fact that more board's for each channel and ground is required).


----------



## johnwmclean

Balanced is as you say 2 extra boards and of course a quad pot.
  1 Sigma22 will power 4 boards for headphone use, use bigger heatsinks and size up the transformer accordingly.


----------



## haejuk

Converting a 2 channel to a 3 channel would just require another board and some re-wiring.  But converting a 2 channel to a balanced 4 channel would require 2 more boards, re-wiring, new input/output jacks, a new volume pot, as well as the related rear/front panel work.  I also believe that the 3 channel build is sort of pointless, there is a post somewhere where jcx pretty much proves this.  People who have built and compared all three say that you are hard pressed to hear any differences between the different versions of the B22.  I would go with 2 channel or 4 channel.  Whatever works for you.


----------



## haejuk

Finally managed to complete my build.  It is my first time doing any case work, and it turned out looking halfway ok.  Listening right now and liking it.


----------



## c12mech

I've started mine.  One sigma board is done.  I only ordered two of the 4700/63 caps so I have to wait for the others to get here before I can finish the other one.  I hope to get the amp boards put together this week.  I have not decided on a case yet so for now it will be on a board on my desk.  I am planning to use a Shallco 46-step switch in an L-pad configuration for the attenuator.  That will take a few days to put together considering it has 176 resistors to connect.  Pictures will follow soon.


----------



## hifimanrookie

maybe a bit offtopic..but has anyone experience with this amp and the exellent he500 headphones? thanks guys!


----------



## DefQon

Quote: 





hifimanrookie said:


> maybe a bit offtopic..but has anyone experience with this amp and the exellent he500 headphones? thanks guys!


 
  Yes.


----------



## hifimanrookie

​


defqon said:


> Yes.



And? How does it pair?


----------



## DefQon

Quote: 





hifimanrookie said:


> And? How does it pair?


 
   
  I have limited experience with the amp's I have tried with the HE-500 so I don't have anything concrete to how well my 3 channel b22 compares besides all the Bursons line of amp/dac (except the new Conductor) and few other OTL amp's that I own. My Bottlehead Crack pairs well with the HE-500's than my b22 does, the b22 is fairly neutral leaning towards bright sig'd, the HE-500's highs can be bright and so it will sound to bright with certain music than the Crack + HE-500. I haven't compared the two and few other amp's long enough to even make a statement about how well they both synergise but I know the HE-500 is not for me which is why I don't pay attention to it. 
   
  I'd think that your 337 amp does better with your HE-500 than the HE-500 does with my b22.


----------



## hifimanrookie

Quote: 





defqon said:


> I have limited experience with the amp's I have tried with the HE-500 so I don't have anything concrete to how well my 3 channel b22 compares besides all the Bursons line of amp/dac (except the new Conductor) and few other OTL amp's that I own. My Bottlehead Crack pairs well with the HE-500's than my b22 does, the b22 is fairly neutral leaning towards bright sig'd, the HE-500's highs can be bright and so it will sound to bright with certain music than the Crack + HE-500. I haven't compared the two and few other amp's long enough to even make a statement about how well they both synergise but I know the HE-500 is not for me which is why I don't pay attention to it.
> 
> I'd think that your 337 amp does better with your HE-500 than the HE-500 does with my b22.


 

 thanks for ur honest reply..the 337 does sound heavenly with my he500! all the best!


----------



## milosz

I have built a single-chassis "3-channel"  Beta-22, with the Sigma PSU of course.  Works great.
   
Would I gain in sound quality by changing this to a two chassis, dual Sigma PSU / balanced Beta 22 (4 channel) ??
   
I had planned to move to balanced (4 channel) for a while, but now I'm re-thinking this.  An "ordinary" Beta 22 is overkill to begin with in many ways- can the balanced version really sound better?
   
I'd love to hear some comments from people who've compared the sound of  a single-ended Beta 22 to a balanced one.
   
My experience with balanced amps is that they "tighten up" the bass a little, but don't really sound that much different otherwise.


----------



## cfcubed

Quote: 





milosz said:


> I'd love to hear some comments from people who've compared the sound of  a single-ended Beta 22 to a balanced one.


 
   
  My opinion FWIW (read posts before & after as well): http://www.head-fi.org/t/243379/roll-call-whos-building-built-or-thinking-of-building-a-beta22/2880#post_8330932
   
  Also I voted with my wallet & sold off my balanced gear (Buffalo32s, Beta22), using the $$$ for other things, in favor of gamma2 + 2-channel Beta22.  Of course the guy who bought my balanced gear voted with his wallet as well but his life & career revolves around music, he has "golden ears' & gets his hearing tested annually.  That he chose Buffalo32s / Beta22 over his much more expensive commercial gear says something about their designs/performance.


----------



## milosz

Thanks.
   
  Very interesting.
   
  I was thinking, "Hey!  Wait!  Why am I converting this amp to 4-board "balanced?" "    And reading in this thread has convinced me that additional sound quality improvement, if any, would be quite minimal and probably inaudible to me.
   
  I bought all the additional amp board parts and also the parts for a second sigma PSU.  I have an extra Beta amp board laying around too, with bad output transistors on it; so now I just fix that, build the other channel and Sigma pSU, and I have a 2-channel Beta  to sell. I even have a Par-Metal case laying around someplace.
   
  I get all the fun of building it (I really like building stuff) and then I get the money back that I put into the parts and the time.  This one, I am going to make it pretty. I wonder how a 3/16" (or even 1/4")  thick polished copper front panel would look on the Par-Metal box?  I am partial to copper.  Maybe add bubinga wood cheeks to the case, too. Bubinga and copper are a really nice combo.


----------



## Senpai3330

For anyone running a fan in their case, how are you powering it? I was planning to just use a typical 12v PC case fan.


----------



## jcx

if you put a fan in your B22 I recommend not powering it - much quieter
   
  you could look at "quiet PC" articles for hints on selecting, mounting, running fans quieter if your really insist on turning it on


----------



## DefQon

jcx I know you and few others prefer the 2 channel over the 3 channel due to the nature of it's engineered design, I've got the DC offset relay installed for my 2 channel which have it's MKP swapped for Wima's and cap's Elna Silmic II's (left over from another build so why not), a nice Valab 24 stepper pot (couldn't tell a diff between a GP one), 16awg "special" spc wiring and Cardas rca jacks for input, what other upgrades would you suggest to having a completely decked out 2 channel? I have built the 3 channel and balanced and like yourself and other's could not hear a single sound difference at all and by the looks of it there is already a active ground with a 2 channel.


----------



## fishski13

if you're not volume matching with a DVM and test tone, all bets are off.
   
  a dual-mono PS will give you best measured performance.
   
  i had a hard time volume matching a balanced B22 with dual-mono PS and stepped attenuator between balanced and unbalanced - running unbalanced was wired dual-mono as well.  i heard a difference, but i also hear a difference between the balanced outputs wired for unbalanced vs unbalanced outputs from my BM DAC1 - again volume matched with various amplifiers.  the balanced XLR wired for unbalanced sounds better than the unbalanced RCAs.  identical wire.
   
  stick to the BOM.  if you have a cap fetish, you could replace the ceramic compensation caps with some film or mica.  space is tight though.
   
  if you feel you need extra power, and/or you feel your source sounds better via balanced, balanced could be considered.
   
  if you feel the need to go high-end with wire, i would recommend various Belden at $0.30-0.40/ft.
   
  personally, i would splurge on a decent pot/SA.  and if going with a single chassis, get an encapsulated/shielded custom wound TX.


----------



## DefQon

Quote: 





fishski13 said:


> if you're not volume matching with a DVM and test tone, all bets are off.
> 
> a dual-mono PS will give you best measured performance.
> 
> ...


 
  Hi fish, thanks for the reply. Nah haven't had the volume DVM'd for matching, it was using the standard 50k RK27 Alps pot before on the amb board of it's own but I felt I needed something more so I tried a spare Goldpoint mini v I had lying around, a sense of more clarity was heard but I had to move that to another fancy amp build I was doing for a friend, so I used a valab stepper that get's good recommendations from here and various other forums (Valab themselves specified that it is matched on both channels and few diyaudio posters measured it).
   
  It is in separate enclosure, running off a single s22. The b22 will be for driving headphones so the single s22 will be plenty for headphone duty, should I need it for pre-amp or speaker functions then I will add in another s22 but I have other better amp's to fill in that role.
   
  I love Belden, used them before for power cables, good quality stuff. 
   
  Thinking of new way's to dress this b22 amp in better clothes. I was originally thinking along the lines using the LCDruino kit and use the AMB attenuator but it would be too much work especially for it to be acting like a pot.


----------



## fishski13

i've preferred the TKD pots over the RK27 and the precise volume control a pot offers over a SA, but am starting to come around to SAs.  i've not tried the Valab, but i do like the Goldpoints and Broskie's.  i have a GP in my own B22.  again, i would splurge on an attenuator/pot, TX, and larger on-board heat sinks before anything else.
   
  i will have a dual-mono balanced B22 in house this summer and am excited to do some more balanced/unbalanced comparisons with my own B22.  both amps are virtually identical component wise and GP SAs.
   
  if you don't need the power of a B22, with the newer generation opamps, the M3 is equally an alternative, albeit different sounding.  while you can still bias the M3 to the same stock B22 quiescent current, 120-160mA, assuming appropriate thermal management and TX sizing, it doesn't have the V-swing of the B22.  still plenty for the large majority of HPs though. you still have the option to up the o11 voltage to 32-36V and use appropriately rated opamps.  again, i wouldn't skimp on an attenuator/pot for the M3.


----------



## preproman




----------



## haejuk

Just a note for anyone building in separate enclosures that are made of anything but steel, you will need a custom shielded transformer for your Sigma22.  I used 2 aluminum cases from parmetal and I had a little buzzing and humming until I replaced the transformer.  Aluminum doesn't offer any shielding against the EMI from the transformer, but it is WAY easier to make holes in with my limited tools


----------



## alota

i had and i have a balanced beta-22 in one chassis.
  never had problems with noise or buzz or hum...


----------



## haejuk

I think it partly depends on what headphones you are using.  I was using Denons which are pretty low impedance and high efficiency so I could hear some of the transformer noise.  In fact, I could hear it VERY clearly with my IEMs and I can still hear much less noise if I try with IEMs, but I can't hear any of the noise with the Denons after I changed the transformer for a sheilded one.  People seem to have a lot of mixed results with single case builds and transformer noise, so there are probably more factors at play than I know about.  The bottom line for me is if you can't hear it, you're good!


----------



## alota

i tried some headphones and never had problems.
  only with the jvc dx-1000 a little hum in the second version of my beta with lower gain.
  very strange


----------



## fishski13

an encapsulated/shielded TX is cheap insurance to prevent EMI in a single chassis build. using shielded wire for longer runs of input wiring to the pot and from the pot to the boards helps with RFI even if housed in a 'shielded' chassis IME.


----------



## DefQon

Quote: 





fishski13 said:


> i've preferred the TKD pots over the RK27 and the precise volume control a pot offers over a SA, but am starting to come around to SAs.  i've not tried the Valab, but i do like the Goldpoints and Broskie's.  i have a GP in my own B22.  again, i would splurge on an attenuator/pot, TX, and larger on-board heat sinks before anything else.
> 
> i will have a dual-mono balanced B22 in house this summer and am excited to do some more balanced/unbalanced comparisons with my own B22.  both amps are virtually identical component wise and GP SAs.
> 
> if you don't need the power of a B22, with the newer generation opamps, the M3 is equally an alternative, albeit different sounding.  while you can still bias the M3 to the same stock B22 quiescent current, 120-160mA, assuming appropriate thermal management and TX sizing, it doesn't have the V-swing of the B22.  still plenty for the large majority of HPs though. you still have the option to up the o11 voltage to 32-36V and use appropriately rated opamps.  again, i wouldn't skimp on an attenuator/pot for the M3.


 
  By dual mono balanced b22 you mean by 2 boards configured into mono config or ?? 
   
  The M3 with bass boost is still on my to build list to see how well it complements my SA3k which supposedly matches very well. But tbh I'm done with all headphone gear, just planning to get a good source and possibly the 007 MK1's and call it a permament end game for me.


----------



## alota

Quote: 





fishski13 said:


> an encapsulated/shielded TX is cheap insurance to prevent EMI in a single chassis build. using shielded wire for longer runs of input wiring to the pot and from the pot to the boards helps with RFI even if housed in a 'shielded' chassis IME.


 
  my amp has nullaudio power cables from the power section to the boards and the moon-audio black dragon in the amplifier section.
  this cable is very good and does not cost a fortune


----------



## fishski13

defqon said:


> By dual mono balanced b22 you mean by 2 boards configured into mono config or ??
> 
> The M3 with bass boost is still on my to build list to see how well it complements my SA3k which supposedly matches very well. But tbh I'm done with all headphone gear, just planning to get a good source and possibly the 007 MK1's and call it a permament end game for me.




i meant to say dual-mono PS, as in a single o22 and TX driving a single balanced channel (2 boards), for a total of 2x o22 and 2x TXs to drive both channels (4 boards).


----------



## DefQon

I wonder if it's possible to configure a 2 channel or 3 channel into a balanced setup. I know there are some discussion over the past 2 years with the passive configuration (i.e. 2 channel) already having a dedicated ground to itself I wonder if you one use this for the isolated ground from each board plus the signal in/out for balanced operation. Or a 3 channel, with the 3rd active dedicated board to handle both the other channel ground.


----------



## alota

Quote: 





fishski13 said:


> i meant to say dual-mono PS, as in a single o22 and TX driving a single balanced channel (2 boards), for a total of 2x o22 and 2x TXs to drive both channels (4 boards).


 
  correct,  but is possible one sigma22 for 4 boards, right?


----------



## DefQon

Quote: 





alota said:


> correct,  but is possible one sigma22 for 4 boards, right?


 
  I've built a b22 using 1 sigma for 4 boards. Not speaker duty though. Still plenty of power.


----------



## preproman

Why not add the second PSU?


----------



## fishski13

Quote: 





alota said:


> correct,  but is possible one sigma22 for 4 boards, right?


 
  yes - just make sure that the heat sinks are sized correctly based on the voltage supply and quiescent bias current of the amp boards since the total current load/power dissipation is spread across less devices/heat sinks.


----------



## Senpai3330

Hey everyone, my Beta22 is build is chugging along, but I'm not sure how the grounding should work out for the layout I've chosen.

It's a 1 Chassis build with the transformer isolated into a smaller aluminum enclosure inside the main body. The box for the transformer is isolated from the main body with rubber feet. I think that places it similar to wiring scheme #2 on the AMB site. 



The IEC Inlet will be in contact with the main chassis. The Input and Headphone Output XLRs will be in contact with main chassis as well. Could someone confirm if this setup causes any grounding issues?

Reference image in case anyone wanted to draw suggestions.


----------



## haejuk

I don't think there is any reason to isolate the transformer in an isolated aluminum chasis inside of the main enclosure.  Aluminum won't provide any EMI sheilding at all.  I think it would be a better idea to just build this as a one case solution using the single case wiring scheme.  The IEC inlet will not have any electrical contact with the main case and can be grounded to the internal chasis if you really want to.  The problem is that even if you ground the IEC ground to the internal aluminum chasis, there is still a chance that a wire leading to that case could come loose and come into contact with the main chasis causing a dangerous situation because it won't be properly grounded.
   
  I hope this makes sense and I could be wrong since I am not an expert, hopefully someone else will weigh in.  I did build a 2 channel B22 with a seperate Sigma22 PSU.


----------



## Senpai3330

haejuk said:


> I don't think there is any reason to isolate the transformer in an isolated aluminum chasis inside of the main enclosure.  Aluminum won't provide any EMI sheilding at all.  I think it would be a better idea to just build this as a one case solution using the single case wiring scheme.  The IEC inlet will not have any electrical contact with the main case and can be grounded to the internal chasis if you really want to.  The problem is that even if you ground the IEC ground to the internal aluminum chasis, there is still a chance that a wire leading to that case could come loose and come into contact with the main chasis causing a dangerous situation because it won't be properly grounded.
> 
> I hope this makes sense and I could be wrong since I am not an expert, hopefully someone else will weigh in.  I did build a 2 channel B22 with a seperate Sigma22 PSU.




I was under the idea aluminum is a very popular material for shielding though? The aluminum box should be preventing EMI leak from the transformer is what I was led to believe.

The issue is that the IEC inlet contacting the outer main body of the amp is not my choice. The flange mount forces the metal body of the IEC inlet to make contact. I'll double check once it's actually mounted to make sure that's the case. However, that means grounding it to the inner transformer box isn't an option.

I do have the components for the ground loop breaker on hand, but I don't quite understand why I need to use it with my set up.

Sorry, I'm not trying to be difficult. I'm just trying to clarify things before rushing ahead.


----------



## DefQon

Generally it's a good practice to keep the trafo's separate from the PCB's in separate enclosures. But you can eliminate interference issues or crosstalk between the components if you have it well isolated/insulated in it's own cover in a single box enclosure.
   
  I prefer the simplicity of wiring and less effort involved with having a single unit enclosure but prefer the look of a dual enclosure one for the amp itself and 1 for the psu. Do post pictures of the build too. I'm in the process of converting my 2 board to possibly a balanced setup (if enough space) so I can steal some ideas off you. hehe


----------



## haejuk

Quote: 





senpai3330 said:


> I was under the idea aluminum is a very popular material for shielding though? The aluminum box should be preventing EMI leak from the transformer is what I was led to believe.
> 
> The issue is that the IEC inlet contacting the outer main body of the amp is not my choice. The flange mount forces the metal body of the IEC inlet to make contact. I'll double check once it's actually mounted to make sure that's the case. However, that means grounding it to the inner transformer box isn't an option.
> 
> ...


 
   
  After thinking about this some more I think that you are basically making a single box enclosure.  The box with the transformer is basically just for sheilding if I understand correctly.  This would neccesitate using the use of wiring as shown in the single enclosure wiring diagram and I am not sure it would matter if the transformer box was isolated or not.  In my own B22 build I used aluminum case for the amp and the PSU and I still got transformer noise until I replaced the transformer with a sheilded one.  It is pretty hard to block out transformer noise without using one that is build sheilded, or at least that is what I was told by Amb.
   
  Once again, I am not 100% sure.  If no one else has any suggestions, you could always ask on the amb labs B22 forum.  I got help from amb himself when I posted my questions there for my build.


----------



## Senpai3330

Thanks, I did make a post there as well, but the board seems to move quite a bit slower. I think I will just install the ground loop breaker under the assumption that I'll essentially be building Option 3.

Also, how exactly does one isolate XLR's from the main chassis? It shares a ground with the 4 amp boards and the output XLR as well as the volume pot which is listed as "connected" to the main chassis in option 3, so is there any point?


----------



## haejuk

That board does move quite a bit slower, but usually you will have some responses within 24 hours or so.  I am not familiar with the balanced wiring scheme, but I can see your question is valid.  The diagrams on amb's site don't seem to address this.  Looking at the B22 gallery on his site I am starting to have a bad feeling about this build as I don't see any balanced B22s that are in a single enclosure.  I don't think I can be of any further help, but I hope someone will address this.  If you get any help on the amb labs forum let us know here.


----------



## Senpai3330

Will do, thanks for the replies.


----------



## Senpai3330

I also have a cookie tin and no shame if it really comes down to using 2 chassis.


----------



## Senpai3330

I figured out a way to still do a pseudo option 2 grounding scheme. The IEC inlet will be insulated from the outer chassis using U-trim (C-trim, edge trim, a lot of names for it but it's the rubber trim PC case modders often use when they make a cut to their chassis) and the ground will be run to inner transformer box still. The flange mount should work fine even with a slightly elastic material around the edge of the cutout. I don't really worry about the grounding wire coming loose and shorting anything because there's literally nothing between the inlet and the inner box. Solid gauge wire over a short distance, should be fine.

Gonna go dote over aesthetic things like electroetching the front panel design and whatnot while I wait for my last 2 boards to come in the mail.


----------



## DefQon

Quote: 





senpai3330 said:


> I also have a cookie tin and no shame if it really comes down to using 2 chassis.


 
  hahaha.
   
  Why not just do a 6 channel? xD
   
http://www.head-fi.org/t/669613/fs-rockhopper-6-channel-beta22-amplifier-price-drop


----------



## Senpai3330

defqon said:


> hahaha.
> 
> Why not just do a 6 channel? xD
> 
> http://www.head-fi.org/t/669613/fs-rockhopper-6-channel-beta22-amplifier-price-drop




Christ just populating 2 amp boards was boring enough to make me antsy. The builder's patience must be incredible.


----------



## DefQon

Shame the original builder wasted there money on 2 extras boards which have no improvement over a 4 board balanced configuration.


----------



## wink

The idea behind the 6 board build is versatility.
   
  properly done it can be used as 2 separate 3 board systems for 2 different inputs & outputs in the same build.


----------



## alota

Quote: 





wink said:


> The idea behind the 6 board build is versatility.
> 
> properly done it can be used as 2 separate 3 board systems for 2 different inputs & outputs in the same build.


 
  of course, to listen two headphones at the same time or with a friend eating a pizza


----------



## Senpai3330

Just a fair word of warning:
It feels great when you're just doing the physical process of building the amp, but once you hit the electrical troubleshooting... I haven't felt this much anxiety in a while. I had to dig into my old medication to handle how awful I felt today


----------



## haejuk

When I built mine I read the directions at least 10 times before I did the testing and biasing.  I was pretty scared to do that too.  When I tested my second board I smoked a part because the cheap clip-on leads I bought shorted the resistor I was measuring the voltage accross to the ground plane.  It turned out not to be so bad, Amb helped me figure out which parts to replace and how to test them.  Don't worry, you can do it!


----------



## Beefy

Quote: 





senpai3330 said:


> I was under the idea aluminum is a very popular material for shielding though? The aluminum box should be preventing EMI leak from the transformer is what I was led to believe.


 
   
  Aluminium is a good shielding material for radio waves, but does diddly squat for magnetic fields from the transformer. Get rid of it and wire as if for a one-box build.


----------



## wakibaki

Quote: 





beefy said:


> Aluminium ... does diddly squat for magnetic fields from the transformer.


 
   
  Absolutely correct.
   
  Don't forget to try out the transformer in different orientations to see which is quietest. This is important, it can make a big difference. Just listen to the amplifier turned up full with a source plugged in but with nothing playing and turn the transformer around every which way to see if you can hear any difference.
   
  w


----------



## haejuk

I found IEMs very handy in determining if you are hearing any transformer noises.  But I built a 2x gain B22, so YMMV.  If you are building 6x or 8x or whatever the default is then you may be able to hear any noises just fine with your regular headphones.  Also, having the source plugged in and not playing is a must, or you will just hear an unterminated connection.


----------



## alota

Quote: 





beefy said:


> Aluminium is a good shielding material for radio waves, but does diddly squat for magnetic fields from the transformer. Get rid of it and wire as if for a one-box build.


 
  ...or one transformer with plastic box like nuvotem-talema and a iron box coated with copper foil


----------



## fishski13

Quote: 





wakibaki said:


> Absolutely correct.
> 
> Don't forget to try out the transformer in different orientations to see which is quietest. This is important, it can make a big difference. Just listen to the amplifier turned up full with a source plugged in but with nothing playing and turn the transformer around every which way to see if you can hear any difference.
> 
> w


 
   
  good advice and something i do will all my builds before drilling out the TX mounting hole.


----------



## Beefy

Quote: 





alota said:


> ...or one transformer with plastic box like nuvotem-talema and a iron box coated with copper foil


 
   
  If you want shielding, don't do a half-assed homebrew job - do it properly and get a factory-shielded unit. l have several SumR ones that are all perfect, and very affordable.


----------



## fishski13

x2 on the SumR recommendation.  they're completely shielded/encapsulated and very reasonable and excellent quality.  i consider the added cost cheap insurance for a noise free, single chassis build.


----------



## haejuk

x3 here.  SumR even custom cut the shielding to fit into my case that was not very tall at no extra charge.


----------



## alota

SumR is U.S. brand?


----------



## haejuk

I think he is based in Canada.


----------



## Beefy

Quote: 





alota said:


> SumR is U.S. brand?


 
   
Let me Google that for you......


----------



## techboy

Where can I find a beta22 builder? Need a 2.0 ch with metal chassis. Ready to use. Budget $500 or less. Can anybody help?


----------



## Beefy

Quote: 





techboy said:


> Where can I find a beta22 builder? Need a 2.0 ch with metal chassis. Ready to use. Budget $500 or less. Can anybody help?


 
   
  I can help by telling you to stop dreaming. Those are *ridiculous* expectations.


----------



## techboy

How is it ridiculous? All parts with a chassis cost barely $350. What is the minimum amount of service charge? How much? Isn't $150 okay for a couple of hours?


----------



## johnwmclean




----------



## alota

Quote: 





techboy said:


> How is it ridiculous? All parts with a chassis cost barely $350. What is the minimum amount of service charge? How much? Isn't $150 okay for a couple of hours?


 
  a couple of hours?
  first: to populate the boards, is a hard work.
  second: calibrate the boars
  third:hole the chassis, wiring, etc.
  fourth: 350 dollars waht components?
  the beta deserve good quality


----------



## fishski13

putting together a BOM and ordering parts is more than 2hrs, much less building the amp.


----------



## Beefy

Quote: 





techboy said:


> How is it ridiculous? All parts with a chassis cost barely $350. What is the minimum amount of service charge? How much? Isn't $150 okay for a couple of hours?


 
   
  If you are happy with a B22 thrown together in a couple of hours, go right ahead.
   
  Hint: you shouldn't be happy with that.


----------



## Greed

Quote: 





beefy said:


> If you are happy with a B22 thrown together in a couple of hours, go right ahead.
> 
> Hint: you shouldn't be happy with that.


 
   
  Is it even possible to assemble an entire B22 in a few hours? Fastest I've heard is 5. That builder (that is able to assemble in 2 hours), whoever they are, is Dr. Octo.


----------



## fishski13

Quote: 





greed said:


> Is it even possible to assemble an entire B22 in a few hours? Fastest I've heard is 5. That builder (that is able to assemble in 2 hours), whoever they are, is Dr. Octo.


 
   
  no way.  sure, stuffing a single O22 and 2x B22 boards in 5hrs, but not chassis work, wiring, biasing and testing.  stuffing boards is the easy part.


----------



## Greed

Quote: 





fishski13 said:


> no way.  sure, stuffing a single O22 and 2x B22 boards in 5hrs, but not chassis work, wiring, biasing and testing.  stuffing boards is the easy part.


 
   
  Yea, I don't think that was taking into account casework - I mean I've been working on my case for 2 weeks... lol.


----------



## greeny

anyone still building their own b22? or looking to build b22?


----------



## DefQon

Quote: 





greed said:


> Yea, I don't think that was taking into account casework - I mean I've been working on my case for 2 weeks... lol.


 
  2 weeks? I've been planning my case work (drilling, board orientation and measurements) in my b22 enclosures for almost a year lol. Need to buy a drill press.
   
  Quote: 





greeny said:


> anyone still building their own b22? or looking to build b22?


 
  Wow, lurking since 2011 with the first post to see who is still building a b22. Welcome to the boards, friend.


----------



## Greed

defqon said:


> 2 weeks? I've been planning my case work (drilling, board orientation and measurements) in my b22 enclosures for almost a year lol. Need to buy a drill press.
> 
> Wow, lurking since 2011 with the first post to see who is still building a b22. Welcome to the boards, friend.




A good drill press does make the job a lot swifter and easier. 

The planning didn't take to long. The troubleshooting has taken the longest. :mad:


----------



## DefQon

Quote: 





greed said:


> A good drill press does make the job a lot swifter and easier.
> 
> 
> 
> ...


 
  Indeed, it is even if one had a steady hand, a hand drill is no match to the precision from that of a drill press. Wish I had my own CNC and engraving machine too, I've contacted a few local suppliers here to get quotes on engraving and milling work to be done on my b22 enclosures, suffice to say it is not cheap, price is about the same as a single b22 board with BOM parts from Glas Jar Audio at $100 a pop.
   
  +1 on troubleshooting, a major headache of any diy process if you run into problems, but you learn a great deal about things once you rectify your mistakes.


----------



## greeny

defqon said:


> 2 weeks? I've been planning my case work (drilling, board orientation and measurements) in my b22 enclosures for almost a year lol. Need to buy a drill press.
> 
> Wow, lurking since 2011 with the first post to see who is still building a b22. Welcome to the boards, friend.




It's been a long while!!  I actually got my parts for quite some time... But the enclosure is putting me off for a long while... Haha hopefully I'm able to get some ideas here for my enclosure.


----------



## DefQon

Yeah indeed. Building the amp is not hard. The enclosure/case part is the final step in DIY that takes the most time and sometimes most expensive part of the project if you want a perfect finished product.


----------



## haejuk

The enclosure was a pain to do.  I found a really old drill press in my dad's basement that fit a hand drill and used that to do my casework.  You can probably find one at your local home improvement store.  A triangle file and a couple of round files also helped a great deal to make larger holes and rectangular holes (like for the IEC power entry).  Of course my B22 was not a real pretty creation and it was made from aluminum, so it was relatively easy to file out the larger holes.  I was always planning to get some custom front panels done to give it a professional look, but once it is done and working, I really didn't care


----------



## greeny

Anyone had considered using wood or acrylic for the panels instead?? Is it feasible?? Both are much easier to work with...


----------



## haejuk

I am fairly sure you could get something like that to work.  I did get a plastic front panel made for my O2 amp and I was in contact with the same guy to make similar front panels for my B22 and S22, but I never got around to planning them out!  I think the only thing you would need to do is ground the volume pot to the metal part of the case with a wire (if you are doing a 2 chassis build, not sure about single enclosure).


----------



## mvrk10256

Does anyone have an estimated finished cost (not including housing) per board?
   
  Also has anyone messed with the gamma dac?


----------



## preproman

Long live the Beta22.  Later this month I hope to get mine re freshed so to speak..


----------



## greeny

Quote: 





mvrk10256 said:


> Does anyone have an estimated finished cost (not including housing) per board?
> 
> Also has anyone messed with the gamma dac?


 
   
  What do you mean by the finished cost per board? You can get the kit from glassjar for abt $100 per board with the parts? You'll have to solder it yourself though.


----------



## mvrk10256

Quote: 





greeny said:


> What do you mean by the finished cost per board? You can get the kit from* glassjar for abt $100 per board with the parts*? You'll have to solder it yourself though.


 
   
  Answer I was looking for thanks. So realistically you will spend $300-$340 on just the naked hardware for a 3 channel setup.


----------



## Greed

Quote: 





mvrk10256 said:


> Answer I was looking for thanks. So realistically you will spend $300-$340 on just the naked hardware for a 3 channel setup.


 
   
  No. You also have to factor in - casework (both chassis and external parts), power supply transformer and board/s, wiring, solder, soldering iron (if you don't have one), misc. tools. I might be missing something.


----------



## mvrk10256

I have all the tools. Forgot the PSU....
   
  Quite a expensive DIY.


----------



## Greed

Quote: 





mvrk10256 said:


> I have all the tools. Forgot the PSU....
> 
> Quite a expensive DIY.


 
   
  Definitely. I wouldn't recommend it if you are trying to build an amp on the cheap. This design is top-notch even though it is dated. It still competes very formidably within the <$1K price range.


----------



## haejuk

Quote: 





mvrk10256 said:


> Does anyone have an estimated finished cost (not including housing) per board?
> 
> *Also has anyone messed with the gamma dac?*


 
   
  I built myself a Gamma2 dac right after I finished my B22.  The only challenge was soldering the surface mount parts.  Some of the legs are just so tiny and it is impossible to see if there are any solder bridges!


----------



## jcx

skip the 3rd channel - its a technically flawed idea that somehow caught the imagination of of many - but fails to improve many of "flaws" it claims to be addressing when looking in detail at the engineering theory and at measurements of other "3-channel" amps
   
  if you worry about gnd contamination and channel crosstalk there is no debating that rewiring with 4-pin "balanced" headphone connector and dual mono amps (separate, dual V, "passive gnd" power supplies for each channel) actually do improve the numbers


----------



## mvrk10256

Quote: 





haejuk said:


> I built myself a Gamma2 dac right after I finished my B22.  The only challenge was soldering the surface mount parts.  Some of the legs are just so tiny and it is impossible to see if there are any solder bridges!


 
  I have the grub dac kit in my mail box right now. Planning on hard wiring it to my Bravo. I always just use a bright lightbulb to check solder bridges, and the smallest .15" Weller tip. 
  Quote: 





jcx said:


> skip the 3rd channel - its a technically flawed idea that somehow caught the imagination of of many - but fails to improve many of "flaws" it claims to be addressing when looking in detail at the engineering theory and at measurements of other "3-channel" amps
> 
> if you worry about gnd contamination and channel crosstalk there is no debating that rewiring with 4-pin "balanced" headphone connector and dual mono amps (separate, dual V, "passive gnd" power supplies for each channel) actually do improve the numbers


 
  Thanks for that. I was wondering the same thing. I am a EE, but my focus is primarily in energy systems - electric motors, batterys, and the such.


----------



## greeny

Quote: 





jcx said:


> skip the 3rd channel - its a technically flawed idea that somehow caught the imagination of of many - but fails to improve many of "flaws" it claims to be addressing when looking in detail at the engineering theory and at measurements of other "3-channel" amps
> 
> if you worry about gnd contamination and channel crosstalk there is no debating that rewiring with 4-pin "balanced" headphone connector and dual mono amps (separate, dual V, "passive gnd" power supplies for each channel) actually do improve the numbers


 
   
  It's kinda too technical for me.. but since i already got my 3 boards... might as well!!


----------



## haejuk

I followed jcx's advice and skipped the 3rd channel board.  It saved me $100 and his arguments made a lot of sense as to why the 3-channel may not be better than 2 channel.  I was also unable to find anyone who definitively said "I have heard two channel and three channel builds and the three channel build sounds better."  The closest I found it someone who said they heard 2 channel, 3 channel, and fully balanced builds and said the sonic differences were minimal, if any.


----------



## Zashoomin

Quote: 





mvrk10256 said:


> Does anyone have an estimated finished cost (not including housing) per board?
> 
> Also has anyone messed with the gamma dac?


 
  I have build a gamma 2.  and yes the biggest challenge is the surface mount.  also you really need to make sure that when you plug it with usb or walwart and you don't short anything I burned out a couple chips the first time 
	

	
	
		
		

		
			





.  But other than that it doesn't require any wiring and is a very nice little dac.  
   
  Also does anyone know the any good enclosures for a 4 channel beta22?  And would you guys suggest separate enclosures for power supply?


----------



## fishski13

Quote: 





zashoomin said:


> I have build a gamma 2.  and yes the biggest challenge is the surface mount.  also you really need to make sure that when you plug it with usb or walwart and you don't short anything I burned out a couple chips the first time
> 
> 
> 
> ...


 
  the amount of experience/chassis work you can do and the quiescent current bias will drive the chassis design.
   
  a single chassis 4 channel B22 could be done with off-board heat sinks and a large chassis like one from the modushop.com.  this would be a very challenging chassis build and not one to undertake unless you have a lot of experience with chassis work and the proper tools.  i would recommend a shielded TX.
   
  an easier solution would be a 2 chassis design.  the 12x12x3 Par-Metal series will accommodate 4 boards and the stock 1.5" heat sinks, but require terracing the boards with stand-offs and precise chassis work.  it's a tight fit.  
   
  personally, a 16x12x3 Par-Metal would be a simpler solution and allow taller heat sinks and the ability to play with the quiescent current bias a bit above 160mA if you wanted.  whether or not to go with 1 or 2 O22s would determine the size of the PS chassis.


----------



## Zashoomin

Quote: 





fishski13 said:


> the amount of experience/chassis work you can do and the quiescent current bias will drive the chassis design.
> 
> a single chassis 4 channel B22 could be done with off-board heat sinks and a large chassis like one from the modushop.com.  this would be a very challenging chassis build and not one to undertake unless you have a lot of experience with chassis work and the proper tools.  i would recommend a shielded TX.
> 
> ...


 
  Thank you for helping out. what is the difference between using 1 or 2 O22's and what case would you recommend for that?


----------



## DefQon

1 O22 will be plenty for just driving headphones 2,3 or balanced operations. But if you really need the extra O22 just for kicks or driving speaker loads, then it doesn't hurt to add it in. You can start off with one O22 then add in another one + trafo if really desired.


----------



## preproman

Go with 2 O22s all the way.  Overkill is good..


----------



## Zashoomin

Quote: 





preproman said:


> Go with 2 O22s all the way.  Overkill is good..


 
  I'm trying to keep the cost down so I think I will stick to one.  But in order to drive audeze lcd 2's and 3's I understand that there would be more power if I had 4 boards instead of say 2 or 3.  Also is it possible to have single ended inputs and outputs with a fully ballanced design?


----------



## preproman

*fishski13 can answer that...*


----------



## sachu

Quote: 





zashoomin said:


> I'm trying to keep the cost down so I think I will stick to one.  But in order to drive audeze lcd 2's and 3's I understand that there would be more power if I had 4 boards instead of say 2 or 3.  Also is it possible to have single ended inputs and outputs with a fully ballanced design?


 
  really it comes down to whether you want a balanced rig or not. If your source is single ended, then keep it simple, build a 2 board, SE B22 running 150mA bias on 2.5 thermalloy heatsinks at 24V rails. THat's plenty of power to drive the LCD2/3s. 
   
  As for your question on SE inputs and outputs with a balanced design. yes. No that's possible. See the amb site for a diagram on how to do this. It is all there.


----------



## DefQon

Quote: 





preproman said:


> Go with 2 O22s all the way.  Overkill is good..


 
  Yeah overkill is good for cost is no object. But his on a budget man. lol
  Quote: 





sachu said:


> really it comes down to whether you want a balanced rig or not. If your source is single ended, then keep it simple, build a 2 board, SE B22 running 150mA bias on 2.5 thermalloy heatsinks at 24V rails. THat's plenty of power to drive the LCD2/3s.
> 
> As for your question on SE inputs and outputs with a balanced design. yes. No that's possible. See the amb site for a diagram on how to do this. It is all there.


 
  +1. Indeed, I've built one of each configuration, 2 and 3 channel designs I heard no difference at all. But going from a 2 channel to balanced there was some gains but not night and day difference, so going SE best keep it simple to a 2 channel or so.


----------



## fishski13

on paper, the LCD3 is speced at 91dB/mW and 45ohm impedance.  this means that to achieve 110dB you need a total of 79mW, with approx 1.9Vrms voltage swing and 42mA current delivery.  while i have spent some time in meet conditions with the LCD3 and the LCD2, i can't comment on subject opinions of power requirements.  having "a little" headroom above this is a good thing for quieter mastered recordings and musical peaks.       
   
  reducing the O22 rails to 24V isn't a bad idea unless you need enough Vswing to drive the HE-6 or K1000.  this means less power dissipated by the heat sinks and allows you to play around with the quiescent current bias.  i prefer 200mA, but have gone up as high as 250mA or so.  a higher bias means more power in Class A, but my preference isn't due to the fact that my HPs need more power in Class A, but rather the devices themselves sound better with my ancillary gears with the higher bias.  a bias of "only" 80mA may sound better to your ears?  i even prefer my M3 with a bias of 150mA but don't have the heat sinks or TX to go comfortably higher.  both the B22 and M3 use the same output MOSFETs.  YMMV.


----------



## DefQon

fischki do you have pictures of your 2 channel?


----------



## fishski13

Quote: 





defqon said:


> fischki do you have pictures of your 2 channel?


 
   
  i have them on my website in the lower right hand corner on the first page with the amber fresnel LED, but basically just the faceplate.  the internals and layout are virtually identical to the other 2 channel B22 with the green LED on my website on the second page under "portfolio", except: the boards are a little more trashed since it's been through numerous mods and rechassis over the past 5 years; the chassis is 3" vs 4" tall; GP SA vs TKD; 1.5" vs. 2.5" heat sinks; 100VA vs 50VA TX; and different tin-platted Belden wire vs. SPC.  the "high ohm" TRS has 100R resistors in series for HPs that need a little extra mid-bass.  the TXs are fully shielded/encapsulated from SumR.


----------



## DefQon

Can't find it. Had the impression yours is a dual mono configuration.


----------



## fishski13

no dual mono. not enough room for the form factor i wanted.  i can send you pics later when i get home from work.


----------



## DefQon

Cool thanks.


----------



## preproman

That's right.. up that bias.  Overkill is the way to go.  I want to push it to the limits


----------



## alota

strange situation in my beta: my builder changed the gain from 8X to 5X and the beta has more power.
  the output level of my source is higher compared to my old source.
  my builder say me that the beta gain is not like in the other amplifier, or rather is not in the input stage but the gain is in the feedback section.
  my apologies if some word is incorrect but i´m ignorant in electronic stuffs


----------



## preproman

Quote: 





alota said:


> strange situation in my beta: my builder changed the gain from 8X to 5X and the beta has more power.
> *the output level of my source is higher compared to my old source.*
> my builder say me that the beta gain is not like in the other amplifier, or rather is not in the input stage but the gain is in the feedback section.
> my apologies if some word is incorrect but i´m ignorant in electronic stuffs


 
   
  The bold may will have a lot to do with it as well.


----------



## alota

Quote: 





preproman said:


> The bold may will have a lot to do with it as well.


 
  probably. i understood your message but what it means "bold"?


----------



## fishski13

Quote: 





alota said:


> strange situation in my beta: my builder changed the gain from 8X to 5X and the beta has more power.
> the output level of my source is higher compared to my old source.
> my builder say me that the beta gain is not like in the other amplifier, or rather is not in the input stage but the gain is in the feedback section.
> my apologies if some word is incorrect but i´m ignorant in electronic stuffs


 
   
  a higher gain means that it will get louder more quickly as you turn up the volume.  if your source is outputting more Vrms than your previous one, then the extra voltage gets multiplied with the gain.  even if you dropped the gain from 8x to 5x, differences in the voltage that the your two sources produce can offset this. 
   
  assuming the O22 is configured to deliver +/-30V, you B22 will be able to swing 43Vp-p, or 15Vrms without a load connected.  with an unbalanced source that outputs a typical 2Vrms, you will need a gain of 8x to achieve the max total voltage swing that the B22 can produce.  if you reduce the gain to 5x with a source that outputs 2Vrms, the max Vswing is reduced to 10Vrms.  while the total Vswing is reduced, it's not entirely correct to say it has less power.  yes, it has less total watts it can produce due to limiting the total Vswing, but it has the same power into less voltage demanding loads.  much above 10Vrms is K1000 and HE6 territory.  assuming a source with 2Vrms, 5x gain is plenty for the marge majority of HPs.  if you can adjust the output from the source, this is a bonus to achieve a reasonable amount of play on the pot and still achieve quiet operation into sensitive HPs.


----------



## Zashoomin

Sorry for so many questions but do you know if it is possible to make a beta22 into a speaker amp and a headphone amp.  From what I understand with a little tinkering that I could get 50W per channel out of a balanced configuration.  Or is that either a headphone amp or a speaker amp?


----------



## fishski13

Quote: 





zashoomin said:


> Sorry for so many questions but do you know if it is possible to make a beta22 into a speaker amp and a headphone amp.  From what I understand with a little tinkering that I could get 50W per channel out of a balanced configuration.  Or is that either a headphone amp or a speaker amp?


 
   
  yes you can, but you need to consider what speakers you're driving, near-field or far-field, and do some maths.  major considerations are TX VA and heat sinking for the extra current demands.  also, the gain required to deliver a decent Vswing for the speakers may be too much for sensitive HPs, resulting in not enough play on the pot or noise.  why don't you do some searching over at the amb.org website and join the forum.  there's plenty of info.


----------



## preproman

Quote: 





zashoomin said:


> Sorry for so many questions but do you know if it is possible to make a beta22 into a speaker amp and a headphone amp.  From what I understand with a little tinkering that I could get 50W per channel out of a balanced configuration.  Or is that either a headphone amp or a speaker amp?


 
   
  B24 for a DIY speaker amp.  Also lots of Nelson Pass amps can be DIY as well.


----------



## DefQon

I'll second the Nelson amps line, got some boards for 3 model of the F series coming my way soon.


----------



## alota

Quote: 





fishski13 said:


> a higher gain means that it will get louder more quickly as you turn up the volume.  if your source is outputting more Vrms than your previous one, then the extra voltage gets multiplied with the gain.  even if you dropped the gain from 8x to 5x, differences in the voltage that the your two sources produce can offset this.
> 
> assuming the O22 is configured to deliver +/-30V, you B22 will be able to swing 43Vp-p, or 15Vrms without a load connected.  with an unbalanced source that outputs a typical 2Vrms, you will need a gain of 8x to achieve the max total voltage swing that the B22 can produce.  if you reduce the gain to 5x with a source that outputs 2Vrms, the max Vswing is reduced to 10Vrms.  while the total Vswing is reduced, it's not entirely correct to say it has less power.  yes, it has less total watts it can produce due to limiting the total Vswing, but it has the same power into less voltage demanding loads.  much above 10Vrms is K1000 and HE6 territory.  assuming a source with 2Vrms, 5x gain is plenty for the marge majority of HPs.  if you can adjust the output from the source, this is a bonus to achieve a reasonable amount of play on the pot and still achieve quiet operation into sensitive HPs.


 
  thank you for explanation


----------



## preproman

Quote: 





defqon said:


> I'll second the Nelson amps line, got some boards for 3 model of the F series coming my way soon.


 
   
  3 different amps?  That's a lot of building..


----------



## DefQon

Quote: 





preproman said:


> 3 different amps?  That's a lot of building..


 
  Yeah the thing is, along with the other boards I have lying around I will probably never get around to building it. My balanced b22 is on the bench just waiting to do case work but cbf, completed half of my KGSSHV off board version, got 3 tube amp's to finish restoring and rebuilding, 3 amps to re-cap and service...Sigh if only money grew on the trees and I could freeze time.


----------



## preproman

Quote: 





defqon said:


> Yeah the thing is, along with the other boards I have lying around I will probably never get around to building it. My balanced b22 is on the bench just waiting to do case work but cbf, completed half of my KGSSHV off board version, got 3 tube amp's to finish restoring and rebuilding, 3 amps to re-cap and service...*Sigh if only money grew on the trees and I could freeze time. *


 
   
   
  Looks like you need a lot of both


----------



## DefQon

Indeed.


----------



## alota

Quote: 





defqon said:


> Yeah the thing is, along with the other boards I have lying around I will probably never get around to building it. My balanced b22 is on the bench just waiting to do case work but cbf, completed half of my KGSSHV off board version, got 3 tube amp's to finish restoring and rebuilding, 3 amps to re-cap and service...


 
  you have so little work to do...


----------



## fishski13

defqon said:


> I'll second the Nelson amps line, got some boards for 3 model of the F series coming my way soon.




the FW designs are simple but require some chassis work/heat sinking cosiderations. i've had a F5 driving FR Fostex and even smaller ATC monitors for years now and have no desire to build another speaker amp anytime soon - just speakers. sounds great driving my K701 too.


----------



## joeyjojo

Quote: 





greed said:


> This design is top-notch even though it is dated. It still competes very formidably within the <$1K price range.


 
   
  I'm surprised nobody picked you up on this. Care to elaborate?


----------



## preproman

Yeah Greed, what you trying to say - You trying to start a fight?


----------



## Greed

Quote: 





joeyjojo said:


> I'm surprised nobody picked you up on this. Care to elaborate?


 
   
  Honestly, a fully decked B22 is still one of the smoothest sounding SS amps I've heard <$1K. It competes very well with some of the other production amps out there like the Mjolnir, Soloist, Violectric, etc. You start to hear some of its flaws and dated designs when you hike above that price range. For example, the first time I heard the B22, I thought this was it. Great sound, good power, and you can design it the way you want = Perfect, right? Well, that is true until you stretch your budget a bit further and delve into the 1500-3000 price range. Now you have some stiff competition, with many designers that know exactly what Hi-End enthusiasts want, and plenty of what they don't want. Now that I've heard some of the higher end SS, Tube, and hybrid amps - the B22 sounds good instead of great. Still a very capable design and product, but the B22 isn't the ceiling by any means. 
   
  When you factor in how much it costs to design a 4-Board, 2 PSU, full loaded (meaning premium caps, res, rca's, pot, etc.) you are talking about $1200+. I know my B22 has cost me atleast that much, and I haven't invest everything I can into it. After buying the GS-X MK II, I don't know if I will. It seems like a fruitless battle to do so. 
   
  I'm not saying by any means the B22 is bad - no way - it is a good amp and if I had to do it over again, I'd probably just build a 2-Channel, 2 PSU design and be done with it. I can't tell you if the 4-Board makes a difference in sound to me because I hardly remember what a 3 channel sounds like... In hindsight, it would be more cost effective and a better value for sure, but that's just the way it goes. I may sell my B22 or keep it, but it does bring you a bit of self-gratification that I (you) built it from the ground up. If you don't have the skills, well then you are still getting a really good amp. 
   
  Quote: 





preproman said:


> Yeah Greed, what you trying to say - You trying to start a fight?


 
   
  I know, I speak fighting words don't I?


----------



## alota

Quote: 





greed said:


> Honestly, a fully decked B22 is still one of the smoothest sounding SS amps I've heard <$1K. It competes very well with some of the other production amps out there like the Mjolnir, Soloist, Violectric, etc. You start to hear some of its flaws and dated designs when you hike above that price range. For example, the first time I heard the B22, I thought this was it. Great sound, good power, and you can design it the way you want = Perfect, right? Well, that is true until you stretch your budget a bit further and delve into the 1500-3000 price range. Now you have some stiff competition, with many designers that know exactly what Hi-End enthusiasts want, and plenty of what they don't want. Now that I've heard some of the higher end SS, Tube, and hybrid amps - the B22 sounds good instead of great. Still a very capable design and product, but the B22 isn't the ceiling by any means.
> 
> When you factor in how much it costs to design a 4-Board, 2 PSU, full loaded (meaning premium caps, res, rca's, pot, etc.) you are talking about $1200+. I know my B22 has cost me atleast that much, and I haven't invest everything I can into it. After buying the GS-X MK II, I don't know if I will. It seems like a fruitless battle to do so.
> 
> I'm not saying by any means the B22 is bad - no way - it is a good amp and if I had to do it over again, I'd probably just build a 2-Channel, 2 PSU design and be done with it. I can't tell you if the 4-Board makes a difference in sound to me because I hardly remember what a 3 channel sounds like... In hindsight, it would be more cost effective and a better value for sure, but that's just the way it goes. I may sell my B22 or keep it, but it does bring you a bit of self-gratification that I (you) built it from the ground up. If you don't have the skills, well then you are still getting a really good amp.


 
  these considerations are obviously personal. i never heard the gsx-mkII but i like the sound of the beta
  about the old design, exist vintage amplifiers that today sound very good


----------



## cfcubed

Quote: 





alota said:


> these considerations are obviously personal. i never heard the gsx-mkII but i like the sound of the beta
> about the old design, exist vintage amplifiers that today sound very good


 
  Agree.  IMO that topic is not related to this thread's forum/title/subject matter, DIY amps and specifically building β22s.  Maybe experiences/suggestions WRT β22 build specifics (e.g. 2-,3-,4-channel, dual-mono, etc) are though.
   
  Now comes something that likewise belongs in a different thread (e.g. "Which high-end DIY amp should I build?").  Though β22 design may be a few years old haven't seen a DIY dynamic headphone reference amp design come along that supplants its performance, drive capability, availability, approachability & support.  If there had I would have considered building it instead of sticking with β22 as my "end game" (w/HE-500s btw).


----------



## preproman

Quote: 





cfcubed said:


> Agree.  IMO that topic is not related to this thread's forum/title/subject matter, DIY amps and specifically building β22s.  Maybe experiences/suggestions WRT β22 build specifics (e.g. 2-,3-,4-channel, dual-mono, etc) are though.
> 
> Now comes something that likewise belongs in a different thread (e.g. "Which high-end DIY amp should I build?").  Though β22 design may be a few years old haven't seen a DIY dynamic headphone reference amp design come along that supplants its performance, drive capability, availability, approachability & support.  If there had I would have considered building it instead of sticking with β22 as my "end game" (w/HE-500s btw).


 
  Here you go:


----------



## alota

Quote: 





preproman said:


> Here you go:


 
  bad boy


----------



## DefQon

Quote: 





fishski13 said:


> the FW designs are simple but require some chassis work/heat sinking cosiderations. i've had a F5 driving FR Fostex and even smaller ATC monitors for years now and have no desire to build another speaker amp anytime soon - just speakers. sounds great driving my K701 too.


 
  That's true. I've got a good power amp chassis that I was going to use for my KGSSHV build but probably not anymore as I wanted everything in a single chassis but not the case as the trafo's and ps board will have to be in a second enclosure. 
   
  I was thinking of housing one of the Pass amp's in it but there will be a lot of empty space.
   
  Funny thing you brought up the F5, have exactly one set of boards for a F5 build.


----------



## Greed

Quote: 





alota said:


> these considerations are obviously personal. i never heard the gsx-mkII but i like the sound of the beta
> about the old design, exist vintage amplifiers that today sound very good


 
   
  Where was I unclear it was my opinion? I used "I" in almost every sentence. Sharing my opinion, nothing else. You obviously like your B22, that's great, I do too. But I don't need to remind people that its your opinion whenever they don't agree with yours. I was answering a question asked, that is all. 
   
  Regarding old design - Vintage does sound nice, but so does modern. Don't want to further "derail" this thread since that is what my answer has lead to I guess. 
   


cfcubed said:


> Agree.  IMO that topic is not related to this thread's forum/title/subject matter, DIY amps and specifically building β22s.  Maybe experiences/suggestions WRT β22 build specifics (e.g. 2-,3-,4-channel, dual-mono, etc) are though.
> 
> Now comes something that likewise belongs in a different thread (e.g. "Which high-end DIY amp should I build?").  Though β22 design may be a few years old haven't seen a DIY dynamic headphone reference amp design come along that supplants its performance, drive capability, availability, approachability & support.  If there had I would have considered building it instead of sticking with β22 as my "end game" (w/HE-500s btw).


 
   
  Was answering a question, I think that is relevant enough, don't you?


----------



## alota

Quote: 





greed said:


> Where was I unclear it was my opinion? I used "I" in almost every sentence. Sharing my opinion, nothing else. You obviously like your B22, that's great, I do too. But I don't need to remind people that its your opinion whenever they don't agree with yours. I was answer a question asked, that is all.
> 
> Regarding old design - Vintage does sound nice, but so does modern. Don't want to further "derail" this thread since that is what my answer has lead to I guess.


 
  easy man. like your, this was just my opinion not a polemic.
  in the end is always a matter of taste and combinations. my apologies if i seemed argumentative


----------



## jc9394

Is GS-X MKII that much better than MKI or beta22? I tried the MKI for a while and still prefer my beta22, I have not heard/tried MKII.


----------



## H22

Well, here goes, I have managed to gather together enough parts to start my first B22 build.
  
 Actually, while I was at AMB's site I also ordered a y1 & y2 kit because I figured a B22 should be fed by something a little better that my Iphone5.
  
 I will start with a 3 channel configuration, however i am second guessing that, I may end up doing a 4 channel even though i do not have a source to take full advantage of it, some day I might.
  
 I know the  B22 was designed to be build with non " boutique" caps, however I happen to have a collection of Elna silmic II caps on hand that i could use, the larger power rail caps i have are 1000uf 50v rather than the
  
 recommended 470uf, outside of PS issues, are there any reasons i shouldn't use these?
  
 Waiting on a mouser order right now, but I am hoping to start populating the boards today if work schedule allows 
	

	
	
		
		

		
		
	


	




.


----------



## H22

I got a good start on the build up. I should probably take some pics, but i cant get too excited about that as there are already tons of images of circuit boards in various states of completion.
  
 I have soldered most of the diodes, as well as all of the constant current devices and transistors.
  
 all of the resistors, pots and caps should be here tomorrow so hopefully i can start the initial set up and testing soon.
  
 I also received my last order from AMB, that included the S22 PS board and  both the y1&y2 boards and giblets. So next pressing issue is to order all the requisite parts for the DAC. 
  
 Now that I have the boards and am asembeling them i find i am more excited about how i am going to house them. I have a few plans floating around in my feeble brain and i hope i can make one look as cool as i picture it.
  
 I want to make the enclosure as small as possible without hampering the amp due to heat concerns.
  
 another thing i have been pondering is what kind of attenuator i will use. I was originally just going to use the 50k blue velvet pot, but after looking at the "light speed" photo-resistant scheme i am thinking about doing my own unique take on a contact-less solution.


----------



## DefQon

h22 said:


> Well, here goes, I have managed to gather together enough parts to start my first B22 build.
> 
> Actually, while I was at AMB's site I also ordered a y1 & y2 kit because I figured a B22 should be fed by something a little better that my Iphone5.
> 
> ...


 
  
 I used 470uf 63v Elna Silmic II's I had lying around. The general rule is 10% tolerance on top of the values you're replacing. Voltage usually doesn't matter but resistance and capacitance does in some cases.


----------



## jcx

for power supply C you need good margin for V rating
  
 you have to allow for peak of AC, high line V and the fact that smaller xfmr have poor regulation == larger V out when not loaded
  
 and its good practice to allow 20% derating after all of the other factors are applied - 50 V rated caps are barely adequate for rectified 24 Vac transformer secondary


----------



## Zashoomin

I am looking to have a preamp output function on my B22.  How would I go about doing that?
 Thanks in advance


----------



## H22

Digikey had some of the 470uf 63v Elna Silmic II's in stock, went ahead and ordered those. B22 boards are complete now except for those  power rail caps and the mosFets.
  
 I am still waiting on some of the power supply components, mainly the triac, so build is on pause till I get the PS put together.
  
 I decided to go with the standard 3 channel config with 8x gain, I can always change it up later if i feel the need to or just want to play with it. I have been doing this long enough i have become quite good at de-soldering components
	

	
	
		
		

		
		
	


	




 .


----------



## fishski13

zashoomin said:


> I am looking to have a preamp output function on my B22.  How would I go about doing that?
> Thanks in advance


 
  
 look under the "Other Options":http://www.amb.org/audio/beta22/ .


----------



## H22

little update just to bump the thread.
  
 Work has kept me busy the last week, 
	

	
	
		
		

		
		
	


	




 hate when that happens.
  
 I  received most of the parts to complete the s22, but I bodged  
	

	
	
		
		

		
		
	


	




  the quantity on a couple of the parts, so waiting on another digikey box to arrive.
  
 The triac I was able to find at digikey was a 100va 24/24 unit, 237-1342-ND hoping this will be enough voltage to supply +-24.
  
 I would like to have all the  finished and tested next week but i doubt that will happen. All I have left to do is assemble the s22 and mount a few remaining parts on the b22
  
 boards, but this weeks schedule is going to be a killer and going on vacation after that.
  
 Its killing me having the first stage of this build so close to finished and not having time to complete it....
  
 Once i finally do get it done then building the case will be the next challenge.


----------



## joeyjojo

h22 said:


> Its killing me having the first stage of this build so close to finished and not having time to complete it....


 
  
 I've got used to that feeling - it's been about 20 months since I ordered the first parts


----------



## Zashoomin

Well I know the feeling but that is because I keep forgetting to order parts and have to wait for them.  I am doing a 2 channel one and have all 3 boards done and just need to work on the enclosure.  20 months though is a long time.  It has only been about a month for mine.


----------



## H22

I was able to finish soldering up the s22 today after work, only took a few minuets, witch was nice as my work day started at 3am and ended at 9:30 pm !

Plugged it in and got just a hair over 48volts across v+ and v-.

There is a slight discrepancy, v+ to ground is 24.042 v
While v- to ground measures out at 24.073 v

So there would seem to be a .031 volt bias to the negative rail, I doubt this will be an issue and I'm guessing it's due to resistor tollerances.

I measured this with my new fluke 289 meter, with a 5 k resistor across v+ and v- to give a small ( 10 ma ( plus led )) load. The 289 is reportedly a very accurate meter. 

So here is a quick pic I snapped after testing it, no burned parts


----------



## DefQon

What gain did you opt for with your b22?
  
 Those ELNA Tonerex cap's look bit different to some of the ones I've been using, what uf/v rating are they, or even better source?


----------



## Zashoomin

I am trying to figure out the encryptions on the side of my transformer and cannot for the life of me figure out which wires go where and why.  It is an avel linberg one.


----------



## DefQon

Picture's please.


----------



## Zashoomin

So there are 4 pads on the S22.  In order ~, G, G, ~.  I assume ~ is signal and G is ground.  also when I look at my IEC connector there is L, N and Ground.  I have no idea which wires should connect to what parts.  

 Thanks in advance.


----------



## DefQon

zashoomin said:


> So there are 4 pads on the S22.  In order ~, G, G, ~.  I assume ~ is signal and G is ground.  also when I look at my IEC connector there is L, N and Ground.  I have no idea which wires should connect to what parts.
> 
> Thanks in advance.


 
 Two primarys binded together is 230v, you'll use I assume 1 one of them for your location, blue is pos, brown is neg/neutral and gry is ground. These hook up to your IEC connector. Two secondary windings two 30v each with it's own ground/neg but you know where that goes on the s22 board.


----------



## joeyjojo

DefQon is wrong in his assumption. Assuming you live somewhere with a 115 V mains supply you want to wire the primaries in parallel (BLU and VIO live, GRY and BRN neutral). Not 100% sure on the secondaries ...


----------



## Zashoomin

defqon said:


> Two primarys binded together is 230v, you'll use I assume 1 one of them for your location, blue is pos, brown is neg/neutral and gry is ground. These hook up to your IEC connector. Two secondary windings two 30v each with it's own ground/neg but you know where that goes on the s22 board.


 
 So violet will be unused?  Blue will be connected to L, brown to N, and Grey to ground.  Red, yellow to ~ and black and orange to G.  am I understanding you correct?


----------



## joeyjojo

zashoomin said:


> So violet will be unused?  Blue will be connected to L, brown to N, and Grey to ground.  Red, yellow to ~ and black and orange to G.  am I understanding you correct?


 
  
 No, you'd only get half the VA rating that way. You need to wire the primaries in parallel with 115 V across each.


----------



## DefQon

joeyjojo said:


> DefQon is wrong in his assumption. Assuming you live somewhere with a 115 V mains supply you want to wire the primaries in parallel (BLU and VIO live, GRY and BRN neutral). Not 100% sure on the secondaries ...


 
  
  


zashoomin said:


> So violet will be unused?  Blue will be connected to L, brown to N, and Grey to ground.  Red, yellow to ~ and black and orange to G.  am I understanding you correct?


 
  
 Sorry Joey is right, primary 115vac windings in parallel for 120vac AC countries, for some reason I looked at it as a multi-tap transformer with 230vac windings as well which is what I'm use to.
  
 For secondary the 2 30v's it will be translated to 30 - 0 - 30, 0v center-tapped with orange and black tied together but the s22 does this for you. 
  
 I've had a bit to drink to night so take my advice with a grain of salt.


----------



## Zashoomin

Thank you both for your help so lets see if I can't get this right this time.  So grey brown are connected to E, blue violet to N, black orange to G, and red yellow to ~.


----------



## DefQon

Blue is positive wire, N is neg.


----------



## H22

What gain did you opt for with your b22?

Those ELNA Tonerex cap's look bit different to some of the ones I've been using, what uf/v rating are they, or even better source?


Got those from digikey, I can't remember the voltage rating off hand, they are either 50 volt or 63 volt, pretty sure they are 63 volt, 4700uf.

I went with a standard build, 3 channel 8x gain


----------



## H22

So there are 4 pads on the S22. In order ~, G, G, ~. I assume ~ is signal and G is ground. also when I look at my IEC connector there is L, N and Ground. I have no idea which wires should connect to what parts. 
-------

That wiring looks the same as the trial I used, if you have 115 volt mains then here is what I did:

Hook blue and violet together, hook grey and brown together. These will go to your hot and neutral from your power cord. I'm not sure witch one is witch or if it even matters ( it is AC after all ?) but I put the wires with the dot (blue and violet) to the hot leg. 

Then for the output, I wired it with the red and orange wires on the center two terminals , these are ground and connected to eachother on the board, then yellow and black for the outer two connections, again as it's AC I don't think it matters witch goes where in the board.


----------



## H22

Actually, looking at it now, possibly the wires with the dots ( 0 volt labeled on the output ) should be connected to the neutral in the mains in? As it's AC and basically a long coil of wire I can't see how it could matter but I'm not an AC guy so please feel free to educate me !


----------



## mcandmar

I agree, Brown is Live and Blue is Neutral.  I have a few toroids and all of them have the dot marked on the neutral side.
  
 Secondary side isnt critical however keeping the convention of dots to the neutral side keeps the AC in phase with mains.
  
 Black and Orange 0v wires are 100% without doubt the secondary, do not connect them to mains!


----------



## H22

Thanks mcandmar, I was wondering about that last night, I'll make sure to change it. 

What sized fuse would you recommend for a 100va triac? Mine is rated for ~ 2 amps output, I need to look at the specs again but I'm guessing input current ( once stabilized) will be less than that (70-80%?) . I'm thinking a 2 amp would be a good starting point? All I have now is a 3 amp, but I'm thinking it would take a pretty good short to pop that.
To be clear I am taking about the mains fuse.


----------



## mcandmar

The peak current will be on initial power up, especially if there is a lot of capacitance in your circuit that needs to charge up.  There is also the debate of slow blow vs fast blow fuses.  I cant see the load of this being anything like a few amps so a 2amp fuse will probably be fine. Certainly a good place to start, the worst that can happen is you pop a few fuses if they are rated to low. To be honest diyAudio is the best place to ask such questions, far more knowledgeable people than i..


----------



## H22

here is a pic from the assembly, boards are now complete except the Fets, it will be a couple of weeks till i can start on it again, once it is set up i will start planning the enclosure, thinking a mix of exotic wood and aluminum.


----------



## Zashoomin

Just completed my first beta 22 build.  It sounds fantastic and is definately an upgrade from my current amp.  Thank you to all those that helped me.


----------



## GrindingThud

Thinking about a 2 channel B22 or a KSA5 build. Waiting for boards..... Got all the chassis stuff in and parts inbound. Should be fun!


----------



## DefQon

Is the bottom one off ebay? I think I have one of those lying aroubd, not sure what size are yours but the ones on ebay can only allow up to 3 boards max on a e22 backplane, 4 boards for balanced won't fit.


----------



## cfcubed

>  4 boards for balanced won't fit.
 Maybe but he's talking 2-channel / passive ground.  A nice way to go - no need for expense/complexity/size of "extra" channels nor the impact of going balanced on source gear, cables, headphone wiring, etc.
  
 Will say you'd be hard-pressed to find a better supported (amb forums, shop, glassjaraudio kits, etc) SS DIY reference amp for dynamic cans than the β22.  Lots of experience with the amp posted around as well.  For me a 2-channel β22 is part of my end-game setup & I've built/listened to a lot of amps.  If you go β22 recommend using 1R R34/R35 (esp. w/TRS jack) & adding zobel network (to avoid perhaps having to later).
  
 Whichever way you go from our PMs I bet an σ22 is going in the little box....  Something like this:


----------



## GrindingThud

You betcha! . I've got to read up on the details of the circuit config...sounds like I have some tailoring options to lock down. 

Yes, just a plain 2 channel to start. If I integrate the heatsinks I might try to get clever.....but for now I just want to get a working system built.

Yes, both cases are from Chinese eBay sources.



cfcubed said:


> >  4 boards for balanced won't fit.
> Maybe but he's talking 2-channel / passive ground.  A nice way to go - no need for expense/complexity/size of "extra" channels nor the impact of going balanced on source gear, cables, headphone wiring, etc.
> 
> Will say you'd be hard-pressed to find a better supported (amb forums, shop, glassjaraudio kits, etc) SS DIY reference amp for dynamic cans than the β22.  Lots of experience with the amp posted around as well.  For me a 2-channel β22 is part of my end-game setup & I've built/listened to a lot of amps.  If you go β22 recommend using 1R R34/R35 (esp. w/TRS jack) & adding zobel network (to avoid perhaps having to later).
> ...


----------



## cfcubed

Think its been a while since there's been detailed activity here for an amp that uses A/C mains.  Four or five people contacted me about the case & may be building σ22s. 
 If any are newish builders respect the importance of safety, I'll mention a few particulars of my build(s) below. 
  
 There are good threads/posts/URLs that detail A/C/mains safety in DIY & builders new to it should certainly seek them out.  E.g. in these builds I used insulated connectors to IEC, a proper chassis ground stack (dedicated screw, lock washers/lock-tite, ring lug, nuts), removed anodizing at chassis ground screw & at parts of enclosure panel mating areas + underside of screws/threads & assured the entire σ22 exterior contacts safety ground.
  
 If building σ22 and/or β22 it pays to carefully review their related info on amb's site & triple-check all your work before powering up.  E.g. a swapped/grounded MOSFET, swapped/maladjusted trimpot, unintended ground/short, slipped probe, pierced solder mask during adjustment/testing are some things to avoid. 
  
 Anyway, in case anyone is considering 2-channel β22 in same case as above know there's significant time overhead to do it (& probably some cursing as well
  

  
 It's a nice quiet build.  Note copper underside of ε12/zobel network/RK40 board is the star ground w/only connection to chassis ground at its mounting screw by headphone jack.  Every "module" can be removed w/o soldering which came in handy for tweaking/lowering the ε12 latch LED brightness  Runs cool & allows trying higher biasing.  BTW I post some other build & parts details here:
http://www.amb.org/forum/post-pics-of-your-builds-t44-690.html#p21728


----------



## Avro_Arrow

Beautiful build.

 Great attention to detail.
  
 p.s. Your table look just like mine


----------



## haejuk

That is a really well planned and executed build!  Love it.


----------



## alota

nice amplifier!!!enjoy...


----------



## DefQon

Is that a Noble pot?


----------



## cfcubed

Thanks guys.  Yep, took quite a while to plan/design/execute the layout - very happy w/the results though.  Even w/after all the builds I've done its difficult to estimate in advance how long a build will _actually_ take
  
 >  p.s. Your table look just like mine
 Heh, yeah its a an old, cheaply "veneered" pressboard repurposed desk but it does the job.  I should take a shot for the pics-of-your-workspace thread.  It's tight, like my builds, but well organized
  
 >  Is that a Noble pot?
 No, its a NOS Alps "Black Beauty" RK40.  Fun fact: Only upon creating a Diptrace lib component for the RK40 did I realize the 27 in RK27 & 40 in RK40 are the pots' widths in mm.  And a lot of Alps pots have passed through my hands
  
 Am enjoying the amp at the moment but may give someone else the opportunity  Now that I've the patterns/process for this particular build down I could spend a couple/few dozen hours making another.
 Note: Next time I'd use allen cap screws for heatsink / "L" bracket attachment - easier clearance WRT β22 & σ22 components.  Also though I noted ease of "module" removal, the liberal use of screw terminals sure made bench testing/assembly easier as well.


----------



## alota

cfcubed said:


> Thanks guys.  Yep, took quite a while to plan/design/execute the layout - very happy w/the results though.  Even w/after all the builds I've done its difficult to estimate in advance how long a build will _actually_ take
> 
> >  Is that a Noble pot?
> No, its a NOS Alps "Black Beauty" RK40.  Fun fact: Only upon creating a Diptrace lib component for the RK40 did I realize the 27 in RK27 & 40 in RK40 are the pots' widths in mm.  And a lot of Alps pots have passed through my hands


 
 i´m really curious about this pot.
 i´ve always heard good things.
 it´s a shame that not exists a quad version


----------



## DefQon

Ah the black beauty was a definite step up from the RK27 standard but still behind the decent steppers out there and the smaller Alpha pots. ALP's is in a way similar to 80's Philips, discontinuing things here and there with zilch backup stock or very very limited quantities.


----------



## H22

My B22 is coming along, this is a pic of the set up phase for one of the boards. I found that mine was no exception, setting the bias current and offset voltage took quite a bit of fiddling. It takes a long time for the temperatures to stabilize. On the second board I set the initial current quite high and let it set for ~20 min before making any further adjustments. This seemed to simplify the process, though I would not recommend doing so without having a reference ( measurements from a known good board ).
  
 I have the L and R boards finished, the Gnd board is almost done but i am waiting on a heat-sink.  I couldn't resist, I went ahead and wired it up in a 2 channel passive ground configuration and gave it a listen this afternoon. 
 I was using my "test" headphones, a set of bose, and using my iphone as the source. It worked great. I wont go into how I thought it sounded, as both the cans and the source are not anywhere near ideal, and my experience with silmic caps is that they need a good dose of burn in, but it didn't do anything wrong and seemed to do a lot right 
	

	
	
		
		

		
		
	


	




.
  
 Hopefully I will be able to get the Gnd board finnished soon and start working on casing it up.
  
 preliminary specs:
  
 3ch b22, single s22 PS @ 48v ( 100 va ) , bias current ~160ma ( .075mv through .47 ohm resistors ) .


----------



## jc9394

Question to all builders, is it true that I should never plug/unplug TRS while the amp is on?  Most of my phones are balanced but just want to make sure I do not do anything that will damage the amp.


----------



## haejuk

It is usually said that if you plug/unplug your TRS quickly then you will probably be ok.  I didn't take any chances and always powered down if I was going to switch out the headphones though.


----------



## jc9394

both 3 and 4 pins balanced are fine?  I have done it multi times with balanced cables.


----------



## Greed

I've read that balanced terminated outputs are fine to swap while the amp is on. Otherwise, SE should be turned off and then swapped. Has something to do with grounding, would have to go back and check out where I read that.


----------



## Jose C

jc9394 said:


> Question to all builders, is it true that I should never plug/unplug TRS while the amp is on?  Most of my phones are balanced but just want to make sure I do not do anything that will damage the amp.


 
  
 Usually it's enough to turn the volume to minimum with TRS connectors. XLR are safe to plug/unplug. If you don't plan to drive speakers and want to use TRS just change the output resistors to 1R or 2R2.
  
 Turning the volume to minimum is always a good practice with any amp when you use TRS connectors.


----------



## jc9394

jose c said:


> Usually it's enough to turn the volume to minimum with TRS connectors. XLR are safe to plug/unplug. If you don't plan to drive speakers and want to use TRS just change the output resistors to 1R or 2R2.
> 
> Turning the volume to minimum is always a good practice with any amp when you use TRS connectors.


 
  
 My beta22 build does not have speaker out.


----------



## naamanf

The TRS shorts signal to ground when plugged/unplugged. If you like replacing MOSFETs go ahead and do it with the power on.


----------



## jc9394

thanks guys, i will keep in mind to power off the beta22 when plug/unplug trs.


----------



## cfcubed

naamanf said:


> The TRS shorts signal to ground when plugged/unplugged. If you like replacing MOSFETs go ahead and do it with the power on.


 
  
 That statement, unqualified (e.g. as it stands), is utter BS & FUD.   Briskly inserting/removing TRS plug with power on & volume down, for a properly constructed / adjusted b22 (w/1R R34/R35s as recommended for TRS), will not/does not cause any problems whatsoever. 
 I've used my b22(s) in this way, briskly inserting/removing headphone TRS plugs if/when necessary, dating back years (e.g. the "budget" b22 in sig - used most weekdays).
 I've no qualms swapping headphones on it "hot", just turn volume down during the brisk insert/remove of TRS plug.  Once on I leave it on for the day, whether swapping cans or not, if not swapping cans I leave 'em plugged in period, even through power on/off cycles (most all my b22 builds have e12s to protect against any DC offset during power up or down).
 To each his own here and this very topic has been discussed ad nauseam here & elsewhere.  People fail on each side of the fence on it. 
 If I didn't have high confidence in my b22 build w/TRS, or its proper adjustment, or it lacked >= 1R R34/R35, then yeah I'd consider powering off during w/the process.


----------



## naamanf

Okay.

Missed the part about using the higher resistance output resistors. If using default .47 ohm resistors my statement stands.


----------



## fishski13

as long as the music is paused and the volume turned all the way down, i've never had an issue with my B22 and 0.47R output FET-Source resistors.  this should be habit for any HP amp though.  that being said, i do recommend 1 or 2R, and a mute switch is fail-safe if primarily rolling TRS without having to power down.  i also prefer a particular Switchcraft TRS jack since they're difficult to short, but they feel industrial and not "hIGH eND".  if you have other people playing with your B22, make sure they know "the rules".  powering down is easy and no big deal.  the B22 can crank out some power.  treat it like a speaker power amp.


----------



## jc9394

fishski13 said:


> as long as the music is paused and the volume turned all the way down, i've never had an issue with my B22 and 0.47R output FET-Source resistors.  this should be habit for any HP amp though.  that being said, i do recommend 1 or 2R, and a mute switch is fail-safe if primarily rolling TRS without having to power down.  i also prefer a particular Switchcraft TRS jack since they're difficult to short, but they feel industrial and not "hIGH eND".  if you have other people playing with your B22, make sure they know "the rules".  powering down is easy and no big deal.  the B22 can crank out some power.  treat it like a speaker power amp.




Thanks Corey, I usually very careful with it and the headphones I have are balanced. I'm considering to bring it to a meet and want to make sure I got it right.


----------



## fishski13

jc9394 said:


> Thanks Corey, I usually very careful with it and the headphones I have are balanced. I'm considering to bring it to a meet and want to make sure I got it right.


 
  
 at the last meet i was at i placed a sign on top of my B22 with polite rules (please and thank yous).  requesting that members ask for assistance before interfacing is not improper either.  pushing the switch and hearing the relay click can be geekishly fun too.


----------



## cfcubed

You make good points Corey esp. regarding meet conditions where much headphone swapping may be happening. 
 And think I owe naamanf an apology for the harshness of my response above.
  
 Had direct experience w/the meet thing @ the 2nd meet I attended.  I'd brought some amps, sources + cans & was talking to someone/working with one set of them when someone walked up & without asking pulled & inserted his cans into my budget b22 (it was power on/volume down).  This was back when it had 0.47R R34/35s (& no e12 btw).  Couldn't react quick enough but saw him insert his TRS plug into it *as slowly as humanly possible*, taking 2 seconds or so to do so!  As if purposely trying to cause smoke.  The amp was fine, perhaps because *it had properly adjusted offset, the most important factor here* (<= 3mv?).  Instructed him about this and have since been wary of exposing my gear to such abuse at future meets.
  
 >  and a mute switch is fail-safe
  
 Don't recall seeing any builds with that.... Is it a momentary switch that lifts ground on the TRS jack?
  
 BTW here's a (good) thread were Ti among others discuss this point: http://www.amb.org/forum/blown-outputs-t2312.html


----------



## fishski13

a DP toggle mute switch could be placed between the outputs from the amp boards to the TRS, only switching the L and R, and effectively removing the TRS from the output.


----------



## cfcubed

fishski13 said:


> a DP toggle mute switch could be placed between the outputs from the amp boards to the TRS, only switching the L and R, and effectively removing the TRS from the output.



Of course but yuk! Might as well use the power switch instead if you must, unless it was some sexy momentary DP


----------



## Xovaan

Hey guys,
  
 I'm about to undertake building a 2 channel b22 with LCduino and an o1 from Glass Jar Audio. I'm interested in using a Par-20 case for the b22/lcduino/o1 setup and a separate enclosure for the o25, o22, and transformers.
  
 1. For anybody who has gone this route, what is a proper way to gauge the dimensions of the LCDuino screen if I plan on having the front panel done with Front Panel Express?
 2. What would you guys recommend for feet for the base of the case?
 3. What is a good case size to fit both transformers, the o25, and o22? The Par-20 cases seem a bit large for something like this.
 4. I have 22awg Belden shielded wiring. What parts of the circuit would benefit most from using this wiring? I've read that any wiring over several inches should be shielded. What's the guideline for hooking up the ground wire in this Belden cable?
 5. Where should I purchase my non-shielded umbilical and board wiring?
  
 Thanks in advance!


----------



## Zashoomin

Does anyone know if it will be ok if I just use 2 Sigma 22 boards supplied by 100VA transformers instead of using 4 in balanced configuration to power speakers.  If I read things correctly, if I set everything up correctly I can output 50W into 8ohms.


----------



## H22

*Does anyone know if it will be ok if I just use 2 Sigma 22 boards supplied by 100VA transformers instead of using 4 in balanced configuration to power speakers. If I read things correctly, if I set everything up correctly I can output 50W into 8ohms. 

If I understand your question correctly, you want to build a 4 channel B22? And you are wondering if you will be ok using only 2 Sigma 22 power supply's with 100VA transformers for speaker use? Yes, I think that you would be fine, 4 sigma 22's would be overkill I think, but for speaker use you might want to upgrade the heatsinks on all the boards.*


----------



## DefQon

2 trafo's and 2 S22 is plenty even for the most demanding speaker duty.
  
 4 S22's will be a waste of money and just plain silly.
  
 Standard heatsinking according to the BOM on AMB is fine for speaker duty but make sure the PSU enclosure has plenty of holes of ventilation especially above crucial areas such as the tip of the heatsink shrouds.
  
 For balanced/single ended headphone duty, 2 S22/2 trafos is overkill.


----------



## joeyjojo

zashoomin said:


> Does anyone know if it will be ok if I just use 2 Sigma 22 boards supplied by 100VA transformers instead of using 4 in balanced configuration to power speakers.  If I read things correctly, if I set everything up correctly I can output 50W into 8ohms.


 
  
 AMB says one S22 per B22 board for speakers (regardless of 2 or 4 board).  Deviate from that and you'll be deviating from the official word.  Anyway, 50 W into 8 ohms would imply a current of over 6 A, which is going to dissipate far too much heat in the MOSFETs for the stock heatsinks.  You should make a thread on the AMB forum and TK will go over the calculations with you.  Offboard heatsinks will be needed, negating some of the gains from cheaping out on the PS.


----------



## Xovaan

Just got my 2ch b22 and lcduino up and running! Gotta say that the sound is surreal, even through my ATH-AD900's! I'll post pics once I order my front panels


----------



## alota

xovaan said:


> Just got my 2ch b22 and lcduino up and running! Gotta say that the sound is surreal, even through my ATH-AD900's! I'll post pics once I order my front panels


 

 too many peoples sais that the beta-22 is not a great deal, the boards are na old design, etc. etc.
 in my opinion(of course i´m a beta-22 owner)this amplifier deserves a lot.
 is not 100% neutral but is near to the neutral and drives very well a lot of headphones
 and the beta-22 improves with better components


----------



## cans4dessert

Does anyone here have much experience with single ended (2-Ch or 3-Ch) B22 paired with HE-6? If you found yourself liking the pairing, how much biasing and gain were you running? I am thinking of getting a new pair of headphones, either HE-6 or LCD-3. Leaning towards HE-6 at the moment for its lower price...


----------



## Zashoomin

cans4dessert said:


> Does anyone here have much experience with single ended (2-Ch or 3-Ch) B22 paired with HE-6? If you found yourself liking the pairing, how much biasing and gain were you running? I am thinking of getting a new pair of headphones, either HE-6 or LCD-3. Leaning towards HE-6 at the moment for its lower price...


 
 Honestly I think that if you are going to power the HE-6 with a beta 22 I would go balanced.  I have heard it with a 2 channel and I thought that it could use a bit more power.  The LCD3's on the other hand sound superb with just 2 channel.


----------



## cans4dessert

Thx Zashoomin. I have no plan of going balanced with my Beta 22 (i've got a 3-Ch setup) any time soon. Just can't find the time =P
 So it seems it would be logical for me to go with LCD-3 based on the recommendations from you and other forum members. No one has yet to suggest pairing with HE-6 over LCD-3. But then again, in the thread "Amps that can drive the HiFiMan HE-6 planar headphones", the OP thought the 3-Ch Beta 22 drove the HE-6 very well. And I wonder if he felt it that way because of the bias current setting of the amp. Perhaps people have varying opinions because of different bias settings??


----------



## Zashoomin

cans4dessert said:


> Thx Zashoomin. I have no plan of going balanced with my Beta 22 (i've got a 3-Ch setup) any time soon. Just can't find the time =P
> So it seems it would be logical for me to go with LCD-3 based on the recommendations from you and other forum members. No one has yet to suggest pairing with HE-6 over LCD-3. But then again, in the thread "Amps that can drive the HiFiMan HE-6 planar headphones", the OP thought the 3-Ch Beta 22 drove the HE-6 very well. And I wonder if he felt it that way because of the bias current setting of the amp. Perhaps people have varying opinions because of different bias settings??


 
 I am not tech exert so I have no idea if you can bias the amp for just as much or close to as much power as a stock 2 or 3 channel beta 22.  But last time I heard the pairing I felt it was a bit lacking. But it is also an opinion so that is just my two cents.


----------



## cans4dessert

Thx for your input. I am far from an expert. I just know how to follow instructions just enough to build a beta 22 =p


----------



## alota

cans4dessert said:


> Does anyone here have much experience with single ended (2-Ch or 3-Ch) B22 paired with HE-6? If you found yourself liking the pairing, how much biasing and gain were you running? I am thinking of getting a new pair of headphones, either HE-6 or LCD-3. Leaning towards HE-6 at the moment for its lower price...


 

 i tried only in balanced mode with a higher output source.
 in my opinion, this is the minimal requirement for the he-6.
 with audeze(i never tried the lcd-3)the situation is different


----------



## fishski13

on paper, a B22 should have no problem powering the HE6.
  
 if you go with 2.5" heatsinks in both the O22 and B22, and size the TX appropriately,  200-225mA quiescent current bias should be achievable, or 400-450mA Class A swing.  i think there are sonic differences between 160mA and 200mA.  depending on preferences, you may like one better than the other.  balancing doesn't double the Class A current delivery since the outputs are in series with one another.
  
 assuming a source of 2Vrms, a gain of 5x or 10Vrms v-swing isn't enough for the HE6.  to achieve the full 15Vrms the B22 is capable of, you need to go with a gain of 8x.  for balanced/4Vrms this means you need a gain of 4x.  if you want to swing the full 30Vrms that a balanced B22 is capable of, then a gain of 8x would be appropriate.
  
 just because your pot may be sitting at 3-5 o'clock doesn't mean the amp is "under-powered".  it's a function of gain.


----------



## alota

fishski13 said:


> on paper, a B22 should have no problem powering the HE6.
> 
> if you go with 2.5" heatsinks in both the O22 and B22, and size the TX appropriately,  200-225mA quiescent current bias should be achievable, or 400-450mA Class A swing.  i think there are sonic differences between 160mA and 200mA.  depending on preferences, you may like one better than the other.  balancing doesn't double the Class A current delivery since the outputs are in series with one another.
> 
> ...


 

 really interesting.
 i came to the end of the pot without any distorsion but is too dangerous for the ears.
 i think that the beta is good for the he-6.
 the problema is the presentation of the bass frequencies with the he-6.
 this headphone does not have a boom boom bass


----------



## fishski13

as long as the gain is within what the max v-swing is, clipping shouldn't occur. driving the HE6 with an unbalanced amp that can only swing 7Vrms, but with a gain of 8x, will clip when the HP requires more voltage than what the amp can deliver and there's still more play on the pot to go "louder".

the 25W B1/F5 is definately not a bassy combo when driving loudspeakers. this combo turns the K701 into bass monsters - i get more bass than any Audeze driven by a typical HP amp. the T50RP turns into mud. i'm sure there's something similar going on with the HE6, albeit maybe not to the same extent.


----------



## jc9394

With my 2x gain balanced beta22 and 2.7V source, it is still lack of power when driving the HE-6 but it sound really really good with LCD-3.


----------



## fishski13

jc9394 said:


> With my 2x gain balanced beta22 and 2.7V source, it is still lack of power when driving the HE-6 but it sound really really good with LCD-3.



 


no doubt. you need mucho more gain than 2x. the voltage requirements for the HE6 or K1000 usually require a dedicated amp with gain structure optimized, especially with a stepped attenuator.


----------



## jc9394

I'm very happy with the setup driving the LCD and HD800, no plans to get the he-6.


----------



## Xovaan

So you're saying the Beta22 can drive the LCD-3 with 2x gain? That's good news! I'm at 12-2 o'clock with my ATH-AD900's  and it's _plenty_ loud.


----------



## cans4dessert

Fishski13:
  
 I do have 2.5" heatsinks with a 100VA trafo. I am currently running gain of x5, but I do have spare components to increase the gain to x8 if I needed to. So if I went on the path of high quiescent current with gain of 8, are you saying I should be able to drive the HE-6 properly? Or do you think it is still safer me to go with LCD3? The beta 22 is my only good amp and I am also concerned about it being too powerful (too little pot play) with gain of 8 for my other future headphones =P


----------



## jc9394

Yes, 2x gain. It is effective 4x since it is balanced and my source is 2.7v out. I usually listen at 4-5 clicks.


----------



## fishski13

cans4dessert said:


> Fishski13:
> 
> I do have 2.5" heatsinks with a 100VA trafo. I am currently running gain of x5, but I do have spare components to increase the gain to x8 if I needed to. So if I went on the path of high quiescent current with gain of 8, are you saying I should be able to drive the HE-6 properly? Or do you think it is still safer me to go with LCD3? The beta 22 is my only good amp and I am also concerned about it being too powerful (too little pot play) with gain of 8 for my other future headphones =P


 
  
 kind of opening a can of worms...and i've never heard the HE6.
  
 the power delivery of the amplifier should be capable of driving the HPs specs with "adequate" headroom and allowing for quieter mastered recordings.  assuming no significant hearing loss, 110dB is plenty.
  
 assuming that the HE6 is 78dB/mW and 43R impedance:
  
 105dB = 501mW, 4.6Vrms, 108mA
 110dB = 1.6W, 8.3Vrms, 193mA
 115dB = 5W, 14.7rms, 340mA
 120dB =  15.9W, 26.2Vrms, 608mA
  
 the O22 has no current limiting.  effective continuous current delivery is going to be determined by the heatsinking, TX VA, and fuse rating.  the stock 1.5" heatsinks are good for 1A continuous and peak much larger, but we're no where near those limits driving the HE6.
  
 assuming a 2Vrms unbalanced source, to achieve at least the 14.7Vrms needed to deliver 115dB, you need a gain of 8x.
  
 in a push-pull Class A design, total Class A current delivery will be 2x the quiescent current.  so a quiescent current bias of 170mA = 340mA, or the current delivery required to stay in Class A at 115dB.  if the load draws more than 340mA, then you're in Class A/B.
  
 if my Benchmark DAC1 as a HP amp or my QRV-08 sounds thin driving my K701 or Fostex T50RP, it's not because its underpowered - it's just not the best pairing.
  
 going back to my B1/F5 anecdote, if any HP is tuned or dampened with an under-driven amplifier, this may affect the sonics if the HP is being driven by a "normal" amplifier.  i really have no idea and am just throwing out ideas as to why people like under-driven speaker amplifiers powering the HE6.
  
 i would think 100VA would be enough for a 3 channel B22 and 200mA quiescent current bias.  you could even take the bias up higher with a 2 channel.  the only reason that i see to take the bias up would be for sonics.  changing the quiescent current bias will affect the sonics somewhat.  going with 2.5" heatsinks is never a bad idea with a B22 - more so on the B22 boards themselves since they're dropping more voltage and dissipating more power across a single MOSFET/heatsink than across the pass MOSFETs in the O22.
  
 a gain of 8x would be fine even with the LCD3.  they're not terribly efficient and you should have no noise issues.  i didn't have any noise issues when driving my K701 and 8x gain.  i dropped the gain to 5x though.  you should be able to get away with a 24 stepped attenuator with decent volume control as well.  once you start driving more efficient HPs, you may want to consider a pot instead or dropping the gain.  changing the gain isn't a huge deal.


----------



## cans4dessert

I thought the HE-6 has sensitivity of 83.5dB/mW with impedance of 50Ohm? I do not know how to do the calculations myself, but will the numbers stay roughly the same? say for 115dB level, will the current draw be still similar to 340mA? Also, on the AMB website, it says the power output for B22 is 18Wrms into 8Ω unbalanced. Is that the maximum power output the amp is capable of in single ended mode regardless of the transformer rating? If so, what limits the output power?


----------



## fishski13

cans4dessert said:


> I thought the HE-6 has sensitivity of 83.5dB/mW with impedance of 50Ohm? I do not know how to do the calculations myself, but will the numbers stay roughly the same? say for 115dB level, will the current draw be still similar to 340mA? Also, on the AMB website, it says the power output for B22 is 18Wrms into 8Ω unbalanced. Is that the maximum power output the amp is capable of in single ended mode regardless of the transformer rating? If so, what limits the output power?



 


oops. my numbers were from memory and incorrect. here's what Tyll measured: http://www.innerfidelity.com/headphone-data-sheet-downloads . 77dB/mW and 53R impedance. which means that on paper, the B22 should be able to drive the HE6 to 113dB with 14.5Vrms and 275mA. if going by the HiFiMan specs, then would would be looking at 119dB with about the same power demands.

P=V*I. the max rail voltages the B22 is spec'd for is +/-30V. you cannot get anymore than the 15.2Vrms uloaded spec. the rated VA for the O22 PS is appropriate for the spec'd B22 power. you can increase the VA for more Class A bias to get more power in Class A, but i honestly have no idea how much more current you could realistically get in Class A/B.

 i can PM you later on how to perform the calcs.


----------



## bbest

Hello!
  
 Have anyone use custom PSU for beta22. Something like this http://www.ebay.com/itm/ULN-PS7-Ultra-Low-Noise-6-0A-High-Current-Power-Supply-for-High-Quality-Audio/231109887461?rt=nc&_trksid=p2047675.m1851&_trkparms=aid%3D222002%26algo%3DSIC.FIT%26ao%3D1%26asc%3D261%26meid%3D3875593153771070086%26pid%3D100005%26prg%3D1088%26rk%3D2%26rkt%3D5%26sd%3D330869867631%26. This PSU with ultralow noise. Original PSU sigma 22 has 102.5 db noise against 132 on ebay's one.


----------



## fishski13

bbest said:


> Hello!
> 
> Have anyone use custom PSU for beta22. Something like this http://www.ebay.com/itm/ULN-PS7-Ultra-Low-Noise-6-0A-High-Current-Power-Supply-for-High-Quality-Audio/231109887461?rt=nc&_trksid=p2047675.m1851&_trkparms=aid%3D222002%26algo%3DSIC.FIT%26ao%3D1%26asc%3D261%26meid%3D3875593153771070086%26pid%3D100005%26prg%3D1088%26rk%3D2%26rkt%3D5%26sd%3D330869867631%26. This PSU with ultralow noise. Original PSU sigma 22 has 102.5 db noise against 132 on ebay's one.


 
  
 i'm not sure if the open-loop gain here defines the PSRR.  i would pose the question at amb.org.


----------



## jcx

the B22 has several design feature that give higher PSRR - separately filtered C-multiplier/Gyrator front end supply, cascodes between all rail referenced and ground referenced stages, grounded shunt R, complementary "balanced" compensation
  
 these should add up to awesome PSRR for the B22 amplifier
  
 a "super regulator" supply for the B22 is more "gilding the lily" than puting a Pd reflective plating layer inside a heavy Au casting (bright Ni or other shiny layer is put under cheap, thin
 Au "plating" because the Au so thin it is actually partially transparent )
  
  
 there is a relation between gains, PSRR in monolithic op amps which don't have a ground pin - all gains are referenced to one or the other of the supply pins - but the B22 doesn't have that limitation


----------



## Teerawit

Well looks like something is in the works....


----------



## funch

Balanced (almost) in the house! Can't wait to see the finished product.


----------



## Teerawit

Some progress with better lighting:
  

  
  
 Didn't realize it takes so long to solder one amp board! I hope to get another one set up tonight to test out dual mono unbalanced.


----------



## funch

Is the Par-Metal case a 16" x 16"? Looks like you have plenty of room in there, unlike the 12 x 12 cases that are popular here.
  
 Take it from an old DIY'er and don't get in a hurry. Disaster will ensue! Take it slow and enjoy the ride, and don't compromise anything 
 to get it done quickly.


----------



## Teerawit

It's a 16x12x3. I didn't like the look of the terraced board arrangement in a 12x12, so I opted for a bigger case which also comes with extra ventilation holes on the top panel. I finished the second board but I stopped because I'm a little daunted by the input wiring. I really want to apply power to the boards to see if everything is okay but I think getting the input and outputs properly wired first will be better...


----------



## Zashoomin

So I just finished my new beta and I thought I would show it off here.  It is fully balanced with 4 channels, has epsilon 24 muting circuit.  
  

 The amp has no back panel because front panel express over milled one of my panels and I had to wait for them to send me a new one. 
  

 Power supply
  

 Off
  

 Back with everything plugged in chaotically.
  
 It sounds great, and is dead silent.  Just burning it in now and making sure everything is working as intended.


----------



## funch

Very nice. Who did the front panel? I really like the script engraving, and the led's around the volume knob is a nice touch.


----------



## Zashoomin

funch said:


> Very nice. Who did the front panel? I really like the script engraving, and the led's around the volume knob is a nice touch.


 
 Front Panel Express did all 4 of my panels.  That script is in their software that they offer for you to use.  The so called LED's are actually just holes that I had them drill half way through the panel 
	

	
	
		
		

		
			





.  With the right light it shines a bit.


----------



## funch

Ah, I see. It must have been the flash that made them look illuminated. On one of my FPE panels that was too thick for the LED to reach through,
 I had a countersunk hole done on the outside of the panel. Worked pretty well.


----------



## fishski13

excellent job Zash!


----------



## Zashoomin

fishski13 said:


> excellent job Zash!


 
 Thanks 
	

	
	
		
		

		
		
	


	




.  Now time to build a Dynahi and Krell KSA 5


----------



## fishski13

the KSA-5 should be a breeze after building a balanced B22.


----------



## Zashoomin

fishski13 said:


> the KSA-5 should be a breeze after building a balanced B22.


 
 I sure hope so.  I ran into so many problems that delayed this amp, not all of them being mine.  I am excited to see which sounds better.


----------



## Zashoomin

A couple more pictures...I have no shame.  I replaced the cheep chinese pot with a goldpoint one.  Looks better and also all the turns feel better.


----------



## Teerawit

Awesome. Did you tap the V+ and V- power rails for the epsilon 12 from the DC input directly or from the amp boards?


----------



## Zashoomin

teerawit said:


> Awesome. Did you tap the V+ and V- power rails for the epsilon 12 from the DC input directly or from the amp boards?


 
 Directly from the power rails.  I think that it makes wiring easier that way.


----------



## SilverEars

I'm curious what the Beta will do to a K701. I know it's bass light, and it's not as easy to drive as typical dynamics.  I wonder if it will drastically change the sound from a typical amp.  Anybody try it on Beta 22?  
  
 Anyway, the HE-6 sounds fantastic on the 2 channel Beta 22.  It's hard to believe it could get better with 4 channels.


----------



## fishski13

I like like the K701 pairing provided you increase the quiescent current to 180mA and add 100R or so output impedance.

Provided you have a gain of at least 8x to achieve the 15Vrms/43Vpp that the B22 is capable of with a source that puts out 2Vrms, an unbalanced B22 has plenty of V to drive the HE6. Balancing will double the Vswing and give you more Class A/B current delivery, but total Class A current delivery will not increase.


----------



## SilverEars

fishski13 said:


> I like like the K701 pairing provided you increase the quiescent current to 180mA and add 100R or so output impedance.
> 
> Provided you have a gain of at least 8x to achieve the 15Vrms/43Vpp that the B22 is capable of with a source that puts out 2Vrms, an unbalanced B22 has plenty of V to drive the HE6. Balancing will double the Vswing and give you more Class A/B current delivery, but total Class A current delivery will not increase.


 
 I guess the output impedance will alter the FR, probably cut off some of that spark the K901 is known to have and boost the low end?
  
 Anyway, I have an interesting question.  Have you guys experienced warm-up period with headphones or your Betas?  I noticed that my HE-6 initially doesn't sound that great until I have it playing for awhile.  Could it be my Beta or HE-6 taking time to warm up?


----------



## fishski13

no proof, but i personally believe that the AKGs were tuned with 100-120ohm output impedance.  adds some needed warmth.
  
 MOSFETs havve a negative tempco and will run at a higher bias initially when cold before dropping after thermal stabilization.  i'm guessing you could be hearing the sonic impact of a different bias?  for me, i prefer the sonics of a slightly higher bias at 180mA, measured immediately after taking the chassis lid off.


----------



## funch

I've always wanted to hear a B22, and figured the only way was gonna be to build my own.


----------



## funch

zashoomin said:


> Power supply
> 
> 
> 
> ...


 
  
 I was curious where you picked up the transformer for the switch circuit. I bought one of the mounting boards, only to discover that
 the trannies for them were unavailable. Thanks.


----------



## Zashoomin

funch said:


> I was curious where you picked up the transformer for the switch circuit. I bought one of the mounting boards, only to discover that
> the trannies for them were unavailable. Thanks.


 
 Allied Electronics.  Mouser and Digikey didn't have them.


----------



## luke99

Hi Funch, thats a nice build. I like the unbilical and the cases. Where do you get those umbilical plugs and how many poles are they? How bot the cases, are these from ebay?


----------



## Zashoomin

luke99 said:


> Hi Funch, thats a nice build. I like the unbilical and the cases. Where do you get those umbilical plugs and how many poles are they? How bot the cases, are these from ebay?


 
 Funch can correct me if I am wrong but the cases look like they are hammond cases (you can find them on mouser, digikey and the whatnot).
  
 The ambilical cord are called speakon connectors and they can be found at redco.com I believe they also have something called powercon which is also similar.  (both quite expensive for connectors as they where made for heavy duty dc use).  I honestly just suggest using something simple like a 3pin xlr.  Much cheaper connectors and works just as well.  Just make sure that you don't mix the connectors up with your balanced input (if you plan on using such a thing.)


----------



## funch

zashoomin said:


> Funch can correct me if I am wrong but the cases look like they are hammond cases (you can find them on mouser, digikey and the whatnot).
> 
> The ambilical cord are called speakon connectors and they can be found at redco.com I believe they also have something called powercon which is also similar.  (both quite expensive for connectors as they where made for heavy duty dc use).  I honestly just suggest using something simple like a 3pin xlr.  Much cheaper connectors and works just as well.  Just make sure that you don't mix the connectors up with your balanced input (if you plan on using such a thing.)


 
  
 Correct-a-mundo. Hammond 1455T2201BU
  
 I don't remember if I used speakon or powercon tbh. The joys of getting old. I considered using XLR's, but decided to
 go with the ones I used as I hadn't ever used them before. Were I to do it again, I would go with XLR's.
  
 BTW, you would need to use 4-pin connectors; 3 for the power supply ( +, -, ground ) plus a separate ground wire from the PS
 ground to the headphone jack.


----------



## Stillhart

Hi all,
  
 I'm seriously considering building one of these.  The only DIY I have under my belt is some cables and a Project Solstice kit.  Do you think something like this is too much to take on at this point?  I think the soldering doesn't look too complex -- it's mostly the wiring, mounting, and various options that intimidate me.  I suspect that if I take my time and plan everything exhaustively, I should be able to pull it off.
  
 Zashoomin, you should know that I was partially inspired by your chat with Tyll.  I'm bummed that I didn't get a chance to listen to yours at CanJam.  
  
 Random question (pre pre planning):  You have a Balanced and SE port on the front.  Are you doing the 4 board thing where you can also do two SE amps (and then just doing one SE amp)?
  
 Thanks!


----------



## Zashoomin

stillhart said:


> Hi all,
> 
> I'm seriously considering building one of these.  The only DIY I have under my belt is some cables and a Project Solstice kit.  Do you think something like this is too much to take on at this point?  I think the soldering doesn't look too complex -- it's mostly the wiring, mounting, and various options that intimidate me.  I suspect that if I take my time and plan everything exhaustively, I should be able to pull it off.
> 
> ...


 
  
 The steps are different for everyone.  I think that with enough patience and help from the amb website that you can build one.  I think you will find the soldering to be no problem at all and the easiest part of the entire process.  The casework and wiring will most likely take the bulk of your time and effort.  I know there are a lot of options, but when it comes down to it there aren't a million options.  For the first project I suggest you keep it "simple" or at least try to.  Though can you plan, you will find that there are many things that you would have never thought of as needed.  
  
 I am glad that I got to inspire at least one person.  That was the goal 
	

	
	
		
		

		
			





.
  
 Ya I am doing the balanced and SE port thing with just one SE amp. The beauty of that setup is that with a balanced or SE source, you can output to single ended and balanced headphones. (though with a single ended source the output won't be truely balanced, it will output to a 4pin xlr...because I dislike trs jacks.)
  
 Anyway good luck with your build and if you have any questions please feel free to ask as many as you would like.


----------



## ambchang

Hi all:
  
 I have the chance to own a 2nd hand b22 for a decent price, but the owner doesn't know what gain it is.
  
 How can I tell what gain the amp is set at?  If it helps, the currently owner plays the HD600 at around 12 to 1 o'clock.
  
 I would eventually want to set it to 5x gain, as I am thinking of having it run phones like HE500, AlphaDogs and such, but what can I do to change the gain?  I have some soldering experience and is not adverse to DIY, but I am not at a place where I can manage overly complex projects.


----------



## MisterX

What are the color codes or number codes on the R3 and R4 resistors?


----------



## ambchang

I haven't received it yet, I will repost when I got it in the mail.
  
 What are some of the combinations?
  
 Thanks for the help.


----------



## MisterX

It may be better that you take a look at the published information.
 Especially if you're considering changing the gain.
  
  
 http://www.amb.org/audio/beta22/


----------



## ambchang

Thanks, I think I got it after going though the parts list.  I will test it once I got the unit and see if it is the right gain.


----------



## JeremiahS

Hi all, 
  
 Let me first say that I am a big fan of Beta22 and it is a bit sad to see that it is under-appreciated. I feel that Beta22 has a sound that offers tube liquidity like the best Krell amps which is very refreshing since most modern amps that I had tried sounded cold and mechanical, all details and technicalities but no soul. 
  
 I'm still not sure but I plan to have one built for me. I have chatted with my good friend who introduced me to his awesomely built Beta22 regarding which configuration offers the best sound. He advised to build one in mono block / dual mono configuration which as far as I understand implies two separate amp modules, two separate power supplies and two separate transformers. He also advised using backplanes to minimize wiring. 
  
 I checked AMB websites for research and found about the Epsilon21 backplane which seems to suit my purpose well. It also can house two boards at the same time which can save space. 
  
http://www.amb.org/audio/epsilon21/
  
 My question is this, can you use one single Epsilon21 for mono block / dual mono configuration? As far as I understand the left and right signal and ground lines have to be separated so can you use one single Epsilon21 board to achieve this? 
  
 Thank you for your kind advice and help.
  
 Regards,
 Jeremiah


----------



## luke99

jeremiahs said:


> Hi all,
> 
> Let me first say that I am a big fan of Beta22 and it is a bit sad to see that it is under-appreciated. I feel that Beta22 has a sound that offers tube liquidity like the best Krell amps which is very refreshing since most modern amps that I had tried sounded cold and mechanical, all details and technicalities but no soul.


 
 Hi Jeremiah,
  
 I am quite curious about this amp but when I read warm and tube like I loose interest. I had an M3 and found it too soft and warm for my liking. Is the Beta22 a similar signature?
 My next amp will be a balanced dynalo, SE version is excellent so I'm going to try balanced but run it SE until I get cans that I can run balanced. I guess the only way to know what the Beta22 sounds like is build one and see for myself.


----------



## JeremiahS

Hi Luke, 
  
 Sorry, I have not heard the M3 before so I cannot comment too much about it. 
  
 However a colleague own the HeadAmp GS-X MK2 which if I am not wrong has the same operating principles as the Dynalo. 
  
 I would say that the GS-X MK2 has a rather bright and cold sound signature, very detailed but for me it is hard to enjoy because it has a glare to its sound especially in the treble. I think someone here have made a comparison review between the GS-X MK2 and other top solid-state amps and he also noted this glare issue. 
  
 The Beta22 has a neutral-to-warm sound signature. It has solid state control and dynamics but at the same time has a tube-like fluidity to its sound. I think it has a sound characteristic that is not so impressive in the first listen but you come to appreciate in long term. 
  
 Another solid state amp that I like is the Luxman P-700u. This is more tube like than the Beta22. 
  
 The unit I tested is a fully-balanced build. Hope this helps. 
  
 Regards,
 Jeremiah


----------



## luke99

I think its real name is an M cubed, its quite well known design: http://www.amb.org/audio/mmm/  
 The amp you are describing is I think the balanced version of the Dynalo I like so much. I get no glare or cold. I find it very transparent and neutral. It has dynamics and good bass. 
 Dynamics is an interesting aspect of amplifiers too. I find that too much slam is very engaging at first and sounds lively, but can begin to sound exaggerated or forced and becomes tiresome. I think the Dynalo is in the middle here. I am not good at describing music, but to quote Nelson Pass "We are in the entertainment business". We all like different things. I just wish I didn't have to build everything to hear it


----------



## Jose R

luke99 said:


> Hi Jeremiah,
> 
> I am quite curious about this amp but when I read warm and tube like I loose interest. I had an M3 and found it too soft and warm for my liking. Is the Beta22 a similar signature?
> My next amp will be a balanced dynalo, SE version is excellent so I'm going to try balanced but run it SE until I get cans that I can run balanced. I guess the only way to know what the Beta22 sounds like is build one and see for myself.


 
 There are many ways to build an M3. Unlike the Beta22, which is a discrete circuit, the M3 employs opamps. Thusly, its sound signature can be *customized*, depending on the builder's preferences.
  
 An M3 in balanced configuration, with the default AD8610 as the output device, is not soft nor warm.
  
 I have not heard a Beta22, but do plan to build a balanced version (I already have the boards) once I am done re-building my SE tube amp.


----------



## luke99

Judging by your avatar you would know I think it had AD8610 opamp but cant remember, I didn't have it long. At the time I think I had ATH-AD700 HP, which wasn't for me, so its hard to know why I decided to get rid of it. I'm not so much into opamp rolling, but I'm quite keen to try the new National opamps in my Sapphire 3.0. That's a very good amp BTW.


----------



## Stillhart

Hi all,
  
 I'm starting the planning stage for my B22 build now.  I want to do a relatively simple build for my first one and then potentially to one with all the bells and whistles after.  I plan on doing a 3-board active ground B22 with a Sigma22 power supply.  No speaker taps, no stepped attenuator or selectable inputs or anything like that.  Just a straightforward B22+S22.
  
 I have a few questions I was hoping someone might be able to help with:

Is it possible to get the Epsilon22 backplane board anymore?
Can anyone recommend a good case for the 3-board beta?  My priority is keeping it compact.  I was thinking of just using the recommended Hammond 1455T220x for the Sigma, but I'm not sure if the 3-board Beta will fit.
Can anyone recommend a good guide on how to do the case work?  That's really the part I'm most worried about.  I don't want to buy a custom front or back plate, I want to cut my own holes and use a dremel to engrave the lettering as needed (with a simple build, it's probably not even needed!)
Recommended gain/attenuation level for HE-560, HE-1000, Q701, HD650?
  
 Thanks, folks!


----------



## Zashoomin

stillhart said:


> Hi all,
> 
> I'm starting the planning stage for my B22 build now.  I want to do a relatively simple build for my first one and then potentially to one with all the bells and whistles after.  I plan on doing a 3-board active ground B22 with a Sigma22 power supply.  No speaker taps, no stepped attenuator or selectable inputs or anything like that.  Just a straightforward B22+S22.
> 
> ...


 
 1.  If amb isn't stocking them anymore you can ask around but one isn't necessary.  
 2.  I get my cases from parmetal, but you can also get some from modushop.  If you are going simple though I suggest you do a 1 chassis build, so you will need someting that can fit 4 boards and a transformer.  Just remember that if you are doing a 1 chassis build, twisting the wires is very important.  It will eliminate a lot of the noise in the circuit.  
 3.  dunno about a guide, but i would not recommend you use a dremel to engrave the lettering unless you have very strong and steady hands, or you are engraving wood/plastic.  (like you said I don't think its needed either)  
 4. the default 8x gain should work wonderfully for everything but IEMs.


----------



## Stillhart

zashoomin said:


> 1.  If amb isn't stocking them anymore you can ask around but one isn't necessary.
> 2.  I get my cases from parmetal, but you can also get some from modushop.  If you are going simple though I suggest you do a 1 chassis build, so you will need someting that can fit 4 boards and a transformer.  Just remember that if you are doing a 1 chassis build, twisting the wires is very important.  It will eliminate a lot of the noise in the circuit.
> 3.  dunno about a guide, but i would not recommend you use a dremel to engrave the lettering unless you have very strong and steady hands, or you are engraving wood/plastic.  (like you said I don't think its needed either)
> 4. the default 8x gain should work wonderfully for everything but IEMs.


 
  
 Awesome, thanks a ton!  I have no idea how to figure out the case size needed, but I'm going to work on it a bit and report back.


----------



## Zashoomin

stillhart said:


> Awesome, thanks a ton!  I have no idea how to figure out the case size needed, but I'm going to work on it a bit and report back.


 
 If you are going with a parmetal case you can get a 16x12x(whatever height you deem fit)  will fit everything comfortably with room to spare. You can go smaller than that but it is going to be a tight.  Or you can even order a custom size from them for a reasonable price, but it won't be as cheep as the chassis they stock.


----------



## amb

The PCB dimensions are documented at the β22 and σ22 websites. You want to arrange the PCBs in the case for optimal signal routing, and place the power transformer as far away from the amp boards as possible. Once you establish the basic layout, then find a case that would fit. You could also go the opposite direction, start with a case and then try to fit everything in, knowing that it may or may not work well, and you may need to go to a different size case. Don't forget to take maximum component height + PCB thickness + standoff height into consideration for case height (internal).

There are lots of example β22 builds at the website gallery, use them as reference and inspiration.


----------



## Stillhart

zashoomin said:


> If you are going with a parmetal case you can get a 16x12x(whatever height you deem fit)  will fit everything comfortably with room to spare. You can go smaller than that but it is going to be a tight.  Or you can even order a custom size from them for a reasonable price, but it won't be as cheep as the chassis they stock.


 
  
 Thanks again.  
  
 Another noob question:  For the voltage of the PSU, it says to keep it between 24V and 30V, with 24 running cooler and 30 providing more power and voltage swing.  I'm tempted to keep it cooler at the expense of some power since I'm not planning on driving anything particularly difficult.  I believe the B22 has gobs of power so losing a bit isn't going to be a big deal, especially if I'm not driving speakers.  Does this sound about right?


----------



## Stillhart

amb said:


> The PCB dimensions are documented at the β22 and σ22 websites. You want to arrange the PCBs in the case for optimal signal routing, and place the power transformer as far away from the amp boards as possible. Once you establish the basic layout, then find a case that would fit. You could also go the opposite direction, start with a case and then try to fit everything in, knowing that it may or may not work well, and you may need to go to a different size case. Don't forget to take maximum component height + PCB thickness + standoff height into consideration for case height (internal).
> 
> There are lots of example β22 builds at the website gallery, use them as reference and inspiration.


 
  
 I'm quite jealous of all the builds with the E22 board.  Any idea if you're going to print more?
  
 For now, I'm thinking a 3" height should suffice, but still looking...


----------



## amb

Newer builds now appear at AMB DIY audio forum, either in the β22 amplifier subforum or the "Post pics of your builds" thread under "General DIY discussions". You can also ask questions there.


----------



## jcx

well some questions are welcome there - its actually a feature for a project to have a fully independent forum that reigns in fanboy attacks against even the slightest deviation from the party line
  
 just try getting a objective response to questioning the theory, show measurements of "3-channel ground" flaws there


----------



## JeremiahS

luke99 said:


> I think its real name is an M cubed, its quite well known design: http://www.amb.org/audio/mmm/
> The amp you are describing is I think the balanced version of the Dynalo I like so much. I get no glare or cold. I find it very transparent and neutral. It has dynamics and good bass.
> Dynamics is an interesting aspect of amplifiers too. I find that too much slam is very engaging at first and sounds lively, but can begin to sound exaggerated or forced and becomes tiresome. I think the Dynalo is in the middle here. I am not good at describing music, but to quote Nelson Pass "We are in the entertainment business". We all like different things. I just wish I didn't have to build everything to hear it


 
  
 Hi Luke, 
  
 I think I can generally agree with you there. I remember testing the Schiit Mjolnir and it has the same "over dynamics" problem you describe there, it got fatiguing real fast with music with lots of saxophone. 
  
 Perhaps this kind of signature is aimed at a younger crowd. I am new to headphones and there is a lot of young people, a lot more than your usual hi-fi speaker crowd. 
  
 What main headphone you are using by the way? 
  
 Regards,
 Jeremiah 
  
  


jcx said:


> well some questions are welcome there - its actually a feature for a project to have a fully independent forum that reigns in fanboy attacks against even the slightest deviation from the party line
> 
> just try getting a objective response to questioning the theory, show measurements of "3-channel ground" flaws there


 
  
 Hi jcx, 
  
 What is your opinion on the 3-channel ground? 
  
 I remember talking about this with my DIY-er friend and he thinks that it is not really necessary. He is a fan of "monoblock" arrangement and his personal Beta22 is also built in such manner. 
  
 He's a bit of artist but I have a lot of respect for him because his Beta22 is seriously awesome sounding. 
  
 I hope I can learn more about this. If I remember right, there is a portable amp that I like, the Triad L3 and it's specifically a 3-channel design. 
  
 Regards,
 Jeremiah


----------



## Stillhart

jeremiahs said:


> snip
> 
> Hi jcx,
> 
> ...


 
  
 +1 I'm interested in hearing more about this as well.  The 3-channel setup is "recommended" for headphones and "gives many of the advantages of balanced".  Those sound appealing.  What's the down side?


----------



## amb

That subject has already been argued to death, a simple search will get you all sides of opinions.


----------



## Stillhart

I'm just looking for a brief summary.  And I don't think it's a simple search, as I wouldn't know what search terms to use.  
  
 Anyways, clearly it's a loaded topic for you.  Perhaps someone else can chime in.


----------



## jcx

there are opinions on subjective values
  
 and there can be different weightings of issues by different engineers leading to different designs, but taken individually several key claims of "3-channel" "advantages" are simply technically wrong
  
 my analysis is engineering based, addresses the incorrect technical claims put forth by the "3-channel" advocates and can be shown to be more accurate in calculation, simulation and measurement
  
  
 the Beta22 is good enough that I doubt the "3-channel" flaws are audible problems, or that the one real advantage re PS currents makes any difference either
  
 but most of the reasons given for using it are simply wrong and causes me as an engineer intellectual distress when I see so many naïve builders being steered wrong - and clear explanations being attacked by fanboys
  
 using Beta22 amps, dual polarity supplies "3-channel mode" wastes money, time, resources for added technical flaws and one never demonstrated improvement in PS rejection for a amp with huge psrr built into the topology
  
  
 and yes I do speculate that dual mono, and the requisite "balanced" 4 pin headphone connector rewiring would be the cheaper route to "better" technical performance given real world system limitations
  
  
 but even common supply, 2-channel with attention to a "technical ground" - heavy copper, proper wiring to "star point" at the TRS gnd should be fine
  
 but 4 pin "balanced" headphone cabling should be better still with the L,R headphone driver's gnd returns routed to each board respectively
  
  
  
 and yes search works, but you may want to do it on different forums if you really want independent views - you can see mine here on head-Fi:
  
http://www.head-fi.org/newsearch?advanced=1&action=disp&search=%223-channel%22&titleonly=0&byuser=jcx&output=posts&replycompare=gt&numupdates=&sdate=0&newer=1&sort=relevance&order=descending&Search=SEARCH&Search=SEARCH


----------



## Stillhart

Thanks, I'll do some reading.
  
 Anyone want to explain how to do dual mono?  I don't see it as one of the options in the official AMB documentation.


----------



## amb

What jcx proposes is a standard two-channel passive-ground configuration, with an independent power supply for each channel. Also, rather than a standard TRS stereo phone jack (which has 3 conductors with a common ground), you use a different connector that lets you separate the left and right grounds and route them directly to each channel's power supply ground (the "star ground points"). HeadRoom's style of two XLR connectors on their balanced amps, or a single 4-pin XLR connector as found on the AKG K1000 headphones can be used to do this. Of course, this scheme requires you to modify your headphones.


----------



## Stillhart

amb said:


> What jcx proposes is a standard two-channel passive-ground configuration, with an independent power supply for each channel. Also, rather than a standard TRS stereo phone jack (which has 3 conductors with a common ground), you use a different connector that lets you separate the left and right grounds and route them directly to each channel's power supply ground (the "star ground points"). HeadRoom's style of two XLR connectors on their balanced amps, or a single 4-pin XLR connector as found on the AKG K1000 headphones can be used to do this. Of course, this scheme requires you to modify your headphones.


 
  
 Thanks, that makes sense.  So from the headphone's point of view, this acts like a balanced connection?  I mean, as long as the headphones are already wired for balanced, this should work with no further modifications to the headphone?
  
 Dual mono seems like an interesting project, but at that point, I'd rather just go balanced.


----------



## amb

stillhart said:


> Thanks, that makes sense.  So from the headphone's point of view, this acts like a balanced connection?  I mean, as long as the headphones are already wired for balanced, this should work with no further modifications to the headphone?



The signal won't be differential, but yes, any headphones already modified in this way will work, as long as the connector type and pin assignments are consistent.


----------



## Stillhart

So the insulation/mounting kit for the heatsinks are pretty pricey.  How do I know if I'll need them or not?  "Close proximity" is a very subjective term...
  
 Also, any recommendations for RCA jacks?  The Neutrik ones look weird... Rean perhaps?


----------



## amb

If there any risk of the PCB-mount heatsinks touching the chassis, top cover, or some other metal object, then you need the mounting kit.

Search for Cardas GRFA or Vampire CM2F and you'll see some nice RCA panel-mount jacks. There are also many clones or similar available on eBay at much lower prices.


----------



## MisterX

The Rean NYS367-* jacks are actually pretty nice considering they're priced around $2 each.


----------



## Energy

Has anyone done a comparison of their β22 to amplifiers like the Schiit Ragnarok?
  
 With declining popularity for the β22, I don't see many opinions circumventing the two.
  
 According to user *ogodei *(source: http://www.head-fi.org/products/schiit-audio-ragnarok/reviews/11797), according to him the GS-X MKII sounds very similar if not the same as the Schiit Ragnarok. In comparison to the GS-X MKII out of my own β22, to my ears I found the β22 to sound almost exactly like it. The only difference was that the β22 was ever so slightly warmer, and i mean barely. I love the GS-X MKII, don't get me wrong. But I've always found them to sound a wee bit cold. They are fantastic for a solid state amplifier, but the added warmth on the β22 just removes that last ounce of digital glare. It just sounds more relaxed and yet somehow manages to add presence. Again, this is very very and I mean, VERY subtle. I've noticed these sonic variations during a direct comparison of the two in BALANCED mode (β22 vs GS-X MKII).
  
 Would love to know if anyone else have had experience with these three amplifiers.
 I currently own the GS-X MKII, β22 Balanced, and am in the process of purchasing a Ragnarok from a fellow Head-Fi for a comparison.
  
 In time I felt the decline of the β22 meant that it was losing in performance, but based on the A/B test's I've done up to this point has proved to me it hasn't. I truly feel like people have gone more towards the path of HeadAmp GS-X MKII or Schiit Ragnarok due to form factor, ease of use, or even hype.. 
  
 Comments?


----------



## FallenAngel

energy said:


> Has anyone done a comparison of their β22 to amplifiers like the Schiit Ragnarok?
> 
> With declining popularity for the β22, I don't see many opinions circumventing the two.
> 
> ...


 
  
 Flavor of the month psychology and "newer is better" mentality. That's all I have to say.


----------



## vixr

I soldered every joint of my B22 and Nate Maher built the stepper... From a true DIY perspective? The B22 is the finest thing I've ever built or listened to.


----------



## FallenAngel

vixr said:


> I soldered every joint of my B22 and Nate Maher built the stepper... From a true DIY perspective? The B22 is the finest thing I've ever built or listened to.


 
  
 Pretty close to my experience as well. I loved my Beta22 and at over $2000 in parts for my personal build, it was the most expensive thing I've ever built.
 In terms of the "hardest" build, the Dynahi tops that list. Damn those custom drilled heatsinks. It also happens to be in the top 2 favorite solid state amps (with the Beta22 as the other obviously).


----------



## musedesign

fault151 said:


> Hi guys, I finally got round to taking some pics of my B22 amp. It has taken me over a year to get to this point and I thought i'd share my hard work with you all. First of all, a *[size=x-large]MASSIVE[/size]* thank you to everyone who has helped me with this project especially, Ti (AMB LAbs), MR Majestic, and johnwmclean. I would not have been able to do it without your help and patience!
> 
> 
> 
> ...


 
  
 Dear Fault151,
   Very impressive work !!
  
 What headphone jacks did you use on the front ?
  
 Thank you !


----------



## Energy

Fault151 has one of the nicest Beta 22 build I have ever seen.

*drops mic*


----------



## canister

musedesign said:


> Dear Fault151,
> Very impressive work !!
> 
> What headphone jacks did you use on the front ?
> ...


 
 These are Neutrik combo jacks.
 http://www.neutrik.com/en/audio/plugs-and-jacks/jacks/combo-i-series/
  
 P.S. I am about to start on my B22 project. 4 board+ twin power supply. This will be my FIRST solid state DIY project. I have always been a tube guy till now.


----------



## Energy

canister said:


> These are Neutrik combo jacks.
> http://www.neutrik.com/en/audio/plugs-and-jacks/jacks/combo-i-series/
> 
> P.S. I am about to start on my B22 project. 4 board+ twin power supply. This will be my FIRST solid state DIY project. I have always been a tube guy till now.




Let me know if you need any help. I finished my project not too long ago. It can be located under the B22 thread "by Energy" on the AMB forums with lots of detailed photos.

I also have a few extra parts if you need any. Just pay for shipping :]


----------



## canister

Hi Energy, thank you for your info and your offer to help. Cheers


----------



## musedesign

canister said:


> These are Neutrik combo jacks.
> http://www.neutrik.com/en/audio/plugs-and-jacks/jacks/combo-i-series/


 
  
 canister,
   Thank you !
  
 Ordered.


----------



## gikigill

Getting a Beta 22 tomorrow, I have a question for fellow owners regarding plugging headphones and DC discharge.. 

How can I safely plug and unplug headphones in the Beta 22 to avoid DC discharge from reaching my headphones?


----------



## canister

Perhaps this link can help you.
 http://www.amb.org/forum/dc-offset-concerns-t3372.html


----------



## gikigill

Thank you for your assistance. I'll look into it.


----------

