# Another PCB Layout - Gilmore Dynalo / Dynamid



## dgardner

I've been looking to test drive some new layout tools for PCB. I've built a Gilmore Dynalo using the toner transfer method with the Headwize project posting. Works great.

 My goal is to complete a new PCB layout and share it with the group. I also plan to have the boards fabricated at a boardshop like PCBnet. Maybe organize a group buy. One of the goals is to create a single PCB that can be populated both bridged or non-bridged. This may have been done by someone else before, but I'm sure another version of the board won't hurt the DIY folks.

 I'd like some feed back from the group to make sure I've incorporated the details eveyone might be intested in. I hope this is helpful, and doesn't open up a can of worms.

Schematic for review

 EDIT:/fixed link.


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## dgardner

Some suggestions are:

 1. Trim pots in parallel with the 500 resistors to dial in FET bias currents.

 2. Trim pot across power rails with wiper to DC ADJ if Op-Amp servo not populated.

 3. What lead spacing would be most universal for Power Rail Bulk Decoupling?
 Would 0.300" be alright to support Electrolytics?

 4. Are larger holes sizes for the output stage emitter resistors desireable?


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## Pars

How about the mods suggested by Sijosae or his fellow Korean DIYer, with the 1N4148 diodes thermally bonded to the output trannies? Not sure how many have tried this or not.

 Also, if a PSU section is done on it, room for alternative diodes such as FREDs or Shottkys would be nice.

 A nice big ground plane would probably be a plus


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## dgardner

Are the diodes you're referring to look like this?






 Which junction temps are you trying to match with the bonding?


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## dgardner

One major question is whether to include some of the better PSU work that has already been done onto the same board. One advantage might be better regulation since there will be no long connecting wires. Lots of very small stand-alone layouts have already been done for just the amp board. I did not find a bridged output version that required no jumper wires. Those who want modularity have other choices.

 Is there any interest in combining a Gilmore PSU and Gilmore Bridged on the same multilayer PCB? This would give first timers a much easier time with the PSU and the Amp as a single build project. Board cost might be higher, but what the heck.

 What might make sense would be to make the PSU section include:
 1) discrete layout for bridge rectifiers, you can pick your own diodes
 2) option for very small caps across the rectifiers.
 3) standard LM317 and LM337 circuits with trim pots.
 4) REF02 + standard OPA548 output op-amps with all the stabilization fixes.
 5) lots of pad options for output caps (if you dare load 'em up)

 It would probably make sense to have inputs on the board from some external torroidal transformer, since no one will agree on that.


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## dgardner

Does anyone know *why* HeadAmp's KG reference amp uses four instances of what looks to be the single ended board? Am I missing something with the bridged output implementation? I thought only one front end circuit was needed to drive the two output sections. Maybe this is a taboo subject.


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## Garbz

In the spirit of modularity I sugest keep them separate. The whole it's easier arguement really goes down the drain when you consider there's only 3 wires to connect between the psu and the ampboard. In my case i've connected the two via some simple screw terminals, but make sure they are marked. I damged a good $40 worth of parts plugging it in backwards.

 My sugestions are:
 1. Keep the amp and psu separate.
 2. Keep decoupling caps (large electrolytics and small films) on the amp board close to the output stage.
 3. Discrete componetns are good for the PSU's rectifiers however they did take up considerable space. Although this might not go down to well consider mayb haveing a plug for rectifiers. There's not a lot of current going through them so plug choices are pretty large, and people could roll their own rectifiers like sijosae does.
 4. PSU should have a groundplane
 5. Option to add a ground loop breaker
 6. Although it's popular to have the parts all over the shop in the psu with separate heatsinks on each, i find if the transformer is 50VA 2x25v then the VRs get HOT. My current PSU layout has all active components on one side allowing me to bolt a massive heatsink onto the side.

 7. For the amp board I'll re-itterate your sugestions. It's imporntant to give poeple the choice of DC offset correction. Some poeple prefer to swap-out LEDs, I prefer to have a 1K 25turn pot in the 500ohm resistor's place.
 Some people prefer to use a Servo, some prefer a large 20K pot from the supply pins to DC-adjust.

 Umm that's all for me 
	

	
	
		
		

		
		
	


	




 /EDIT: consider larger capacitance next to the output stage. a 300mil electrolytic could easily be a 470uf 16v FK series Black Gate like in my case. While the total of your caps comes to the same as mine, I have space for 0.1uf bypass caps next to each of them.


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## Pars

For the Sijosae-posted mods, check this thread, post 18 I believe. The output transistors are the ones the diode is bonded to.


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## dip16amp

Quote:


  Originally Posted by *dgardner* 
_Does anyone know *why* HeadAmp's KG reference amp uses four instances of what looks to be the single ended board? Am I missing something with the bridged output implementation? I thought only one front end circuit was needed to drive the two output sections. Maybe this is a taboo subject._

 

 The problem with the bridged output design is that there are two outputs per channel and only one opamp servo to adjust the two DC offsets. The DC offset problem mainly comes from the dual FET 2SJ109 and 2SK389 packages which can change the DC offset as much as a 100 mV between each FET within the same package.
 I straighten the pins of the J109 and K389 and rebend them to fit inline on a 16 pin socket which allow me to swap between the two FETs in the dual package. Out of five J109 and five K389, I only found one of each that would cause less than 10 mV of DC offset difference without the opamp. When the opamp servo is installed, it can only drive the DC offset somewhere inbetween the two different DC offsets. Most of the DC offsets ended up over 100 mV on the other FETs.
 It is much cheaper and easier to have an opamp servo for each output than to try getting good FETs that match themselves. This way, I can get each DC offset less than 10 mV without the opamp by swapping ends of the FETs and changing LEDs. Then when I put in the opamp, it will drive the DC offset to less than 1 mV. 
 For balanced inputs and balanced outputs, it's just four seperate channels wired the same. For unbalanced inputs, the negative outputs would probably have the second stage connected to the other 5K ohm resistors while the positive outputs would be wired normally. The servo would probably also be wired differently for the negative output.


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## dgardner

Thanks for inputs and the explanation! Makes sense to me now. Does anyone want to take a shot at what the opamp server wiring would look like for the bridged output - negative output amp - with unbalanced input? (See previous post)


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## dip16amp

Quote:


  Originally Posted by *dgardner* 
_Thanks for inputs and the explanation! Makes sense to me now. Does anyone want to take a shot at what the opamp server wiring would look like for the bridged output - negative output amp - with unbalanced input? (See previous post)_

 

You may have to connect the negative output to the other input of the opamp if it doesn't work like you have it.


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## dgardner

Here is an update to the schematic. It incorporates circuitry for the suggestions listed above.

Schematic - Page 1
Schematic - Page 2
Schematic - Page 3
Schematic - Page 4


 For *bridged mode*, some questions still remain. 
 1) Exactly how do the servo(s) need to be connected? There are two now.
 2) What is the wiring look like for a balanced input?
 3) What is the wiring look like for an unbalanced input?
 4) How is the negative output leg going to be driven?
 5) How would an XLR input connector get wired?
 6) Will dual mono headphone wiring be required? I assume - yes.

 Any help clearing up these last questions would be much appreciated.

 The goal is *no* long & nasty jumper wires going across the board, especially in bridged mode. Tiny bare wire jumps between some 0.100" holes seems ok to me if that's what it will take to get non-bridged and bridged out of the same layout nicely.

 EDIT:/fixed links


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## amb

dgardner,

 With your addition of D7, D8, D9 and D10, you need to reduce the value of R34 and R43 from 510 ohms to around 200 ohms. Without this change you will overbias the output stages, and cause the output transistors to run too hot and possibly damaging them.

 Now for your questions:
If you are using two completely independent amplifiers for the non-inverted and the inverted sides of the balanced amp (for a total of four amplifiers for the stereo pair), the servos for each should be connected exactly the same as in the unbalanced setup.
For balanced inputs, then you will have two XLR jacks, one for the left channel and one for the right. The + signal on the XLR connector should go to amp-A's input, the - signal to amp-B, and the "ground" pin to the signal ground. See the image below. Note I used the same resistor number designations as in your pdf schematic. The triangles denote each amplifier block, with the amp-A's "+" input being the same as your diagram's "Input A", and amp-B's "+" input being your diagram's "Input B".
For unbalanced inputs, you will need to modify amp-B to actually be inverting. This could be most easily done in the manner shown in another image below. Basically, you need to add Ra and Rb. Ra should be the same value as R23/R57 (in your case 1K ohms), whereas Rb should be the same value as R22/R55 (10K ohms).
Amp-A's output goes to the "+" terminal of your headphone transducer and amp-B's output goes to the "-". Note that you will need to rewire your headphones so that the left and right channels' "-" wires are separated from each other, so that you'll have a 4-wire setup rather than a 3-wire.
See above.
Yes, that's what "balanced" is all about.









 Hope this helps.


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## dgardner

Here is the latest update to the schematics I intend to goto layout with. If anyone would like to provide any more input, now is the time.

Schematic - Page 1
Schematic - Page 2

 Here are a couple of supplementary pages that incorporate amb's information and attempt to show some the basic system level connectivity of a dynalo and a dynamid. This might be helpful to newbies that are studying the Gilmore Amplifier project pages for the first time. 

Schematic - Page 3
Schematic - Page 4

 Next up, I hope to post the component place views and the ground planes sections. Right now, I'm pretty sure that a four layer board is the way I'll go. The top will be a ground fill, the two inner layers will be for routing, and the bottom layer will be split planes for the power supply rails & maybe more ground plane under the FETs.

 If anyone has ground plane ideas for a four layer stackup, now is the time to share them.

 EDIT:/fixed links


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## amb

Looks good dgardner. One suggestion: In your schematic #4, you might want to wire the amp's signal ground lines to the XLR output connectors' pin 1 anyway, even though the headphones won't use it. This is so that if you connect the balanced output of the headphone amp to another device's balanced input using standard XLR-XLR interconnect cables, it would also work.


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## amb

Oh and four layer boards? I hope you have a pretty deep pocket 
	

	
	
		
		

		
			





. They will be spendy in small quantities.


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## dgardner

I don't mind the cost of the four layer board if it provide real benefits. I've been building up 6 dynahi boards (2 layer) and working on the prototype dynahi power supply (2 layer) lately. 

 BUT... I'm getting back on *this* project on Monday. I'm thinking that a two layer board with a topside ground plane and some bottomside power rail fills might do the trick and then the price stay under $200 for a 20 piece proto run. Otherwise, four layer boards from North American suppliers seem to fetch a minimum of $400 for a 20 piece order.

 I think there's lots of people who will want to build this board. The dynahi is too big, hot, and expensive for a lot of folks. Hope to post a few updates later next week...


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## Garbz

Indeed there's a lot of people who have built this


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## jogor

hi, been searching for a resonably priced dynalo/dynamid pcb. dgardner, thank you for initiating and sharing. i will definitely join in the group buy if my wallet permits. by the way, is MPS8099/MPS8599 a much better choice compared to 2SA1015/2SC1815 specs/performance wise (to anyone who tried them)? i could not find mps8x99 specs sheet 
	

	
	
		
		

		
		
	


	




 and vendor as well, thanks again.


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## amb

Quote:


  Originally Posted by *jogor* 
_hi, been searching for a resonably priced dynalo/dynamid pcb. dgardner, thank you for initiating and sharing. i will definitely join in the group buy if my wallet permits. by the way, is MPS8099/MPS8599 a much better choice compared to 2SA1015/2SC1815 specs/performance wise (to anyone who tried them)? i could not find mps8x99 specs sheet 
	

	
	
		
		

		
		
	


	




 and vendor as well, thanks again._

 

The MPS8099/8599 were Motorola, but is now On Semiconductor:
http://www.onsemi.com/site/products/...PS8099,00.html
http://www.onsemi.com/site/products/...PS8599,00.html

 These are good transistors and can be used in lieu of the 2SC1815/2SA1015. Note the pin-outs are different! Here are some basic comparisons:

 2SC1815/2SA1015:
 Vce 50V, Ic 150mA, Pd 400mW, hfe 100 typ, Ft 100MHz

 MP8099/8599:
 Vce 80V, Ic 500mA, Pd 625mW, hfe 100 min, 300 max, Ft 150Mhz

 One advantage of the 2SC1815/2SA1015 is that its hfe is very linear over a wide Ic range. This makes them easier to match.

 The MPS8099/8599 are available from Digikey. The 2SC1815/2SA1015 are available from BD Enterprises.


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## dgardner

Quote:


  Originally Posted by *amb* 
_The MPS8099/8599 are available from Digikey. The 2SC1815/2SA1015 are available from BD Enterprises._

 

The 2SC1815/2SA1015 are also available from MCM.


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## dgardner

Can anyone tell me what the hole spacing, hole size, and body diameter would be for Black Gate caps in the 100-200uF range. I can't seem to find a datasheet out there. Right now, I have 0.300" leadspacing for eletrolytic bulk caps. I've heard that's too small for Black Gate users. Help!


 I found ELNA Cerafines Caps. These have 10mm diameters and 5 mm lead spacing. Should live happily in a 0.200 lead space cap footprint if the holesize is generous enough.

 What other esoteric electrolytic caps do people want to be able to use???


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## Garbz

What that's not what i said further up. 300mils holespacing is fine for 470uf 16v blackgates which I use in my Dynalo. 200mils (5mm) is suitable for the 220uf 25v BGs i had in my old one.

 Also now that i've got mine working i can confirm that a 1k pot inplace of the 500ohm bias resistor does wonders for DC offset. No matching required


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## dgardner

Garbz - what's the body diameter on the .300 caps?


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## Garbz

600mils

 /EDIT: take a guess what changed in this post


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## dgardner

EDIT: See post below for latest updates...

 I'll add some notes to this thread about the layout. But for now, here is something to look at...


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## skyskraper

hey has there been any progress on this? 

 im assuming this is a lot easier to work on then the dynahi, and can fit in a smaller enclosure? if so then im in


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## dgardner

Update hopefully tomorrow....


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## dgardner

Schematic

Bottomside and Silkscreen

Bottomside, Silkscreen, Ground plane

Silkscreen and pads

Fabrication

 Please take a look and provide any comments you have.

 Notables:
 Fits a Eurocard size.
 Two amps per board each with a servo. (bridgeable for one XLR input).
 Plenty of capacitor size options.
 Pots in desired locations.
 Two layer construction with power and ground planes.

 Target date for first pass ordering of about a dozen boards is end of the day 12/22/2004.


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## dgardner

10 peices of the first pass boards have been ordered. Anyone with an interest in building up a few can PM me.


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## skyskraper

quick question, at this net cafe your schematic doesnt want to display for some reason (not your fault, crappy slow machines they have here are responsible). but iirc, the dynalo needs +/-16v. will i be ok with +/-15v? or is it essential to have the 16v either end???

 i ask simply because i have a nice +/-15v psu pcb populated and running nicely with a toroid from another project that isnt being used presently.....

 dg: can you please pm me to let me knwo what the story is with the boards etc you mentioned in pm before? 

 thanks


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## dgardner

Boards arrived:

 Out of town at the moment... Won't be able to build one up for confirmation until this Friday. 
	

	
	
		
		

		
		
	


	




 EDIT: Original Copy Machine scan
Topside View
Bottomside View

 EDIT: Revised Images


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## Garbz

nice picture, it looks like it was taken through a noisy electron microscope.


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## dgardner

This is what images look like when you scan with a copy machine....


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## Garbz

The boards do look like they came out beautifully in the end. I love the almost exclusive use of large planes for power and ground.


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## dgardner

I populated one board last night. Went together pretty well. Still missing some caps and the LEDs. Didn't bother to thermally bond the diodes to the output transistors yet. A few parts (like the pots) are cramped and some silkscreens for the connector hookup are needed. 

 I'll revised the layout before the next go around and consider a group buy if there is enough interest. 
	

	
	
		
		

		
		
	


	




 This morning I'll start the testing. Test results to be posted before anyone get boards first-pass prototypes shipped to them..


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## dgardner

Here's the list of first-round interested parties:

 dgardner (me) - 6
 skyskraper - 2
 stackofhay - 2
 Earwax - 2
 jmedin - 2
 ShiroZ - 1
 jogor - 2, plus 4 dynahi psu
 z2trillion - 1 or 2
 scott916 - 1

 This pretty much exhausts the stock from the 20 piece build. 

 Some bad news: 
	

	
	
		
		

		
		
	


	




 I thought I was going to get a discount for this order that would have put the price at around $5 ea. That did not turn out. So my cost on these is $10ea + shipping. If anyone is *not* interested at $10ea anymore, please PM me.

 Exceptions are:
 jogor - working a swap arrangement.


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## skyskraper

i need one board for stereo operation right? at least thats how ive read the schematic and board. pls correct me if im wrong as i havent had much time to spend on it.


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## dgardner

One board for stereo.


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## skyskraper

what value are you using for c8/9/23-26? the schematic reads 100uF. so i was thinking 120uF 25v.....

 edit: or 50v 100uF


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## dgardner

I popped in a 120uF 63V, Panasonic EEU-FC1J121 (Digi-Key P11271-ND). Same series as used on the dynahi's. It was the only thing in my parts bin that fit. Nothing magic about it.

 Options... Options.... Options.... let the fun begin.


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## skyskraper

oh yeah tell me about it. ive been pouring over catalogs all day thinking about it. but i am going to have to wait until i get the boards to start speccing it out. 

 btw if anyone wants a board, i only need one, i would be happy to let my other one become available again


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## dgardner

This board is running!! Jammin' a little Jack Johnson pretty hard on it right now. DC offsets are around 5mV at startup and the servos drop to 1mV or less within about 30 seconds. Idle currents in line for all stages.

 Errata List: (so far no show stoppers)

 1) LED polarity silkscreens are backwards.
 2) Bourns 3296 series pots don't have a big enough outline/keepout.
 3) Terminal Connectors don't have any markings. (kinda dangerous)
 4) C8 interferes with R44.


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## dgardner

Quote:


  Originally Posted by *skyskraper* 
_oh yeah tell me about it. ive been pouring over catalogs all day thinking about it. but i am going to have to wait until i get the boards to start speccing it out. 

 btw if anyone wants a board, i only need one, i would be happy to let my other one become available again 
	

	
	
		
		

		
		
	


	


_

 

FYI all caps with "box" outlines are ideal for WIMA type poly caps. Specifically the MKS4 and MKS2 series. The red caps in the picture are 4.7uF 63V, MKS4475J63-6 from Epassives.

 C10,11,21,21 can take a 22.5mm, 15mm, or 7.5mm lead space.

 C1,2,3,4,12,13,14,15,16,17 take a 7.5mm lead space, but any small axial or radial cap will fit. I was planning to put 0.1uF and 0.01uf values in these locations.


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## Pars

I'd be interested in one if it is available or someone backs out. Nice looking boards, and I really like the ground plane. PM me if something frees up, or just put me down for it.

 Chris


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## skyskraper

if dgard hasnt offered my board to someone else you can take it if you like


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## jogor

wow! this is awesome, i cant wait to get my hands on those boards. 
 keep it up dan.


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## Archeopteryx

I would be interested in buying a board if someone has an extra. Are there plans to do another run if there is interest?


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## skyskraper

i cant speak authoritatively, but im under the impression that these are protoboards and a full run will be done once theyre thumb's upped 
	

	
	
		
		

		
		
	


	




 gawd im not looking forward to matching all these transistors for dynalo and dynahi!@#


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## dgardner

I put the first pass prototype board in a Hammond 1455N1601 Enclosure to confirm the fit. I planned for this option... Everything fits. Not a heck of a lot of room for creative connector placements. I also tried the +15/-15 Elpac wallwort and it works fine. I have a variable out source driving it so I skipped the pot. Gee... almost portable...


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## dgardner

Quote:


  Originally Posted by *Archeopteryx* 
_I would be interested in buying a board if someone has an extra. Are there plans to do another run if there is interest?_

 

Sure thing.


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## skyskraper

approximately whats the profile height of the board? i want to put it in a 1ru case but im not sure if itll fit....


 for those of u who cant get elpacs or would rather not, u should check out this board. i have one driving the power in to my steiner synthacon replica (which i really should finish) and its done a nice little job so far. cheap and easy. means u dont need another powerpack floating around. i intend on using it in my dynalo


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## dgardner

The board as I constructed it in the image above has the tallest part at 0.65 inches, and that's the electrolytic cap. Board is .062 thick and you need some standoffs of course. Should easily fit inside 1U which is about 1.5 inches.


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## skyskraper

shaweet 
	

	
	
		
		

		
		
	


	




 racking up gear makes life so much easier.

 do you have an updated BoM for it or would you like me to continue working on it?


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## dgardner

Quote:


  Originally Posted by *skyskraper* 
_for those of u who cant get elpacs or would rather not, u should check out this board. i have one driving the power in to my steiner synthacon replica (which i really should finish) and its done a nice little job so far. cheap and easy. means u dont need another powerpack floating around. i intend on using it in my dynalo_

 

I've been toying with the idea of laying out a dynahi-style power board, scaled way down in output current that would have about the same board size and outline as this dynalo board. The group buy dynahi ps board could also be used with resistor value changes. I've built the headwize project version of the KG dynalo power supply before, but did it point-to-point on perf board. I did the bring up testing with that supply.


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## dgardner

Quote:


  Originally Posted by *skyskraper* 
_do you have an updated BoM for it or would you like me to continue working on it?_

 

I started one. I could use some help completing it. Who wants to take it over? BOM.xls


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## skyskraper

ahh sweet, ill finish it off this evening for you 
	

	
	
		
		

		
		
	


	




 its much further along then mine hehe


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## awpagan

I am interested in one of these boards for the future
 whats best for a 250ohm load
 somewhere between lo and high but mid? why bridge a class A


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## Pars

Quote:


  Originally Posted by *dgardner* 
_I've been toying with the idea of laying out a dynahi-style power board, scaled way down in output current that would have about the same board size and outline as this dynalo board. The group buy dynahi ps board could also be used with resistor value changes. I've built the headwize project version of the KG dynalo power supply before, but did it point-to-point on perf board. I did the bring up testing with that supply._

 

You might search out BoyElroy's posts from a year (or two) ago. He had several PSUs laid out for a Gilmore Dynamic that looked pretty good... provisions for FREDs, etc.

 Also, last time I checked with epassives, they only did volume (rather high) sales of Wimas. TAW Electronics does small orders, but be specific with them over what you want (including lead spacing). I got some MKS4s for my headamp V2 board from them, and even though they spec'd the proper lead spacing (15mm), they shipped me some that I couldn't even find in Wima's catalogs (22.5mm) which wouldn't come close to fitting. They were very good about getting me the right ones though, and I would recommend doing business with them if you can't meet epassives volume requirements. BTW, they still have some of the discontinued Wimas, like the MKC polycarbonate, etc.

 Dan, your prototype looks very nice! What kind of SIP pins did you mount all the transistors on? I assume you intend to leave it this way (I toyed with doing that also). DC offset sounds quite reasonable... what did it look like without the servo in?


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## dgardner

Quote:


  Originally Posted by *Pars* 
_What kind of SIP pins did you mount all the transistors on? I assume you intend to leave it this way (I toyed with doing that also)._

 

For the transistors, I used some gold plated SIP sockets that were the breakaway kind. I picked 'em up in a surplus store, so I don't have a part number. I've found that SIP sockets with the least amount of plastic are the easiest to cut and work with. The socketed resistors are the same, but have the plastic strip body cut completely away. The FETs are actually in a cut 20-pin Zigzag socket. (remember zigzag memories?... oops I'm dating myself)

  Quote:


  Originally Posted by *Pars* 
_DC offset sounds quite reasonable... what did it look like without the servo in?_

 

Without the servo, one side was only 5mV! My best initial match of a Gilmore amp ever. The other side started at around 25mV, after a few cranks on the pot I got it really low. With the op-amps out, the offsets did not drift much, as expected.

 I matched the transistor Hfe's within about 1%. Overkill for matching, but I had about 200 transistors to start with.


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## Garbz

The Fets also fit in 2 SIP strips layed side by side. I didn't do it in mine because I only had the 4 to begin with so no swapping would be done. 
	

	
	
		
		

		
			





 For the record I had better offset values (<2mV) with the OPA134 than with the OPA227 (~5mV)


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## dgardner

Quote:


  Originally Posted by *Garbz* 
_For the record I had better offset values (<2mV) with the OPA134 than with the OPA227 (~5mV)_

 

Wise guy... I meant best match ever "personally".


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## Pars

You both cheat cuz you've got pots in yours... 
	

	
	
		
		

		
		
	


	







 Yeah, since amb or someone determined that the opa27/227 were not FET input, I was thinking about the opa132/134 also.

 Mine starts off around 5mV one channel, ~2mV in the other with the servo in (and this is cold, as in basement). It quickly goes to around ~1mV both channels within a minute, and drifts around until it stabilizes, but no more than 4mV worst case, usually hanging around +/- 2mV until it warms up at <2mV, typically < 1mV.

 Dan,

 Can you detail your matching methods for both the transistors (I think I have those down pretty good), and more importantly the FETs?

 Also, did the BOM get completed? If not, I can have a run at it, since I have the headamp one.

 Chris


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## skyskraper

chris: ive got it almost done. just need to fill in the designations 
	

	
	
		
		

		
		
	


	




 would u be so kind as to share the headamp one anyway? my email is sean at inthemix dot com dot au


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## Pars

Sean,

 ugem


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## dgardner

Quote:


  Originally Posted by *Pars* 
_Also, did the BOM get completed? If not, I can have a run at it, since I have the headamp one._

 

See post #56 above for the BOM link. Looks like you're already coordinating with skyskraper to avoid a duplication of effort. I would welcome the help. You may not have noticed, but some columns are hidden for estimating the unit cost. You may want to unhide them.


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## Garbz

My inital matching of transistors gave me 6mV despite not having the correct transistors as half I ordered were GR rated 
	

	
	
		
		

		
		
	


	




 Anyway I used my DMM to read the hFE, each transsitor spent about 20 seconds in the DMM to get a reading of about 160 - 190 depending. The PNP's were slightly higher then the NPNs. I lined them up on a scale from 170 to 200 and then selected all the ones that ended up in the middle of the resulting bellcurve. (combined that is, so the top of the NPNs and the bottom of the PNPs)


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## Pars

Yeah, per the matching thread with amb, I am using a fixed base resistor of 220K and 9V bench supply. SInce I know the exact resistance, I measure Vb and Ic for each transistor. Flip all the leads and do the PNPs, then throw all the data into a spreadsheet and calculate hFE.

 Per the last post (a few days ago) in my Dynalo thread from awhile back, I actually pulled all of the transistors from the V2 board and measured them also. I replaced 3-4 transistors and got the one channel I was having problems with much better. It also allowed me to observe and measure/replace with a much clearer idea of what I was doing and with results that matched pretty much what my intent/prediction was in the circuit.

 One thing that I noticed (which may be obvious to some of you), was that the closer I could get the voltages on the bases of the third stage to balance between the two sides of one channel (bases of the 2SA1015s versus the 2SC1815s), the lower the offset. Setting up the first stage transistors at the same hFE resulted in pretty much the same voltage (within 10mV) on the bases, giving the lowest offset. I then balanced the hFEs as close as possible for the output transistors. Its at a point where I can live with it now. The pot you guys use would obviously help alot here.

 Next board I build will be well matched initially (this one I didn't match anything initially... big mistake as I had to pull resistors at times to accurately measure them. They're matched now 
	

	
	
		
		

		
		
	


	




 ).


----------



## Earwax

This is getting exciting, I got my transistors yesterday, the resistors should arrive today. Still need to order caps and trimmers. 

 But I have a question. What gain is this amp set for using the default values and how do you change it? I probably want a gain of about 4 or 5.


----------



## dgardner

Quote:


  Originally Posted by *amb* 
_If I recall, the feedback resistors on the dynahi is 2K ohm around the amp and 100 ohm to ground. Since you have already reduced the 2K to 1.2K, I wouldn't recommend reducing that much further. However you could increase the 100 ohm resistor value. The gain of the amp is computed by: G = (R1 / R2) + 1, where R1 is the "2K ohm" resistor and the R2 is the "100 ohm". With a 1.2K/100 resistors you still have a gain of 13 which is too much for Grados. Try changing the 100 ohm resistor to something like 560 ohms, and it will give you a gain of around 3._

 


 Borrowing from the "Gain In Dynahi Thread", G = (R1 / R2) + 1, where R1 is the "10K ohm" resistor and the R2 is the "1K ohm". See locations R7,16,37,46 on the board. I would guess that raising R2 would be the way to go to lower the gain.


----------



## dgardner

Quick note on the pots. The schematic says 100K, but I would recommend a Bourns 3296W Series 10K pot.


----------



## dgardner

First wave shipments should go out Friday. I'm on the road again right now. PM's have been sent to those who have not provided mailing address and paypal info. Price $10 ea + shipping.

 dgardner6
 skyskraper 2
 stackofhay 2
 Earwax2
 jmedin2
 ShiroZ1
 jogor2
 z2trillion1
 scott9161
 Pars1
 -----
 20 

 Secord order requests so far: (order date needs to be determined)
 Any other interested parties should send me a PM with quantity, shipping address, and paypal information. Price: between $5 and $10 depending on order size.

 Archeopteryx 1
 awpagan 1
 vladco 3
 -----
 5


----------



## skyskraper

sorry guys ive been laid up hardcore with the flu so havent been able to finish the bom yet.


----------



## dgardner

Boards are packaged and ready to ship. Paypal invoices sent for boards. Paypal invoices for exact shipping amount will be sent right after shipment is complete. USPS tracking numbers will be sent to US buyers.

 skyskraper
 stackofhay
 Earwax
 jmedin
 ShiroZ
 jogor
 scott916
 Pars

 ---
 jogor - dynalo boards ready. waiting for arrival of your dynahi ps boards to ship with it. will ship together.


----------



## Pars

Thanks Dan! Paid. You should have just billed for USPS (like $5 if that would have covered it)


----------



## jogor

dan, please advise your shipping address and send it via pm. will probably send you stuff right after i get back. thanks!


----------



## dgardner

Board shipped out Jan 15, 2005 at around noon. All payment requests have been sent out for the boards and the shipping. USPS tracking numbers sent with the shipping payment request. Thanks to those who have already paid!


  Quote:


  Originally Posted by *dgardner* 
_Boards are packaged and ready to ship. Paypal invoices sent for boards. Paypal invoices for exact shipping amount will be sent right after shipment is complete. USPS tracking numbers will be sent to US buyers.

 skyskraper
 stackofhay
 Earwax
 jmedin
 ShiroZ
 jogor
 scott916
 Pars
_


----------



## Earwax

The boards arrived today. Did you use Imagineering for these? They look very good. 

 Has the BOM been finished? No hurry, just wondering if I should start tracking down the last few pieces. 

 Thanks!


----------



## skyskraper

i sent the bom back to dan on monday for final checking over, if you want i can email it to you


----------



## dgardner

Quote:


  Originally Posted by *Earwax* 
_The boards arrived today. Did you use Imagineering for these? They look very good._

 

Yes. Imagineering. aka PCBnet.com

  Quote:


  Originally Posted by *Earwax* 
_Has the BOM been finished? 
 Thanks!_

 

Definitely need to finish that up tomorrow.


----------



## skyskraper

the pcb's arrived today.

 did you get the BOM earlier in the week? there were just a couple of caps i wasnt sure of the schematic values.


----------



## dgardner

Quote:


  Originally Posted by *skyskraper* 
_the pcb's arrived today.

 did you get the BOM earlier in the week? there were just a couple of caps i wasnt sure of the schematic values._

 

Yes, I got it thanks alot for the help. I just got home tonight from a biz trip.


----------



## skyskraper

ah sweet. 
	

	
	
		
		

		
			





 its time for me to start ordering parts, my psu is done and working nicely. apart from the op amps and led's i have nothing else hehehe.


----------



## Pars

Dan,

 Got my board on Wednesday... thanks, looks really good.

 Have you gotten your prototype to the point of listening yet (I think I recall you had...). If so, any comments on sound versus your homebrew PCB Gilmore? 

 Chris


----------



## dgardner

Quote:


  Originally Posted by *Pars* 
_Dan,

 Got my board on Wednesday... thanks, looks really good.

 Have you gotten your prototype to the point of listening yet (I think I recall you had...). If so, any comments on sound versus your homebrew PCB Gilmore? 

 Chris_

 

My only comment would be that this board is a noticeable improvement from my home etch version. The ground plane and power rail capacitors have a pretty noticable effect on the sound to me. My home etch boards had no bulk capacitors. I have listened to the new board with an Elpac wall supply and the Gilmore PSU with the OPA548 outputs. There is a small improvement that's hard to characterize. I have not listened long enough to comment intelligently. Also, I have wired up my Senns for dual mono now as part of completing  my bridged dynahi.  (a frightening powerhouse) Next I need to build up the bridged version of the dynalo with two pieces of this layout.


----------



## dgardner

Now that many of you have received the board, a couple of important notes to remember.

 1) The LED silkscreens are all backwards. Populate LEDs opposite the silkscreen.

 2) Please see the previous posted images in this thread that show the power connector and output labeling. If you hook up power incorrectly, parts will get damaged.

 3) When installing the pots, preset the wipers to the 10K position. Double check the resistance across each of R11, R15, R41, R45 before you powerup. If the pot wipers are properly set to 10K, you will see around 500 ohms across these resistors. If the pots are dialed the wrong way, you may something much lower or closer to zero. The amp will not run then.


----------



## dgardner

BOM (Excel)
BOM (pdf)

 Worst case cost is around $70. You can certainly do better with a little scrounging around the local surplus shops. Especially for things like trim pots and capacitors. Please report errors and emissions to me via PM.


----------



## skyskraper

i just matched the resistors and soldered up the whole board apart from a couple of trim pots, and the fet/transistors. 

 that was a seriously unfun experience.


----------



## dgardner

Don't be fooled by the layout, it is correct. But it does not flow exactly like the schematic. The power rails on the physical board are not visually oriented the same as the schematic.


----------



## bg4533

Is that board for a balanced amp?


----------



## skyskraper

nah its for stereo operation, balanced requires two boards. which makes it a dynamid 
	

	
	
		
		

		
			





 i just realised i put my 4 trimpots in, but i populated two of the optional positions and not r14 and r44. doh! i'll go grab a couple more trimpots so i can power it up whilst waiting for the transistors to arrive. 

 here is a pic of my partly populated board. clicky


----------



## skyskraper

just a quick question on matching the 2sj109 and 2sk389's, i was thinking about ordering 6 of each, would this be ok to match? i ordered 24 of each the q's, as matching pairs from a larger pool is a lot easier im sure, but i wasn't sure about the fet's. the 2sj109 is fuxn expensive (like 56x) compared to the q's, and the 2sk389 is like 27x the cost. so i wanted to not spend more then i really had to. i guess i could pool the unused fet's in to a dynahi pool for the future. but im pretty skint atm thats all.

 could i get away with just ordering a pair or quad of each fet?

 also any other dynalo builders, whats the sort of highest useful capacitance value we can use before it starts to become a waste of time? i had some 120uF 25v i got from RS for a few cents each, so i used those. but more uF = better, so i was wanting to know how far i should go before the diminishing returns hit hard.


----------



## bg4533

Quote:


  Originally Posted by *skyskraper* 
_nah its for stereo operation, balanced requires two boards. which makes it a dynamid 
	

	
	
		
		

		
		
	


	


_

 

Thanks, I realized that after looking at it a bit more. The way the boxes are around each section confused me. 

 I haven't kept up with this post, but what power supply are you using to power this amp?

 I have a Subsonic Gilmore board on the way and I am still trying to decide how I want to power it.


----------



## skyskraper

ah, well, i had one of these spare and populate from another project so thats what im using for it. i suppose the easiest would be to get the +/-15v elpac dan is using (and headamp uses), or going to radioshack or somewhere that sells kits and buying a kit (theyre only like $4usd in aust), adding a transformer, and you're set.


----------



## dgardner

Quote:


  Originally Posted by *skyskraper* 
_i just realised i put my 4 trimpots in, but i populated two of the optional positions and not r14 and r44. doh! i'll go grab a couple more trimpots so i can power it up whilst waiting for the transistors to arrive. 

 here is a pic of my partly populated board. clicky_

 

I'd recommend you remove/desolder those two pots in R63 and R64 since you look like you are installing the OPAMP servo. Also, remember the LED silkscreens are backwards. I can't see if you have the LEDs "properly reversed". Otherwise it looks great!!


----------



## jmedin

1) I was just wondering if anyone has tested the board *WITH/WITHOUT * the 2 "new" bias diodes in the output section VS.* just * the (higher value) resistor WITHOUT the diodes?






 2) What function do the diodes provide if they are *not* _physically _ coupled to the output transistors?






 3) Does it help to lower output offset voltage?


 Thanx in advance!


----------



## dgardner

The purpose of the D3,D4,D7,D8 tracking diodes is to counteract the fact that the current through the output transistors will increase as they get hotter. Output transistor gain (or Hfe) increases with temperature. By adding these diodes, they lower the bias current of the output transistors as the diodes warm up in a porportional way to maintain more stable temperature operation. They have no real effect on output voltage offset.

 1) I was just wondering if anyone has tested the board *WITH/WITHOUT * the 2 "new" bias diodes in the output section VS.* just * the (higher value) resistor WITHOUT the diodes?

 Use 200ohms for R19 and R49 when the diodes are IN. Use 500 or 511 ohms when the diodes are JUMPERED AS SHORTS.

 2) What function do the diodes provide if they are [U*]not*[/U] _physically _ coupled to the output transistors?

 They don't give give as much tracking if they are not in thermal contact with the output transistors. I need to post a picture on how to bond them. Other people have done this successfully. Not bonding them is not bad, but doesn't really give you the full benefit of the thermal tracking.

 3) Does it help to lower output offset voltage?

 They do not impact offset voltage.


----------



## skyskraper

yup i made sure i put the led's in backwards to the pcb screening. 

 i was going to desolder the trimpots, but i had no patience for it when i tried. i'll have another crack later.

 any answer on the capacitance and transistor q's?


----------



## Pars

Quote:


  Originally Posted by *skyskraper* 
_<snipped>
 any answer on the capacitance and transistor q's?_

 

Not sure on the capacitance question. I know that Justin at headamp uses 4x 6800uf in the PSU section of the V2SE (or was that 8200uf?). The V2 board did not have any provisions for filter caps past the PSU like dan's layout does, and was limited to 25mm caps on the PSU section (you might be able to squeeze in 30mm, but it would really be tight).

 As far as the transistors (and FETs) go, I would probably order 2 sets of the FETs at a minimum in order to ensure a good match. I am going to get some of the single FETs (2SJ74/2SK170) just to see what they match up like, but since they aren't on the same substrate, who knows? As far as the BJTs go, double the quantity would probably be good. Make sure that your supplier gives you the same grade (hFE range), cuz if they don't matching them will be fun. I think all of mine so far have been GR grade (from mcm... not sure what bdent has).

 Anyone know whether one "grade" is supposed to better? The lowest hFE range? Highest? Or are they just different?

 Chris


----------



## dgardner

Quote:


  Originally Posted by *skyskraper* 
_just a quick question on matching the 2sj109 and 2sk389's, i was thinking about ordering 6 of each, would this be ok to match? i ordered 24 of each the q's, as matching pairs from a larger pool is a lot easier im sure, but i wasn't sure about the fet's. the 2sj109 is fuxn expensive (like 56x) compared to the q's, and the 2sk389 is like 27x the cost. so i wanted to not spend more then i really had to. i guess i could pool the unused fet's in to a dynahi pool for the future. but im pretty skint atm thats all._

 

If you buy 2 pieces of each FET the amp will certainly work and deliver fine audio performance. You should be able to trim the offset to 1mV or less, but you will need to use one of the pots. But, thats what they are there for. If you buy 3 three pieces of each FET then measuring or swapping them around will improve the initial conditions of getting a low DC offset. In the end, yo uwill not get a better sound amp, IMHO, but you will get the satisfaction of having better matched parts and less use of the pots.

  Quote:


  Originally Posted by *skyskraper* 
_also any other dynalo builders, whats the sort of highest useful capacitance value we can use before it starts to become a waste of time? i had some 120uF 25v i got from RS for a few cents each, so i used those. but more uF = better, so i was wanting to know how far i should go before the diminishing returns hit hard._

 

100-200uF in 4 or 6 of the electrolytic locations is more than enough for me. 5x or 10x more won't fit and wouldn't be worth it to me. I used 120uf x 4 locations. Lots of folks are building dynahi with less bulk capacitance and they sound great.


----------



## skyskraper

cool so ordering multiples of the fets isnt really needed, nice 
	

	
	
		
		

		
		
	


	




 i think i'll still grab 6 of each so i can populate both pcb's without a huge ammount of stress. 

 seeing as this is my first solid state amp, i'm a little unsure of the dc offset measurement, am i correct in assuming that i measure still between the ground and the output of the transistor stage?

 as for the caps, im running 120uF 25v numbers, i'll not worry about going any higher if there are not going to be any real benefits.


----------



## dgardner

Quote:


  Originally Posted by *Pars* 
_Anyone know whether one "grade" is supposed to better? The lowest hFE range? Highest? Or are they just different?_

 

Check out the datasheets for the transistors. Gain is grouped into ranges and given a letter code which is marked on the part when it is sorted by the manufacturer. It should not effect quality. Notice how wide the range is though, even within the same gain class. The actual operating point of the amp's idle currents will be slightly different between low gain transistor and high gain transistors, but can be tweaked if you want to get really retentive.


----------



## dgardner

Quote:


  Originally Posted by *Pars* 
_Not sure on the capacitance question. I know that Justin at headamp uses 4x 6800uf in the PSU section of the V2SE (or was that 8200uf?). The V2 board did not have any provisions for filter caps past the PSU like dan's layout does, and was limited to 25mm caps on the PSU section (you might be able to squeeze in 30mm, but it would really be tight)._

 

If you feel you need huge bulk/filter capacitance, then deal with it in your power supply design. Gotta draw the dividing line somewhere.


----------



## Pars

Quote:


  Originally Posted by *dgardner* 
_Check out the datasheets for the transistors. Gain is grouped into ranges and given a letter code which is marked on the part when it is sorted by the manufacturer. It should not effect quality. Notice how wide the range is though, even within the same gain class. The actual operating point of the amp's idle currents will be slightly different between low gain transistor and high gain transistors, but can be tweaked if you want to get really retentive._

 

Dan,

 Yeah, I've read the datasheets. The lower gain range seems to be a tighter spread (from memory), so I was just curious whether one was preferred over the other for some reason.

  Quote:


 If you feel you need huge bulk/filter capacitance, then deal with it in your power supply design. 
 

I don't particularly 
	

	
	
		
		

		
		
	


	




 Yeah, I knew that because you are providing some filter cap allocation closer to the devices, that total capacitance would be divided between the actual PSU and caps on the amp board.

 Since Dr. Gilmore spec'd a very fast smaller cap immediately following the main PSU filter bank (the 4.7uf Illinois Cap with the 1200V/dt slew rate), does having the filter caps right on the amp board past this cap counteract/interfere with this somewhat? I know he mentioned in the PSU board thread that if the PSU boards did not accomodate these fast caps, he would wire them between the PSU and the amp boards for a Dynahi.

 I had picked up a pair of BC snubber caps (2.7uf polypro IIRC) that have similar specs for slew rate and had planned to use them in one of these PSUs.


----------



## dgardner

Quote:


  Originally Posted by *Pars* 
_Dan,
 Since Dr. Gilmore spec'd a very fast smaller cap immediately following the main PSU filter bank (the 4.7uf Illinois Cap with the 1200V/dt slew rate), does having the filter caps right on the amp board past this cap counteract/interfere with this somewhat? I know he mentioned in the PSU board thread that if the PSU boards did not accomodate these fast caps, he would wire them between the PSU and the amp boards for a Dynahi.

 I had picked up a pair of BC snubber caps (2.7uf polypro IIRC) that have similar specs for slew rate and had planned to use them in one of these PSUs._

 

This stuff can be modeled and measured. I just look for low equivalent series resistance (ESR) on the caps. To me, looking for a high slew rate cap is just another way of looking for a low ESR cap. This is not a digital switching circuit, but normally placement of the decoupling caps are best when the trace inductance and resistance from the cap to the switching element is as low as possible. This means ground planes and close proximity placements. I tried to put the smallest caps the closest to the output transistor connections to the power rails. The small caps typically have the best high frequency response and are most effective with very close placement. Any tweakers out there can debate me on this. Maybe my digital-guy side is showing.


----------



## skyskraper

quick question, considering my board's current state, when connected to the psu, should the led's still light up? or do i need to install the fet's/transistors first? my psu is working perfectly, and i plugged the board in to the psu and nothing. the op amps weren't getting warm (thank christ almost), the caps didn't explode, but what didnt happen was the led's lighting up. im 99% sure i put them in reverse to the silk screening but i will check it out tomorrow. but i wanted to check if i was stressing out over nothing.....


----------



## Pars

I wouldn't think it would hurt anything. I probably would not put the opamps for the servo in until last, as you want to decrease the offset the most you can before you enable the servos. The LEDs will not light up (at least I don't think they will) before at least the two first stage transistors are in (IIRC).


----------



## dgardner

My advice - Put all the parts in except the OP Amp before any power is applied. Socket that part for sure. Then, get all of your offset adjustments made *before*you jump in an start running audio throught it. Also, make sure you something connected to the input before testing, (or at least have the input pulled to ground with a pot or resistor)


----------



## skyskraper

ok well i thought op amps plus other non fet/transistor parts + power = lit led's. ill wait till my fets and transistors arrive then power it up next hehe.


----------



## qbe

What value of resistor should be used connected between output and ground?

 Edit - I mean between input and ground?


----------



## amb

Quote:


  Originally Posted by *qbe* 
_What value of resistor should be used connected between output and ground?
 Edit - I mean between input and ground?_

 

If you're not going to be wiring a volume control pot or stepped attenuator at the input, and you are only testing without a source connected, then a 1K ohm should do it. Remove the resistor after you're done testing. If you're going to be leaving a resistor there permanently (and I think there should be one), use a 470K ohm or 1M ohm. This is to prevent the input FET's gate from going open-circuit (and thus losing its input bias) if you disconnect the source with the power on.

 If you will be wiring a volume control to the input, then I suggest a 1K ohm in series from the pot wiper to the input, then a 470K or 1M ohm resistor from there to ground. Test with the volume turned all the way down.


----------



## dgardner

R65 and R66 are the locations that place a resistor to ground on the board.


----------



## qbe

Amb,

  Quote:


 If you will be wiring a volume control to the input, then I suggest a 1K ohm in series from the pot wiper to the input, then a 470K or 1M ohm resistor from there to ground. Test with the volume turned all the way down. 
 

I will test with just the 1K res to prove things. But yes I will be wiring in a volume control pot. So from your suggestion, is the below circuit the way to wire it up?

 DGardner,

  Quote:


 R65 and R66 are the locations that place a resistor to ground on the board. 
 

Thanks for this, but I had already laid out my own board which I have populated and am currently debugging. If I had known you were doing it, I wouldn't have bothered - I would have used yours.

 qbe


----------



## amb

Quote:


  Originally Posted by *qbe* 
_I will test with just the 1K res to prove things. But yes I will be wiring in a volume control pot. So from your suggestion, is the below circuit the way to wire it up?_

 

No, the 1K resistor should go between the _wiper_ of the volume pot and the input terminal on the PCB. See the schematic for the M³ here for an example (see R1):
http://www6.head-fi.org/forums/showp...41&postcount=1


----------



## qbe

Oh now I understand. When you said "from the pot wiper to the input" I thought you meant the signal input. But Input to the PCB has made it clearer to me. I will start testing tomorrow (it's late and I'm very tired tonight) and hopefully it'll be all good.

 Thank you for helping (and sorry to hijack the thread)

 qbe


----------



## stackofhay

I got this done last night -- still waiting for a few parts, but it is going
 together nicely.

 I'm planning to use a tuned down DYNAHI power supply board for this. 
 It is overkill for sure, but I have the parts here so what the heck!? 
 The whole thing will go into a metal chassis I have on-hand. After 
 I perfect the prototype, I'll re-mount in something fancier.

 ALPS Pot and Cardas RCA's with silver plated OFC is about as far as 
 I'll go on this one!

 Some notes:

 Installed transistors are all matched. Pairs and sets are matched 
 within-set and within-pair to 1% or better. All matching was done 
 at 10mA. (other devices have not yet been matched, and are not installed).

 Resistors are not matched - they measure to within better than .25%. 
 This is good enough for me.

 Electrolytic caps are Nichicon PW(M), low ESR / 105C high 
 reliability type.

 Missing poly caps are Vishay (waiting for an order)

 LED's are matched to within .05V after 1 minute warm-up.

 Tweak pots for current sources are not populated yet -- I want 
 to see how things go with no servo, no pots, grounded input etc... 
 before I start introducing adjustable elements to the equation.

 Cardas solder -- who knows if it makes a difference, but it is nice 
 to work with.

 Those with sharp eyes will note that the emitter resistors are 
 22.1 ohm, not 25. Mouser was backordered and I did not want to 
 wait. I will leave things like this for now, and may reduce the bias 
 currents a bit to compensate if things get too toasty. I'm pretty 
 comfortable that things will be fine.

 I have not decided how to mount the temp compensating diodes 
 yet... or if I'm going to use them at all. Ideally they should be coupled 
 to the output devices in some way. We'll see.

 NOTE: I have a BOM for this with Mouser part numbers. 
 I sent a *corrected* 
	

	
	
		
		

		
		
	


	




 copy to DGARDNER and will send 
 a copy to anyone who wishes -- PM me. With this, you can enter 
 the number of amps you wish to build, then cut/paste the part 
 numbers and quantities into Mousers "bom import" tool -- magic!

 More to follow!


----------



## JRjr

I'm having trouble finding anyplace that will sell the WIMA caps in small quantities.Where do you folks that use them buy them?


----------



## dgardner

Quote:


  Originally Posted by *JRjr* 
_I'm having trouble finding anyplace that will sell the WIMA caps in small quantities.Where do you folks that use them buy them?_

 

Try www.tawelectronics.com.
 $30 minimum order I think.


----------



## Pars

Quote:


  Originally Posted by *dgardner* 
_Try www.tawelectronics.com.
 $30 minimum order I think._

 

Hi Dan,

 No minimum when I ordered from them and I only bought (4) 4.7uf (gilmore) caps.

 Chris


----------



## JRjr

Quote:


  Originally Posted by *Pars* 
_Hi Dan,

 No minimum when I ordered from them and I only bought (4) 4.7uf (gilmore) caps.

 Chris_

 


 I take it you have to call them,since I see no online order forms.Thanks for the info Dan and Chris.


----------



## Pars

I just used the sales email link under contact (IIRC). Calling them wouldn't hurt, though. Be very specific (down to the lead spacing). They quoted me the correct cap, but shipped ones with lead spacing (big) that I couldn't even find in the Wima datasheets (????). They promptly rectified the situation, to their credit.


----------



## dgardner

Last time I ordered the MKS4 475J63 with 22.5mm leadspace. Pars is right, this is not listed in the catalog table. Catalog seems to say 15mm. Another reason why I made the cap locations hold various lead space parts.

http://www.wima.com/navig/pr.htm


----------



## Pars

Quote:


  Originally Posted by *dgardner* 
_Last time I ordered the MKS4 475J63 with 22.5mm leadspace. Pars is right, this is not listed in the catalog table. Catalog seems to say 15mm. Another reason why I made the cap locations hold various lead space parts.

http://www.wima.com/navig/pr.htm_

 

There is another version (which is the one I needed for the V2 board without the provisions that Dan made) for 15mm LS. I think the 15mm LS is the std version, the 22.5mm is the one they initially shipped, even though the email quote showed 15mm (the lady I was dealing with via email was off the day I placed the order).


----------



## stackofhay

FWIW, I used a Cornell Dubilier part, Mouser 5989-100v4.7. About $1.35 ea.

 Fits perfectly into the max lead spacing provided on Dgardner's boards.

 They are a nice brown color that matches the Vishay resistors well...


----------



## stackofhay

Quick question to the group:

 I'm planning to use a DYNAHI power supply board for my DYNALO proto.

 I'd appreciate any comments on this approach...

 Changes I'm making:

 24/24 15VA transformer (will be 25.5 RMS loaded at 1/2 capacity)
 1N4002 diodes
 Generic .22uF ceramic for snubbers
 LM317 regulators tuned for 20V output
 Change gain of OPA541 to 3.2x (roughly) to get 16V at V+ out
 1 ohm current limit resistor (1A Imax) - I know this is higher than needed...
 6x 4700/35V Cornell 105 deg C snap-in caps (only 25mm tall!).

 MUCH SMALLER heatsinks than for Dynahi

 I know it is gross overkill, but I have an extra board here, and enough extra OPA's and REF02's etc... so all I'm really buying to do this are the transformer (Avel toroid), the electrolytics and the 1 ohm resistors.

 Comments appreciated!


----------



## Pars

Quote:


  Originally Posted by *stackofhay* 
_24/24 15VA transformer (will be 25.5 RMS loaded at 1/2 capacity)_

 

I wouldn't go that high. The TE62074 (digikey) 18/18 35VA is what headamp uses. Going higher on voltage will heat the regulators, etc. up more.
  Quote:


 1N4002 diodes 
 

I'd at least use UF4002s, maybe a bit more. I personally am going to use 31DQ10 Schottkys in my V2 board I'm building up, but haven't gotten the xfrmr or a couple of other parts yet...
  Quote:


 Generic .22uF ceramic for snubbers 
 

per the article I read on snubbers, these should be a calculated resistor/capacitor. with Schottkys, I'm not going to use snubbers.
  Quote:


 LM317 regulators tuned for 20V output 
 

you'll also need an LM337...
  Quote:


 Change gain of OPA541 to 3.2x (roughly) to get 16V at V+ out
 1 ohm current limit resistor (1A Imax) - I know this is higher than needed...
 6x 4700/35V Cornell 105 deg C snap-in caps (only 25mm tall!).

 MUCH SMALLER heatsinks than for Dynahi

 I know it is gross overkill, but I have an extra board here, and enough extra OPA's and REF02's etc... so all I'm really buying to do this are the transformer (Avel toroid), the electrolytics and the 1 ohm resistors.

 Comments appreciated! 
 

not overkill at all. the dynahi PSU board is basically just a beefed up dynalo circuit. changing the stuff out to what was published for the dynalo should work just fine (search in the dynahi psu thread... I think someone asked about this).


----------



## stackofhay

Thanks for the reply Pars!

 I'll rethink the transformer -- I'm just thinking that the regulators and the op amps each need a bit of headroom to work comfortably in their linear operating range -- you are right though, there will be extra heat to get rid of...

 Question 1: why use anything more than generic diodes in this application? Just curious. I'll do a search for the snubber reference and see if there is a comment on diode characteristics as well.

 Question 2: The dynahi PS schematic shows 2 LM338 regulators in a fairly non-traditional configuration -- at least on the negative side. You suggest a 337 -- perhaps I've been out of this game for about 20 years too many and I'm missing the obvious but isn't the board wrong for a 337? I'll look in the dynahi PS thread.

 Thanks for the feedback -- I appreciate it. It has been a LOOOONG time since I've even looked at a schematic!


----------



## dgardner

The dynahi PSU uses two positive voltage regulators to form the postive and negative rails. The dynahi psu schematic is on my resource web page.


----------



## Woody

Quote:


  Originally Posted by *stackofhay* 
_Question 1: why use anything more than generic diodes in this application? Just curious. I'll do a search for the snubber reference and see if there is a comment on diode characteristics as well._

 

A good question. There seems to be a belief that fast diodes in the rectifier of a linear power supply "improves" the sound of the amp it powers.

 The only downside I can see to using standard silicon rectifier (slow) diodes is that pre-reg ripple will be slightly higher, as there will be marginally less charging time and an increased period when the diode is reverse conducting at switch off. But I cant believe this could be measured in terms of sonic output from the amp.

 A definite downside to using the fast diodes is the "ringing", possibly at RF frequency that may appear on the rectified output at the point the diodes switch off.

 I'm going to hedge my bets and go for a ultra fast soft recovery diode. This will hopefully mean I will not need the snubber caps across the diodes. I'm planning to build the psu then check for RFI/"ringing" with a scope and an RF probe/sniffer.

 Can anyone else justify the use of fast diodes in this application in view of the possible downsides ?


----------



## Pars

Quote:


  Originally Posted by *Woody* 
_I'm going to hedge my bets and go for a ultra fast soft recovery diode. This will hopefully mean I will not need the snubber caps across the diodes. I'm planning to build the psu then check for RFI/"ringing" with a scope and an RF probe/sniffer.

 Can anyone else justify the use of fast diodes in this application in view of the possible downsides ?_

 

The soft recovery types were what I meant (apparently the General Semi UF400x series is a soft recovery type). I replaced the 1N4002 diodes in my Rotel CD player with the UF4002s and could hear a difference for the better (tho this may be quite subjective). Since the dynahi PSU board is already set up for them, I don't see any reason not to use something like the Fairchild (Harris) RHRP series or the Stealths in them. I'd be interested in your findings however. My scope only goes out to 100MHz, and I'm currently questioning whether it is working properly right now (I get rather large noise traces if I don't have one of the probes grounded)

 The snubber article I referred to was the one by Jim Hagerman, and is pretty easy to find.

  Quote:


  Originally Posted by *dgardner* 
_The dynahi PSU uses two positive voltage regulators to form the postive and negative rails._

 

Ooops, my bad. I hadn't looked at the schematic obviously.


----------



## stackofhay

r.e. Diodes -- I have hundreds of 1N400X diodes here, and I'll build at least one power supply with them. Looking at Mouser, it seems that fast soft-recovery diodes are pretty cheap in the 50V 1A range -- just what I need for this assembly (Dynalo +/-16V) of the board (too bad they just shipped my latest order...)

 It will be interesting to see what these do for the sound -- however, I'm always somewhat leery of any observations made without a direct A/B. That's OK -- it's what makes this fun!


----------



## skyskraper

argh waiting for transistors to arrive whilst i can only listen to a battery powered pimeta is getting _really_ frustrating. 

 the terminal blocks ive used for j2 and j4 look a bit big to fit in j1 and j3 with the fet's installed, what do u guys reccomend using for j1/3 now?

 dan for future boards, maybe it would be cool to have a little bit more space between d5 and r40 just to make populating it the board a tad neater 
	

	
	
		
		

		
			





 edit: is anybody planning on using a crossfeed with their amps? i have a tangent linkwitz board spare, but thought something like the meier might be a better option. does anyone have any advice they could offer me?


----------



## dgardner

Quote:


  Originally Posted by *skyskraper* 
_the terminal blocks ive used for j2 and j4 look a bit big to fit in j1 and j3 with the fet's installed, what do u guys reccomend using for j1/3 now?_

 

I would just direct solder the input wiring into the holes on J1 and J3. I never really intended to stuff that terminal block. I just wanted two large holes to work with.


----------



## skyskraper

ok my fet's arrived, but they have 3 front legs and 4 back ones, should i simply trim the middle front leg for which there is no hole?

 also what process should i test in? inset fet's, test powersupply section, then insert the transistors and test the voltage etc around the circuit to make sure everything is ok, then run output to ground and test with and audio load then hook **** up properly ?

 edit, at what point should the led's light up?


----------



## skyskraper

never mind, i must have some strange led's, i put them in backwards to the silk screen and they didnt light up, so i tried reversing them and they do. wonder where they came from. only ever seen led's with a "backwards" configuration on technics 1200's before.


----------



## dgardner

This is a preview of the updates to the board moving from Rev B to Rev C.

 Notables:
 1 - fixed LED silkcreens.
 2 - enlarged electrolyic body diamter to 12.5mm.
 3 - added 5mm/7.5mm combo footprints on small caps.
 4 - added terminal block silkcreens.
 5 - fix space cramping problems around pots.


----------



## Pars

Looks good Dan. How much interest have you seen in another run of these? Also, is there still any interest in a PSU board for these, or does everyone feel the Dynahi PSU board is the way to go?

 Chris


----------



## dgardner

Quote:


  Originally Posted by *Pars* 
_How much interest have you seen in another run of these?_

 

I would probably just order another 20-30 pieces. If a full blown group buy message was posted, that would be ok, but I don't think I could coordinate it in a timely fashion without a helper.

  Quote:


  Originally Posted by *Pars* 
_Also, is there still any interest in a PSU board for these, or does everyone feel the Dynahi PSU board is the way to go?_

 

I like the dynahi psu schematic concept, but not the layout and the heatsink approach. For the dynalo, I would like a 1U high design that has an AMVECO type transformer right on the board, coupled to a scaled down dynahi PSU circuit.


----------



## Pars

Quote:


  Originally Posted by *dgardner* 
_I would probably just order another 20-30 pieces. If a full blown group buy message was posted, that would be ok, but I don't think I could coordinate it in a timely fashion without a helper._

 

If there was sufficient interest, I would be willing to assist.

  Quote:


  Originally Posted by *dgardner* 
_I like the dynahi psu schematic concept, but not the layout and the heatsink approach. For the dynalo, I would like a 1U high design that has an AMVECO type transformer right on the board, coupled to a scaled down dynahi PSU circuit._

 

I would prefer an off-board transformer (for a Plitron or whatever). I guess provisions for an onboard Amveco would not prohibit that, as long as there were pads for wiring an off-board. Yes, the heatsinking on a dynahi is completely unnecessary for a Dynalo PSU.


----------



## stackofhay

I would go for at least one, possibly two of the new boards.


----------



## skyskraper

the psu i got from cgs.synth.net is nice because you can lay the caps down and it will fit in a 1ru case easily. it doesn't have a board mounted transformer, but a quick trip to the hardware store got me a nice bolt to mount it almost flush with the bottom of the case. 

 the psu itself is cheap to purchase and light on parts, a few diodes, a couple of voltage regulators, and a few caps. total cost to assemble one (including the pcb itself) was around 10-14usd.


----------



## steinchen

I'd take 2 boards if there is enough interest


----------



## bg4533

I am interested in a board or 2 if more are made.


----------



## stackofhay

My first Dynalo board is up and running in the lab. A few oddities cropped up during the sort-out and I thought I'd ask here.

 First: The NPN/PNP pairs are REALLY WELL MATCHED (within 1% across any pair, or set). FETs were not matched (I have no extras). LED's are also well matched.

 1. With no offset adjusting pots or servo op amps installed I saw -43mV for each channel -- they were within 3mV of each other over a 1 hour warm up. I measured around and saw that all bias currents were well matched. Installing a 25K resistor in place of one of the pots in each channel brought the offset to less than 2mV on either channel, warm or cold. Nice. Don't ask me why, but I prefer adding the resistor to swapping LEDs...

 2. Feeding a square wave through the amp -- I see a slight overshoot (not ringing, just a single overshoot/recovery of the signal) in the output. My source and probes are well grounded / terminated / compensated and I'm running the amp into 150 ohms (tried other loads too, no difference). With amp gain set to 10 (11?), putting about 5pf (mica cap) across the gain feedback resistor calms the overshoot perfectly. 

 I'll reserve judgment until I have the board mounted in a metal case, but right now, it sure performs well on the bench (with the cap added). Very clean and very quiet.

 No listening yet -- I wanted to be certain that the offset issue was taken care of before hooking up any low impedance cans.

 DGARDNER -- please consider adding pads for this compensating capacitor on your Rev B board.


----------



## dgardner

Quote:


  Originally Posted by *stackofhay* 
_DGARDNER -- please consider adding pads for this compensating capacitor on your Rev B board._

 

Layout will be changed.


----------



## KarlDL

I'm interested in at least 4 boards, since it's probably easier to adapt existing boards to the variant I have in mind than to roll my own boards. Not to mention the advantage of group input on the design!


----------



## Erik S.

I'm also interrested in 2 or 3 boards if they're to be made.


----------



## eastside504

i'll be interested in 4 boards.


----------



## dgardner

This is a preview of the updates to the board Rev C.

 Notables:
 1 - fixed LED silkcreens.
 2 - enlarged electrolyic body diamter to 12.5mm.
 3 - added 5mm/7.5mm combo footprints on small caps.
 4 - added terminal block silkcreens.
 5 - fix space cramping problems around pots.
 6 - added compensation cap in feedback loop
 7 - rotated signal input terminal blocks
 8 - added power-on LED with an LED current program resistor (for front panel)
 9 - moved tracking diodes closer to output transistors.

 Comments are welcome...


----------



## steel

I'm interrested in 2 boards if they're to be made.

 thanks...


----------



## walangalam

Just a comment.

 As a dynalo owner I know how hot the output stage gets. C10-11,21-22
 are too close, and they will get hot, I mean hot, as you-cant-touch-it-for- more-than-2-secs hot.

 The space is there so you could move it a little bit farther.


----------



## Archeopteryx

I'd also be interested in two boards. Thanks.


----------



## stackofhay

walangalam said that the output stage gets too hot to touch. 

 I'm confused by this as I've had mine running for a week with a 5Vp-p output into a 150 ohm load. My output stage is biased with 16.5mA per device and output devices are barely hot to the touch, certainly not even close to "can't touch for more than 2-seconds" hot. You can put your finger on any one of the devices indefinitely with no pain or even minor discomfort.

 My transistors are all Hfe matched to within about a percent. The Emitter resistors are 22 ohm vishays. All transistors are about the same temp (best I can measure)

 The big filter caps barely get warm.

 Clearly this is a different experience, and I'm just mentioning this to add more data to the discussion.


----------



## walangalam

hmm. Are you running with stock 16.3V per rail? The emitter resistors should drop .4V, giving 16ma per tranny. They should get hot.

 If you are running stock, then I might be occilating... but I dont hear anything bad. I have also rebuilt the amp completely, but same temps.

 I really should invest in a scope.


----------



## art633

hi all, I'd be very interested in at least 4 boards. 

 Are there any power supply boards still available? I'm a tad confused as to which PSU thread is which ( came in here a little late - hey come on I may be getting old but I'm only a junior member!!! )

 wishes M


----------



## Porksoda

I would also be interested in a couple boards


----------



## dgardner

Quote:


  Originally Posted by *walangalam* 
_hmm. Are you running with stock 16.3V per rail? The emitter resistors should drop .4V, giving 16ma per tranny. They should get hot._

 

I think Pd is roughly (16.4-0.4) * 0.016 = 256mW per transistor. The T0-92 case has a thermal resistance (Theta-JA) of about 160 C/W. That means you can expect a 40C rise on the package. At room temp that means about pack temps of 64C or 147F in open air. The device is rated at 400mW.


----------



## Pars

I haven't run mine for very long, as I am still finishing up the PSU, but when I did have it on for about half an hour or so at 16-16.4V, the output trannies, while warm, certainly weren't what I would call hot. I'm sure I could leave my hand or finger on there for at least a minute without it becoming uncomfortable. And IIRC I was dropping about 0.4V across the emitter resistors.

 Chris


----------



## walangalam

I havent looked into the occillation theory yet. FYI I'm using sijosae pcb, which is pretty much tried and tested. It might be the power supply I'm using, which is the original Gilmore PS that has been known to be unstable in certain configs. I will go and replace the supply with a generic one and see.

 Could it just be the transistors I'm using? I got all GR types from MCM, which is the worst grade of all.

 dgardner: It certainly is hotter than 64C. I have a Radioshack thermometer that goes up to 70C and the temp exceeds it, without even being in contact with the transistors.

 Thanks to this thread... I didnt even know I had a problem!


----------



## stackofhay

Regarding temp of output transistors...

 They get "very warm" but not so hot that you can't touch them for 20 seconds. I am running 16.5V rails with 22R emitter resistors. 

 As DGARDNER mentions, the ThetaJA for this package is, well, rotten. This means that the plastic is a pretty good insulator. This means that your finger will potentially conduct enough heat from the package surface to make touching the transistors possible, even if the initial temp is 40 degrees above ambient.

 (decided to do some actual measurements...)

 In a 14 degree (C) basement, the transistors are sitting at around 45 degrees (C) per a non-contact thermometer reading... About what one would expect.

 The amp has been on for a week, running off my heavily tweaked DYNAHI power supply -- set to 16.5V per rail.

 I think the amp is running normally and that the transistors are far from meltdown.

 BTW, the max Pd spec for these devices is 400mW (over rated ambient temp range) per the data sheet. 

 These *will* get hotter once this thing is bundled into a box!


----------



## stackofhay

More observations:

 My amp is now running in what I hope is the final configuration. I'm sure there will be some need for minor tweaks, but so far so good.

 My configuration:

 AVEL 22V 15VA transformer

 DYNAHI power supply modified for 16.5V operation -- small heat sinks, 317 regulators, 35V caps, cheap soft recovery diodes, 1 ohm series current limiting resistors, changed values of 541"+" feedback resistors and hand matched the 10K pair on the "-" side. I adjusted the regulator voltages so that the thermal load was shared evenly across the regulator and op amp stages, so using small cheap heatsinks is possible (the regulators and op amps are running at 25 degrees C above ambient).

 DYNALO Rev. A board -- Extremely tight matching of transistors and LED's. 22 ohm emitter resistors (Mouser was out of 25's), 25k resistor in place of one of the adjusting pots for each channel, otherwise no pots are installed. I installed a 10pF cap across each channel's feedback resistor to calm some observed overshoot. There is still a touch (tiny) of a glitch at the start of the leading edge of square waves -- I need to look into this further.

 Still have not listened to it... that will come this weekend!

 Observations:

 Power supply is spooky quiet -- no noise at all. Nice and stable too.

 DYNALO board is equally quiet. Frequency response is quite extended -- -3dB point was well above 500KHz before I added the 10pF caps. I've not measured it since. DC offset roams a bit, but never more than 5mV in any direction under any circumstances I've measured. Touching the output transistors to selectively cool one bank will change the DC offset, then the servo kicks in and slowly reels it back... very cool.

 Avel transformer could probably be 18V or 20V to save a little on power supply heat.

 More to follow!


----------



## stackofhay

After 4 hours of drilling, filing, mounting, wiring etc... listening has FINALLY begun...

 I was held up for about 1/2 hour by a OP27 that died for no apparent reason. 

 I did a final test of the amp before plugging in my cans, and observed 35mV of offset on the left channel -- the offset dropped to 2mV when I removed the OP27. After hunting around for a bit I found no problems, so throwing caution to the wind, I plugged in a new amp, and voila, the servos are both working fine!

 IMPRESSIONS:

 Initial impressions are that this amp provides incredible detail and lots of impact. Much more "up front", clear and articulated than my PPA 1.1 with BB627's and quad 634's per output (diamond buffers soon?).

 There is a nice amount of space/air around acoustic instruments, and the background is DEAD silent -- very cool. There is a really nice crisp snap to transients and quite a bit of inner detail is apparent, especially for well recorded A'Capella and acoustic cuts. I'm quite pleased.

 I'm listening to WAV files on my PC using my Chaintech card's oversampled Wolfson outputs- modded with blackgates. Interconnect is Zu, cans are 650's with a smurf blue Cardas cable. I'll hook it up to my main stereo once it has broken in a little.

 My wife is actually the ultimate critic in our family. It takes her 30 seconds to form an impression and opinion -- and she's invariably right...

 Her take is "this is the best one (you've) built yet. (Listening to the MFSL Supertramp Crime of the Century CD).

 I tend to agree. 
	

	
	
		
		

		
			





 (other's she's heard are PIMETA with ADI 86xx and PIMETA with OPA627 and a PPA with OPA627/637's and quad BUF634's per channel.

 Unlike some of my other projects, this one is actually in a chassis!

 My DYNALO configuration is pretty much as described in an earlier email... tweaked DYNAHI power supply, well matched DYNALO board and all premium grade components. I added 10pF across the feedback resistor, and the amp produces nearly perfect SQUARE waves at well over 100KHz. 

 I'm using a ALPS "Blue Velvet" for volume control. Chassis interconnect wire is some funky OFC stuff a friend had custom made for braiding custom speaker cables and interconnect -- it's about 19 ga and consists of two distinct layers of conductors with the inner twisted in a direction opposing the outer layer -- very funky...

 I think the gain is too high for my application and I'm probably going to drop it by half later tonight. I'll also run some RMAA tests too, to see if the figures confirm what my ears hear.

 I have the boards mounted in a aluminum chassis I had lying around, nothing special in terms of packaging yet -- I wanted to get a feel for the sound before dumping a bunch of cash into a stepped attenuator, cardas jacks and a nice case with a shiny blue pilot light...

 I'll post some pictures (it is far from impressive -- believe me) later if I can figure out how...

 A side note -- playing music for several hours, the output transistors are running much hotter than they were in the lab into a dummy load -- go figure.
 I can still touch them for 10 seconds or so before I feel the urge to pull away, but they are hotter, for certain.


 FOLLOW UP:

 If anyone is interested in what I did to my power supply, I have a marked up schematic and specs for the heatsinks, transformer, etc... let me know and I'll send you what I have.


----------



## stackofhay

OK -- final tweaking done for now.

 Reduced feedback resistors to 4.99K
 Increased caps across feedback resistors to 33pF
 Placed 20pF cap across R17/R47

 Now the amp makes nice pretty square waves with no overshoot and nice sharp edge at the start of rise/fall.

 That's it for now -- back to listening!







 I'm going to try the Ety's later... this should be interesting -- an up front amp with full frontal buds...


----------



## qbe

Or anyone else ... 
	

	
	
		
		

		
		
	


	




 In this post you say  Quote:


 I measured around and saw that all bias currents were well matched. 
 

1. What are the bias currents you are referring to? 
 1.1 With reference to Kevin's original circuit (copy attached as a GIF), is it through the 500ohm resistor and then through the SA1015 and SC1815?
 1.2 Or is it through the 1k resistor then through the SA1015 and SC1815?
 1.3 Or is it through the 25ohm resistor and then through the SA1015 and SC1815?
 1.4 Or are the currents through all of the above matched with their respective pairs?

 2. I presume to measure the current you just pull the leg of a resistor and put the DMM in series with the resistor and its respective transistor?

 3. Using the 500ohm resistor as an example, measuring the current between the 500ohm and the 2SA1015, will that current be constant through the resistor, transistor, the 200ohm resistor, one side of the 2SJ109 and the 5k resistor?

 4. And should the current measured in 3. above be the same as that flowing through the equivalent "leg" which goes through one half of the 2SK389?

 Hope some of that makes sense to you 
	

	
	
		
		

		
		
	


	




 - Thanks

 qbe


----------



## qbe

Oh, and DGardner, I think I might please get 2 or 4 boards if they go for sale, and depending on costs etc.

 qbe


----------



## stackofhay

Hi QBE,

 I took out the servo amps, shorted the inputs (actually, I installed 51 ohm resistors) and let the amp warm up for 15 minutes, then I just sniffed around with a voltmeter -- measuring the drops across resistors in complementary positions. I did not go much farther than that. These positions would be in the current sources, diff pairs, each output transistor's emitter resistor, etc... I just wanted to ensure that the gross operation of the amp was correct before I started "fixing" things.

 My voltmeter is a fluke 45 bench meter so it is not appropriate to compare ppm differences.

 BTW, with no servo amps installed, both channels sit within 1 or 2 mA of ground -- nice.

 I have some experiments to do later (snow day) and will report if I find anything interesting.

 Good luck!


----------



## Pars

Well, I finally got the PSU of the V2 I'm building done and wanted to report. It works great, better than the bench supply I was using. Offset had already been tweaked using the bench supply. With the GIlmore PSU, it is even more stable than before. Without servos installed, I was measuring 2-3mV on one channel, the other was less than 1mV. Offset seems to move less than with the bench supply. V+ and V- measured at the servo opamp socket was a perfectly-balanced 16.15V for both + and -. I assume that the 22.6K resistor on the V+ OPA548T would be what I need to adjust if I wanted to get it to exactly 16.4V? 

 All resistors in the amp were matched with my HP3268A (out of cal). I know I can trust it for relative measurements but not sure how accurate it is for absolute measurements. I guess I can find out when my Mouser order gets here as I ordered a couple of 0.1% IRC resistors. I also ordered a Protek 608 to replace my Ratshack DMM (good deal at tequipment.net on sale for $115, normally $199).

 I have started building the dgardner Dynalo board. I know Dan did this, but I installed SIP sockets for all the transistors, and cut up zig-zag sockets for the FETs. Anyone see any problems with doing a socketed version in terms of performance and long-term reliability?

 I don't have the amp cased up yet, a pot in or any in/out jacks, etc., but I did do some listening last night using a PCDP and Grado SR-60s. It really sounds good, and no hum once I rotated the transformer. I think I'm going to use the Par Metals 12"x8" case and not mount the transformer on the board to keep it moved away as much from the board. Hum-wise it didn't seem to make that much difference, as even board mounted I could get it to the point that I couldn't hear any noise. I can't wait to get the dgardner board done as I think it should be even quieter with the ground plane.


----------



## dgardner

Quote:


  Originally Posted by *qbe* 
_2. I presume to measure the current you just pull the leg of a resistor and put the DMM in series with the resistor and its respective transistor?_

 

Remember that I=V/R, so if you know the value of the resistor and you can measure the voltage across it, you can compute the current through it. So, the DC current measurements at idle are simply done by looking at the voltages across several key resistors. No need to ever lift the leads to measure current.

 Examples:

 1 - The Red LED, 500ohm resistor, and transistor, for m a constant current source. The LED forward voltage is about 1.7V, the transistor Vce is about 1.0V, and R=500, so the current is about (1.7-1.0)*500 or 2mA.

 2. The 2mA is shared 50/50 through the two legs of the JFET. So, the 5K resistors will have 1mA flowing through them. You should see about 5v dropped across each of them. V=I*R, V=(.001)*(5000), V=5v. The two 5000ohm resistors for a given JFET should show and equal 5v drop across them. Slight variations are due more likely to mismatches inside the matched pair. 5-10% variations in the voltage drops across 5000ohm pair is not uncommon, even with 1% resistors.

 3. Jumping right to the output stage. The idle current of each output transistor can easily be measured by looking at the voltage across one of the 25ohm emitter resistors. I=V/R. Measure the voltage. Expect about 0.375 volts. Compute the exact current as I=(measured V)*(25). Anything in the range of 13mA to 18mA is ok. This number goes up as the unit gets fully warmed up. For fun, you can measure across each of the 25ohm resistors and see the variations. These are due to resistor value differences and gain mismatches in the output transistors. 2-3% variation in these voltage is normal.


----------



## JRjr

I'd be interested in a few more boards if you make them.


----------



## dgardner

The plan is definitely to fabricate the revised and updated version. Due to my level of business travel, I need help to orchestrate what I believe will be a small group buy of about 50-100 boards. The board database is complete and ready to order. Perhaps someone (like PARS) should announce a group buy thread an gather up the total demand. Pricing will likely be $10ea unless we get enough pieces to get price breaks. I'll be happy to get the various quantities quoted at Imagineering.


----------



## dgardner

Group buy thread started for Rev C boards.

http://www6.head-fi.org/forums/showthread.php?t=108445


----------



## Erik S.

Hi!

 Since the group buy of the boards has already started, I'm going to aquire the needed parts. So I need some help to fill in the blanks of the BOM that was provided earlier in this thread. I have found the parts that were missing, but if they're the right ones, I don't know 
	

	
	
		
		

		
			





 (no knowledge about electronical compononts whatsoever).

 Here goes:

 Digi-Key:
 CAP - Monolithic Ceramic - 0.1uF, 25V or greater - P4923-ND
 CAP - Poly Film Type - 0.1uF, 25V or greater - 478-2244-ND
 CAP - Large Poly Film Type - 4.7uf, 25V or greater - P10987-ND

 If these parts are no good, tell me what to buy and where (preferably MCM, Mouser and Digi-Key)

 All help appreciated

 Erik S.


----------



## Pars

Quote:


  Originally Posted by *Erik S.* 
_Hi!

 Since the group buy of the boards has already started, I'm going to aquire the needed parts. So I need some help to fill in the blanks of the BOM that was provided earlier in this thread. I have found the parts that were missing, but if they're the right ones, I don't know 
	

	
	
		
		

		
		
	


	




 (no knowledge about electronical compononts whatsoever).

 Here goes:

 Digi-Key:
 CAP - Monolithic Ceramic - 0.1uF, 25V or greater - P4923-ND_

 

399-2081-ND (Kemet) would be a good one. The Panasonic you have listed looks like it would be fine also.
  Quote:


  Originally Posted by *Erik S.* 
_CAP - Poly Film Type - 0.1uF, 25V or greater - 478-2244-ND_

 

495-1275-ND Epcos Met. Polypropylene is what I used. Fits great.
  Quote:


  Originally Posted by *Erik S.* 
_CAP - Large Poly Film Type - 4.7uf, 25V or greater - P10987-ND_

 

 Those should fit. This spot can take lead spacing up to 22.5mm.
  Quote:


  Originally Posted by *Erik S.* 
_If these parts are no good, tell me what to buy and where (preferably MCM, Mouser and Digi-Key)

 All help appreciated

 Erik S._


----------



## Erik S.

Thanks for the help Pars 
	

	
	
		
		

		
		
	


	



 Been wondering for days if these were the right parts.


----------



## Pars

No problem Erik. You can't get Wima MKS4s for the 4.7uf caps in Norway? 
	

	
	
		
		

		
		
	


	




 BTW, Garbz got some kind of "naked" Siemens film caps from RS (in Australia) that he used and liked alot for the 4.7uf caps on a self-etched Gilmore he built. If you are interested in hunting these down, he gave an RS part number for them. Search for a Gilmore thread in the last year (can't remember whether it was here or on headwize).

 Also, someone correct me if I'm wrong, but isn't Epcos Siemens?


----------



## Erik S.

I found the MKS4 here in Norway, but they were quite expensive, $4 each.
Link to Epcos info from Digi-Key (pdf).


----------



## dgardner

Erik S - WIMA 4.7uf cap are USD$1.69 
 I'm sure we can arrange to send you some.


----------



## skyskraper

i bought my caps from rs in aust too, the film's are evox mmk's and the ceramics were kemets. both not too pricey at all. 

 with the 2sa1015 and 2sc1815 should i match idss, hfe, or both? my output transistors finally arrived yesterday


----------



## amb

Quote:


  Originally Posted by *skyskraper* 
_with the 2sa1015 and 2sc1815 should i match idss, hfe, or both? my output transistors finally arrived yesterday 
	

	
	
		
		

		
		
	


	


_

 

No such thing as Idss for bipolar transistors. Just match the hfe.


----------



## skyskraper

well that shows the depth of my solid state knowledge! thanks


----------



## Erik S.

Quote:


  Originally Posted by *dgardner* 
_Erik S - WIMA 4.7uf cap are USD$1.69 
 I'm sure we can arrange to send you some._

 

I like the sound of that 
	

	
	
		
		

		
			





 YGPM


----------



## Erik S.

What brand of resistors do you use in the Dynalo?

 Since Digi-Key has all the resistors needed, I might go for Yageo.
 Is it any significant difference between Yageo and Vishay-Dale?


----------



## Pars

Erik,

 I think that a couple of people here have used the Yageo and liked them. I personally like the BC, though Digikey seems to be out of some values needed (4.99K, IIRC). They do however also carry Phoenix, which appears to be a buyout of a Philips factory (BC then) in Brazil, and they appear to be identical to the BC (even the manuf. part numbering scheme). Those are what I would use if I were getting everything from Digikey. The std. size 0.4W at $0.19 each are the ones I have used. BC also has a compact size that runs more ($0.32 each?)... I would use the std. size, slightly smaller than the Vishay-Dale RN60s.

 Chris


----------



## Erik S.

Thanks again for the help Pars 
	

	
	
		
		

		
		
	


	




 Gonna sit down tomorrow and calculate the costs of the alternatives I have.


----------



## dgardner

Dynalo in 9x9x3 lmbheeger mod-u-line enclosure:
 (70's retro look, love it or leave it.)






Front Panel (jpg)
Size Panel - heatsink bolt-thru (jpg)
Rear Panel (jpg)
Inside view - dynalo rev b + dynahi psu set to +16v/-16v (jpg)
Dynahi psu configured for dynalo
Dynalo rev B board (jpg)


----------



## Pars

Really nice job Dan! Is that an Amveco pancake transformer I see stuck in the back? What power switch/IEC is that? Is it fused also? I like that one.

 Have you noticed any noise (hum) dependent upon transformer position? With that V2 I am currently trying to finish up (case on order), I can get quite a bit of hum depending upon transformer rotation. If you toss the transformer into another axis (like I think you did), does that put most of the EMI field onto a different plane (i.e., do torroids radiate mainly around themselves, and not so much from their top or bottom)?

 Still waiting on some parts from Mouser for the Rev. B board, but it is 90% built up (Mouser was out of the 24.9 ohm resistors, so those are on back order, then they shorted me half of my 200 ohm resistors... grrrr).


----------



## dgardner

Quote:


  Originally Posted by *Pars* 
_Is that an Amveco pancake transformer I see stuck in the back? What power switch/IEC is that? Is it fused also?_

 

Avmeco 70075 transformer. No hum whatsoever. IEC power inlet is from a surplus store, sorry no P/N for you. No fusing.


----------



## skyskraper

ive done the hfe testing of my output transistors. and grouped them roughly in to pairs. it seems ive got much tighter readings and pairings of the 2sc1815's then the 2sa1015's. do i simply use the pairs in the same location left to right, or do i match left to right and then find the accompanying transistor pairings with the closest readings on in the accompanying left right positions? 

 also would it be better to use the higher hfe reading transistors in the earlier positions or later positions?

 edit: i ask coz my pairs of 2sa1015's range from 225 to 290. as opposed to my 2sc1815's range from 170-180 for the 6 pairs


----------



## amb

skyskraper, I don't know what you mean by left and right, but if you're talking about the relative positions on the board within each channel, it makes no difference; they are electrically in parallel.

 What is more important is to try to use the closest matches for all of the NPNs so that the current distribution is about the same down each branch, and do the same for the PNPs, and hopefully you could get the NPNs and PNPs to match as well. Obviously it's harder to match between the NPNs and PNPs, but do the best you can.


----------



## dgardner

skyskraper - you might also want to review the Matched transistors in Dynahi thread. Posts 63-66 are worth reading.


----------



## skyskraper

amb: i meant left and right channels on the amp board. 

 dan: thanks i was planning on using those posts as a guide to reducing dc offset once the transistors were installed. 

 i was planning on matching the positions down the current flow of the amp between the left and right channels. im assuming that it doesn't matter whether i go from low (relative) hfe to high hfe down the chain of transistors? also whats the highest acceptable level of dc offset that i should use as a measurement point for the channels. i simply measure between input ground and output ground, then inpute left and output left, then input right and output right? or is it better to measure between input ground left and output left, then the same for the other channel?

 edit: just saw, 10mv. then let it settle in


----------



## amb

Quote:


  Originally Posted by *skyskraper* 
_amb: i meant left and right channels on the amp board._

 

There is no need to obsess about left and right channel matching when it comes to transistor hfe.


----------



## skyskraper

so it would be a better idea for me to say group the tightest npn's for one channel then the next tightest group for the other channel (and same for pnp's)?


----------



## amb

Quote:


  Originally Posted by *skyskraper* 
_so it would be a better idea for me to say group the tightest npn's for one channel then the next tightest group for the other channel (and same for pnp's)?_

 

Yeah, that's fine.


----------



## steinchen

but transistor matching is not unconditional neccessary for a working amp, is it ? the pots and the servos will put the offset nearly down to zero (if I understand some infos right). Matching transitors is for minimizing takeover distortion and maximizing performance.

 I got problems getting the trannies here in Europe. Could only get 2SJ 109 *BL* and 2SK 389 *BL*, are the BL types ok for the Dynalo ? Can't find the 2SA1015 and 2SA1815 at all, even bdent.com is out of stock. Is it possible to get a set with the pcbs ?


----------



## amb

Quote:


  Originally Posted by *steinchen* 
_but transistor matching is not unconditional neccessary for a working amp, is it ? the pots and the servos will put the offset nearly down to zero (if I understand some infos right). Matching transitors is for minimizing takeover distortion and maximizing performance._

 

The purpose (and importance) for matching transistors differ depending on which transistors we're talking about. At the output stage of the dyna{lo,hi}, since there are multiple pairs of transistors in parallel, matching the hfe between the NPNs helps to equalize the amount of current flowing through each branch. There are emitter resistors to help this too, so the matching is not too critical. The match between the NPN and the PNP sides are for making the transition between the two halves more linear, but since the output stage is operating in class A for most loads, the transistors never cut off so again the importance of matching here is not that great.

 For the input differential stage, though, the matching is important for keeping the basic DC offset low, and to allow the global feedback to do its job properly, minimizing distortion.


----------



## amb

Quote:


  Originally Posted by *steinchen* 
_Could only get 2SJ 109 *BL* and 2SK 389 *BL*, are the BL types ok for the Dynalo ?_

 

Yes, the BL is actually the preferred grade.


----------



## skyskraper

im getting a bit confused now ive powered my board up and started taking measurements. 

 can someone please let me know which way is the right way for me to be measuring dc offset.

 input to output?
 input ground to output signal?
 input signal to output ground?

 some measurements are way way off, some are close to what i want. when i connect common to output signal, positive to input signal (on my dmm, set to mv) i get 1-3mV of offset. when i switch the polarity of the probes around the figure moves around all over the place! 
	

	
	
		
		

		
			








 after i've got this amp done i intend to publish a build diary to help others who are building it when the group buy gets in to swing!

zing thats it's current state


----------



## dgardner

Quote:


  Originally Posted by *skyskraper* 
_can someone please let me know which way is the right way for me to be measuring dc offset._

 

 With the audio input tied to ground with a 10K resistor, measure the output+ terminal with respect to power supply ground. just use the two terminals on the output connector block.


----------



## skyskraper

and tieing input to ground is done with r65/66 locations right?


----------



## dgardner

Quote:


  Originally Posted by *skyskraper* 
_and tieing input to ground is done with r65/66 locations right?_

 

 righto.


----------



## skyskraper

beautiful. im just letting the circuit settle in before i take some final readings. right now its very low dc offset with the op amp in, -1mV on one channel and 1mV on another, although im not sure my meter's resolution is fine enough for those to really be accurate figures, it fluctuates +/-3mv with nothing connected to it


----------



## Pars

Quote:


  Originally Posted by *steinchen* 
_but transistor matching is not unconditional neccessary for a working amp, is it ? the pots and the servos will put the offset nearly down to zero (if I understand some infos right). Matching transitors is for minimizing takeover distortion and maximizing performance.

 I got problems getting the trannies here in Europe. Could only get 2SJ 109 *BL* and 2SK 389 *BL*, are the BL types ok for the Dynalo ? Can't find the 2SA1015 and 2SA1815 at all, even bdent.com is out of stock. Is it possible to get a set with the pcbs ?_

 

Have you tried FIBRA-BRANDT in Germany? I know Justin of headamp used to order all the trannies from them, but did mention that they were only cost-effective for large orders. Not sure if that applies to you since you are in Germany...

 BL are fine (that's what mine are from MCM). My 2SA1015s and 2SC1815s are GR. All from MCM.


----------



## skyskraper

been listening for a couple of hours now. mmm this is lovely. 

 for my millionth question, what resistor should i change to lower the gain? i've read a few posts and am just uncertain, it seems r2 should be increased to decrease the gain, but i'm not 100% on it.

 big thanks to all of you guys who've answered my q's to date, im starting to understand whats going on in the circuit now


----------



## Erik S.

dgardner told me that the gain is controlled by R7 & R16 for one amp and R46 & R37 for the other amp, where R7 and R37 are 1K ohm, R16 and R46 are 10K ohm. To lower the gain increase the value of R7 and R37.

 (I actually helped someone... I think 
	

	
	
		
		

		
		
	


	




)


----------



## Erik S.

Anyone know of a European version of the Elpac PSU? Or do I have to dive into another DIY project? 

 (Maybe learn how to solder first 
	

	
	
		
		

		
		
	


	




 )


----------



## skyskraper

thanks! i'll give that a shot 
	

	
	
		
		

		
		
	


	




 i couldnt find an off the shelf 220-240v -15,0,15 supply so i built my own using a pcb for a psu from another project. seems the 7815/7915 are only outputting 13.9v each atm though (i have a feeling the led's on the board are responsible for that!), seeing as my toroid is a 18-0-18, after rectification i should have enough power to run higher rated regulators


----------



## steinchen

Quote:


  Originally Posted by *Pars* 
_Have you tried FIBRA-BRANDT in Germany? I know Justin of headamp used to order all the trannies from them, but did mention that they were only cost-effective for large orders. Not sure if that applies to you since you are in Germany...

 BL are fine (that's what mine are from MCM). My 2SA1015s and 2SC1815s are GR. All from MCM._

 

reichelt.de carries all needed trannies, didn't find them in the first try because they are listed as "SA 1015" and not "2SA1015" ... what a huge difference a little blanc can make ...

 prices are quite reasonable so I'll buy a whole bunch of them for matching


----------



## amb

Quote:


  Originally Posted by *skyskraper* 
_seems the 7815/7915 are only outputting 13.9v each atm though_

 

That doesn't sound right. The regulators shouldn't be that far off. I think perhaps the regulator isn't seeing sufficient voltage at its input.

  Quote:


 seeing as my toroid is a 18-0-18, after rectification i should have enough power to run higher rated regulators 
	

	
	
		
		

		
		
	


	



 

Measure the AC voltage at the transformer secondary, as well as the DC voltage before the regulators and it should be clear what's going on.


----------



## skyskraper

i will do 
	

	
	
		
		

		
		
	


	




 report to come


----------



## skyskraper

weird seems to be reading ok now. put it down to user error 
	

	
	
		
		

		
			





 i still think i might try swapping in higher voltage regulators. +/-18v


----------



## Pars

Ran across these and they were so cheap, I just had to order a couple. This is the Elpac as used by headamp, etc. +/- 15V linear.

here

 I'll let you know when I get them as I had never even heard of these guys. To their credit, I had a email that they had shipped about 2 hours after placing the order.


----------



## MisterX

Dang it..... I don't need or want any of those Elpacs but at that price they are gonna be calling me all day long. 
	

	
	
		
		

		
		
	


	




 Nice find..... let us know how that company treats you.


----------



## SnoopyRocks

Quote:


  Originally Posted by *Pars* 
_Ran across these and they were so cheap, I just had to order a couple. This is the Elpac as used by headamp, etc. +/- 15V linear.

here

 I'll let you know when I get them as I had never even heard of these guys. To their credit, I had a email that they had shipped about 2 hours after placing the order._

 

Nice find. That is a great price indeed. So good that I ordered a couple. They were quick to send me email confirmation of the order but no tracking number yet. Hopefully it goes through. 
	

	
	
		
		

		
		
	


	




 At this price, it's not worth the money or effort to even consider making your own power supply. Thanks for the heads up.


----------



## Pars

Quote:


  Originally Posted by *SnoopyRocks* 
_At this price, it's not worth the money or effort to even consider making your own power supply._

 

I don't know about that, as the Gilmore supply is extremely clean and stable. I guess it depends on what your end use for the amp is. I think I may take my first dgardner board (which is nearly complete) and use it as a lite for work since the Elpac will be somewhat more transportable than a Gilmore PSU plus the amp. BTW, the FedEx ground tracking number they gave me didn't show up until late that night or the next day. We'll see what kinda box of rocks they shipped me


----------



## Porksoda

So... tempting...

 I am tempted to use it and then use a low drop-out rendition of the Jung Super-regulator to squelch any noise. Exactly how quiet are these supplies?

 EDIT: Ah heck, what's $17 in the long run for what is otherwise a $40 power supply?


----------



## SnoopyRocks

Quote:


  Originally Posted by *Pars* 
_I don't know about that, as the Gilmore supply is extremely clean and stable. I guess it depends on what your end use for the amp is. I think I may take my first dgardner board (which is nearly complete) and use it as a lite for work since the Elpac will be somewhat more transportable than a Gilmore PSU plus the amp. BTW, the FedEx ground tracking number they gave me didn't show up until late that night or the next day. We'll see what kinda box of rocks they shipped me 
	

	
	
		
		

		
		
	


	


_

 

You're right about the end use. I probably should have qualified that statement. There's seemingly no shortage of people willing to spend $$$ for the last half (arbitrarily chosen to be dramatic 
	

	
	
		
		

		
		
	


	




) a percent of improvement. Seriously though, my impression from reading about the differences people have observed with the headamp gilmore lite w/ the elpac compared to the upgraded power supply is that the difference is subtle, though noticable with the right source, cans, ic's, recording and of coarse ears. 
	

	
	
		
		

		
		
	


	




 That is it say that it is ostensibly not a good bang for the buck upgrade. To implement a significantly better power supply would take considerably more money and time. For my purposes, this makes it an easy choice, especially at only $10. Besides, there are ways to improve the elpac performance...a pi filter comes to mind for a simple passive implementation. I'd be curious to see how much measurable difference there will between a the elpac and a more robust power supply. Maybe I'll put mine through some real (audio precision) lab testing when I finish to find out definitively.


----------



## skyskraper

seems i have zeee noise. its like a high pitched hum, but too high pitched to really be a hum. i'm assuming this is oscillation or a grounding issue. its uniform across both channels and not unique to one

 currently i don't have a pot hooked up. simply iec->transformer->psu->amp for the power chain. trs -> amp ->trs for the signal. 

 the noise is present whether i have a source connected or not. the i/o jacks are isolated from the case as is the iec socket. do i need to connect the ground on the iec to the case? i have a feeling this high frequency noise is somehow psu related, shielding required possibly? or do i need to connect the signal ground to the case or maybe psu ground to the case? argh no idea here 
	

	
	
		
		

		
		
	


	




 !!!

 here is a pic for reference's sake. pic 108kbs 

 dc offset is fine (sub 1mv) on both channels.

 ill keep playing with it for the moment, but any suggestions would be appreciated....


----------



## bg4533

Quote:


  Originally Posted by *Pars* 
_Ran across these and they were so cheap, I just had to order a couple. This is the Elpac as used by headamp, etc. +/- 15V linear.

here

 I'll let you know when I get them as I had never even heard of these guys. To their credit, I had a email that they had shipped about 2 hours after placing the order._

 

Thanks. I guess I am going to have to order a few of these. Has anyone dealt with this company before? I am a bit skeptical, but it is worth a shot I guess.

 Pars, when is your PSU supposed to get there? If it is the next day or so I might just wait to see how your order turns out.


----------



## SnoopyRocks

Quote:


  Originally Posted by *bg4533* 
_Thanks. I guess I am going to have to order a few of these. Has anyone dealt with this company before? I am a bit skeptical, but it is worth a shot I guess.

 Pars, when is your PSU supposed to get there? If it is the next day or so I might just wait to see how your order turns out._

 

They have been pretty good so far. I placed my order late in the morning (pst) on Monday. Confirmation via email was quick. The fedex tracking number came on Tuesday morning. Fedex says that it left from Carson, CA (LA area) on Tuesday and should get here on Friday. So far so good.

 Can someone confirm the part number for the panel mount female adapter for this power supply (elpac wm071-1950 D5)? The CUI inc SD-50SN (Digikey CP-1250-ND) seems like it will work. 

Digikey CP-1250-ND
Elpac WM071


----------



## Pars

Sorry, wasn't watching this thread yesterday. Its supposed to be delivered today. I'll let ya know tonight.

 When using their tracking number (FedEx ground), I noticed that the package is 1 lb. No way two of these could only weigh 1 lb. packed. Guess I'll find out...


----------



## SnoopyRocks

Quote:


  Originally Posted by *Pars* 
_Sorry, wasn't watching this thread yesterday. Its supposed to be delivered today. I'll let ya know tonight.

 When using their tracking number (FedEx ground), I noticed that the package is 1 lb. No way two of these could only weigh 1 lb. packed. Guess I'll find out..._

 

That's odd. Fedex says that my package only weighs 1 lb also. Yet elpac specs the units at 1.5 lbs each. Hmmm...


----------



## Ozymand

In preparation for building a Dynalo, I also ordered that power supply. Put in the order late Tuesday night, got the shipping confirmation this morning.. and as of 2PM, I have the supply in my hands. Also the tracking on the box says 1 lb. as well. Ah well, it's here in my hands.. one part down, a whole lot more go to.


----------



## Pars

Got mine as well, as advertised. Haven't tested them yet, but they appear to be brand new, in the Elpac box (couldn't remember the pinout, and didn't have any DIN jacks handy). Speaking of which, I placed an order with Mouser today for some other stuff (still waiting for my 24.9 ohm Dales to finish up my Rev. B board, btw), and then remembered the DIN jacks (Neutrik NYS-325). So I placed a sep. order for them, then called Mouser to ask them to add it into the other order for shipping. They said with their "new" system, they could no longer do that! To which I replied, "and this system is supposed to be an improvement?". To which she replied "Well, yes sir! It sure is". A**h&les. So 3 DIN jacks @$0.50 ea., with a $6+ UPS charge... it seems like I ALWAYS forget something when I place an order... oh well, my fault.


----------



## skyskraper

anyone able to lend a hand to my problem? i havent had a chance to play with my amp since i posted due to school being insane. id appreciate any insight


----------



## Pars

Skyscraper:

 Hmm, took a look at your pic. I wouldn't think that the problem would be your PSU/tranny too close (although you could try rotating the tranny while listening and see what happens). I know the Gilmore I'm building on a V2 board is sensitive to where the tranny is pointing, although at the right angle the tranny can be right on the board (amp and PSU are on the same board, about 8" x 7") and its quiet. The noise I was hearing from this was definitely a hum tho.

 Are you sure that PSU is up to the task on this? I know before I had built the Gilmore PSU, I was powering mine from a B&K bench supply and the supply itself oscillated... it must have been right on the edge because when I shortened up the leads from 3' to 1', it worked fine. Other than that, I'll email you the tweaks that stackofhay did to his and sent me.

 Chris


----------



## skyskraper

cool thanks for the email. i will be working on the amp tonight, going to try power it from some batteries (4x9v) and see how that works


----------



## skyskraper

i havent grounded the case and psu board and amp board to the iec mains ground out of fear of killing myself, should i do that (i know ground is relative hence i left it out)

 or maybe using metal pcb standoff's is causing the problem?

 or is it possible that since i didnt put a pot in and i havent put resistor in its place that, that may be causing it?

 im just trying to figure out my options before i crack it open again tonight/day


----------



## Pars

If you don't have a pot it, you should have resistors in place (probably around 1/2 Meg or something like 475K) instead (can't remember the resistor numbers, but they are in parallel with the inputs.. R60 something).

 My V2 is not grounded to the IEC (yet), etc. and its quiet (tho it does have a pot). It was quiet before on the bench supply (once I got that ironed out) with 475K resistors installed without the pot in. So I don't think that this is a ground issue (could be wrong).

 I noticed in your pics what appears to be a rather long input signal wire running back somewhat close to the PSU section... I'd keep an eye on that also.


----------



## dgardner

skyskraper - Another quick check for noise sources would be to chop the end off a shielded RCA cable, strip the end back a bit, and solder it right to the inputs of the amp board. If this doesn't eliminate the noise, leave it on, and continue to hunt in other areas.


----------



## Pars

Anyone waiting for 24.9 ohm Vishay-Dales at Mouser (like me), they are back out to sometime in April on backorder. They had originally told me they would have some on March 8th.

 I did however find they have a small stock of a 24.3 ohm RN60D (same part number, 0.21 ea), so I just had them sub these. This value is not listed in the Mouser catalog... I did a scan of RN60D part numbers and ran across it. Part number 71-RN60D-F-24.3. I didn't want to drop down to the 1/8W RN55s, and thought the RN65s would be too big.

 I think my next one I'm going to go back to Roedersteins, like I did my V2 board in.


----------



## SnoopyRocks

Gilmore_Dynalo_BOM.xls 

 I've finished (for now anyway) my version of the BOM. My final total, including a 1455 series hammond case, is $87.25 exluding shipping. This represents a humble implementation of the Dyanlo - inexpensive volume pot and power supply. Hopefully I haven't missed anything. 
	

	
	
		
		

		
		
	


	




 This update fills in specific parts for those left open previously - some caps and miscillaneous hardware. Additionally, I've made two substitutions: 





> 1) Koa Speer 1/4 watt Metal Film Resistors ($0.03) instead of the RN60 series ($0.21)
> 2) Murata trim pots (Mouser PN 490-2875-ND $0.85) instead of the Bourns ($2.50)


The net savings is about $16. I don't see a significant change in quality with these changes. 

 I didn't really do much digging as far as the capacitors are concerned: suggestions appreciated.


----------



## skyskraper

weird. i swapped r65 and r66 for 220ohm resistors, now the oscillating is gone in the left channel but not the right 
	

	
	
		
		

		
		
	


	




 really need to find some actual time to work on this.


----------



## robzy

I have a question - how important is the thermal bonding to the Dynalo? Does it affect sound quality?

 Rob.


----------



## Pars

No effect on sound quality, and the jury is out on whether it is even needed/beneficial or not. I built one with thermal bonding and I see no better DC offset stability than the V2 board I built (which does not have the provision for this). On the Rev. B dgardner board that I built, I did go back and forth between the original 510 ohm resistors/no diodes, and the diode configuration, and really noticed no differences. When I do another one, it will be without.

 Dan has done a much more extensive thermal bonding with a heatsink type arrangement on top of the output trannies, so he might comment as to what he found.

 I know that Geoff (stackofhay) built his without and did not see any point in doing this arrangement.

 -Chris


----------



## dgardner

This feature is for thermal stability, and in my opinion does not impact the sound positively or negatively. I haven't performed any benchtop measurements to compare audio performace with/without the feature. Consider it to be just another tweak.


----------



## robzy

So essentially thermal bonding is useless and i should not bother? (Useless i guess is a bit harsh of a word, but you get what i mean).

 Rob.


----------



## Pars

Yeah, I guess thats about the gist of it. This came about because of a recommendation of a friend of Sijosae's (look earlier in this thread, or on headiwize, if your interested), which suggested that doing this, with a few resistor tweaks elsewhere and a 14.4V +/- PSU would provide much better stability (DC offset-wise). I haven't tried this in conjunction with the other resistor tweaks, but I just haven't seen these claims born out in actual benefits. And I was the one who suggested to Dan during the board design/development phase to take this into account. Well, I guess its alot easier to put in jumpers if you don't want to implement this than it is to try to add this later


----------



## dgardner

No worries. Jumper wire the diodes and put the 510R back in and be done with it. For that matter, you can leave all the caps off the board and probably not notice it.


----------



## robzy

Okay, thanks for that - this also makes it much easier to socket my trans 
	

	
	
		
		

		
		
	


	




 One other question - is matching between the two channels important? For example, i know the two Red LEDS for one channel should have the same forward voltage drop, but should the two Red LEDS on the other channel have the same voltage drop as the other channel? (And thats the same with transistors and whatnot...?)

 Rob.


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## amb

Quote:


  Originally Posted by *robzy* 
_One other question - is matching between the two channels important? For example, i know the two Red LEDS for one channel should have the same forward voltage drop, but should the two Red LEDS on the other channel have the same voltage drop as the other channel? (And thats the same with transistors and whatnot...?)_

 

The only thing you need to worry about matching between the two channels are the feedback resistors. Other than that, just match things as well as you could within each channel.


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## robzy

Quote:


  Originally Posted by *amb* 
_The only thing you need to worry about matching between the two channels are the feedback resistors. Other than that, just match things as well as you could within each channel._

 

Which resistors are the feedback resistors? (Im kind of a noob at this discrete amplifier stuff)

 Rob.


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## amb

Quote:


  Originally Posted by *robzy* 
_Which resistors are the feedback resistors? (Im kind of a noob at this discrete amplifier stuff)_

 

R16 <-> R46
 R7 <-> R37


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## Pars

Quote:


  Originally Posted by *robzy* 
_Okay, thanks for that - this also makes it much easier to socket my trans 
	

	
	
		
		

		
			





 One other question - is matching between the two channels important? For example, i know the two Red LEDS for one channel should have the same forward voltage drop, but should the two Red LEDS on the other channel have the same voltage drop as the other channel? (And thats the same with transistors and whatnot...?)

 Rob._

 

In an ideal world, both channels would match exactly. The primary measurement that you should be paying attention to is DC offset. Do whatever you have to in each channel to get the offset as low as possible. In the real world this will probably mean that your LEDs, etc. will not match identically between channels.


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## robzy

Okay, thanks for that 
	

	
	
		
		

		
		
	


	




 Can anyone point me to info on matching the transistors JFETS? I have no idea what to do when it comes to them and cant seem to find any info on them.

 Rob.


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## amb

Quote:


  Originally Posted by *robzy* 
_Okay, thanks for that 
	

	
	
		
		

		
		
	


	




 Can anyone point me to info on matching the transistors JFETS? I have no idea what to do when it comes to them and cant seem to find any info on them.

 Rob._

 

You want to select and use the 2SK389 and 2SJ109 dual-JFETs such that the two devices within the package have the closest Idss. It would also be nice if the 2SK389 also matches the 2SJ109, but in practice this is a lot harder to achieve without a very large number of them to choose from.

Tangent's opamp bias article has a section in there about measuring JFET Idss. Have a look. Basically, the setup should look like this:






 Use your multimeter's DC mA scale to read the Idss directly. Pay special attention to the polarity of the battery and multimeter for N-channel and P-channel tests. You could also use a DC power supply instead of the battery, I recommend something around the 9V-12V range.


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## robzy

Okay, that seems easy enough 
	

	
	
		
		

		
		
	


	




 What about the other transistors though? (i meant to ask about JFETs & Tranisistors). I recall reading that i dont just have to match Idss but other things to?

 And also - appr. how many JFETS & transistors should i order to get decent matches?

 Rob.


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## steinchen

the bjt trannies are matched by their hfe values

 you should take a look at the Dynalo construction thread
http://www.head-fi.org/forums/showthread.php?t=118586

 links to transistor-matching threads are in post #5


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## robzy

Cool, thanks for that 
	

	
	
		
		

		
		
	


	




 Rob.


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## Blorton

I picked up one of the Rev. C extras from Dan and will start ordering parts soon. Thanks dude! (I shoulda ordered two.)

 I was just curious - has anyone completed a balanced setup yet? I've been listening to balanced mode directly out of the newly acquired DAC-1 to the 650's and it's not bad at all. Would really be something with a proper amp stage in there. If only there was a kickbutt affordable diy kit I could build one from. 
	

	
	
		
		

		
		
	


	




 Seriously, I'd sure appreciate hearing about any particular changes that need to be made for balanced mode. (I know I need two boards - should've ordered that many. Doh!)

 Cheers!
 Dan


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## robzy

Quote:


  Originally Posted by *Blorton* 
_Seriously, I'd sure appreciate hearing about any particular changes that need to be made for balanced mode._

 

I do beleive that for balanced mode you would need two boards.

 Rob.


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## Icy006

I would like to make a transportable Dynalo. Seeing that it's the same eurocard sizing as the PPA battery board, seems like these two could make a lovely match.

 But of course, this amp is a class-a solid state beast, right? Does anyone have an idea of current draw on the Dynalo? I'm mostly interested in rough numbers for reasonable listening volumes on Grado cans.

 Also, what about supply voltage? Is there a clear minimal value, a point where there is a noticeable difference, and an upper limit where it stops mattering?

 I have a battery board rigged for 19.2 volts with 800mAh capacity cells. If this is sufficient voltage and the current draw is no more than a third of an amp, this could yield a couple hours of runtime.


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## skyskraper

around about 160ma for the whole amp linky 
 remember though you need a dual voltage supply so +15v and -15v.


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## dgardner

Quote:


  Originally Posted by *Icy006* 
_Also, what about supply voltage? Is there a clear minimal value, a point where there is a noticeable difference, and an upper limit where it stops mattering?._

 

Remember, this is a discrete transistor amp not an operational amp IC. The operating points within the amp don't "scale" with big changes in supply voltage. You can get away with maybe 14.5V to 17V without much trouble. If you drop below or go above that, you should expect to do some re-engineering of the resistor values to get ideal performance.


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## bg4533

Just for clarification I believe dgardner means +/- 14.5V-17V


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## Icy006

Great info, thanks.

 jar pointed out to me that Headroom sells an inexpensive power brick used in many of their amps that puts out +15/-15 volts. If it can handle the current draw and puts out relatively clean power, I think I might be going this route, as it lets me case the Dynalo in something transportable.


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## dgardner

I popped open one of my ELPAC WM071-1950 wall warts. Inside is a transformer, rectifier, 7815, 7915 and a 1000uF output cap on each. Not bad for starters... You only need about 200mA per rail max for a dynalo. Typical is about 150mA per rail if built to spec.


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## Icy006

Hrm, looks like the elpac WM071-1950-D5 can handle 240mA per rail, nice. In stock at Newark for about forty smackers. I've had good luck with my WM080 24v so I think I'll check this out. Thanks Dan.


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## jar

The headroom power supply is also rated at 240 mA per rail. It's labeled Advanced Power Solutions APS48-ER125. I can't find this model on Advanced Power Solutions' web site for some reason.


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## bg4533

The Headroom PSU looks nice since it has a cord that plugs into the wall instead of just a huge brick. It can be difficult to find a place to plug in the Elpac.


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## CB600F

Hi there,

 << Finally I started an electronics project again. It has been a while. >>

 Has anyone been fiddling around with the dynalo and the SWCAD III Spice simulator? (Or any other spice simulator for that matter)
 I have just started with my first simulations and it seems to simulate the amp pretty well. I tried some other transistors like the bc547b; no shocking differences there. I thought the opamp would make a difference, but after adjusting simulation resolution there was no noticeable difference.

 Regards,

 David

 PS. I also posted this message on the construction thread


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## dgardner

The op amp is the dc offset servo. It should not have any real impact on the frequency respsonse or any other part of AC Analysis.


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## Garbz

Indeed the DC servo kicks in under 1 or 2 Hz doesn't it? It should not modulte the signal audibly at all!


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## bg4533

Quote:


  Originally Posted by *Garbz* 
_Indeed the DC servo kicks in under 1 or 2 Hz doesn't it? It should not modulte the signal audibly at all!_

 

.05Hz according to the original Headwize article.


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## CB600F

Quote:


  Originally Posted by *dgardner* 
_The op amp is the dc offset servo. It should not have any real impact on the frequency respsonse or any other part of AC Analysis._

 

I know what the opamp is for, but I wanted to know if it added an AC component to the circuit: apparently not. In my simulation the DC offset servo isn’t working at all. I tried different LED’s and so on; no result at all. I’ll be working on that for now. I haven’t been working with electronics for quite some time, so I’ll probably goof up once in a while. 
	

	
	
		
		

		
			





 I'm probably doing something wrong with the simulation.


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## Nospam

Quote:


  Originally Posted by *bg4533* 
_The Headroom PSU looks nice since it has a cord that plugs into the wall instead of just a huge brick. It can be difficult to find a place to plug in the Elpac._

 

That's why I bought a bunch of these:
http://www.cyberguys.com/templates/s...search=&child=

 or if you want higher quality:
http://www.cyberguys.com/templates/s...search=&child=


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## dgardner

Another thread supporting construction questions on the Dynalo Rev C project is here.


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## Icy006

Quote:


  Originally Posted by *jar* 
_The headroom power supply is also rated at 240 mA per rail. It's labeled Advanced Power Solutions APS48-ER125. I can't find this model on Advanced Power Solutions' web site for some reason._

 

I got this power supply to use with my Dynalo.

 Just a heads-up to those who would do the same thing: it uses a 5-pin din connector, but the pins are in a 270 degree configuration, not the more common 180 degree layout.

 I ordered this 180 degree one by mistake, which does not work. I should have ordered something more like this 270 degree one .


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## GeeKo

Hi all
  I have problem with finding good 24.9 ohm resistors   R23 - R30, R53- R60
  May I replace them with different value ??


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## bada bing

Mouser shows a few hundred of both RN55 and RN60 Vishay/Dale (1/8 watt and 1/4watt) in stock.
http://www.mouser.com/ProductDetail/Vishay-Dale/RN55D24R9FB14/?qs=sGAEpiMZZMu61qfTUdNhGy2XqlsoYCVGaHnL7ELbeOo%3d
http://www.mouser.com/ProductDetail/Vishay-Dale/RN60D24R9FB14/?qs=sGAEpiMZZMu61qfTUdNhG%252bW6BexHzDUms0DkBv%252bx1ME%3d
   
  If you're using a DGardner -now AMB- provided board, the 1/4watt RN60 fit fine, but there is no electrical reason to not use the smaller 1/8watt RN55.
   
  You really used the way-back machine to dig up this post, hehe.


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## cobaltmute

You can save money if you like by using the CMF60 instead of the RN60:
   
http://ca.mouser.com/ProductDetail/Vishay-Dale/CMF6024R900FHEK/?qs=sGAEpiMZZMu61qfTUdNhG6m%2fO%252b4TgF7jIIvngwgJgfg%3d
   
  Same part, just different markings on the exterior.


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## GeeKo

But with mouser there is only one problem
 *Delivery Charge: 40,00 €*


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## Pars

How about these:
   
http://uk.farnell.com/vishay-bc-components/mrs25000c2499fct00/resistor-mrs25-1-24r9/dp/9466347
   
  Not sure where in Europe you are. The BC resistors are decent. You need to stay around 25 ohms for these or the output current will increase (too low) or decrease (too high), You could always parallel pairs of 49.9 ohm for example.


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## GeeKo

Hi
  Finally I decided to use Elpod Resistors. They are Polish made, price similar to Dale (if You order 50pcs)  and what most important they have positive opinions.


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## Zsubbo

Is there a way to source one of those PCBs ?


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## Avro_Arrow

I don't think there are any more boards available anywhere.
  If there was enough interest, maybe someone would do another run.
  The best spot for information is here.
   
  Maybe with D. J. Gardner's permission, you could use his layouts.


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## Zsubbo

Thanks for the fast reply, what did you mean by using his layout ? (I mean using it in a group by, so that way I can give back something to the community, or using it just to make 2 for myself ?)
   
  And what about the power supply, does an AMB sigma11 will be good enough, or I should look somewhere else for a better power supply - in case I can get hold of a PCB


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## Avro_Arrow

Actually, the σ22 would be a good power supply to use.
  The Dynalo needs a dual rail power supply.
   
  In the DIY community, it is just polite to ask if you want
  to use someone else's design. Many people state up front
  that their design is free to copy or modify as long as it is
  for DIY purposes. If you ask politely, he may even let
  you use his Gerbers (the design files you send to the board house).
   
  The only caution for the Dynalo is the the parts are getting a bit rare.
  Make sure you have a source for parts before you get a board made.


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## Zsubbo

Yeah, I was looking at the transistors, they are getting pretty expensive (I can get them from AMB or off ebay, matched or cheap - i do not know if these are genue or not), is there any other parts that I should worry about ?


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## kevin gilmore

There is also this undergoing final testing, with a bipolar front end and all available parts
  prototype
http://gilmore.chem.northwestern.edu/multiamppic.jpg
   
  should be final version
http://gilmore.chem.northwestern.edu/kgdynalobal2.jpg


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## Zsubbo

It certainly looks good, does it use the same hard to find transistors, or something else ?


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## Avro_Arrow

Answer to post 279:
   
  Both the input FETs and output transistor are out of production.
   
  The input FETs were already changed once from the original
  design due to lack of components ( the original input FETs were
  2SJ109/2SK389).
   
Linear Systems now makes replacements for 2SK170 (LSK170)
  and the 2SK389 (LSK389).
   
  Too bad they don't have (yet) replacements for either 2SJ109 or 2SJ74.
   
  I see AMB still has stock on all the FETs and transistors for the Dynalo,
  so you have stock if you can afford the price. AMB used to have Dynalo
  boards but I guess the stock is all gone. Maybe you can ask him if he
  is planning any more boards.


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## Avro_Arrow

Hey, that looks good Kevin. Do you have a projected kit cost?
   
   
  Quote: 





kevin gilmore said:


> There is also this undergoing final testing, with a bipolar front end and all available parts
> prototype
> http://gilmore.chem.northwestern.edu/multiamppic.jpg
> 
> ...


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## kevin gilmore

By the way that is a balanced board.
   
  I have no idea what it is going to cost.
  that340 input chip is $6.40
  opa445 if you want to run +/-20 are $11 each or $6.50 each in smt plus the brown dog adapter  (2 are needed)
  everything else is pretty cheap.
   If you can get the singles fets, 4 fets fit
  nicely into the socket in place of the that340. And there
  are 2 different kinds of feedback one is supersymmetry.


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## Zsubbo

I'll wait for this, it looks interesting, will it be able to drive my K1000s ? and where can I read more about this project ?


----------



## liamstrain

Quote: 





kevin gilmore said:


> By the way that is a balanced board.
> 
> I have no idea what it is going to cost.
> that340 input chip is $6.40
> ...


 
   
  Any update on this, Kevin?


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## kevin gilmore

kerry is doing this.  I don't have much time till next year.


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