# Best Tube Headphone Amp To DIY



## Kitarist

So i'm thinking about making my own tube headphone amp

 Price doesnt matter as long as its "you get the best quality for the money"

 What do you suggest? (also include links please)

 Thanks!!!


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## iamthecheese

Do you have any experience with previous DIY projects?

 I think every pure tube amp DIY project requires working with high voltage.


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## LingLing1337

The Oatley K272A was a very easy build. But if you have tons of DIY experience, then probably the Zana Deux.


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## Kitarist

Quote:


  Originally Posted by *LingLing1337* /img/forum/go_quote.gif 
_The Oatley K272A was a very easy build. But if you have tons of DIY experience, then probably the Zana Deux._

 

I need some schematics or something for those two


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## pabbi1

Like to read? I suggest Cavalli Audio and Pete Millett's DIY Audio pages for several recommendations, with discussions and schematics. It is a start, which will help you to formulate some more specific questions that will get better opinions.


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## keyid

Quote:


  Originally Posted by *LingLing1337* /img/forum/go_quote.gif 
_The Oatley K272A was a very easy build. But if you have tons of DIY experience, then probably the Zana Deux._

 

there is a zana diy?


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## FallenAngel

Budget? Experience level (safe at high voltages)?


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## Kitarist

I already stated... it doesnt matter 
	

	
	
		
		

		
			





 i'm happy for a budget or a very experienced level


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## the_equalizer

Quote:


  Originally Posted by *Kitarist* /img/forum/go_quote.gif 
_I already stated... it doesnt matter 
	

	
	
		
		

		
		
	


	




 i'm happy for a budget or a very experienced level_

 

You've made clear that you have no budget restrictions; but *your* experience level is not clear, have you ever built a circuit handling 100 volts and upwards ?

 cheers!


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## chesterqw

i had a good shock from a 250v 330uf capacitor.
 luckily with my right hand :x

 so you would better buy some protection!


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## gabriel-dan

Check out beezar.com for PMillett's Starving student and Hybrid MiniMAX Kits.
 I recently built a starving student kit and it is a pretty decent little amp in terms of SQ for the money.


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## Kitarist

Quote:


  Originally Posted by *the_equalizer* /img/forum/go_quote.gif 
_You've made clear that you have no budget restrictions; but *your* experience level is not clear, have you ever built a circuit handling 100 volts and upwards ?

 cheers!_

 

I built a guitar tube amp and guitar effects pedals


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## WyldRage

I've been looking at several headphone amps, mostly because my budget will not allow me to do anything else until next year. Here's what I consider the most interesting:

 - Cavalli Audio's _Bijou _The Bijou Headphone Amplifier 
 - Bottlehead's _S.E.X._ Single Ended eXperimenter's Kit
 - Hagerman Technology's _Castanet _Hagerman Technology LLC: Castanet Vacuum Tube Headphone Amplifier DIY Kit
 - Mapletree Audio Design's _Ear+ HD_ Welcome to Mapletree Audio Design

 As well as several Hybrids: CTH, SOHA II, Millett MAX, MiniMAX and Starving Student. Several of these are in kit form at Glass Jar Audio and beezar.com welcome page

 Now, I've only built the MiniMAX, and I like it, but I cannot do any comparaison. So choose one, build it and enjoy it, until you get the DIY bug again. I bet you can't build just one.

 I know I can't.


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## Kitarist

Thanks for a great reply gonna check these out!!!


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## Kitarist

bump


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## nikongod

Quote:


  Originally Posted by *LingLing1337* /img/forum/go_quote.gif 
_But if you have tons of DIY experience, then probably the Zana Deux._

 

Or a SinglePower, or something else all together if you prefer their sound signature over the ZD's sound signature.
  Quote:


  Originally Posted by *keyid* /img/forum/go_quote.gif 
_there is a zana diy?_

 

There is a lot of info in this thread:
here
 (and me making an ass of myself, Im very good at that) Between that, what can be gathered from photos of the insides of the amps, and peoples commentary on the design of the amp that it could certainly be done.

 There is also "not" enough info about the amp that you are basically on your own designing, building, and testing it. I guess once you have the basic topology given to you the rest is working out operating points and getting the thing dialed in (which I imagine will involve a lot of work tuning the global feedback loop). 

 I guess its a smaller problem than tuning feedback loops but its also going to need an adequately quiet PS (the plate resistor in that thread is lower than the plate impedance... PSR before feedback is going to be basically non existent) that can put out the required current at whatever B+ you wind up at, and however many amps its going to take to run the heaters. More fun. Its a very ambitious project.

 For a combination of morality in supporting a great builder, its stable price second hand (buy it used, sell it for about the same amount a year later), and the difficulties that WILL be encountered designing & building it yourself I would say just buy one built if you want it. 

 dsavitsk's comment in that thread about 6c33 by its self as a headphone amp is intriguing though 
	

	
	
		
		

		
			





 I foresee it being about exactly as much work to design your own thing even with the ideas of others pushing you along as to clone the ZD. I guess I speak for myself, but I prefer doing more myself. 
  Quote:


  Originally Posted by *Kitarist* /img/forum/go_quote.gif 
_bump_

 

Why not search it out? You will learn more about the inner workings of headphone amps this way... Plenty of the DIY stuff has been reviewed very well if you have questions about the differences once you narrow it down.


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## regal

The Hagerman is the best on your list for low ohm phones if you use better output transformers.


 You first need to let us know what impedance phones you want this to be designed around?


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## Kitarist

Well something that runs both very well low and high ohm phones


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## Parafeed

Quote:


  Originally Posted by *regal* /img/forum/go_quote.gif 
_The Hagerman is the best on your list for low ohm phones if you use better output transformers._

 

I'm trying to figure out the logic of that statement. Care to explain? What's wrong with the EAR for low R phones. It also uses the same Hammond 119DA's as output transformers. 

 By what criteria is the Hagerman 6H30 circuit "best on your list for low ohm phones"? Are you prejudiced towards the EAR because of the cathode follower?

 Based on experience, not guesswork, if the OP was to build the Hagerman 6H30 design, I'd suggest he replace the Hammond 157G plate chokes (or put two in series each side) before considering higher quality OP iron.


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## regal

Quote:


  Originally Posted by *Parafeed* /img/forum/go_quote.gif 
_I'm trying to figure out the logic of that statement. Care to explain? What's wrong with the EAR for low R phones. It also uses the same Hammond 119DA's as output transformers. 

 By what criteria is the Hagerman 6H30 circuit "best on your list for low ohm phones"? Are you prejudiced towards the EAR because of the cathode follower?

 Based on experience, not guesswork, if the OP was to build the Hagerman 6H30 design, I'd suggest he replace the Hammond 157G plate chokes (or put two in series each side) before considering higher quality OP iron._

 

I don't consider the Ear a DIY design, I mean they don't post the schematic and they charge $80 to assembly it?, who in their right mind would consider this DIY? The Hagerman can be built from the schematics with higher quality components, no need to purchase a "kit".


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## Parafeed

Quote:


  Originally Posted by *regal* /img/forum/go_quote.gif 
_I don't consider the Ear a DIY design, I mean they don't post the schematic_

 

I downloaded an EAR+ manual from the Mapletree site. Page 6 contains the complete schematic.

  Quote:


  Originally Posted by *regal* /img/forum/go_quote.gif 
_who in their right mind would consider this DIY?_

 

Someone who wants to build it, not because they want to save $80, but because they want the pleasure of building and tweaking it. Not everything is about saving money.

  Quote:


  Originally Posted by *regal* /img/forum/go_quote.gif 
_The Hagerman can be built from the schematics with higher quality components, no need to purchase a "kit"._

 

The same applies to the EAR.

 Again, what makes the Hagerman 6H30 design better suited to low impedance phones?


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## Kitarist

Relax guys


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## Kitarist

Bumpy


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## regal

Quote:


  Originally Posted by *Parafeed* /img/forum/go_quote.gif 
_I downloaded an EAR+ manual from the Mapletree site. Page 6 contains the complete schematic.



 Someone who wants to build it, not because they want to save $80, but because they want the pleasure of building and tweaking it. Not everything is about saving money.



 The same applies to the EAR.

 Again, what makes the Hagerman 6H30 design better suited to low impedance phones?_

 



 The Hagerman is DIY, he posts his schematics and you are free to build as you like with or without his kit. The EAR is not DIY its a $700 package that you bolt together that consists of a nice case. Any time you are paying for a design it is not DIY, sorry, its a commercial amp. Mapletree does no allow to build their amps from the schematic. I asked.


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## Parafeed

Quote:


  Originally Posted by *regal* /img/forum/go_quote.gif 
_Where can I get a schematic of the EAR without paying $700?_

 

EAR+ HD2 Owners Manual


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## regal

Quote:


  Originally Posted by *Parafeed* /img/forum/go_quote.gif 
_EAR+ HD2 Owners Manual_

 

Thanks, nice design but I certainly wouldn't pay $700 for $150 in parts cost. I also don't like the 56 ohm resistors on the output, but I have experience with the Hagerman design which is very similiar to the DNA Sonnet if you make some upgrades. The Mapletree has a good reputation but its thread is in the Amp section not DIY forum, they don't encourage people to DIY there amp for $200. I guess they want you to spend $500 for the case, just don't understand their concept.


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## Parafeed

Quote:


  Originally Posted by *regal* /img/forum/go_quote.gif 
_Thanks, nice design but I certainly wouldn't pay $700 for $150 in parts cost._

 

No comment.

  Quote:


  Originally Posted by *regal* /img/forum/go_quote.gif 
_I also don't like the 56 ohm resistors on the output,_

 

That is a bit strange, isn't it. Padding the 600:8 output with a resistor rather than connecting the 600:4 directly to the low imp jack. I was told by an owner of the EL84 SE that the 600:4 is directly connected to the low imp jack. 

  Quote:


  Originally Posted by *regal* /img/forum/go_quote.gif 
_but I have experience with the Hagerman design which is very similiar to the DNA Sonnet if you make some upgrades._

 

What sort of upgrades? Changing to series feed? LOL.

  Quote:


  Originally Posted by *regal* /img/forum/go_quote.gif 
_The Mapletree has a good reputation but its thread is in the Amp section not DIY forum, they don't encourage people to DIY there amp for $200. I guess they want you to spend $500 for the case, just don't understand their concept._

 

I've just been told that Lloyd has removed the links to the manuals from his website, possibly due to concern about his circuits being copied in the Far East. However, he obviously hasn't physically removed the manuals from the site. That link I gave - the pdf owners manual is hosted on the Mapletree site.


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## nikongod

Quote:


  Originally Posted by *Kitarist* /img/forum/go_quote.gif 
_Bumpy_

 

Dude! people gave you 5 or 6 links on page 1 to rock solid projects that are well documented and can be built with nothing but basic tools.

 If those are not good enough, I would encourage designing your own thing. Its a very rewarding experience and you can call it your own.
  Quote:


  Originally Posted by *Parafeed* /img/forum/go_quote.gif 
_That is a bit strange, isn't it. Padding the 600:8 output with a resistor rather than connecting the 600:4 directly to the low imp jack. I was told by an owner of the EL84 SE that the 600:4 is directly connected to the low imp jack._

 

The exact value of this resistor changes depending which version of the amp/which version of the schematic you have. 

 It was my experience that the EAR can be noisy (both hum and random noise) into low impedance headphones without these resistors. 

 I think that PSR & noise in general would improve by a WIDE margin by replacing the 12ax7 with 12sn7/12au7/12dj8 with a big old plate resistor or CCS. Considering how the 12ax7 is run in this circuit I am sure this will change the sound of the amp in general, but from something very similar I built its totally worth a try.


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## Parafeed

Quote:


  Originally Posted by *nikongod* /img/forum/go_quote.gif 
_It was my experience that the EAR can be noisy (both hum and random noise) into low impedance headphones without these resistors._

 

Yes, there was some discussion about it over in the owners thread. I remember thinking at the time that putting a 32R resistor in series with the 8R tap gave a 6db reduction with Grado's, but using the 600:4 config was only 3db. 

  Quote:


  Originally Posted by *nikongod* /img/forum/go_quote.gif 
_I think that PSR & noise in general would improve by a WIDE margin by replacing the 12ax7 with 12sn7/12au7/12dj8 with a big old plate resistor or CCS. Considering how the 12ax7 is run in this circuit I am sure this will change the sound of the amp in general, but from something very similar I built its totally worth a try._

 

An CCS'd ECC88 driving a EL34 cathode follower is what I'm listening to right now.


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## nikongod

Quote:


  Originally Posted by *Parafeed* /img/forum/go_quote.gif 
_An CCS'd ECC88 driving a EL34 cathode follower is what I'm listening to right now. 
	

	
	
		
		

		
		
	


	


_

 

My amp is a CCS'd 6sn7 into 5998/6as7 cathode follower with cathode CCS. I wanted to run the 6dj8/ecc88 but I salvaged the PCB & case for the basic topology from something else so I didnt get to pick 
	

	
	
		
		

		
		
	


	




 Do you transformer couple the output or run OTL? I have mine set up to run both ways for different headphones and single driver speakers


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## Parafeed

Quote:


  Originally Posted by *nikongod* /img/forum/go_quote.gif 
_My amp is a CCS'd 6sn7 into 5998/6as7 cathode follower with cathode CCS._

 

I've been fiddling around with drivers in front of the cathode follower.... 6H30, 6SN7, C3g (triode strapped), 5965..... But I found some ECC88's that I had forgotten about, Siemens CCa's and Amperex, so that's where I'm at right now. My EL34 CF is CCS'd too. 

  Quote:


  Originally Posted by *nikongod* /img/forum/go_quote.gif 
_Do you transformer couple the output or run OTL? I have mine set up to run both ways for different headphones and single driver speakers_

 

Both. OTL - I've been listening to 600R T1's coupled to the cathode of the EL34 using 100uF poly Obligattos. That's what I'm listening to right now. Transformer - I've had a pair of TL-404's hooked up, but I've not spent much time listening to that config. The T1's through those Obligatto caps sound very good.


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## regal

Interesting finding, I setup a very similiar design only as an analog stage to a DAC, Broskie calls it a Constant Current Draw Amp, I used CCS's as well. In the DAC I didn't like what the cathode follower did to the sound and ended up eliminating the cathode follower which gave much better results. I understand that cathode followers are very load dependant so that may have been the issue so I may revist this for headamp usage if you guys are liking the sound.


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## Parafeed

Quote:


  Originally Posted by *regal* /img/forum/go_quote.gif 
_Interesting finding, I setup a very similiar design only as an analog stage to a DAC, Broskie calls it a Constant Current Draw Amp, I used CCS's as well. In the DAC I didn't like what the cathode follower did to the sound and ended up eliminating the cathode follower which gave much better results. I understand that cathode followers are very load dependant so that may have been the issue so I may revist this for headamp usage if you guys are liking the sound._

 

It's easy to make generalizations. Cathode followers do sound "compressed" compared to the same tube without feedback. But then feedback does that. (Clue: So does damping the glass envelope of a tube when used as a triode without feedback. Try a tube as a cathode follower. Then listen to it again with a plate load. Then put a heavy tube damper on top of it or slide on a couple of silicon O rings. Notice anything? Like the damped tube sounds very similar to using it as a cathode follower. I wonder why that could be? LOL.)

 Hours of fun can be had with a pair of the Hammond 119DA's, a driver, and trying various tubes as the cathode follower output. I prefer the EL34, but I've tried the EL84, 5881, 6L6, 7581, KT88, 6550 - most of what would be considered the mainstream "audio" pentodes strapped as triodes. I'm not really a fan of the regulator tubes. 

 Slightly off the beaten track, the A2134 is a great sounding tube when strapped as a triode and used as a cathode follower to drive phones via a step-down transformer.


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## regal

Quote:


  Originally Posted by *Parafeed* /img/forum/go_quote.gif 
_It's easy to make generalizations. Cathode followers do sound "compressed" compared to the same tube without feedback. But then feedback does that. (Clue: So does damping the glass envelope of a tube when used as a triode without feedback. Try a tube as a cathode follower. Then listen to it again with a plate load. Then put a heavy tube damper on top of it or slide on a couple of silicon O rings. Notice anything? Like the damped tube sounds very similar to using it as a cathode follower. I wonder why that could be? LOL.)

 Hours of fun can be had with a pair of the Hammond 119DA's, a driver, and trying various tubes as the cathode follower output. I prefer the EL34, but I've tried the EL84, 5881, 6L6, 7581, KT88, 6550 - most of what would be considered the mainstream "audio" pentodes strapped as triodes. I'm not really a fan of the regulator tubes. 

 Slightly off the beaten track, the A2134 is a great sounding tube when strapped as a triode and used as a cathode follower to drive phones via a step-down transformer._

 

So would you say you prefer a good cathode follower to a classic SET plate output w/ SE gapped OPT ? I notice on your sig you are all parafeed, are these cathode follower?


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## Parafeed

Quote:


  Originally Posted by *regal* /img/forum/go_quote.gif 
_So would you say you prefer a good cathode follower to a classic SET plate output w/ SE gapped OPT ?_

 

My general philosophy - use the right tool for the job. If you need a hammer, don't improvise with a screwdriver. But there are several different hammers to chose from.

 As a general rule I like the DHT SET (without feedback) sound with speakers. Though I do use OTL's as well, with a heap of feedback. I feel that DHT SET doesn't work so well with headphones. Yes, I prefer parafeed to series feed, but that isn't a be all and end all in itself. Cathode followers can sound good, but they can sound truly terrible. The same is true for any circuit. If it sounds good, then that's what matters, not the topology.

  Quote:


  Originally Posted by *regal* /img/forum/go_quote.gif 
_I notice on your sig you are all parafeed, are these cathode follower?_

 

No, all the amps in my sig are plate choke loaded, parafeed. Although, the 6H30/6C45 amp uses the 6H30 as a cathode follower, direct coupled to the cathode of the 6C45. There is a paragraph about each if you look at my profile, here. The 300B amp is a partial feedback (resistor from the 300B output plate to the driver plate) design.


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## Kitarist

Anyone ever built anything on their own without any instructions?


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## regal

Quote:


  Originally Posted by *Kitarist* /img/forum/go_quote.gif 
_Anyone ever built anything on their own without any instructions? 
	

	
	
		
		

		
		
	


	





_

 

Yes, best advice is to go to the tubecad website and start reading from the beginning. Once you understand how to read tube curves it'll start making sense.


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## theHof

I've been looking at some of the HeadWize diy projects, and I'm just wondering if there are any tube amps I could run balanced output instead of the 1/4inch output or if it'd be possible to something like this balanced. Or how would something like this perform with balanced out put instead of the 1/4 inch?


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## nikongod

Quote:


  Originally Posted by *theHof* /img/forum/go_quote.gif 
_I've been looking at some of the HeadWize diy projects, and I'm just wondering if there are any tube amps I could run balanced output instead of the 1/4inch output or if it'd be possible to something like this balanced._

 

Quite a few of the circuits over there have been modified to run balanced with effort ranging from simply putting 2 amps back to back (4 separate channels) to others which deliberately couple the 2 phases in various ways.

 While I firmly believe there are some inherent advantages to balanced circuitry, there are also some disadvantages. 

 For what head-fi says: I would rather build (or buy) a balanced amp than one which sounds decent (regardless of how its made). Seriously, try to sell an amp with only 1/4" jacks. I triple dogie dare you. Clone any number of SET amps with floated OPT's that are currently in vogue but ONLY ground the secondary of the transformer and only put a 1/4" plug on it. Try to sell it for parts cost. Throw the ruiles in the face of the forum, and say what you knocked off to the ohm, mili-amp, and the volt. 

 Why did you bother to build that SET amp if it isnt even balanced? This oxymoron brought to you by nikongod.
  Quote:


 Or how would something like this perform with balanced out put instead of the 1/4 inch? 
 

Throw caution to the wind, disregard well known safety practices, and disconnect the secondary from ground. taah-daah! its balanced. As an ironic point, that amp uses a push-pull output stage which actually is balanced regardless of what you do to the safety benefits of having the secondary of the transformer grounded.

 I still haven't figured out how to get both halves of a balanced signal through 1 triode.

 That amp is actually a neat circuit, and the single PCB makes for a nice first HV tube amp project although it needs a bunch of work & mods to work with headphones. At the time of posting this, the quoted text in my signature links to the thread about an older variant of that amp. Do what blackie says. at the very least try it! Searching 11ms8 will get you a thread here with lots of info on what it used to be. Dont build the 16W one, try the 8W one. The fact that the gain & cathodyne triodes are separate from the output pentodes (unlike the original version) is quite attractive to me.


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## regal

The whole balanced is best fad started years ago on head-fi when people were driving their 300 ohm senns with SS amps that had a gain of 2. When they went balanced they had more voltage and current so the herd accepted that balanced was required for the ultimate sound. 

 A properly designed tube amp doesn't need balanced outputs. Unless your amp is a few hundred feet away from your headphones be a good DIYer and not get stuck on fads, look for solid engineering.


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## nikongod

Quote:


  Originally Posted by *regal* /img/forum/go_quote.gif 
_The whole balanced is best fad started years ago on head-fi when people were driving their 300 ohm senns with SS amps that had a gain of 2. When they went balanced they had more voltage and current so the herd accepted that balanced was required for the ultimate sound._

 

Ignoring electrostatic amps...
 futerman was doing it in the 70's on his OTL monsters.

 The first (obvious) balanced headphone amp was the blockhead, which had gain of way-a-lot in an SE configuration and 6dbmore than way a lot balanced. give up.

 After that came a few DIY amps. I would hope that a DIYer has the knowledge and self discipline to select a good gain for himself.

 Then came the singlepower balanced OTL amps. what fun. 2 common cathode 6sn7 (or better!) as the gain stage. I see gain in the 20-30 range how about you?

 The RSA B52 rolled up on the scene: I dont know what the voltage gain is on his gear. My guess is 7 SE/14balanced based on the schematics I have seen & an educated guess.

 *note: the gain of the B52/SP amps may sag somewhat in response to low impedance loads. numbers are into a high impedance load.
  Quote:


 A properly designed tube amp doesn't need balanced outputs. 
 

could you elaborate on that?

 Yet again you start up with "properly designed", What does that mean? Some people quite enjoy OTL amps, can you support this statement in the face of that?

 Others like push-pull transformer coupled amps. Again, can you back it up? 

 A whole lot of nothing, but thanks for posting drivel.
  Quote:


 Unless your amp is a few hundred feet away from your headphones be a good DIYer and not get stuck on fads, look for solid engineering. 
 

Its a shame you are this closed minded, and have taken this as your argument for "the only reason" to go balanced. Bummer.


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## Beefy

Am I the only one who is thoroughly fed up with regal and Parafeed's frequent bickering? Take it to PM guys


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## nikongod

Quote:


  Originally Posted by *Beefy* /img/forum/go_quote.gif 
_Am I the only one who is thoroughly fed up with regal and Parafeed's frequent bickering? Take it to PM guys 
	

	
	
		
		

		
		
	


	


_

 

I dont think you are alone.

 OTOH, most of it is regal spouting rubbish and Parafeed calling him on it. Check it out, its quite consistent. Really the only reason its coming down to Parafeed is he is very good at calling it and dosnt seem afraid to at all.. There is plenty of fail in plenty of regal's posts.

 From what I have read from Parafeed he seems like a nice guy when he isnt pointing out the fail in regal's posts, and is clearly a knowledgeable designer regardless. Id happily take his advice on a tricky q and probably be better for it.


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## Parafeed

Quote:


  Originally Posted by *Beefy* /img/forum/go_quote.gif 
_Am I the only one who is thoroughly fed up with regal and Parafeed's frequent bickering? Take it to PM guys 
	

	
	
		
		

		
		
	


	


_

 

I wouldn't call it bickering, but I'm sorry if my occasional taking issue with regal in public is irritating. Generally I bite my tongue. Sometimes it is hard to do so when bad advice is given or a slight is aimed at a commercial design or designer, especially when regal makes some sort of "negative" comment, (usually totally unjustified or tenuous to say the least), that might cost the manufacturer concerned a sale. It's not personal.


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## regal

Look in this thread Parafeed and I weren't bickering, we were sharing our experiences with different designs. NikonGod on the other hand jumps in with personal attacks and tries to prove how smart he is. I've contributed to the DIY community many times, my goal here isn't to the same as yours. I like to see people learn, learn from others and their mistakes/successes, and go to great lengths to avoid seeing a guy running up his credit card on a commercial amp he can't afford. DIY is about sharing schematics/designs, having fun building an amp that competes with anything on the market, not trying to prove how clever you are.


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## unl3a5h3d

Is the Millet Max to difficult for a first DIY. I have made many cables and understand most of the circuits and what not. Although I have never soldered to a PCB I think I could get the hang of it very quickly. I am afraid to sink nearly $200 into a kit for one I might mess up.


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## Beefy

If you are afraid to lose your money, then DIY is a bad idea - whatever your skill level. Even the best can have projects that fail, and I don't spend a cent unless I am willing to get nothing out of it.

 That being said, you could do a LOT worse than the Millett Max variants. The MiniMax kit from Beezar runs for $220 and that includes a most excellent custom-machined case. Documentation and forum support is superb, and if everything goes in the right place and you follow the setup instructions it should work first time.


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## Juaquin

It's probably not a good place to start if you're worried about losing it all. Start with a cMoy. Even if you never really use it, it's a good place to work out the kinks. The most expensive part you can fry is a few bucks, and the whole thing is less than $25 if you massively screw up. A cheap kit from eBay (like this one) or elsewhere will get you familiar with working on a PCB - it won't sound particularly great but you'll get an idea of how it's done.


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## regal

Quote:


  Originally Posted by *unl3a5h3d* /img/forum/go_quote.gif 
_Is the Millet Max to difficult for a first DIY. I have made many cables and understand most of the circuits and what not. Although I have never soldered to a PCB I think I could get the hang of it very quickly. I am afraid to sink nearly $200 into a kit for one I might mess up._

 

Soldering to a PCB is no more difficult than soldering a wire. Tangent has videos on his site about soldering. If you understand most of the circuits thats the most important part and the Millet Max has an excellent support structure. With a kit you can't go wrong, I say go for it.


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## Listen2this1

You can not go wrong with the Millett Max, Mini, or SS. What TomB has put into the documentation is un-matched. If you come across a problem there is a good chance that someone else has had it. On top of all this they all sound good. I am really enjoying my SS. It's simple but the sound to dollar ratio is better than any tube set-up out. (Of course this is my opinion)


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## Parafeed

Quote:


  Originally Posted by *regal* /img/forum/go_quote.gif 
_NikonGod on the other hand jumps in with personal attacks and tries to prove how smart he is._

 

Here we go again..... From where I am sitting he is smart! 
	

	
	
		
		

		
			





 Solid engineering is throwing away the TRS connector! I didn't reply to your "balanced" post because NikonGod did. I always put balanced outputs. ie. 4 wire connection on my amps, not because the outputs are true differential, but because there is a sonic benefit to be had with "clean" grounding. Pretty much everything I DIY is P2P with a star ground. Running two chunky "ground" wires from the "star" to a 4 pin XLR output provides a sonic benefit over a single shared ground to a TRS connector. With a transformer output, from the negative end of each transformer secondary, I run two wires. One to the star ground, one direct to the individual channel- on the 4 pin XLR headphone socket. This is the "cleanest" return path for the signal. If you do not believe there is a benefit to be had, or that these amps are not "properly designed", that's fine by me. Do these amps need a "balanced" output, no. Does a headphone benefit from a 4 wire connection, yes! This has nothing to do with any arguments about differential circuits, CMR, bridged != balanced, gain, noise, slew rate, etc. etc.


----------



## EloyDark

Quote:


  Originally Posted by *Parafeed* /img/forum/go_quote.gif 
_Here we go again..... From where I am sitting he is smart! 
	

	
	
		
		

		
		
	


	




 Solid engineering is throwing away the TRS connector! I didn't reply to your "balanced" post because NikonGod did. I always put balanced outputs. ie. 4 wire connection on my amps, not because the outputs are true differential, but because there is a sonic benefit to be had with "clean" grounding. Pretty much everything I DIY is P2P with a star ground. Running two chunky "ground" wires from the "star" to a 4 pin XLR output provides a sonic benefit over a single shared ground to a TRS connector. With a transformer output, from the negative end of each transformer secondary, I run two wires. One to the star ground, one direct to the individual channel- on the 4 pin XLR headphone socket. This is the "cleanest" return path for the signal. If you do not believe there is a benefit to be had, or that these amps are not "properly designed", that's fine by me. Do these amps need a "balanced" output, no. Does a headphone benefit from a 4 wire connection, yes! This has nothing to do with any arguments about differential circuits, CMR, bridged != balanced, gain, noise, slew rate, etc. etc._

 

Couldn't be said better...
 One question though, why not float the secondary and drive the phones on a floating OPT? This is the way most interstage transformers work, after all, to carry balanced signal in long wires, right?


----------



## Parafeed

Quote:


  Originally Posted by *EloyDark* /img/forum/go_quote.gif 
_One question though, why not float the secondary and drive the phones on a floating OPT? This is the way most interstage transformers work, after all, to carry balanced signal in long wires, right?_

 

Safety consideration. Although it is unlikely, with a series feed transformer you have HT on the primary. Insulation fails and you have HT on the secondary. Less of a risk with parafeed as you have the capacitor connection from the plate to the transformer primary. 

 I might be cloth eared, but many times I've listened to a floating secondary and the same again with one of the legs tied to ground. I can't hear a difference, so with no sonic benefit to weigh against the safety risk (however unlikely) I ground the transformer secondary. YMMV. IMHO, most of the benefit to be had from a 4 wire output to the phones is as I said above - clean grounding and not using a TRS connector.


----------



## regal

Quote:


  Originally Posted by *Parafeed* /img/forum/go_quote.gif 
_Safety consideration. Although it is unlikely, with a series feed transformer you have HT on the primary. Insulation fails and you have HT on the secondary. Less of a risk with parafeed as you have the capacitor connection from the plate to the transformer primary. 

 I might be cloth eared, but many times I've listened to a floating secondary and the same again with one of the legs tied to ground. I can't hear a difference, so with no sonic benefit to weigh against the safety risk (however unlikely) I ground the transformer secondary. YMMV. IMHO, most of the benefit to be had from a 4 wire output to the phones is as I said above - clean grounding and not using a TRS connector._

 

4 wire output to the phones makes sense for clean grounding, but I stand by my statement that balanced drive for a tube amp causes more problems than it is worth. You will never find tubes matched close enough to produce each phase, IMO it is a waste of money.


----------



## nikongod

Quote:


  Originally Posted by *regal* /img/forum/go_quote.gif 
_4 wire output to the phones makes sense for clean grounding, but I stand by my statement that balanced drive for a tube amp causes more problems than it is worth. You will never find tubes matched close enough to produce each phase, IMO it is a waste of money._

 

from the (mini) writeup by SY on DIYaudio the point about tube matching is in my mind pretty well dis-proven.
link
 Some concerns are brought up with regards to balance at high voltage swings further into that thread, but who would really build a circuit like he did with 2 totally different triodes in a real world app? I could not be bothered to see if his experiment was repeated with both halves of a non-selected double triode: the way you would expect a LTP to be built.

 I think that shows how easy it is to make a balanced gain stage with good phase balance. Next up are the output stages.

 Unless you do something amazingly bad, the outputs are going to be loaded quite symmetrically! In an OTL tube amp a pair of tube buffers (White cathode follower, or simple cathode follower) which has fairly consistent gain regardless of what tubes you use (within reason), A SS buffer where 2 samples can easily be built with very similar gain, or a push-pull output stage which could be built as a long tail pair just like the gain stage with balance set by the load. 

 I probably agree more than disagree with you on the point of "4 channel" amps, but there is no reason that you cant have a 2 channel balanced amplifier that works exceptionally well AND Im not totally convinced that a 4-channel amp cant work well. Indeed, based on every balanced headphone amp ever made (with a few exceptions for balanced amps that suck, and differential balanced amps) they have been shown to work VERY well in the past. I think that there are better ways than "4 channel" amps, but sadly too few people even build on perfboard any more. Its not on the PCB, it dosnt get built.

 As an an example of a 2 channel balanced amp:
link
 With the "negative phase" added on, cut the amp in half like your standard "4 of these amps" running in the same box headphone amp... you cant. The left amp is both phases, and they can not be separated. The 2 phases reinforce each other nicely as a team, and counteract each others errors as a team.


----------



## luvdunhill

Quote:


  Originally Posted by *nikongod* /img/forum/go_quote.gif 
_As an an example of a 2 channel balanced amp:
link
 With the "negative phase" added on, cut the amp in half like your standard "4 of these amps" running in the same box headphone amp... you cant. The left amp is both phases, and they can not be separated. The 2 phases reinforce each other nicely as a team, and counteract each others errors as a team._

 

oh no! the heresy!


----------



## nikongod

I feel the sudden urge to match jfets.


----------



## Parafeed

Quote:


  Originally Posted by *regal* /img/forum/go_quote.gif 
_I stand by my statement that balanced drive for a tube amp causes more problems than it is worth. You will never find tubes matched close enough to produce each phase, IMO it is a waste of money._

 

I'll preface by saying that I'm not trying to be argumentative, but how many balanced headphone circuits have you built and listened to? (Balanced == differential, not balanced == bridged.) 

 Without getting bogged down into what sounds good on paper - perfect AC balance from a LTP, K&K's differential headphone amp design, (the circuit used for the Moon Audio amp if I remember correctly), is a good starting point. (I've built this with paralleled 6H30 output tubes as well.) In terms of dynamics, this will leave the 6EW7 direct coupled amp you proposed building in the other thread, crying in a corner.


----------



## pabbi1

Quote:


  Originally Posted by *Parafeed* /img/forum/go_quote.gif 
_Without getting bogged down into what sounds good on paper - perfect AC balance from a LTP, K&K's differential headphone amp design, (the circuit used for the Moon Audio amp if I remember correctly), is a good starting point. (I've built this with paralleled 6H30 output tubes as well.) In terms of dynamics, this will leave the 6EW7 direct coupled amp you proposed building in the other thread, crying in a corner. 
	

	
	
		
		

		
		
	


	


_

 

Heh, this Raven design (with 6h30 and 6n23) has left me crying in the corner... and pity I used all that pretty Lundahl iron. 
	

	
	
		
		

		
		
	


	




 Mayhaps Doug can sort it all out, and I'll be able to hear this proper. We heard it once for a few hours, but only by the grace of God, and, well, Marc... all because I ain't matching no jfets.


----------



## nikongod

I vote you strip the PCB's and point-to-point the Raven. I want to hear about how it sounds.


----------



## regal

Quote:


  Originally Posted by *Parafeed* /img/forum/go_quote.gif 
_I'll preface by saying that I'm not trying to be argumentative, but how many balanced headphone circuits have you built and listened to? (Balanced == differential, not balanced == bridged.) 

 Without getting bogged down into what sounds good on paper - perfect AC balance from a LTP, K&K's differential headphone amp design, (the circuit used for the Moon Audio amp if I remember correctly), is a good starting point. (I've built this with paralleled 6H30 output tubes as well.) In terms of dynamics, this will leave the 6EW7 direct coupled amp you proposed building in the other thread, crying in a corner. 
	

	
	
		
		

		
			



_

 

Still a 2 channel amp, with a transformer/phase splitting, no advantage of balanced vs unbalanced inputs. Signal is combined at the driver stage and split again at the output transformer. Probably 3rd harmonic dominant. Why compare this to an SET amp, thats apples and oranges?


----------



## luvdunhill

Quote:


  Originally Posted by *regal* /img/forum/go_quote.gif 
_Still a 2 channel amp, with a transformer/phase splitting, no advantage of balanced vs unbalanced inputs_

 

one thing to point out. I'd argue that there is definitely is still an advantage of the balanced inputs in this case. 

 You'll have to think outside of the box and take the system as a whole, something few people do .. but.. ready?

 The benefit is in the fact that the output stage of the source is balanced.

 That alone is a huge advantage.

 So, if you A/B this amp with SE input and balanced inputs being used, do you think they would sound different? I bet they will!


----------



## regal

Quote:


  Originally Posted by *luvdunhill* /img/forum/go_quote.gif 
_
 The benefit is in the fact that the output stage of the source is balanced.

 That alone is a huge advantage._

 


 My experience has been that sources measure better when the differential outputs of the DAC are transformed to unbalanced, this is how we get the CMRR that the DAC chips are rated for, in other words measure the differential output of a 24 bit DAC and they have a 16 bit S/N ratio. Now this might be achieved at the headphones after your amp.


----------



## luvdunhill

Quote:


  Originally Posted by *regal* /img/forum/go_quote.gif 
_My experience has been that sources measure better when the differential outputs of the DAC are transformed to unbalanced_

 

then why build a balanced amp? 
	

	
	
		
		

		
		
	


	




 transformers can transform quite well in fact...


----------



## Parafeed

Quote:


  Originally Posted by *luvdunhill* /img/forum/go_quote.gif 
_I'd argue that there is definitely is still an advantage of the balanced inputs in this case._

 

There are several advantages of this circuit design, even down to isolating SE input ground via the transformer. 

 But as per usual, regal dismisses what he does not understand and then goes on to talk about CMRR in a later post. LOL. It's a lost cause.


----------



## Parafeed

Quote:


  Originally Posted by *pabbi1* /img/forum/go_quote.gif 
_Heh, this Raven design (with 6h30 and 6n23) has left me crying in the corner... and pity I used all that pretty Lundahl iron. 
	

	
	
		
		

		
		
	


	


_

 

I don't know the history..... You had a problem with building it?


----------



## sachu

FWIW,

 In my experience balanced makes little to no difference. This was again vindicated at the recent Portland meet where the Exstata+SR404 run out of the Meridian G08 source made no difference if it was being driven in balanced or unbalanced output mode. Albeit this was under meet conditions so perhaps there was some micro detail that we couldn't pick up or something, but off the cuff to two of us who listened to balanced v/s SE couldn't pick out any difference at all.


----------



## regal

Quote:


  Originally Posted by *Parafeed* /img/forum/go_quote.gif 
_There are several advantages of this circuit design, even down to isolating SE input ground via the transformer. 

 But as per usual, regal dismisses what he does not understand and then goes on to talk about CMRR in a later post. LOL. It's a lost cause._

 



 Not dismissing it, just don't think its worth a 3rd order dominant P-P type amp to say "I'm balanced." Again is it worth the cost over a simple SET amp?

 If we're back to personal attacks, Parafeed are there any amps you haven't built? You seem to have built them all ! lol, 

 Again maybe you should start contibuting to these forums instead of blasting and boasting of how rich and powerful you are. You've been here since 2005 and contributed how many DIY designs? zero. Stick to your opinions and stop making personal attacks, we all appreciate you sharing your knowledge/experiences but it doesn't have to be mixed with pompous personal attacks. We are here to learn, are you?


----------



## dsavitsk

Quote:


  Originally Posted by *regal* /img/forum/go_quote.gif 
_Not dismissing it, just don't think its worth a 3rd order dominant P-P type amp to say "I'm balanced."_

 

I think you miss the point of balanced vs single ended vis-à-vis distortion numbers. If balanced added 3rd harmonic distortion while reducing 2nd, then there would be something to your argument. But, it doesn't. It simply cancels the 2nd, making the stage lower distortion overall. So, a differential amp may be "3rd order dominant", but this is a misnomer as there isn't any more 3rd order distortion than in a single ended stage. Moreover, it isn't like the single ended's 2nd order distortion hides the 3rd order harmonic distortion -- you still get both. A differential amp is simply lower in distortion in some places, and equivalent in others.

 At any rate, there is a popular canard on the internet that says that tubes sound better than solid state because they add 2nd harmonic distortion and this sort of distortion is pleasant sounding. But, this simply isn't true. Tubes sound good because they are more linear devices than transistors. This is despite the added 2nd harmonics, and they sound even better of you can get rid of it.

  Quote:


  Originally Posted by *regal* /img/forum/go_quote.gif 
_Again is it worth the cost over a simple SET amp?_

 

Something often forgotten in this sort of argument is that, for the most part, a differential design will have good PSRR relieving one of the cost of a power supply. A "simple" single ended amp generally won't, so you have to spend more money on the power supply. Pick your poison.


----------



## nikongod

Quote:


  Originally Posted by *regal* /img/forum/go_quote.gif 
_maybe you should start contibuting to these forums instead of blasting and boasting of how rich and powerful you are. You've been here since 2005 and contributed how many DIY designs? zero. Stick to your opinions and stop making personal attacks, we all appreciate you sharing your knowledge/experiences but it doesn't have to be mixed with pompous personal attacks. We are here to learn, are you?_

 

He has shared valuable information in several places in this thread. he had a schematic free to the taker up in another thread you posted I think it came down when it became obvious that thread was almost as worthless as this one.

 On that note, why should anyone really feel compelled to post a schematic or design?
  Quote:


  Originally Posted by *regal* /img/forum/go_quote.gif 
_ DIY is about sharing schematics/*designs*, having fun building an amp that competes with anything on the market, not trying to prove how clever you are._

 

Why cant DIY be about sharing ideas as well as schematics & designs? Many people get more from DIY for hearing about something new they can work into what they already have than just "here is another schematic most people who can point-to-point could have drawn up from a quick description" 

 Many people would consider posting a schematic of an amp they could pull from any tube textbook a thinly veiled attempt to prove how clever one is.

 The bit about "competes with anything on the market" is nice & ironic. I guess DIY designs should be included despite being the "wrong" topology (what does right/wrong mean?). Anything includes quite a lot of things after all. Indeed, it could be said that its impossible to design/build an amp that "competes with anything on the market" and as such it is irresponsible to post schematics that are clearly sub-optimal (whatever optimal means).

 From another post of his, I agree that once you get to a certain point you learn more by taking a rough idea and figuring out how to make it work and tune it to your own preferences yourself. 

  Quote:


  Originally Posted by *sachu* /img/forum/go_quote.gif 
_FWIW,

 In my experience balanced makes little to no difference. This was again vindicated at the recent Portland meet where the Exstata+SR404 run out of the Meridian G08 source made no difference if it was being driven in balanced or unbalanced output mode._

 

The first stage of the exstata is a differential pair phase splitter. The amp is balanced regardless of what signal you put in.

 Unless the designer screwed something up (unlikely, the last versions of the schematic I saw looked quite nice) there should be little difference between the 2 inputs.

 FWIW, from my previous experiments with it, I preferred the balanced inputs on my STAX gear, using a transformer to convert a SE signal to balanced rather than the input differntial pair. I dont know what changed so it may not be worth much.

 Welcome back


----------



## Parafeed

Quote:


  Originally Posted by *regal* /img/forum/go_quote.gif 
_Not dismissing it_

 

You dismissed it as "Still a 2 channel amp". That was the beginning of your reply. It's too frustrating trying to have a conversation with you.

  Quote:


  Originally Posted by *regal* /img/forum/go_quote.gif 
_are there any amps you haven't built?_

 

Of course. Are there any topologies I've not built, probably not.

  Quote:


  Originally Posted by *regal* /img/forum/go_quote.gif 
_blasting and boasting of how rich and powerful you are._

 

Rich and powerful..... I don't have a clue what you are talking about.

  Quote:


  Originally Posted by *regal* /img/forum/go_quote.gif 
_You've been here since 2005 and contributed how many DIY designs? zero._

 

Eh? I spend most of my time communicating via PM and email, not in public. Twice I've been asked for circuit diagrams, unsolicited, from people I don't know on Head-Fi. Twice I've provided them, with the proviso that they are not published so that a) I don't have to support them, and b) I don't need to explain them to nitwits who look at a fully balanced, (not bridged), differential design and then comment that "the signal is combined at the driver stage and split again at the output transformer".


----------



## TimJo

Quote:


  Originally Posted by *nikongod* /img/forum/go_quote.gif 
_From another post of his, I agree that once you get to a certain point you learn more by taking a rough idea and figuring out how to make it work and tune it to your own preferences yourself. _

 

This is my goal. But as I'm finding, it requires a lot of reading. The more studying I do though, the easier it's becoming to filter the good advice from the pool of information that is posted on this here interweb, which is a good thing.


----------



## regal

Quote:


  Originally Posted by *Parafeed* /img/forum/go_quote.gif 
_b) I don't need to explain them to nitwits who look at a fully balanced, (not bridged), differential design and then comment that "the signal is combined at the driver stage and split again at the output transformer"._

 


 I didn't see that the schematic had the bottom tubes flipped 180*, but see thats your problem you call people nitwits and boast yourself up instead of sharing ideas and thoughts. A simple "no look the tubes are 180* turned" instead you get off on by putting people down and _trying_ to make yourself look good.


 And since there are so many nitwits out there you don't want to deal with explain how the amp is fully balanced when the two phases of the input are bridged at the primary of the input transformer ?


----------



## nikongod

Does it matter that the tubes are drawn upside down? Is it a normally accepted convention? I draw my own schematics whichever way the symbols fit on the paper best. I guess some convention makes sense as it makes for a fun time when revision one is drawn horizontally and rev2 is vertically (and when you file them as rev one and rev 2 on the topic of conventions). Is there any formally accepted convention for drawing tubes in a differential configuration? SS circuits are always drawn with both complementary devices next to each other facing the same way.... I have seen tube schematics drawn both ways. GRRR. 

  Quote:


  Originally Posted by *regal* /img/forum/go_quote.gif 
_I didn't see that the schematic had the bottom tubes flipped 180*, but see thats your problem you call people nitwits and boast yourself up instead of sharing ideas and thoughts. A simple "no look the tubes are 180* turned" instead you get off on by putting people down and trying to make yourself look good._

 

 Quote:


  Originally Posted by *regal* /img/forum/go_quote.gif 
_Still a 2 channel amp, with a transformer/phase splitting... Probably 3rd harmonic dominant. Why compare this to an SET amp, thats apples and oranges?_

 

If you knew it was not a SET amp, and you knew it had a transformer as a phase splitter, what else could it be? Does it matter how the symbols are drawn at that point?

 You are backpedaling after writing off a solid design.


----------



## regal

Quote:


  Originally Posted by *nikongod* /img/forum/go_quote.gif 
_Does it matter that the tubes are drawn upside down? Is it a normally accepted convention? I draw my own schematics whichever way the symbols fit on the paper best. I guess some convention makes sense as it makes for a fun time when revision one is drawn horizontally and rev2 is vertically (and when you file them as rev one and rev 2 on the topic of conventions). Is there any formally accepted convention for drawing tubes in a differential configuration? SS circuits are always drawn with both complementary devices next to each other facing the same way.... I have seen tube schematics drawn both ways. GRRR. 





 If you knew it was not a SET amp, and you knew it had a transformer as a phase splitter, what else could it be? Does it matter how the symbols are drawn at that point?

 You are backpedaling after writing off a solid design._

 



 I'm not writing it off, the topic of the thread is "Best Tube Amp to DIY". This amp has expensive iron a lot of tubes, not the greatest output impedance. And I still question with the single input transformer and the two separate phases connected at the input if it is the Best AMP to DIY. Its surely a fine a fine amp, I just always point out the negatives I see as discussion points, Parafeed takes offense to this but this is how engineering design teams work. The idea is to prove the questioner wrong, defend the design.

 One thing I wanted to throw out there for this thread is I see a lot of respected members like Zanth, HeadphoneAddict, etc say that the old Melos SHA-Gold was one of the finest amps, some even say better than a ZD for Grados. The company is defunct, the schematics out there. Do you think this would be a good Best Tube amp to DIY candidate ?


----------



## Kitarist

Wow this is getting huge


----------



## regal

Quote:


  Originally Posted by *Kitarist* /img/forum/go_quote.gif 
_Wow this is getting huge 
	

	
	
		
		

		
		
	


	





_

 

What headphones are you planning on using with this amp ?


----------



## Kitarist

Grado 225 and Sennheiser 650


----------



## nikongod

Quote:


  Originally Posted by *regal* /img/forum/go_quote.gif 
_I'm not writing it off, the topic of the thread is "Best Tube Amp to DIY". This amp has expensive iron a lot of tubes, not the greatest output impedance. And I still question with the single input transformer and the two separate phases connected at the input if it is the Best AMP to DIY. Its surely a fine a fine amp, I just always point out the negatives I see as discussion points, Parafeed takes offense to this but this is how engineering design teams work. The idea is to prove the questioner wrong, defend the design._

 

Im going to skip output impedance. I think everyone else here agrees its been beaten to death. If you think its that important, outdo it. A little better than 20ohms Zo with all the secondaries paralleled.

 Regarding your stated grievances:

 Expensive iron: Part of that is that the designer of this amp is the USA importer of lundahl. Id cut him some slack, he offers the schematic freely, let him use it as an add. Some of the transformers can EASILY be exchanged for others (the power transformer & choke could be replaced with a hammond) and the input transformers could be switched for something else if the step up option was not required. Sadly I cant think of much (anything? I welcome alternatives, although its too late for me) that does what the LL1689pp does at a similar price point. The amorphous core is very expensive, but there is the normal core OPT, like what any alternative would have.

 some prices at the time of posting:

 The input transformers:
 The lundahls in the amp are $80 each.
 The lundahls closest to the other stuff here are $68
 Jensen 10K:10K transformers cost between $70 and $100
 Sowter 10K:10Kct are $43british pounds=$65 each
 Cinemag 10K:10K are $50 each

 Output transformers:
 The (non amorphous) lundahl LL1689 are $130 each
 Jensen and cinemag make transformers that can take push-pull DC for line out duty but only provide 600 and/or 150ohm outputs. bummer.
 Sowter doesn't make a Push-pull headphone transformer. Their SE transformers do have configurable secondaries like the lundahl. They start at 70british pounds=105usd for one which makes no claim to run 32 ohm headphones and jump to 100pounds/150usd for the one that does. Then they go up 
	

	
	
		
		

		
		
	


	



 Electraprint and magnequest will make you whatever you want, for sure. What is a 10Kct:4*150 going to cost? Whats the secondary DCR? They make nice transformers, but do you want to own the first 10Kct:4*150 transformer they made? output taps are not the same as multiple secondaries on a transformer. The space you waste to get windings for a 600ohm tap is bandwidth you dont get on the 32 ohm one. Parallel those suckers. Use every single winding every time you hook something up.

 Yea lundahl transformers are expensive, everyone agrees, but their prices are not out of line when viewed in contrast to other MFR's of similar or even unknown quality. 

 A lot of tubes:
 It has 2 double triodes/ch and 1 rectifier tube. 5 bottles in the whole amp. The rectifier tubes it uses are like $6. You can buy the audio tubes for about $100 or perhaps a bit less if you use russian input tubes. A few beans for shipping and its $110 for all the tubes. Could he have used uncommon tubes that were $5 for input and $7 for output, sure! However 6h30 and 6dj8 (and the russian variant) are still in production and many people already have them in their parts bins & tube collections. When viewed in that light, you may only need to buy the rectifier tube for $6. The fact that people who might build the circuit have the tubes (and have no doubts as to future availability) is key if you are going to draw up a PCB. If you like the design but not the tubes he selected, take the basic idea for free like he gave it and modify it to use whatever.

 The input transformers. HUNH? 
  Quote:


 the single input transformer and the two separate phases connected at the input 
 

What do you mean? 
 The way this is shown in the schematic is exactly how 50% of anyone using an input transformer into a differential amp would set it up. The other 50% would set it up with the CT floating and the balance set by matched resistors to ground. Regardless of which camp people prefer they all agree that there is really nothing unique or unusual here at all. The "resistors to ground camp" will no doubt have something to say about the center tap being used like it is like they always do. The center tap camp will have a thing or 2 of their own to say about the resistor people. I vote for a cage match to the death regarding the superiority of center tapping with windings VS resistors to ground. Its been raging for as long as there has been hi-fi audio, were not going to finish it here, its another thing just not to get into.

 As they sit the input transformers accept a single ended or balanced signal without change to the actual active circuitry. They isolate the source from the inputs of the amp which is quite nice. (Is the raven ground loop proof? Indeed!) They output a balanced signal regardless of what is fed in. In the event that you manage to drive the input tubes into grid current (ok thats insanity, but maybe...) the transformer sucks it quickly to ground without the blocking effects of a cap. Considering that not everyone who would build this amp has a balanced source (for better or worse, we are not talking about sources here), and that even if they do have a balanced source other advantages apply its an extremely elegant way to do many things with 1 part. .

 The raven is a very solid well thought out design.
  Quote:


  Originally Posted by *regal* /img/forum/go_quote.gif 
_One thing I wanted to throw out there for this thread is I see a lot of respected members like Zanth, HeadphoneAddict, etc say that the old Melos SHA-Gold was one of the finest amps, some even say better than a ZD for Grados. The company is defunct, the schematics out there. Do you think this would be a good Best Tube amp to DIY candidate ?_

 

I have a modified Melos SHA-gold/maestro

 I like the amp QUITE a lot. In many ways I think it is a runner up for "best" grado amp, in others not as much and its really all subjective. 

 I really like the overall tone of the Melos but it clearly has tone which to some is an issue. My best attempt at nailing down the tone is that the bass is a little on the loose side, BUT the top end has good detail and separation. A strength of the melos (how do "better" amps fail at this? I consider this a basic test of quality. whats the point in anything else if this dosnt work...) is that the image placement and separation is excellent. With the melos you can "walk around" in a well recorded performance and hear precisely where everything is coming from with all they layers shining through very well.

 Compared to the ZD the Melos does give up bass control and detail, but there is something about the melos that draws me in. The impact with HP-1000 on the melos is really well balanced with the rest of the music. The ZD got more detail, and a flat dead "thump". I certainly side with them in saying that the Melos is a better grado amp than the ZD, although I think its all about the faults of the amp working better with the faults of the Grado.

 With the HP2 the ZD had a more controlled bottom end but I think almost a "too controlled" bordering on etched/brittle top end. The ZD got more of the minute details out of the HP2 than the Melos but I really just wanted to smash the ZD to little bits after a few minutes. It was a technically excellent and simultaneously totally unsatisfying.

 Not all headphones sound good to me on the melos, and Id say that more sound good on the ZD although the thought of something a little thin like an AKG K701 on the ZD flat out scares me. Either way listening to an HP-1000 on a melos is something I think everyone should do. An RS-1 on a melos would be a second pick. If you ever get a Sony R10 or qualia 010 in the same room as a melos try that too, its a VERY good pairing. The sonys sound good on ZD too, Im just in fanboy mode now and very few people think to try the kings of dynamics with that old clunker...

 I guess now that my opinion of the amps is out there there are some issues with the Melos. It is a noisy amp. I think some of the noise could be reduced with a better board layout than melos gave us but dsavistik's work on his melos SHA-1 (SHA-1 actually has a better board layout than the gold in many ways, although the HV regulator is better on the gold.) never got his to the point of a totally silent amp. My own (less scientific attempts) on my gold have fluctuated between dead quiet and still some hiss. I dont know where the hiss comes from, and to make matters worse its intermittent and happens with tubes that are quiet in my phono stage! I could pull my hair out or just listen, so I just listen. It is quiet enough that it dosnt bother me but it is something to look out for. 

 As a VERY far fetched idea of a possible source for an alternative:
 In many ways the Cavalli SOHA 2 looks close to a Melos on paper, perhaps with some upgrades hidden in there that take it a step or 2 beyond the Melos as far as design is concerned although I would immagine that they will change the sound even if some other changes are undone.

 In particular, the gain stage is similar to the Melos gain stage, LTP with CCS tail. They both idle the tubes at a similarly low plate current (2ma SOHA2 VS 1.6ma Melos) and operate with similarly low voltages across the tubes (melos runs with about 30V between plate and cathode, SOHA2 looks like about 38V from what I could get off the cavalli site). The SOHA uses current mirrors on the plate where the Melos uses plate resistors. The other KEY difference in the gain stage is the way that the tail CCS & bias of the tube is done. The Melos has the CCS to ground, and the grids of the triodes are actually ~20V above ground. The input coupling caps on a Melos are NOT optional 
	

	
	
		
		

		
		
	


	




 The Soha2 has global feedback, Melos does not. Yea, this is going to be the big one in the difference between the 2. I think thats just the sound Alex likes, but he usually makes it easily removable. I guess there is something to say for him because many people like the way his designs sound. On that note note he dosnt mention the option of removing the feedback loop in the write ups on his site like he does for some of his other amps, I wonder if the amp goes unstable without it or if there was another reason. Perhaps he wanted to keep options to a minimum to reduce build errors? Maybe this has been discussed in a different thread.

 The output stages are different, although simultaneously sort of similar. The are both single ended, they both use a small transistor to drive a large output transistor, and both have the output transistor DC coupled to the load. The SOHA is all BJT, where the Melos is all FET. The SOHA has the CCS to set the current of the output follower, where the Melos uses the tube heater.

 Maybe they work out similarly, maybe they dont. Maybe disabling the feedback loop throws the amp unstable and blows the **** out of it. I dont know.


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## sachu

Quote:


  Originally Posted by *nikongod* /img/forum/go_quote.gif 
_The first stage of the exstata is a differential pair phase splitter. The amp is balanced regardless of what signal you put in.

 Unless the designer screwed something up (unlikely, the last versions of the schematic I saw looked quite nice) there should be little difference between the 2 inputs.

 FWIW, from my previous experiments with it, I preferred the balanced inputs on my STAX gear, using a transformer to convert a SE signal to balanced rather than the input differntial pair. I dont know what changed so it may not be worth much.

 Welcome back 
	

	
	
		
		

		
		
	


	


_

 


 Thanks Ari. 

 Now, i brought up the exstata cause i believe a few people who listened to the prototype amp at RMAF swore that there was huge difference between differential and SE. But the new amp I honestly couldn't pick out any differences in the type of input being used. Could be my hearing is shot, could be the other folks were imagining things or possible that the Meridian G08 is a POS source.


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## regal

Thanks for the info on the Melos, very informative. I have a lot of experience with the SOHAII and its big brother the StackerII. The SOHAII has a lot of potential, you can remove the negative feedback, he just put that in so you could roll a lot of tubes and have similiar gain. It is a dead silent background amp. I found that the tube was biased too low and posted a mod on how to raise the bias to 2.75ma per section. This is still too low to compete with the best as a 6DJ8 needs at least 5 mA's too sound real good. 

 I guess a am very enthuastic about hybrids and do tend to get overly negative with tubes +iron, I think in 10 years we will be laughing at ourselves for using iron in tube headphone amps, thats just an opinion. The Melos sounds unique in the hybrid realm in that the bass isn't too tight (SS-like) with grados, that's the only issue I have with the hybrids I've built , it must have to due with the simple mofset output? I would like to try a HV-better powersupplied SOHAII with a Melos buffer.


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## nikongod

Quote:


  Originally Posted by *regal* /img/forum/go_quote.gif 
_Thanks for the info on the Melos, very informative. I have a lot of experience with the SOHAII and its big brother the StackerII. The SOHAII has a lot of potential, you can remove the negative feedback, he just put that in so you could roll a lot of tubes and have similiar gain. It is a dead silent background amp. I found that the tube was biased too low and posted a mod on how to raise the bias to 2.75ma per section. This is still too low to compete with the best as a 6DJ8 needs at least 5 mA's too sound real good._

 

Np
 Thanks for confirming my guess at the feedback thing.

  Quote:


 I guess a am very enthuastic about hybrids and do tend to get overly negative with tubes +iron, I think in 10 years we will be laughing at ourselves for using iron in tube headphone amps, thats just an opinion. 
 

I think well be in about a similar place. 30 years ago, they were saying exactly the same thing about power amps.

 Tubes work very well with transformers. Its quite possible to make a headphone amp that sounds great and measures well with 1 tube and a transformer. Depending on what you want for speakers maybe them too. but very good sounding simple amps can be made with tubes. Transistors, eeeeh. A few single transistor amps have been tried, but do any really catch on? They are simple voltage followers or very simple gain stages both of which inevitably have high input capacitances/currents for BJT's. Neither has good bandwidth: A single SS power transistor without something to drive it is apt to roll off in the audio band or do uglier things. What the audio industry did in the 70's was say we are trying to outdo a transformer coupled tube amp, and look at that expensive output transformer that we no longer need and how we can buy power transformers that dont have heater windings. That buys a LOT of transistors and STILL comes out to a lower part cost. So rather than look for a more linear device, just wrap 3 or 4 or more of whatever you can get in more feedback. The problem is EVERY device adds its own distortion (and distorts the distortion from the previous stage). you cant get enough negative feedback with version 6? Add another transistor to get more feedback to get the THD you want. its easy! People have been trying it for years, and it simply dosnt work. The single transistor amps dont hold up when you scrutinize them closely, nor do the more complicated amps with lots of feedback around lots of transistors to get a good THD number. There is probably a happy medium with transistors and it may be a hybrid, or an amp built exclusively with transistors designed for audio use 
	

	
	
		
		

		
		
	


	




 (I think nelson pass is on the right track here but he is stuck using the transistors he can get like everyone else who uses SS), but there is certainly a place for transformer coupled tubes.

 Transistor MFR's have never really made any honest effort to improve their devices for audio. and why should they? If they make the next generation of transistors with much more gain, the audio guys can apply more feedback and get better THD! For sure they make enough that work out, but at best there are VERY few audio specific transistors and that borders on none. 

 OOH! interesting tangent: Some crazy folks have made transformer coupled SS amps, using the SS transistors under high voltages/low currents like you would expect a tube to run. neat stuff. 
  Quote:


 The Melos sounds unique in the hybrid realm in that the bass isn't too tight (SS-like) with grados, that's the only issue I have with the hybrids I've built , it must have to due with the simple mofset output? I would like to try a HV-better powersupplied SOHAII with a Melos buffer. 
 

I have also guessed that the output stage contributes to the way the melos sounds, but never really looked into it much. 

 I'd say build just the output stage as a buffer and try it out with either source resistors or CCS on the output mosfet.

 as another guess, have you tried an output stage with mosfets, or just BJT? I have not followed the hybrid scene for some time but know everyone was leaning towards BJT :facepalm: Even just switching to mosfets in the same basic topology can change the sound a bunch.


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## dsavitsk

Quote:


  Originally Posted by *regal* /img/forum/go_quote.gif 
_tube was biased too low and posted a mod on how to raise the bias to 2.75ma per section. This is still too low to compete with the best as a 6DJ8 needs at least 5 mA's too sound real good._

 

 Quote:


  Originally Posted by *regal* /img/forum/go_quote.gif 
_I guess a am very enthuastic about hybrids and do tend to get overly negative with tubes +iron, ... The Melos sounds unique in the hybrid realm in that the bass isn't too tight (SS-like) with grados, that's the only issue I have with the hybrids I've built , it must have to due with the simple mofset output?_

 

a) the Melos runs something like 1mA through the 6dj8

 b) the "too tight" bass from many solid state amps is due in large part to the too low Z out and too high damping factor.

  Quote:


  Originally Posted by *nikongod* /img/forum/go_quote.gif 
_Tubes work very well with transformers. ... Transistors, eeeeh._

 

Best Grado amp I've built/heard is all transformer coupled, all solid state. Runs at ~32V


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## regal

Quote:


  Originally Posted by *dsavitsk* /img/forum/go_quote.gif 
_a) the Melos runs something like 1mA through the 6dj8 :_

 

I'll quote Jack from ElectraPrint: "Triodes all have one thing in common and thats, the least amount of distortion is when the plate is near full dissipation or highest current/ voltage. its in the books"

  Quote:


  Originally Posted by *dsavitsk* /img/forum/go_quote.gif 
_b) the "too tight" bass from many solid state amps is due in large part to the too low Z out and too high damping factor.:_

 

This would explain why the Melos performs well with Grados as it has a relatively low damping factor for a hybrid. I just have a hard time grasping that concept as when you design a sub amp you want a low damping factor because of the stiff drivers (physical damping), a Grado driver is about as opposite of a subwoofer as I can think of.


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## adamus

Quote:


  Originally Posted by *dsavitsk* /img/forum/go_quote.gif 
_
 Best Grado amp I've built/heard is all transformer coupled, all solid state. Runs at ~32V 
	

	
	
		
		

		
		
	


	


_

 


 interesting. best amp i have built for grados is the starving student
	

	
	
		
		

		
		
	


	




 no joke, lovely synergy. 

 bijou + grados .... hmmm not great
 soha II / soha 1: ok
 darkvoice 336 - horrible
 ZD: not bad

 I must book a slot in the crazy clinic...


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## regal

Quote:


  Originally Posted by *adamus* /img/forum/go_quote.gif 
_interesting. best amp i have built for grados is the starving student
	

	
	
		
		

		
		
	


	




 no joke, lovely synergy. 

 bijou + grados .... hmmm not great
 soha II / soha 1: ok
 darkvoice 336 - horrible
 ZD: not bad

 I must book a slot in the crazy clinic..._

 

Not crazy that amp has as much in common with the Melos that Mr Grado tunes his designs with than most any other, thanks for the input.

 Agree 100% on the P-P amps with Grados, have yet to hear one that sounds good with them.


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## Parafeed

Quote:


  Originally Posted by *regal* /img/forum/go_quote.gif 
_I'll quote Jack from ElectraPrint: "Triodes all have one thing in common and thats, the least amount of distortion is when the plate is near full dissipation or highest current/ voltage. its in the books"_

 

That'll be another way of saying - stay away from the knee of the curves. Good advice, except a lot of vintage stuff doesn't take too kindly to be run at max dissipation. I've learnt that the hard way, with burnt out screen grids on Mullard EL84's and great sounding vintage 6SN7's that have gone noisy when run hard. For drivers, use a CCS or choke, make sure they are not driving low impedances and run 'em sensibly. Low distortion and long life.


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## adamus

or how about solid state choke (gyrator?), people seem to like them in the 'anti-triode' thread over on diyaudio. they sim like a choke.

 I am playing with a dac otuput stage at the moment. It has responded very well (and not a subtle change) to led bias. I am going to knock up some dn2540n5 cascode regs for a CSS a some point soon, it will be interesting to hear the change as i am now very familiar with the current sound.


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## Parafeed

Quote:


  Originally Posted by *adamus* /img/forum/go_quote.gif 
_or how about solid state choke (gyrator?), people seem to like them in the 'anti-triode' thread over on diyaudio. they sim like a choke._

 

Anti-triode? Got a link to the thread over on diyAudio? 

 My only experience with an electronic choke (gyrator) and capacitance multipliers comes with having used the DIYHiFiSupply Universal Power Supply modules. The thing is, at least with that implementation, although the ripple is very low and by rights it should sound excellent due to the lack of electrolytics, I found that it "strangled" the sound - compressed dynamics.


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## adamus

starts here...

Anti-Triode SEPP, how to do best? - diyAudio

 Read from page 7 onwards if you want to cut to the chase.


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## Parafeed

Quote:


  Originally Posted by *adamus* /img/forum/go_quote.gif 
_Anti-Triode SEPP, how to do best? - diyAudio_

 

Some interesting ideas. Anti-triode: I can't help but think that if I wanted to maximise voltage swing and source 2xIq into the load, then I'd use SRPP to start with and 2 triodes, rather than subbing silicon for the upper triode. Mu-follower's: taking the low impedance output from a silicon loaded tube doesn't sound good. Use a mu follower with a high gm/gain triode as the cathode follower and a CCS instead of the load resistor. (I tried a direct coupled beta follower after reading Morgan Jones, but preferred the sound of a CCS'd mu-follower, even though it still needed a coupling cap from the gain triode to drive the top cathode follower.) The constant voltage gyrator is more appealing. Anyway, food for thought. Thanks for the link.


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## adamus

no problem.

 The proof will be in the listening. I may have a go with a gyrator sooner rather than later.

 That threas is a good read, some interesting ideas...


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## Kitarist

this is getting huge


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## netsky3

Quote:


  Originally Posted by *LingLing1337* /img/forum/go_quote.gif 
_The Oatley K272A was a very easy build. But if you have tons of DIY experience, then probably the Zana Deux._

 

Is good this amp? Is so cheap...
	

	
	
		
		

		
		
	


	



 I've bought one k272 few days ago but i don't think that have a particular sound quality for his price.


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## Volkum

Not much on the Bijou? I was looking at that for my first tube build--what do you guys think? My experience with DIY thus far has been:

 STEPS + PPAv2 + ε12 (currently moving all that from hammond cases into a single par-metal case)
 y1+y2 + σ25

 Nothing high voltage as of yet, but I'd like to think I'm intelligent and cautious enough that I won't have a mishap of the electrocution sort.


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## regal

Quote:


  Originally Posted by *Volkum* /img/forum/go_quote.gif 
_Not much on the Bijou? I was looking at that for my first tube build--what do you guys think? My experience with DIY thus far has been:

 STEPS + PPAv2 + ε12 (currently moving all that from hammond cases into a single par-metal case)
 y1+y2 + σ25

 Nothing high voltage as of yet, but I'd like to think I'm intelligent and cautious enough that I won't have a mishap of the electrocution sort._

 

The Bijou is first class for 600 ohm headphones using 100uf oil output caps, but it isn't a top rated amp for low impedance phones IMO.


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## Volkum

Quote:


  Originally Posted by *regal* /img/forum/go_quote.gif 
_The Bijou is first class for 600 ohm headphones using 100uf oil output caps, but it isn't a top rated amp for low impedance phones IMO._

 

New phones are on my list to obtain before I do another build. I'll keep that in mind though. At this point I'm just planning ahead.


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## Leny

Quote:


  Originally Posted by *Kitarist* /img/forum/go_quote.gif 
_So i'm thinking about making my own tube headphone amp

 Price doesnt matter as long as its "you get the best quality for the money"

 What do you suggest? (also include links please)

 Thanks!!!_

 


 Why tube, why not semiconductor?


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