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OTL DIY kits other than Bottlehead? - Page 2

post #16 of 37
Quote:
Originally Posted by Tjj226 Angel View Post
 

 

 

I think you need to go explore more EL34 designs. 

 

Cute, thanks for implying that I am not familiar with amp designs. 

 

There is nothing inherently wrong with the EL34, or even pentodes (gasp!), but I am mostly curious why one would suggest such a powerful tube to put barely any power at all into a headphone.

Can you justify the suggestion to use such a powerful tube when less powerful tubes may offer very compelling advantages? El84, and the various "German post" tubes spring to mind immediately as things I would rather see in a headphone amp.

 

If more power is what we need for headphones why not just look at KT88 designs? Because we don't need more power. We need better linearity. We need lower noise. We need so little power it is often hard to measure. 


Edited by nikongod - 12/24/13 at 9:19am
post #17 of 37
Quote:
Originally Posted by nikongod View Post
 
Quote:
Originally Posted by Tjj226 Angel View Post

 

Once you have done that, go find a decent EL34 based amp and build it using point to point methods. 

 

EL34 to drive dynamic headphones? 

I would question this advice. 


only 50W - why not? "stupid printed circuit board," too ... I never knew ...

post #18 of 37
Quote:
Originally Posted by nikongod View Post
 

 

Cute, thanks for implying that I am not familiar with amp designs. 

 

There is nothing inherently wrong with the EL34, or even pentodes (gasp!), but I am mostly curious why one would suggest such a powerful tube to put barely any power at all into a headphone.

Can you justify the suggestion to use such a powerful tube when less powerful tubes may offer very compelling advantages? El84, and the various "German post" tubes spring to mind immediately as things I would rather see in a headphone amp.

 

If more power is what we need for headphones why not just look at KT88 designs? Because we don't need more power. We need better linearity. We need lower noise. We need so little power it is often hard to measure. 

 

No? I thought you were commenting on the fact that EL34s sounded bad or something. 

 

I am well aware that the EL34 is a high power tube, but power tubes do offer different sound signatures than your average preamp tube. I am not a fan of using preamp tubes to power headphones. It sounds a bit more flat than using power tubes as triodes.  

 

There are several EL34 amp designs that can use a variety of power pentodes and run them as a triode too, so you can also get a much wider range of sound signatures which is kind of fun. Like I personally like the valve art 350bs since they have a nice full body and warm sound. I can not get the 350b sound out of a 12au7 or something like that. 

 

This is one of the DIY EL34 amps that my friend built. It is a speaker amp, but we used a resistor box to make it adaptable for headphones. I also have a pic of my 350b amp. They are all speaker amps that still kill those stupid darkvoice and deceware amps. 

 

post #19 of 37
Quote:
Originally Posted by tomb View Post
 


only 50W - why not? "stupid printed circuit board," too ... I never knew ...

Printed circuit board cost extra money. If you do not have some sort of complicated IC going into your build, then they are a waste of money. But I mean if you want to spend 15 bucks on a printed board rather than spend it on upgrading the quality of your capacitors and resistors, then who am I to stop you. 

post #20 of 37
Quote:
Originally Posted by Tjj226 Angel View Post
 
Quote:
Originally Posted by tomb View Post
 


only 50W - why not? "stupid printed circuit board," too ... I never knew ...

Printed circuit board cost extra money. If you do not have some sort of complicated IC going into your build, then they are a waste of money. But I mean if you want to spend 15 bucks on a printed board rather than spend it on upgrading the quality of your capacitors and resistors, then who am I to stop you. 

So you get your friend to build the point-to-point high-voltage amp and that gives you the chance to criticize printed circuit boards.  Maybe you'd want a point-to-point DAC, too?

post #21 of 37
Quote:
Originally Posted by tomb View Post
 

So you get your friend to build the point-to-point high-voltage amp and that gives you the chance to criticize printed circuit boards.  Maybe you'd want a point-to-point DAC, too?

 

You argument astounds me. First off, I make the amps. He just designs them. Second off, the point is still valid no matter who makes the amps. If I gave you an option of either saving having amp amp with no printed circuit board vs spending an extra 15 bucks just to have a circuit board, which one would you take? Let me say that smart people would save the extra 15 bucks. 

 

Finally, I had already made an exception for complicated IC circuits like dacs or solid state amps or what not. 

 

There is a time and place for circuit boards. All tube amplifiers are is neither the time nor the place. 

post #22 of 37
Quote:
Originally Posted by Tjj226 Angel View Post
 
Quote:
Originally Posted by nikongod View Post
 

 

Cute, thanks for implying that I am not familiar with amp designs. 

 

There is nothing inherently wrong with the EL34, or even pentodes (gasp!), but I am mostly curious why one would suggest such a powerful tube to put barely any power at all into a headphone.

Can you justify the suggestion to use such a powerful tube when less powerful tubes may offer very compelling advantages? El84, and the various "German post" tubes spring to mind immediately as things I would rather see in a headphone amp.

 

If more power is what we need for headphones why not just look at KT88 designs? Because we don't need more power. We need better linearity. We need lower noise. We need so little power it is often hard to measure. 

 

No? I thought you were commenting on the fact that EL34s sounded bad or something. 

 

I am well aware that the EL34 is a high power tube, but power tubes do offer different sound signatures than your average preamp tube. I am not a fan of using preamp tubes to power headphones. It sounds a bit more flat than using power tubes as triodes.  

 

There are several EL34 amp designs that can use a variety of power pentodes and run them as a triode too, so you can also get a much wider range of sound signatures which is kind of fun. Like I personally like the valve art 350bs since they have a nice full body and warm sound. I can not get the 350b sound out of a 12au7 or something like that. 

 

This is one of the DIY EL34 amps that my friend built. It is a speaker amp, but we used a resistor box to make it adaptable for headphones. I also have a pic of my 350b amp. They are all speaker amps that still kill those stupid darkvoice and deceware amps. 

 

 

Not that I'm hanging my hat on your quote above, but to suggest EL34's, build a resistor box, etc., and then talk about saving $15 on a PCB seems an astounding argument to me, but hey - whatever floats your boat.  You might think twice about offering that kind of advice to others, though.

post #23 of 37

Big difference between a few cents for some resistors and 15 bucks for a circuit board, but what ever. 

post #24 of 37

How about a Bijou?

post #25 of 37
Castanet....not OTL, it's a parafeed:
http://www.hagtech.com/halfkit.html


Aw, discontinued....

The Bijou looks fun
Edited by GrindingThud - 12/25/13 at 8:49am
post #26 of 37

cool thread, I want to start building next year. I was gonna start with the bottle head first but i was told OTL's can be dangerous and to start somewhere else. What would you guys suggest for someone who has never built before? Are DIY portable amps like this difficult ¬

 

 

I dont really mind what amp or amp type it is, I just wanna start somewhere safe and easy. 

post #27 of 37
Quote:
Originally Posted by Tjj226 Angel View Post


This is one of the DIY EL34 amps that my friend built. It is a speaker amp, but we used a resistor box to make it adaptable for headphones. I also have a pic of my 350b amp. They are all speaker amps that still kill those stupid darkvoice and deceware amps. 




I heard it's not good for the amp with common ground of the output of the output transformers. Did you have trick with the resistor box?
post #28 of 37
Quote:
Originally Posted by MDR30 View Post


I heard it's not good for the amp with common ground of the output of the output transformers. Did you have trick with the resistor box?

 

No. I am not 100% sure what you are talking about, but I think you are talking about noise being transmitted through the grounding wire? We have not had a single issue with hum or noise. The resistor box is an extremely simple design with no tricks or anything of the sort. 

post #29 of 37
With loudspeakers, L and R + and - are kept separate on a standard amp, but if you connect a headphone (with resistors), ground of L and R are united (only three contacts on a TRS plug) and apparently may cause a havoc with the output transformers having a common ground. Distorsion, overheating in the seconadary windings?

Must be some tube amp aficionados out there who know how to solve this problem.
post #30 of 37
Quote:
Originally Posted by MDR30 View Post

With loudspeakers, L and R + and - are kept separate on a standard amp, but if you connect a headphone (with resistors), ground of L and R are united (only three contacts on a TRS plug) and apparently may cause a havoc with the output transformers having a common ground. Distorsion, overheating in the seconadary windings?

Must be some tube amp aficionados out there who know how to solve this problem.

 

Mmmmm we have not seen this problem with any of our amps. 

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