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Help with picking a DIY headphone amp

post #1 of 12
Thread Starter 

I recently built a CMoy amp from the design on tangent's site and added my own flair to it in a couple of ways. I appreciated the simplicity of it and the elegance within this simplicity.....but I could see its flaws....although I don't have a quality amp in it yet (have a BB opa2132 on order and the current one in it  is a TL082C from radio shack DX) I know that that isnt the only issue with its quality. It doesnt sound "bad" per se it just doesn't sound "life changing". So I now want to complete a heftier amp that can reproduce at a much higher quality. I have a list of things I would LIKE to have in it and I have some ideas for ones I want to build (all of them also from tangent's site) 

 

What I want:

 

  bass boost: For real high power, punch you in the face, implode your eardrums with awesome sauce bass hits. (My headphones of choice are...well....different. Unlike the other audiophiles on this forum I went a different route for finding headphones. I decided to buy a gimmick just for the hell of it and see if anything came of it. If you want to see what I bought click here. I think I found a diamond in the rough (although the company has quality issues) because these are the bassiest headphones I've ever owned (bass is very important to me because I am a dubstep fan and I do a bit of producing from time to time) I am happy with them am not in the mood to be chided for buying a gimmick. I understand that its a gimmick, but they actually do punch out hard bass.)

  load forberance: I want an amp that has the ability to still reproduce highs when the bass is super heavy. I have an issue with my device and type of music that the highs some times get drowned out when the bass is heavy and then they POP Out when the bass goes down for a moment creating a terrible effect.

  Form factor that can fit within a backpack/laptop bag: I will use this for listening while at school and walking around so I'd like to have it in my backpack and just plug my stuff up to it in there.

  battery life: the pack that comes with it should last at least half a day (I could possibly build 2 packs and switch out in the day)

  general quality: I want it to be incredibly crystal clear. When I got my new headphones I heard things in my music that I had never heard before because of their ability to reproduce heavy and high frequencies well. It had more depth and the soundstage was incredible. If I could get a similar upgrade from an amp that would be wonderful.

  bells and whistles: I like features that I can configure and turn on and off to adjust for what I'm doing at the present moment. I can say that when I got my first Android device and got PowerAmp I was amazed. I could control the full equalizer on a device that could actually reproduce volume. (my desktop has ok volume and the lappy has crap for volume and although both have EQs they aren't very advanced (even though the desktop has dolby digital 7.1 built in) The point of me saying this is that when I was able to tweak I was happy.

 

 

Ideas I have for amps that might fit the Bill:

 

PPA

PPA v2 -- seems like best choice but also most expensive

PIMETA v2 -- seems like second best but I really wanted to up it to the PPA v2 from this to get the extra features and quality

 

possibly:

META42 -- heard about this somewhere and seemed like it might fit

 

 

ANY HELP OR ADVICE IS WELCOME! 

 

thank you in advance

 

 

 

post #2 of 12

Despite the deranged ranting of various shills on the amp subforum, no amps are life changing. There are subtle differences, sure, but for true night and day you just gotta bite the bullet and buy new headphones. 

 

Food for thought:

If you mix your music to sound "right" using a system that is +20db from 100hz down, how will it sound in some poor guy's car? 

How will it sound on i-buds? 

Is the "massive bass" in your final mix a result of your bloated headphones or is the bass going to come through the way you want on a system that measures more or less flat? 

Everything should be mixed on a system that measures as flat as possible. Let the end user apply his own biases. 

 

Since it sounds like you like to listen as well as mix (cool!) I see 2 headphones in your future. 

 

Since you will have 2 sets of headphones soon you can even test your mixes on several systems! 

post #3 of 12
Thread Starter 
Quote:
Originally Posted by nikongod View Post
 

Despite the deranged ranting of various shills on the amp subforum, no amps are life changing. There are subtle differences, sure, but for true night and day you just gotta bite the bullet and buy new headphones. 

 

I am happy with my headphones and they were indeed life changing. I'm just looking for something to give them a bit more oomph.

 

 

Quote:
 

Food for thought:

If you mix your music to sound "right" using a system that is +20db from 100hz down, how will it sound in some poor guy's car? 

How will it sound on i-buds? 

Is the "massive bass" in your final mix a result of your bloated headphones or is the bass going to come through the way you want on a system that measures more or less flat? 

Everything should be mixed on a system that measures as flat as possible. Let the end user apply his own biases. 

 

I mix on 5 sets of headphones and speakers: Some minimalistic desk speakers with no sub to hear it on the average joes system (with flat EQ), My headphones to hear the epic bass quality (normally heavy bass EQ), some i-buds (blehck...normally only listen once to hear how much they degrade my sound) some skull candy "smokin buds" (better than i-buds because they at least get /some/ bass and normally used with a /slight/ bassy EQ) and an old pair of generic plantronics headphones that I use a flat EQ on.

 

I understand the importance of testing to multiple systems ;) the main thing I want this amp for is listening because I'm also a programmer and tend to listen to 1-5 hour mixes whilst I program (plus I just like listening throughout the day). 

 

Quote:
 

Since it sounds like you like to listen as well as mix (cool!) I see 2 headphones in your future. 

 

Since you will have 2 sets of headphones soon you can even test your mixes on several systems! 

I will most likely get some audiophile quality headsets in the near future just for the hell of it (as I am happy with my current headphones).

 

But my question remains unanswered. I'm still not sure which of these amps I should build next..... :/

post #4 of 12

Fair enough. A lot of people come looking for the amp to be the end all be all fixer of problems with their headphones.... As long as you are mostly happy with your headphones. 

That being said, I would lean towards the Pimeta or the Meta42, with some tweaks. Probably a bit more strongly towards the Meta42, because it is easier to build on perfboard and integrate all of the extra features. 

 

Bass boost, of course. 

Adjustable output impedance (ideally 47, ~75, and 120ohms)

Depending on your opinion of it, crossfeed. 

 

If you are not familiar with them, look up the Xin supermacro for ideas of the features on what used to be the best portable amp on earth. Or was it the Xin supermini? The medium size one with 4 switches on the front. Its a shame he is so unresponsive to customers, his product was amazing. 

post #5 of 12
Thread Starter 
Quote:
Originally Posted by nikongod View Post
 

Fair enough. A lot of people come looking for the amp to be the end all be all fixer of problems with their headphones.... As long as you are mostly happy with your headphones. 

That being said, I would lean towards the Pimeta or the Meta42, with some tweaks. Probably a bit more strongly towards the Meta42, because it is easier to build on perfboard and integrate all of the extra features. 

 

Bass boost, of course. 

Adjustable output impedance (ideally 47, ~75, and 120ohms)

Depending on your opinion of it, crossfeed. 

 

If you are not familiar with them, look up the Xin supermacro for ideas of the features on what used to be the best portable amp on earth. Or was it the Xin supermini? The medium size one with 4 switches on the front. Its a shame he is so unresponsive to customers, his product was amazing. 

Thanks. I think the "ideal" output impedance would be <4 ohms as I have some very efficient headphones (32 ohms) so 4 would be 1/8 of the impedance of the headphones creating a desireable dampening factor. (I do hope that I am not spewing bs and that I understand this adequetely) I'll definitely look at the Pimeta and Meta42 as a PPA would be a large investment atm. crossfeed is not terribly important to me although I've never really tried it (I think I had a source once that did it but either it didn't do it well or it didn't make much difference) and of course bass boost is important to me (just added a pot to my cmoys bass boost and now its ****ed for some reason (think the pots too big but its what i could pick up at RadioShack (its a 100k ohm pot )) part of it is probably due to the crappy TL082C opamp in it currently too (have an opa2132pa on the way)) anyway thanks for the help and I'll look into this "Xin" too....can just about any feature be applied to just about any amp?

post #6 of 12
  • backspace119,
  •     money can be a setback in DIY, but there are tons of components available in the stuff people throw away...old DVD players, CD players, car stereos... lots of junk out there that you can salvage parts from. I have lots of containers filled with perfectly good parts that I took from dead devices...heatsinks, opamps, caps, switches, on and on...

Edited by vixr - 2/4/14 at 3:53pm
post #7 of 12
Quote:
Originally Posted by backspace119 View Post
 

Thanks. I think the "ideal" output impedance would be <4 ohms as I have some very efficient headphones (32 ohms) so 4 would be 1/8 of the impedance of the headphones creating a desireable dampening factor. (I do hope that I am not spewing bs and that I understand this adequetely) I'll definitely look at the Pimeta and Meta42 as a PPA would be a large investment atm. crossfeed is not terribly important to me although I've never really tried it (I think I had a source once that did it but either it didn't do it well or it didn't make much difference) and of course bass boost is important to me (just added a pot to my cmoys bass boost and now its ****ed for some reason (think the pots too big but its what i could pick up at RadioShack (its a 100k ohm pot )) part of it is probably due to the crappy TL082C opamp in it currently too (have an opa2132pa on the way)) anyway thanks for the help and I'll look into this "Xin" too....can just about any feature be applied to just about any amp?

 

There is some disagreement about what the "right" output impedance is for headphones. 

There is the "high damping factor" camp, which is 4ohms or less. 

There is the middle camp - which is why I put the 47 & 75ohm resistors there

And there is the "IEC standard output impedance" camp, which is the 47 in series with the 75ohm resistors to get 120ohms. 

I think the matter is complicated by the fact that different headphones respond differently to output impedance (or damping factor - just different ways of saying the same thing) Since there is no absolute standard for headphones (the newer IEC standards pretty much say that MFRs can do whatever they want) it pays to have a few options. With these options you get more ways to change the sound of various headphones. 

 

Stuff like output impedance can be added to any amp, but bass boost or a gain switch* does not always work as planned. 

 

*A gain switch is a waste of effort. Just use voltage gain of 2 or 3 for a "one amp to run them all" amp. Use gain of 1 for an amp that is just for low impedance/high sensativity headphones. 

post #8 of 12
Thread Starter 
Quote:
Originally Posted by vixr View Post
 
  • backspace119,
  •     money can be a setback in DIY, but there are tons of components available in the stuff people throw away...old DVD players, CD players, car stereos... lots of junk out there that you can salvage parts from. I have lots of containers filled with perfectly good parts that I took from dead devices...heatsinks, opamps, caps, switches, on and on...

i've actually pulled some parts out of old devices myself for other projects but i'm not sure if I've ever had an opamp pass through in one of them....I do have some heatsinks and resistors and caps but most of the electrical components would be sub par for audio so the only things that I can really use are pieces of enclosures and heatsinks (neither of which I need at the present moment)

post #9 of 12
Thread Starter 
Quote:
Originally Posted by nikongod View Post
 

 

There is some disagreement about what the "right" output impedance is for headphones. 

There is the "high damping factor" camp, which is 4ohms or less. 

There is the middle camp - which is why I put the 47 & 75ohm resistors there

And there is the "IEC standard output impedance" camp, which is the 47 in series with the 75ohm resistors to get 120ohms. 

I think the matter is complicated by the fact that different headphones respond differently to output impedance (or damping factor - just different ways of saying the same thing) Since there is no absolute standard for headphones (the newer IEC standards pretty much say that MFRs can do whatever they want) it pays to have a few options. With these options you get more ways to change the sound of various headphones. 

 

Stuff like output impedance can be added to any amp, but bass boost or a gain switch* does not always work as planned. 

 

*A gain switch is a waste of effort. Just use voltage gain of 2 or 3 for a "one amp to run them all" amp. Use gain of 1 for an amp that is just for low impedance/high sensativity headphones. 

I'll give the higher impedances a go and see what happens. as for gain, I'm looking for a bump in my sound levels so I think I'll leave it around my current 5.7 setting. Could I use a pot on the output impedance to have it adjustable? (this is what you were referring to in the meta42 right?)

post #10 of 12
Quote:
Originally Posted by backspace119 View Post
 

Could I use a pot on the output impedance to have it adjustable? (this is what you were referring to in the meta42 right?)

 

For sure you can use a pot to change the output resistance. I built something like that (as a standalone box to put on any amp) once. 

 

I have 2 concerns:

1:I'm not sure if you can get "transportable" 250--500ohm stereo pots, but I have never really looked. You can definitely get 1" (24mm) stereo 500ohm pots.

2: At low resistances 500ohm pots don't have the greatest matching.  

post #11 of 12
Thread Starter 
Quote:
Originally Posted by nikongod View Post
 

 

For sure you can use a pot to change the output resistance. I built something like that (as a standalone box to put on any amp) once. 

 

I have 2 concerns:

1:I'm not sure if you can get "transportable" 250--500ohm stereo pots, but I have never really looked. You can definitely get 1" (24mm) stereo 500ohm pots.

2: At low resistances 500ohm pots don't have the greatest matching.  

I've heard that about pots in general (more like I read about it in tangent's article) and I do see the issue here....maybe it could be linear instead of logarithmic? or would that not matter?

post #12 of 12
Quote:
Originally Posted by backspace119 View Post
 

I've heard that about pots in general (more like I read about it in tangent's article) and I do see the issue here....maybe it could be linear instead of logarithmic? or would that not matter?

 

I would lean towards a linear pot. 

You may still run into matching issues though. 

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