Where do I start? (re: need a DIY amp project) - Page 2 - diyAudio
Go Back   Home > Forums > Amplifiers > Headphone Systems

Headphone Systems Everything to do with Headphones

Please consider donating to help us continue to serve you.

Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving
Reply
 
Thread Tools Search this Thread
Old 3rd December 2013, 10:25 PM   #11
EmmEff is offline EmmEff  Canada
diyAudio Member
 
Join Date: Nov 2013
Location: Ontario, Canada
I really like the look of that RJM amp. Thanks for that heads-up. I'm researching now...
  Reply With Quote
Old 19th December 2013, 02:48 AM   #12
diyAudio Member
 
Marine Boat's Avatar
 
Join Date: Oct 2011
Op-amps are your friends! They are the closest thing to an ideal amplifier that you'll find. The LM1875 to LM3886 series power amps have found extremely wide acclaim in the audio community, both in terms of measurements and listening tests, and are essentially little more than high-power op-amps. Most op amps, on the other hand, are made for line-level use, and usually expect a load higher than about 600 ohms. Some op-amps can push a lot more, and make great output stages. The O2 is a good example, will leave you with $200 in your pocket to spend on music, and in terms of sound quality it surpasses the limits of the human ear (based on what data we have available). Your Grados will love it: The Objective2 (O2) Headphone Amp DIY Project Of course, if you want to go a more raw DIY route, there's the tried-and-true combination of a good op-amp for voltage gain and a good buffer for current gain.
Quote:
Originally Posted by abraxalito View Post
As you like to tinker, I recommend you start by winding a couple of ferrite transformers. That's because in my experience, typical headphone amps lack in dynamics due to inadequate power supplies for driving low impedances. If you wind a trafo with a 5:1 turns ratio (say) that will make your 32ohm headphones look like 800ohms to an amp - the dynamics will be noticeably better on practically any amp, assuming it still has enough voltage swing.

Mouser stocks some suitable cores now : 6695272521 Fair-Rite | Mouser

Since the sonic benefits of classA (IME) relate to having much lower load-induced noise on the supply, such a trafo will have an AB amp sounding much closer to classA.
That's dubious, and a lot more trouble than it's worth. It's also really, really easy to make an adequate power supply. Seriously, you won't need anything more than an 500 milliamps at most for those Grados. Also, negative feedback will bring the output impedance of the amp to almost nil even if the power supply has an output impedance of a few ohms. Even the best audio transformers will contribute much more distortion than all the rest of a sensibly designed headphone amp. If you think 32 ohms is a problem, try talking to those speaker people with their 4- and 8-ohm loads! Also, do you have any evidence that hooking up a load to a class A gives and messes up the power supply less than with class AB? I've never heard this before.
Quote:
Originally Posted by woodturner-fran View Post
I strongly recommend the sapphire amp kit from RJM. The kit is easy to assemble, sounds really great and will come in well below your budget. Richard is great to deal with too and helpful with support should you need it.

Thread here:

RJM Audio Sapphire Desktop Headphone Amplifier

Apart from being able to solder through hole components, the thing you need to be most careful with is to use twisted pair for the inputs and outputs.


Fran
There seems to be some woo-woo going on in that design... Honestly, I can't recommend paying for woo-woo. Money is valuable but woo-woo isn't.

Last edited by Marine Boat; 19th December 2013 at 03:03 AM.
  Reply With Quote
Old 19th December 2013, 03:14 AM   #13
diyAudio Member
 
abraxalito's Avatar
 
Join Date: Sep 2007
Location: Hangzhou - Marco Polo's 'most beautiful city'. 700yrs is a long time though...
Blog Entries: 105
Send a message via MSN to abraxalito Send a message via Yahoo to abraxalito Send a message via Skype™ to abraxalito
Quote:
Originally Posted by Marine Boat View Post
That's dubious, and a lot more trouble than it's worth.
Do please go on to explain why, I'm all ears.

Quote:
It's also really, really easy to make an adequate power supply.
Sure, but is 'adequate' what the OP wants? - ISTM he's concerned about getting great sound quality. That doesn't happen in my experience with merely 'adequate' supplies - they deliver merely adequate SQ.

Quote:
Even the best audio transformers will contribute much more distortion than all the rest of a sensibly designed headphone amp.
I suspect the evidence here isn't on your side - the Audio Precision test equipment uses one of the best audio transformers and I haven't heard them saying that's limited by transformer distortion.

Quote:
Also, do you have any evidence that hooking up a load to a class A gives and messes up the power supply less than with class AB?
Does the evidence of ears count or are you a measurements only kind of guy? I should point out that merely having a classA amp does not guarantee that it won't mess with the PSU. Only a subset of classA amps leave the power supply invariant.

Quote:
I've never heard this before.
So are you here to learn something new?
__________________
I have the advantage of having found out how hard it is to get to really know something... how easy it is to make mistakes and fool yourself. - Richard Feynman

Last edited by abraxalito; 19th December 2013 at 03:19 AM. Reason: Originally messed up the quoting and replied to a part directed at Fran.
  Reply With Quote
Old 19th December 2013, 07:59 AM   #14
00940 is offline 00940  Belgium
diyAudio Member
 
Join Date: Sep 2003
Location: Paris
Marine boat has a point though... it's much easier (and cheaper) to build a very good amplifier for 32r loads than to wind audio transformers of a similar quality. There's about zero chance for a beginner to wind even a decent one.

One could buy a pair of sowter 8665 though. Doesn't come cheap.
__________________
Ben.
  Reply With Quote
Old 19th December 2013, 08:12 AM   #15
diyAudio Member
 
abraxalito's Avatar
 
Join Date: Sep 2007
Location: Hangzhou - Marco Polo's 'most beautiful city'. 700yrs is a long time though...
Blog Entries: 105
Send a message via MSN to abraxalito Send a message via Yahoo to abraxalito Send a message via Skype™ to abraxalito
He has a point for building an 'adequate' amplifier. If that's what the OP wants then I'll let him have the floor for the rest of this thread

I'm a beginner myself at winding trafos - they're very easy to wind the way I do them, which is a totally naive way probably far from the optimum because I've only been making them a couple of months having started from scratch. But I was so impressed with the results I decided to share my findings. Quite possibly the real trafo experts (BudP springs to mind) would class my trafos as very far from 'decent' yet they've sounded wonderful so far on headphones (not at all so wonderful on speakers though which reason I've yet to discover).
__________________
I have the advantage of having found out how hard it is to get to really know something... how easy it is to make mistakes and fool yourself. - Richard Feynman
  Reply With Quote
Old 21st December 2013, 07:55 PM   #16
diyAudio Member
 
Marine Boat's Avatar
 
Join Date: Oct 2011
Quote:
Originally Posted by abraxalito View Post
Do please go on to explain why, I'm all ears.

Sure, but is 'adequate' what the OP wants? - ISTM he's concerned about getting great sound quality. That doesn't happen in my experience with merely 'adequate' supplies - they deliver merely adequate SQ.
I was being modest.
Quote:
Originally Posted by abraxalito View Post
I suspect the evidence here isn't on your side - the Audio Precision test equipment uses one of the best audio transformers and I haven't heard them saying that's limited by transformer distortion.
The people at AP may be magicians, but I don't think they can get their DC coupling with a transformer.
Quote:
Originally Posted by abraxalito View Post
Does the evidence of ears count
I'd accept a blind or double-blind test gladly. Unless you can hear with your eyes I don't think that will be a problem!

Quote:
Originally Posted by abraxalito View Post
or are you a measurements only kind of guy? I should point out that merely having a classA amp does not guarantee that it won't mess with the PSU. Only a subset of classA amps leave the power supply invariant.
The neat thing about audio is that, before getting to the transducer, the signal is electrical. The same electrical signal moves the same speaker (or earphone) in the same way and makes the same sound under the same conditions. We can measure electrical signals so tiny and precisely that we can measure the signal long before the speaker (or BA driver, etc.) makes any detectable movement, and long, long before the threshold of human hearing is breached. But no. I'm not a measurements-only kind of guy. I just wanted to say all that.
Quote:
Originally Posted by abraxalito View Post
He has a point for building an 'adequate' amplifier. If that's what the OP wants then I'll let him have the floor for the rest of this thread

I'm a beginner myself at winding trafos - they're very easy to wind the way I do them, which is a totally naive way probably far from the optimum because I've only been making them a couple of months having started from scratch. But I was so impressed with the results I decided to share my findings. Quite possibly the real trafo experts (BudP springs to mind) would class my trafos as very far from 'decent' yet they've sounded wonderful so far on headphones (not at all so wonderful on speakers though which reason I've yet to discover).
I'll let you have the floor if the OP wants what's in the bold type!
  Reply With Quote
Old 21st December 2013, 10:52 PM   #17
diyAudio Member
 
abraxalito's Avatar
 
Join Date: Sep 2007
Location: Hangzhou - Marco Polo's 'most beautiful city'. 700yrs is a long time though...
Blog Entries: 105
Send a message via MSN to abraxalito Send a message via Yahoo to abraxalito Send a message via Skype™ to abraxalito
Quote:
Originally Posted by Marine Boat View Post
The people at AP may be magicians, but I don't think they can get their DC coupling with a transformer.
What DC coupling would that be?

Quote:
I'd accept a blind or double-blind test gladly. Unless you can hear with your eyes I don't think that will be a problem!
I'll take that as a 'no' then.
__________________
I have the advantage of having found out how hard it is to get to really know something... how easy it is to make mistakes and fool yourself. - Richard Feynman
  Reply With Quote
Old 21st December 2013, 11:20 PM   #18
diyAudio Member
 
Join Date: Jan 2008
http://ap.com/download/file/658

AP 525-585 family, DC or AC coupling.

Nothing about transformers.

Got any measurements demonstrating performance of your hand built transformers? Or doesn't it bear discussion and publicity, a secret degenerating?
  Reply With Quote
Old 21st December 2013, 11:30 PM   #19
diyAudio Member
 
abraxalito's Avatar
 
Join Date: Sep 2007
Location: Hangzhou - Marco Polo's 'most beautiful city'. 700yrs is a long time though...
Blog Entries: 105
Send a message via MSN to abraxalito Send a message via Yahoo to abraxalito Send a message via Skype™ to abraxalito
I wasn't talking about their low-end stuff, rather the 2700 series.

No. Measurements are no demonstration of performance of audio kit, listening is. It'd only be a secret if I'd made measurements but refused to disclose them - rather I've made none.
__________________
I have the advantage of having found out how hard it is to get to really know something... how easy it is to make mistakes and fool yourself. - Richard Feynman
  Reply With Quote
Old 21st December 2013, 11:46 PM   #20
diyAudio Member
 
Join Date: Jan 2008
http://ap.com/download/file/183

p10:

Quote:
Unless otherwise noted, all specifications assume dc coupling, rms detection, and
auto-ranging operation.

No transformers here either.

AP doesn't have any low end stuff, or subjective fluff.
  Reply With Quote

Reply


Hide this!Advertise here!
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
DIY AMP start project - Help choosing one sagi4422 Tubes / Valves 10 13th December 2012 11:46 AM
Advice on how to start a LM3875 amp project fatbob Chip Amps 12 8th April 2008 03:15 AM
first DIY amp start up-yowza HELP! mr mojo Tubes / Valves 13 8th September 2005 11:44 AM
I think I'm ready to start my first DIY project Corn-Picker Everything Else 24 23rd October 2002 03:21 AM


New To Site? Need Help?

All times are GMT. The time now is 09:18 AM.


vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2014 DragonByte Technologies Ltd.
Copyright 1999-2014 diyAudio

Content Relevant URLs by vBSEO 3.3.2