Cheap but linear headamp - 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 1st May 2013, 01:54 AM   #1
diyAudio Member
 
Join Date: Feb 2009
Default Cheap but linear headamp

Hi Folks!

By request from my friend I made (of may be 90% trough) layout of simple standalone two layer PCB for amplifier mentioned earlier in parallel universe.
Schematic of this version can be found here. This guy also has on the board preamplifier with volume control and simple output DC protection.
If anyone will be interested in construction of this thing, I can provide gerber files and BOM.
And an addition few 3D pics of the PCB (not the latest version one though).
Attached Images
File Type: png post1.png (305.4 KB, 249 views)
File Type: png post2.png (99.8 KB, 241 views)

Last edited by Sergey888; 2nd May 2013 at 12:36 PM.
  Reply With Quote
Old 2nd May 2013, 02:50 AM   #2
diyAudio Member
 
Join Date: Jun 2004
Location: Connecticut
Thanks, but looks like there is an issue with the schematic post.
  Reply With Quote
Old 2nd May 2013, 12:36 PM   #3
diyAudio Member
 
Join Date: Feb 2009
Fixed schematic link.
  Reply With Quote
Old 2nd May 2013, 08:07 PM   #4
diyAudio Member
 
Join Date: Jun 2004
Location: Connecticut
Very interesting design, I'm sure it's an awesome performer. It looks like you are using a form of modified integrator compensation around the TPA6120?

Also curious as to how you arrived your zobel network values?
  Reply With Quote
Old 2nd May 2013, 10:01 PM   #5
jcx is offline jcx  United States
diyAudio Member
 
Join Date: Feb 2003
Location: ..
clamping is helpful in composite amps - I show a scheme for diode feedback clamping the input op amp that should give faster recovery, input op amps would draw less current in clipping:

Click the image to open in full size.


High loop Gain Composite Op Amp Circuits



filtering the input op amp supply is OK, but you can afford to add sub regulation to a lower V - whatever the input op amp is happy with
could be Zener shunt reg - could take up less room than big electrolytic C, works down to DC




while a project schematic may benefit from the mediafire service - it was a major pain for me

for discussion please just use forum attachment or img so I can see something without changing browsers, downloading
  Reply With Quote
Old 3rd May 2013, 01:10 AM   #6
diyAudio Member
 
Join Date: Feb 2009
HI Jcx

I actually was thinking about this sort of clamp (not exactly the same, but essentially the same structure) and actually prototyped it but decided to give it a miss for couple of reasons:
1. Clipping and recovery for this device will not be a part of normal operation. It has a gain of 1 and used with DAC which has 2Vrms output. So clipping is excluded, except start up and power down, where more sophisticated clumping circuit didn't make too much difference.
2. This clump has some parasitic capacitance from output of opamp to its input, and this capacitance is non-liner. I observed some difference in distortion level while clamp was connected. The difference was not particularly large, and when amplifier is heavily loaded it is below practical level, but still, when you know that it is somewhere over there...
I could try to use PIN diodes, which typically have 5-10 times lower capacitance than bav99, but I did,'t get to this point.

Post regulation was crossing my mind as well, but result was satisfying with simple RC - why to bother.
  Reply With Quote
Old 3rd May 2013, 01:27 AM   #7
diyAudio Member
 
Join Date: Feb 2009
Hi Chris

Zobel values where some sort of attempt to kill two birds and at the same time to use existing on the board values.
I was chasing two things 1. Disconnect amplifier on a high frequency from potentially capacitive load and give it more of less stable active loading. 2. Sort of "terminate cable", or in other words introduce some losses on high freq.
I would prefer to have some what larger inductor value, but it's size was getting impractical.
  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
PGA2310 Headamp jtavrisov Headphone Systems 2 24th January 2012 01:09 PM
Preamp and Headamp 2 in 1? GLooP Headphone Systems 14 15th January 2012 01:44 AM
It's my AD815 headamp Kochkurov Maxim Chip Amps 16 11th May 2006 12:44 PM
cheap linear digital pot search xplod1236 Digital Source 4 29th September 2004 02:52 AM
another chip headamp digi01 Chip Amps 6 23rd June 2004 04:18 AM


New To Site? Need Help?

All times are GMT. The time now is 06:05 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