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 30th September 2007, 08:37 PM   #1
x-pro is offline x-pro  United Kingdom
diyAudio Member
 
x-pro's Avatar
 
Join Date: Apr 2003
Location: London
Default My A.N.T. "Amber" headphone amplifier

As I plan to release an updated version soon, here is a complete circuit of my SE Class A and "zero negative feedback" headphone amplifier design from 2004, using my idea I've published here:

Non-feedback parametric linearisation in FETs

It works well with most medium to high impedance headphones (from 60 to 600 Ohm). For low impedance headphones the output FET could be replaced by a device with a higher transconductance at 100 mA.

This circuit and a short description also now available as a PDF file on my website here: http://www.ant-audio.co.uk /Theory/ANT Amber Headphone Amplifier.pdf . As usual - free for a private builder, not for production. If somebody would like to build a copy, I would be happy to explain in this thread how to select the FETs for it and what replacement parts could be used.

Enjoy!

Alex
Attached Images
File Type: gif ant_amber_v1.gif (8.4 KB, 1112 views)
  Reply With Quote
Old 30th September 2007, 10:57 PM   #2
dimitri is offline dimitri  United States
diyAudio Member
 
dimitri's Avatar
 
Join Date: Oct 2002
Location: retired
Send a message via ICQ to dimitri
Default Re: My A.N.T. "Amber" headphone amplifier

Hello Alex,
Glad to see one more implementation of Richard Knapp (Spatial Audio) patents, dated 1985 and earlier. Probably it will be nice to show some appreciation while "borrowing" his ideas.
Attached Images
File Type: gif rknapp.gif (4.3 KB, 857 views)
  Reply With Quote
Old 30th September 2007, 11:08 PM   #3
x-pro is offline x-pro  United Kingdom
diyAudio Member
 
x-pro's Avatar
 
Join Date: Apr 2003
Location: London
Default Re: Re: My A.N.T. "Amber" headphone amplifier

Quote:
Originally posted by dimitri
Hello Alex,
Glad to see one more implementation of Richard Knapp (Spatial Audio) patents, dated 1985 and earlier. Probably it will be nice to show some appreciation while "borrowing" his ideas.
First of all, Dimitri, I did not "borrow" anybody's ideas. If I know about the previous work I would always mention it. However in this particular case I can see no relevance to my circuit at all, except some similarity in configuration. There is no capacitor in my circuit . Q5 and Q7 in my circuit only provide for a current source load, temperature compensated to match the amplifing pair below. And the cascoded combination of two FETs was known well before 1985 and described in "The Art of Electronics".

Secondly, I really don't like your tone. Sorry.

Alex
  Reply With Quote
Old 1st October 2007, 12:24 AM   #4
Tim__x is offline Tim__x  Canada
diyAudio Member
 
Join Date: Jun 2004
Location: Edmonton area, Alberta
There's a NatSemi app note somewhere (I'm not sure of the date) with a circuit similar to the on Dimitri posted, they called it a mu-follower. I can't recall if they used the Greek U-like mu, or just "mu".
  Reply With Quote
Old 1st October 2007, 12:25 AM   #5
Gordy is offline Gordy  United Kingdom
diyAudio Member
 
Join Date: Nov 2006
Thanks for the post and the info Alex.
  Reply With Quote
Old 1st October 2007, 12:26 AM   #6
Tim__x is offline Tim__x  Canada
diyAudio Member
 
Join Date: Jun 2004
Location: Edmonton area, Alberta
A quick google shows that it not a NatSemi invention, but dates back to tubes, and is certainly older than any patent from the 80's.
  Reply With Quote
Old 1st October 2007, 12:39 AM   #7
x-pro is offline x-pro  United Kingdom
diyAudio Member
 
x-pro's Avatar
 
Join Date: Apr 2003
Location: London
Quote:
Originally posted by Tim__x
A quick google shows that it not a NatSemi invention, but dates back to tubes, and is certainly older than any patent from the 80's.
Yes, the "mu-follower" is well known for the tube circuits and there is a certain connection between that and the circuit Dimitri posted. However, as I've pointed out already, my circuit has nothing to do with either of these . In my case the cascode is adjusted for a minimum THD and the top pair of the devices is just a current source, nothing more. The only reason to use a same matched combination of devices was a near-perfect temperature compensation. Actual load in the VAS is R15 and the gain could easily be made several times higher if required by just increasing value of R15. VAS here is a complete DC amplifier, with no capacitors in the signal path and no LF roll-off. The LF limit is set by the output capacitor and the headphone impedance.

Cheers

Alex
  Reply With Quote
Old 1st October 2007, 04:28 AM   #8
Tim__x is offline Tim__x  Canada
diyAudio Member
 
Join Date: Jun 2004
Location: Edmonton area, Alberta
I never meant to imply your cicruit was "borrowed".
Just an off-topic comment on the patented circuit mentioned not being very original.

I see yours as nothing more than a cascode (not that there's anything wrong with 'just a cascode').

At this point, there are very few functional arrangments of three terminal devices that have not been done before.
  Reply With Quote
Old 1st October 2007, 08:47 AM   #9
x-pro is offline x-pro  United Kingdom
diyAudio Member
 
x-pro's Avatar
 
Join Date: Apr 2003
Location: London
Quote:
Originally posted by Tim__x
At this point, there are very few functional arrangments of three terminal devices that have not been done before.
True . In my circuit it is not the arrangement by itself but a combination of parameters and the working point that is important to get a much improved linearity without the feedback.

Cheers

Alex
  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
What makes an amplifier "bright", "warm", or "neutral"? JohnS Solid State 51 13th December 2009 06:42 PM
Headphone amps: How much "headroom" is enough? Artie Headphone Systems 11 28th June 2009 05:02 PM
Beyerdynamic's Headzone headphone promise "perfect spatial impression" Nordic Headphone Systems 1 28th August 2007 09:10 PM
Hi-Fi News "Headcase"009 headphone amp. Raymond Headphone Systems 0 15th March 2003 03:46 PM
"Digital" headphone amp from Crystal/Cirrus peranders Headphone Systems 0 19th April 2002 07:36 AM


New To Site? Need Help?

All times are GMT. The time now is 10:12 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