Preamp & headphone amp designs - 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 30th April 2002, 04:28 PM   #1
diyAudio Member
 
Join Date: Mar 2001
Location: Brazil
Default Preamp & headphone amp designs

Hi!

I am willing to try some preamp and headphone amp quality designs.

The first option I am considering are two variations designed by Walt Jung, one published in Audio Electronis (when it was The Audio Amateur) and the other on a three-part article on Electronic Design.

The first used an AD744 on its first stage and an AD811 on the second. The other uses an AD823 and an AD812 respectively.

On the second design he applied more local feedback for error correction and exgtend bandwidth. The chips are also dual, probably to make a more compact stereo arrangement.

A variation of this circuits can be implemented as a headphone amp.

Has anyone built these circuits?

If you're not familiar with these circuits I can attach them.



Carlos E. Martinez
  Reply With Quote
Old 30th April 2002, 05:52 PM   #2
mlloyd1 is offline mlloyd1  United States
diyAudio Member
 
mlloyd1's Avatar
 
Join Date: Feb 2001
Location: illinois
Hi:
I've built both. I still use the first one (AD744 + AD811) built almost 10 years ago. Currently, the original serves as my primary preamp and another unit built later serves as a headphone amp for my Beyer DT990 phones. Pics on page 2 of my web site.

Sounds great: very low distortion, wide bandwidth, very stable (I've had no oscillation problems at all in spite of the speed of the AD811), and low noise.

The Analog Devices web site probably has more info. Look for Analog Dialogue, volume 27, number 1, 1993" Op Amps in Line-Driver and Receiver: Part 2 Audio Applications" as one example.

If you're looking for PCBs, Audio Express had a project a few years ago using this scheme in a preamp. The name escapes me at the moment (Ryan, maybe? Some else will fill it in). I know they still had boards as recent as last year.

What do you want to know exactly?
mlloyd1
  Reply With Quote
Old 30th April 2002, 06:15 PM   #3
diyAudio Member
 
Join Date: Mar 2001
Location: Brazil
Default Preamp quest

Thanks for your comments: it's exactly what I was looking for.

My quest is a preamp that is transparent enough as no preamp at all. And I am interested in knowing how good different designs sound, if possible compared to the same reference.

Until now it has been difficult to convince myself into using active preamp, as I have been quite satisfied with the passive control I use: just selection switch and volume pot in the signal path.

But I know I maybe wrong in that approach, so I'm willing to try a different way, be it solid state (chip or discrete), valve or even transformers for low level signals.

For power amps I'm more into solid state, as I'm not too convinced a transformer can so good interfacing with a real speaker.


Carlos
  Reply With Quote
Old 30th April 2002, 09:58 PM   #4
mlloyd1 is offline mlloyd1  United States
diyAudio Member
 
mlloyd1's Avatar
 
Join Date: Feb 2001
Location: illinois
I remember now; the project was the Valkyrie Preamp by Grayson King.
mlloyd1
Quote:
Originally posted by mlloyd1
.....Audio Express had a project a few years ago using this scheme in a preamp. The name escapes me at the moment ......
mlloyd1
I also just remembered to point out - VERY IMPORTANT -
If you use the AD811 with +/- 15V rails, USE A HEATSINK!!!
It's a high quiescent current device.
Good Luck!
  Reply With Quote
Old 1st May 2002, 12:49 AM   #5
diyAudio Member
 
Join Date: Mar 2001
Location: Brazil
Yes, the Valkyrie was an adaptation of that Jung arrangement.

The supply was not too sophisticated, just using LT1085/1033 regulators, but it probably was a fine preamp.

Later on I got to know that you shouldn't use large capacitors at the output of these regulators, and they did on that project.

A version of the Jung lineamp using Jung's latest low noise regulators seemed to be the reference used by Gary Galo on his Audio Electronics/ Audio Express tests. I don't know if he still does.

Yes, you had to put heatsinks on the AD811 if you went over +/-12V on the supply. I wonder why they didn't release it in a heatsinkable version as they do on buffers. Or did they?

You certainly have to heatsink if you use that preamp as headphone amplifier, which Galo also did. It seemed to beat Ben Duncan's headphone amp, which is powered by gel batteries. That was on another test.

One thing I am curious on is using the AD812 (which is a dual 811 if I am not wrong) and parallel the chips to handle more current on a headphone amp version.

You said you also tried the second Jung version for this lineamp?


Carlos
  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
Tube headphone amp designs? ambience exists Headphone Systems 27 30th May 2009 03:14 AM
Discrete phono preamp designs? Paul Ebert Analogue Source 68 9th January 2008 01:01 PM
Digital preamp designs? Helix Digital Source 11 13th September 2001 12:14 PM


New To Site? Need Help?

All times are GMT. The time now is 12:40 PM.


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