Discrete Opamp Open Design - diyAudio
Go Back   Home > Forums > Source & Line > Analog Line Level

Analog Line Level Preamplifiers , Passive Pre-amps, Crossovers, etc.

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 22nd August 2012, 06:22 PM   #1
EUVL is offline EUVL  Europe
diyAudio Member
 
Join Date: Oct 2003
Default Discrete Opamp Open Design

This is to follow the idea to design a discrete opamp by joint effort, without hi-jacking John Curl's Blowtorch II thread.

The origin of the discussion can be found here :
http://www.diyaudio.com/forums/analo...ml#post3136059


Patrick
__________________
xen-audio.com

Last edited by EUVL; 22nd August 2012 at 06:24 PM.
  Reply With Quote
Old 22nd August 2012, 06:30 PM   #2
EUVL is offline EUVL  Europe
diyAudio Member
 
Join Date: Oct 2003
Would be grateful if the moderator can copy the following posts from the blowtorch II thread also to here:

post #26829, ..831~..883, ..837~..842.


Thanks in advance,
Patrick
__________________
xen-audio.com
  Reply With Quote
Old 22nd August 2012, 06:33 PM   #3
jcx is offline jcx  United States
diyAudio Member
 
Join Date: Feb 2003
Location: ..
goals/target applications?

a good MC phono pre /= decent condensor mic capsule buffer

improving SOTA requires knowing what it is, where the theoretical limits are

SG-Acoustics Samuel Groner Discrete OpAmps

look for the op amp distortion measurements paper - shows some commerical discrete op amps and lots of monolithic with a good set of objective measurements
  Reply With Quote
Old 22nd August 2012, 06:36 PM   #4
diyAudio Member
 
Join Date: Jun 2011
What performance do you require?

Input impedance, supply voltage, PSRR, CMRR, gain, current drive? Output stage class? Short circuit withstand?

edit:

cross post jcx
  Reply With Quote
Old 22nd August 2012, 06:48 PM   #5
wayne is offline wayne  United States
diyAudio Member
 
Join Date: Jan 2002
Location: Northern California
Here is a discrete op Amp. Seven SMT packages that are readily available.
not SOA but works via solder simulation.
Attached Images
File Type: jpg discreteOpAmp.jpg (178.4 KB, 5916 views)
  Reply With Quote
Old 22nd August 2012, 06:50 PM   #6
RNMarsh is offline RNMarsh  United States
diyAudio Member
 
RNMarsh's Avatar
 
Join Date: May 2012
Location: 2457 Cascade Trail; Cool, CA. 95614
What is the end goal? Got to define that first.
It seemed, from JC's thead, it was to be a better Jensen 990 using similar or OpAmp topology?
  Reply With Quote
Old 22nd August 2012, 07:12 PM   #7
diyAudio Member
 
dirkwright's Avatar
 
Join Date: May 2011
Location: Virginia
This is a huge subject with many commercial designs already out there.
  Reply With Quote
Old 22nd August 2012, 07:20 PM   #8
RNMarsh is offline RNMarsh  United States
diyAudio Member
 
RNMarsh's Avatar
 
Join Date: May 2012
Location: 2457 Cascade Trail; Cool, CA. 95614
see JC thread -- goal: 627 performance in discrete design.

IMO cant require IC for dc servo in low gain apps and no large bulky coupling caps required to use this 627 goal equivalent.
  Reply With Quote
Old 22nd August 2012, 07:58 PM   #9
diyAudio Member
 
dirkwright's Avatar
 
Join Date: May 2011
Location: Virginia
Quote:
Originally Posted by RNMarsh View Post
see JC thread -- goal: 627 performance in discrete design.

IMO cant require IC for dc servo in low gain apps and no large bulky coupling caps required to use this 627 goal equivalent.
OK, to get that here, from your post:

1) 8 transistors or less
2) drives 30 ohms with -105dB harmonics from 20Hz->20kHz
3) S/N -110dB (input shorted, 1Vrms output, unweighted)
4) no DC servo
5) DC offset on output less than 2mV under normal time/temp range
6) all of above with gain = 10 or less

Seems impossible to me but hey go for it. I got nothing.

Last edited by dirkwright; 22nd August 2012 at 08:16 PM.
  Reply With Quote
Old 22nd August 2012, 08:20 PM   #10
diyAudio Member
 
bear's Avatar
 
Join Date: Apr 2002
Location: New York State USA
Afaik, the 990 used this for the front end:

http://www.ti.com/lit/ds/symlink/lm394.pdf

_-_-bear

Also, why is this going to be anything worthwhile (wrt the above specs for example) since there are a slew of ultra super low distortion monolithic IC opamps now available??
__________________
_-_-bear
http://www.bearlabs.com -- Btw, I don't actually know anything, FYI -- [...2SJ74 Toshiba bogus asian parts - beware! ]
  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
Discrete OPAMP audio-gd Vendor's Bazaar 27 20th September 2012 04:02 PM
discrete opamp help blackpowderaudio Parts 0 16th December 2009 03:46 PM
THAT transistor headphone amp (250ma discrete opamp) design sanity check. Russ White Headphone Systems 19 13th December 2007 12:52 PM


New To Site? Need Help?

All times are GMT. The time now is 07:00 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