Integrated regulators for smart bias control - diyAudio
Go Back   Home > Forums > Amplifiers > Solid State

Solid State Talk all about solid state amplification.

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 25th August 2004, 07:54 PM   #1
diyAudio Member
 
darkfenriz's Avatar
 
Join Date: Jun 2004
Location: Warsaw
Question Integrated regulators for smart bias control

Hallo
Just a weird idea to use LM317/LM337 regulator pair in a configuration like in the attachment
Is it worth considering or just rubbish???

(no values, simulation or whatever -just an idea)
Attached Images
File Type: jpg reg.jpg (38.0 KB, 165 views)
  Reply With Quote
Old 25th August 2004, 08:48 PM   #2
johnnyx is offline johnnyx  United Kingdom
diyAudio Member
 
Join Date: Jan 2004
Location: manchester
How will the regulators pass the signal between VAS and output stage?
  Reply With Quote
Old 25th August 2004, 09:11 PM   #3
diyAudio Member
 
darkfenriz's Avatar
 
Join Date: Jun 2004
Location: Warsaw
Won't they??
hmm.. good question indeed..

maybe it was too bizzare to be possible
If I change the part like this will it solve:
Attached Images
File Type: jpg reg2.jpg (13.5 KB, 131 views)
  Reply With Quote
Old 25th August 2004, 09:57 PM   #4
Stocker is offline Stocker  United States
diyAudio Member
 
Join Date: Dec 2003
Location: Austin
assuming it 'could' work,

what about temperature stability?
__________________
Jesus loves you.
  Reply With Quote
Old 25th August 2004, 10:09 PM   #5
hughmon is offline hughmon  United States
diyAudio Member
 
Join Date: Jun 2004
Location: Los Angeles
In concept at least, it could work. One of the problems with three terminal regulators is that the output amp basically has 741 performance, only with a higher output current (read slow and noisy). The net result would be that you'd have to slow the amp down with a huge comp-cap, possibly to the point of where it wouldn't even do the top end of audio well. Temperature issues aside, why in the world would you want to use a clunk of a regulator like that in that kind of application??
  Reply With Quote
Old 26th August 2004, 01:37 AM   #6
Stocker is offline Stocker  United States
diyAudio Member
 
Join Date: Dec 2003
Location: Austin
If you can't get the high-frequency response, it may make a novel sub amp.
__________________
Jesus loves you.
  Reply With Quote
Old 26th August 2004, 08:46 PM   #7
diyAudio Member
 
darkfenriz's Avatar
 
Join Date: Jun 2004
Location: Warsaw
Quote:
Temperature issues aside, why in the world would you want to use a clunk of a regulator like that in that kind of application??
eeeeeeeeeh...
no reason, just a play, wanting to find new ways or maybe dead-ends
i was wondering if it is theortically possible
thanks and cheers
  Reply With Quote
Old 26th August 2004, 09:24 PM   #8
The one and only
 
Nelson Pass's Avatar
 
Join Date: Mar 2001
Why not try just one regulator and attach it's "ground"
to the Collector of the VAS current source?
  Reply With Quote
Old 26th August 2004, 09:40 PM   #9
diyAudio Member
 
Join Date: Feb 2001
Location: Columbia, SC
I used a 317 to bias a MOSFET output once. It worked, but I don't remember the details. I think I was using it to hold the output of two LF351s apart by the bias voltage.

Grey
  Reply With Quote
Old 26th August 2004, 09:50 PM   #10
johnnyx is offline johnnyx  United Kingdom
diyAudio Member
 
Join Date: Jan 2004
Location: manchester
A TL431 programmable Zenner type regulator might be better, to fix the voltage between the gates of the output MOSFETS. If these were lateral types, this could be set for the zero-temp-co point, about 70mA IIRC. VMOS fets need temperature compensation, so it wouldn't be appropriate for them. Lateral MOSFETS have a lower gate threshold voltage though, so the 2,5v min for the TL431 may be too high.

The LM317 type regulators have a very high input impedence; the input voltage can change a lot, but the current through it depends only on the load resistance and output voltage. They can be used as a current source (or sink). This is why I said they will not pass the signal. Bypass caps could transfer the signal though, and the regulators do need bypass caps...

You've got me thinking
  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
Remote control for integrated tube amp Driller99 Tubes / Valves 8 13th August 2012 08:20 PM
Bias control problem with n-channel amplifier (Anthony E. Holton) Hielke02 Solid State 4 1st May 2011 06:54 PM
how do i add volume control on front of bias mosfet?? AudioGeek Solid State 0 19th November 2005 10:12 PM
you guys are smart.. :D help :( SkinnyBoy Power Supplies 22 19th May 2005 09:36 AM


New To Site? Need Help?

All times are GMT. The time now is 07:20 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