Split Feedback - diyAudio
Go Back   Home > Forums > Amplifiers > Solid State
Home Forums Rules Articles diyAudio Store Gallery Wiki Blogs Register Donations FAQ Calendar Search Today's Posts Mark Forums Read

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
Thread Tools Search this Thread
Old 14th May 2002, 03:18 AM   #1
diyAudio Member
Join Date: Oct 2001
Location: Southwest
Default Split Feedback

Wrinkle your brows on this one guys.
Looks rather interesting.
  Reply With Quote
Old 14th May 2002, 03:41 AM   #2
diyAudio Member
Join Date: Feb 2001
Location: Columbia, SC
Well, for one thing, a "non-inductive resistor" is hardly a good stand-in for most real world loudspeakers. You could start a prolonged argument as to whether the guy's logic is flawed on this point. I'm just noting this in passing.
You're losing power when you remove a pair of output devices. In the case of one pair, when you add a pair to act as proxies, you're going to load the power supply down; possibly with dire consequences.
I'd question some amplifiers' stability when faced with modifications to the output stage.
Assuming that you can get the thing to work (for this, I'd recommend designing an amp from the ground up, rather than modifying an existing one), I have no doubt that it sounds different...but does it sound better?
Sounds like sophistry to me.

  Reply With Quote
Old 14th May 2002, 05:05 AM   #3
jam is offline jam  United States
diyAudio Member
jam's Avatar
Join Date: May 2001
Location: Auburn, CA, USA
A very interesting idea. He is actually compensating for non-linearities in the output stage (with feedback) but the reactive nature of the load will not affect the the feedback loop.

Might be a good, idea the only problem I see is the output stage (not in the feedback loop) has to be large to maintain a low output impedence.

This might make a good comparison to a circuit with nested feedback loops.

  Reply With Quote
Old 14th May 2002, 09:49 AM   #4
Join Date: Apr 2002
His idea is not new. I bet your friend Nelson Pass knows this one, man.

  Reply With Quote
Old 14th May 2002, 09:00 PM   #5
The one and only
Nelson Pass's Avatar
Join Date: Mar 2001
Actually I have not encountered this, although it is
an interesting and imaginative idea.

Of course it won't correct for things that a real life
load will do, but then again we aren't always looking
for that either.
  Reply With Quote
Old 15th May 2002, 05:05 AM   #6
diyAudio Member
Join Date: May 2001
I have also never seen this idea before and think it has great merit
  Reply With Quote
Old 16th May 2002, 08:37 PM   #7
diyAudio Member
jan.didden's Avatar
Join Date: May 2002
Location: The great city of Turnhout, BE
Blog Entries: 8
I looked at it, I wouldn't say interesting, rather weird. Look at the schematic under 'this is it':
He uses feedback to linearize the output of the block 10. Due to the nature of feedback, this will result in the input to '10' to be heavily distorted. Then he uses this heavily distorted node to feed the stage that drives the speaker. And claims it sounds much better....
As I said, weird.
  Reply With Quote
Old 16th May 2002, 10:40 PM   #8
diyAudio Member
Join Date: Feb 2001
Location: Columbia, SC
I've been mulling this over and it might be interesting to pursue for drivers that present a purely resistive load, i.e. ribbons, planars, etc. I still don't like the idea of modifying an existing circuit, but a from-the-ground-up design might be interesting.
Hmmm...wonder if it's too late to stick this into the Aleph-X...

  Reply With Quote
Old 17th May 2002, 10:25 AM   #9
diyAudio Member
Greg Erskine's Avatar
Join Date: Jan 2002
Location: Sydney/Australia
I though it sounded plausible until I saw another one of his pages.


Think this will work?

  Reply With Quote
Old 17th May 2002, 07:02 PM   #10
The one and only
Nelson Pass's Avatar
Join Date: Mar 2001
I guess Altmann is more than a one idea guy.

It strikes me that the SPLIF amp will work better if you
can presume matching between the output stages, and
if you adjust the load of the fed-back stage to look like
the speaker load.
  Reply With Quote


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
Altmann's Split Feedback concept tigro Tubes / Valves 1 18th January 2009 10:07 AM
How to figure gain on split-load with positive feedback? GordonW Tubes / Valves 4 21st May 2008 05:24 PM

New To Site? Need Help?

All times are GMT. The time now is 02:50 AM.

vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2017 DragonByte Technologies Ltd.
Copyright 1999-2017 diyAudio

Content Relevant URLs by vBSEO 3.3.2