Does that qualify as "X" ? - Page 2 - diyAudio
Go Back   Home > Forums > Amplifiers > Pass Labs

Pass Labs This forum is dedicated to Pass Labs discussion.

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 31st March 2009, 12:33 AM   #11
diyAudio Member
 
Join Date: Nov 2007
Location: Dallas
Some comments or ballpark component values
might be helpful in understanding your intent.

Got too much goin-on there to guess function
from component topology alone.
  Reply With Quote
Old 6th April 2009, 12:19 AM   #12
diyAudio Member
 
Bernhard's Avatar
 
Join Date: Apr 2002
Location: Munich
Each side has its own differential input amplifier (da).

The outer da inputs serve for the input signal and also get feedback from the other side.
They are connected trough the impedances of the signal source and the input resistors which form some kind of R_magic.

The inner da inputs get feedback from the same side and are also connected to each other with some kind of R_magic.

There is also feedback from the same side to ( the connection of all three transistors of ) the da on each side and again there is a R_magic connecting the da's.

Each R_magic is small compared to R_feedback, so each of the feedback nodes receives signal parts from both sides.

Because the output signals ( = feedback signals ) are out of phase, the primary part of the signal from the dominating side is strongly attenuated by R_magic, but the error part - that is different between signals fom each side - is not.

I did a simulation with different 1V error spike sources on each output and the result is that each side reduces it's own error to 0,5V and reamplifies the error of the other side to 0,5V.

Both errors appear on both sides with 50% of original amplitude and are in phase and cancel each other on the load.
  Reply With Quote
Old 7th April 2009, 09:13 PM   #13
diyAudio Member
 
Bernhard's Avatar
 
Join Date: Apr 2002
Location: Munich
Default schematic updated

I found that the low impedance feedback connections are unnecessary, but the x resistor remains.

The circuit now optimized for +/- 10 V swing performs as follows in sim:

harmonics down to

+/- 2V swing -140 dB
+/- 10V swing -125 dB
+/-20V swing -86 dB

optimized for +/- 20 V swing:

+/- 2V swing -126 dB
+/- 10V swing -100 dB
+/-20V swing -98 dB
  Reply With Quote
Old 29th January 2013, 12:22 PM   #14
diyAudio Member
 
Bernhard's Avatar
 
Join Date: Apr 2002
Location: Munich
I never tried to built that thing and now after long time start to work again on the schematic.

At the moment in simulation it shows major improvements.

It can also work with no ground but has common mode output offset some hundred mV. 1 giga ohm proforma.

Looks any good ?

With output of 1V, k3 even more down...

Click the image to open in full size.
  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 Does Fostex "Rated Input" and "Music Power" mark02131 Full Range 5 13th October 2012 05:18 AM
What makes an amplifier "bright", "warm", or "neutral"? JohnS Solid State 51 13th December 2009 06:42 PM
"Void free" or "no core gaps" plywood rick57 Multi-Way 6 14th March 2007 01:09 PM
Some final pics of "Stacks" revisited and "Askew" with stand Andy G Multi-Way 2 3rd February 2005 06:07 AM
Anyone used Scan-Speak's "Flow Resistors" or "Aperiodic Vents"? Ignite Multi-Way 3 18th November 2001 08:42 AM


New To Site? Need Help?

All times are GMT. The time now is 07:21 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