Quad 22 interstage cap? - diyAudio
Go Back   Home > Forums > Amplifiers > Tubes / Valves
Home Forums Rules Articles diyAudio Store Gallery Wiki Blogs Register Donations FAQ Calendar Search Today's Posts Mark Forums Read

Tubes / Valves All about our sweet vacuum tubes :) Threads about Musical Instrument Amps of all kinds should be in the Instruments & Amps forum

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 11th April 2013, 03:18 PM   #1
neskor is offline neskor  Serbia
diyAudio Member
Join Date: May 2008
Default Quad 22 interstage cap?

I'm trying to restore my Quad 22 preamp.
On the internet there are two different schematics.
On first early version there is no input cap, interstage cap is 5000pF and output cap is 0.047uF.
In second (improved) version there is a input cap and interstage cap is now 820pF and output is 0.1uF.
Reason for input cap is known, output is changed probably to improve bass respone, but I don't know why this drastic change from 5000pF to 820pF for interstage cap?
Attached Images
File Type: jpg quad 22 - control unit 1.jpg (79.0 KB, 41 views)
  Reply With Quote
Old 11th April 2013, 03:22 PM   #2
DF96 is online now DF96  England
diyAudio Member
Join Date: May 2007
In the later version has R26 been increased in value, perhaps to 10M so that the triode now uses grid current bias? That would explain a change in coupling cap, to maintain the same 20Hz rolloff.
  Reply With Quote
Old 11th April 2013, 03:29 PM   #3
neskor is offline neskor  Serbia
diyAudio Member
Join Date: May 2008
They didn't change R26 in any revision, it was always 1.5M.
  Reply With Quote
Old 11th April 2013, 05:03 PM   #4
DF96 is online now DF96  England
diyAudio Member
Join Date: May 2007
I can't believe that they intended a 120Hz LF cutoff. Is this section within a global feedback loop? That might explain it - the change could then reduce subsonic peaking.
  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
Quad 22 Wiring tinkerbelt Tubes / Valves 5 10th November 2012 03:31 PM
Quad II/ Quad 22 parts/ parts units WANTED hatrack71 Swap Meet 0 3rd March 2011 01:05 PM
WTB: Any Quad II or Quad 22 units- working or not or parts for them hatrack71 Swap Meet 3 29th August 2010 02:46 PM
Zen Quad 22 johnm Tubes / Valves 0 13th June 2008 03:21 PM
Quad 22 Valve Amps WARREN Tubes / Valves 9 11th September 2004 10:39 AM

New To Site? Need Help?

All times are GMT. The time now is 04:31 PM.

vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2016 DragonByte Technologies Ltd.
Copyright 1999-2016 diyAudio

Content Relevant URLs by vBSEO 3.3.2