MULLARD 5-20 build with mods - Page 6 - diyAudio
Go Back   Home > Forums > Amplifiers > Tubes / Valves

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
Reply
 
Thread Tools Search this Thread
Old 11th February 2014, 10:21 PM   #51
rleejr is offline rleejr  United States
diyAudio Member
 
Join Date: Apr 2007
Quote:
Originally Posted by SY View Post
If they're direct coupled, it's important. If they're AC coupled, it isn't.
Sy,

Does this mean that if I have a LTP with 43K plate loads and a CCS in the tail, and the first grid is AC coupled via a 0.22u cap followed by a 1 Meg resistor to ground, while the second grid is only AC coupled via a 0.22u cap to ground, that there will only be balanced currents through the loads during signal (program) conditions? At idle with no signal applied, only the first triode will conduct due to the cathode bias via the 1 Meg resistor? Is this correct? When I built my amp, I measured a voltage drop on one triode load but no drop on the second.

Thanks,
Ron
  Reply With Quote
Old 11th February 2014, 11:28 PM   #52
SY is offline SY  United States
diyAudio Moderator
 
SY's Avatar
 
Join Date: Oct 2002
Location: Chicagoland
Blog Entries: 1
What's the DC reference of the grid that's cap coupled to ground?

If the input half of the diff amp is DC ground referenced, take the second section grid straight to ground. At AC, your balance will then be as perfect as the matching of the plate resistors. At DC, the plate voltages will vary unless the sections are perfectly matched or you put some sort of adjustment in the cathodes.
__________________
You might be screaming "No, no, no" and all they hear is "Who wants cake?" Let me tell you something: They all do. They all want cake.- Wilford Brimley
  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
Mullard 5-20 JDeV Tubes / Valves 137 17th February 2010 04:53 PM
Mullard 5-20/Maplin 4-20 modification to NON-Ultra Linear mode???? vinyvamos Tubes / Valves 1 28th January 2006 04:07 PM
Another Mullard 5-20. GeirW Tubes / Valves 3 30th November 2004 12:45 PM
My Mullard 5/20 billinchile Tubes / Valves 25 14th October 2004 09:16 PM


New To Site? Need Help?

All times are GMT. The time now is 05:30 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