Better place for noise to put the Global Feedback resistor - 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
Reply
 
Thread Tools Search this Thread
Old 9th September 2015, 02:10 PM   #1
ygg-it is offline ygg-it  Italy
diyAudio Member
 
ygg-it's Avatar
 
Join Date: Feb 2008
Default Better place for noise to put the Global Feedback resistor

Hello, since the GNF wiring is long, is better to put the feedback resistor (in parallel with a pF capacitor) close to the cathode or close to the OT output?
  Reply With Quote
Old 9th September 2015, 02:14 PM   #2
Merlinb is offline Merlinb  United Kingdom
diyAudio Member
 
Merlinb's Avatar
 
Join Date: May 2006
Location: Lancashire
Close to cathode.
  Reply With Quote
Old 9th September 2015, 03:27 PM   #3
rayma is online now rayma  United States
diyAudio Member
 
Join Date: Apr 2011
Location: Upper midwest
Quote:
Originally Posted by ygg-it View Post
Hello, since the GNF wiring is long, is better to put the feedback resistor (in parallel with a pF capacitor)
close to the cathode or close to the OT output?
Yes, close to the cathode. Always minimize connection lengths to higher impedance circuit nodes.
At the same time, keep the other end of the feedback resistor away from the low level circuitry,
to minimize coupling from the amplifier output.
  Reply With Quote
Old 9th September 2015, 06:54 PM   #4
diyAudio Member
 
kstagger's Avatar
 
Join Date: Dec 2003
Location: Grand Rapids
This may be overkill, but I often use shielded wire from the secondary to the feedback resistor.
  Reply With Quote
Old 9th September 2015, 07:03 PM   #5
SY is offline SY  United States
diyAudio Moderator
 
SY's Avatar
 
Join Date: Oct 2002
Location: Chicagoland
Blog Entries: 2
Quote:
Originally Posted by kstagger View Post
This may be overkill, but I often use shielded wire from the secondary to the feedback resistor.
So do I. It also allows the common of the output to be returned directly to the bottom of the input stage cathode resistor, which is the right place for it.
__________________
"You tell me whar a man gits his corn pone, en I'll tell you what his 'pinions is."
  Reply With Quote
Old 9th September 2015, 08:06 PM   #6
diyAudio Member
 
Join Date: Dec 2010
Location: Nottingham, NH
Quote:
Originally Posted by SY View Post
So do I. It also allows the common of the output to be returned directly to the bottom of the input stage cathode resistor, which is the right place for it.

I will have to try this. I usually just ground one side of the shield.
  Reply With Quote
Old 9th September 2015, 08:31 PM   #7
SY is offline SY  United States
diyAudio Moderator
 
SY's Avatar
 
Join Date: Oct 2002
Location: Chicagoland
Blog Entries: 2
Make sure that this is the only ground path for the secondary.
__________________
"You tell me whar a man gits his corn pone, en I'll tell you what his 'pinions is."
  Reply With Quote
Old 9th September 2015, 09:39 PM   #8
diyAudio Member
 
Join Date: Dec 2010
Location: Nottingham, NH
Quote:
Originally Posted by SY View Post
Make sure that this is the only ground path for the secondary.

Yes, thanks SY for clarifying.
  Reply With Quote
Old 9th September 2015, 09:40 PM   #9
diyAudio Member
 
zigzagflux's Avatar
 
Join Date: Oct 2006
Location: Charlotte, NC
Good application for cheap coaxial cable.
  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
Best place to put relay? Fusion916 Solid State 5 1st February 2013 11:07 AM
Articles on Global Feedback albertli Tubes / Valves 4 1st February 2010 06:57 AM
Best place to place bleeder resistor in a power supply? G Tubes / Valves 13 4th August 2004 10:26 AM
What's the best place to put the crossover? Bricolo Multi-Way 15 28th June 2003 12:29 AM
Feedback network silences op-amp resistor noise mrfeedback Solid State 0 5th April 2003 01:06 PM


New To Site? Need Help?

All times are GMT. The time now is 05:26 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
Wiki