Go Back   Home > Forums > >

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

Plate-to-plate negative feedback: pro and cons
Plate-to-plate negative feedback: pro and cons
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
Old 9th February 2017, 05:42 AM   #1
ygg-it is offline ygg-it  Italy
diyAudio Member
 
ygg-it's Avatar
 
Join Date: Feb 2008
Location: ITALY
Default Plate-to-plate negative feedback: pro and cons

If you refer to http://www.tubebooks.org/tubedata/RC16.pdf page 27 you will find the description of the "inverse plate-to-plate feedback".

I've included it in my tube amplifier and tested "by ear" with small amount on NF (very large R), but still combined with my original -6dB GNF network.

Sound is nice, much more clean and detailed, but unfortunately I lost gain and some dynamic as I was expecting.

THD slight increased but sound is better...

Only few people is using the p-p NF, so I'm wondering if it is just because of the gain/dynamic lost or because it is very difficult to tune in order to get real sound improvements?
  Reply With Quote
Old 9th February 2017, 08:30 AM   #2
45 is offline 45  Italy
diyAudio Member
 
45's Avatar
 
Join Date: Dec 2008
Location: UK
Quote:
Originally Posted by ygg-it View Post
but unfortunately I lost gain and some dynamic as I was expecting.

THD slight increased but sound is better...
That points to the driver stage which is not up to the task. THD should be lower.
Anyway you should measure how THD changes with the load (speaker). You can first try with various resistive loads. That is the main reason why this fb should be used. Maybe you see less distortion. Pentodes can give very good distortion figures on fixed load but they are weak on variable loads such as speakers.
  Reply With Quote
Old 9th February 2017, 06:42 PM   #3
LJT is offline LJT  Norway
diyAudio Member
 
Join Date: Nov 2015
Is this the same feedback mechanism as used by the Baby Huey?

Best regards
Lars
  Reply to this post

Reply


Plate-to-plate negative feedback: pro and consHide this!Advertise here!
Thread Tools

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

Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
Center-tapped Plate Choke vs. OPT for PP plate loads rongon Tubes / Valves 10 20th February 2017 12:05 AM
Triode plate resistance == internal negative feedback? jcx Tubes / Valves 57 21st July 2016 10:06 PM
Plate to cathode feedback kenev Tubes / Valves 5 9th November 2015 08:02 PM
Simplified pentode Loftin-White with plate-plate feedback homeskillet Tubes / Valves 17 3rd August 2013 04:58 AM
plate to plate feedback - measurements hidnplayr Tubes / Valves 39 29th November 2010 08:52 AM


New To Site? Need Help?

All times are GMT. The time now is 04:03 AM.


Search Engine Optimisation provided by DragonByte SEO (Pro) - vBulletin Mods & Addons Copyright © 2021 DragonByte Technologies Ltd.
Resources saved on this page: MySQL 15.00%
vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2021 DragonByte Technologies Ltd.
Copyright ©1999-2021 diyAudio
Wiki