Go Back   Home > Forums > >

Analog Line Level Preamplifiers , Passive Pre-amps, Crossovers, etc.

NFB types
NFB types
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 2nd December 2020, 12:44 PM   #1
nironiro is offline nironiro  Croatia
diyAudio Member
 
Join Date: Jun 2013
Default NFB types

Hi,
Anybody knows what is the different in those two types of NFB?
What are the advantages of putting NFB ground capacitor in the position A?

I saw that NFB in some cassette decks playback amplifier and wonder why they put capacitor at that position.

Thanks in advance for answers!
Attached Images
File Type: jpg nfb type.jpg (35.9 KB, 134 views)
  Reply With Quote
Old 3rd December 2020, 10:48 AM   #2
MarsBravo is offline MarsBravo
diyAudio Member
 
MarsBravo's Avatar
 
Join Date: Feb 2017
NFB B is the usual circuit (with a small cap over the feedback resistor), a separate RC series branch controls the hf-feedback better. NFB A is to bypass the large groundcap (with lesser hf bandwidth) so the hf feedback works even better.
__________________
Y/Yo=(1-X/Xo)exp2 <> Y/Yo=(e)exp(X/Xo){Xo=kT/q}
  Reply With Quote
Old 3rd December 2020, 04:44 PM   #3
nironiro is offline nironiro  Croatia
diyAudio Member
 
Join Date: Jun 2013
Tnx MarsBravo, that sounds reasonable.

There are even more variations of NFB, one Grundig phono preamp have output cap included in the feedback loop.
  Reply With Quote
Old 4th December 2020, 07:12 PM   #4
lcsaszar is offline lcsaszar  Hungary
diyAudio Member
 
Join Date: Mar 2004
Location: Budapest, Hungary
Whatever you include in the feedback loop forward path, its nonlinearity will be reduced by the NFB. Whatever you include in the feedback loop feedback path, its nonlinearity will appear at the output.
  Reply With Quote
Old 5th December 2020, 06:39 AM   #5
MarcelvdG is offline MarcelvdG  Netherlands
diyAudio Member
 
Join Date: Mar 2003
Location: Haarlem, the Netherlands
There is less signal current flowing through the electrolytic capacitor in case A, so it will distort less (for a given capacitor type).
  Reply to this post

Reply


NFB typesHide 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
Commercial Solid State Amps with jumper controlled Modes "without NFB" and "with NFB" tiefbassuebertr Solid State 12 28th February 2014 05:27 PM
Source/emitter global NFB amp jcarr Solid State 48 19th December 2008 09:22 PM
NFB and Electron Propagation (from Blind Testing) mikek Everything Else 135 29th March 2003 09:31 PM
NFB volume control Joel Tubes / Valves 5 13th December 2002 04:24 PM


New To Site? Need Help?

All times are GMT. The time now is 05:08 AM.


Search Engine Optimisation provided by DragonByte SEO (Pro) - vBulletin Mods & Addons Copyright © 2021 DragonByte Technologies Ltd.
Resources saved on this page: MySQL 14.29%
vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2021 DragonByte Technologies Ltd.
Copyright ©1999-2021 diyAudio
Wiki