question about input stage of this amp - Page 2 - diyAudio
Go Back   Home > Forums > Amplifiers > Solid State
Home Forums Rules Articles diyAudio Store Gallery Wiki Blogs Register Donations FAQ Calendar Search Today's Posts Mark Forums Read

Solid State Talk all about solid state amplification.

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 21st June 2002, 03:02 PM   #11
Join Date: Feb 2002
Location: As far from the NOSsers as possible
Default The original version

Dubbed the "Universal Tiger", Popular Electronics, Oct. 1970.

Attached Images
File Type: gif tiger.gif (33.8 KB, 471 views)
  Reply With Quote
Old 15th July 2002, 08:15 PM   #12
diyAudio Member
Join Date: Feb 2002
Location: Germany
Originally posted by Nelson Pass

The output coil and resistor are similarly hangovers from the
old days. They were in the original RCA manual, and most
designers use them because monkey-see-monkey-do.

I have never seen a case where they stabilized an unstable
amp, nor where their absence caused instability, and so I
don't use them.
Well, I found they can be quite useful, but only when using nasty loads. I tried to remove the coils or only replace them with lower values on several commercial designs - sometimes made the amps oscillate heavily when driving a square wave into a 3 R resistive load!

I try to make my own designs stable with all kinds of loads, including 100 pF - 10 uF stacked film capacitors on the output. Found I could not eliminate the coil completely if I did not want to limit the bandwidth but was able to do with 1/100 of what is commonly used.

  Reply With Quote
Old 15th July 2002, 11:55 PM   #13
diyAudio Member
Join Date: Jul 2001
Location: Orleans, France
Use of output coil is very dependent of what kind of load is connected, but also of phase margin and gain in the overall feedback loop. In fact, this is the same thing because at very high frequencies the amp becomes a current generator, and the reactance of the load is the essential part of the current/voltage converter at the output.

The major problem is that one cannot divine what kind of load can be connected by the artless user... which always reads the carefully prepared "user manual" after the disaster.

Regards, P.Lacombe.
  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
Input Stage Question Havenwood Solid State 1 2nd February 2009 04:35 PM
Input stage question/criticisms speakerguy79 Solid State 0 19th May 2007 08:17 PM
current bias j-fet input 2sk170 ,2sj74 at input stage YUTK Solid State 11 2nd June 2005 03:34 AM
question about input stage demons_wing Solid State 7 8th May 2004 01:51 AM
Differential Input Stage - Question thylantyr Solid State 8 23rd April 2003 01:33 PM

New To Site? Need Help?

All times are GMT. The time now is 11:25 AM.

vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2017 DragonByte Technologies Ltd.
Copyright 1999-2017 diyAudio

Content Relevant URLs by vBSEO 3.3.2