F4 power amplifier - Page 99 - diyAudio
Go Back   Home > Forums > Amplifiers > Pass Labs

Pass Labs This forum is dedicated to Pass Labs discussion.

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 31st July 2007, 08:47 PM   #981
diyAudio Member
 
R-K Rønningstad's Avatar
 
Join Date: Jan 2006
Location: Oslo
Quote:
Originally posted by Nelson Pass


C3/R25 and C4/R24 are bootstrap networks for the front end.
They slightly improved the maximum output and bandwidth, but
their primary purpose is to protect the JFETs from over-voltage.


R24 and R25?
or ?
  Reply With Quote
Old 31st July 2007, 09:38 PM   #982
The one and only
 
Nelson Pass's Avatar
 
Join Date: Mar 2001
Quote:
Originally posted by Kashmire
DC servo to null the output DC offset due to potentiometer drift, natural changes during the warmup phase, etc.

Depends on what you want. I get <10 mV after warmup.

  Reply With Quote
Old 31st July 2007, 09:39 PM   #983
The one and only
 
Nelson Pass's Avatar
 
Join Date: Mar 2001
Quote:
Originally posted by R-K Rønningstad
R24 and R25?
Yes.....


  Reply With Quote
Old 31st July 2007, 10:37 PM   #984
diyAudio Member
 
R-K Rønningstad's Avatar
 
Join Date: Jan 2006
Location: Oslo
Ahhh! I was looking at http://www.firstwatt.com/downloads/f4_om.pdf.
Could not believe you did not knew your own design .

rkr
  Reply With Quote
Old 31st July 2007, 11:38 PM   #985
spencer is offline spencer  Hong Kong
diyAudio Member
 
Join Date: Jun 2004
Location: Hong Kong
Send a message via MSN to spencer Send a message via Skype™ to spencer
Mr. Pass,

I do not have 220uF capacitor handy for C4 and C5 and I am now using a 330uF capacitor. Is that fine? Yes the drift of DC at out put is easily adjusted within 10mV. The drift is mainly on the bias of the mosfet when the amp warms up (from 0.3A till 0.5x A per fet).

Spencer
  Reply With Quote
Old 1st August 2007, 01:04 AM   #986
Zen Mod is offline Zen Mod  Serbia
diyAudio Member
 
Zen Mod's Avatar
 
Join Date: Jan 2003
Location: ancient Batsch , behind Iron Curtain
Quote:
Originally posted by spencer
..........

I do not have 220uF capacitor handy for C4 and C5 and I am now using a 330uF capacitor. Is that fine? Yes the drift of DC at out put is easily adjusted within 10mV. The drift is mainly on the bias of the mosfet when the amp warms up (from 0.3A till 0.5x A per fet).

Spencer

sometimes even your ( or mine- whatever) fancy schmancy 220uF elco have enough tolerance to approach 330uF in real life ;
accent is on "sometimes" , but that's the fact.
so- why worry........ at least not in that position ............
just use same specimens in sym. positions
__________________
my Papa is smarter than your Nelson !
clean thread; Cook Book;PSM LS Cook Book;Baby DiyA ;Mighty ZM's Bloggg;Papatreasure;Papa...© by Mighty ZM
  Reply With Quote
Old 1st August 2007, 02:11 AM   #987
diyAudio Member
 
Join Date: Dec 2003
Location: Midwest
OK ... thanks guys ... looks like a DC servo is overkill with the F4 topology. Great forum, thanks.

Also, R-K, thanks for answering the C3/R25 and C4/R24 question with a Pass original quote. I appreciate the clarification.
  Reply With Quote
Old 1st August 2007, 05:59 AM   #988
Gyuri is offline Gyuri  Hungary
diyAudio Member
 
Gyuri's Avatar
 
Join Date: Nov 2003
Location: Budapest
Default C3/R25 and C4/R24

Dear RKR!

Look at this:

http://www.passlabs.com/np/f4-power-amp.pdf

Regards:

Gyuri
  Reply With Quote
Old 1st August 2007, 08:15 AM   #989
diyAudio Member
 
R-K Rønningstad's Avatar
 
Join Date: Jan 2006
Location: Oslo
Default Re: C3/R25 and C4/R24

Quote:
Originally posted by Gyuri
Dear RKR!

Look at this:

http://www.passlabs.com/np/f4-power-amp.pdf

Regards:

Gyuri

Yes, that was the one I searched out, and made me understand it all.

RK
  Reply With Quote
Old 2nd August 2007, 04:21 PM   #990
diyAudio Member
 
Join Date: Sep 2006
Quote:
Originally posted by cviller


If you had read the thread you would know that "some guy" from Lowther-America has compared them already. It is pointless to keep asking questions already answered in this thread - it is too long already!
Thank you for the comments, I had read the thread, especially this one (http://www.diyaudio.com/forums/showt...12#post1260712), i reckon is the one you refer to, but was hoping to get a bit more from a comparison between the F1 and the F4. Kind regards
  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
Rockford Fosgate Power 20001 bd amplifier power rating?? pachoorion Car Audio 8 8th May 2011 10:49 PM
Power transformers versus amplifier output power..what is your option? destroyer X Solid State 38 9th May 2009 05:23 PM
McIntosh Power Amplifier Power Guard johnnyrt Solid State 2 23rd August 2007 10:22 PM
Output power for a power amplifier Progg70 Solid State 33 10th September 2006 08:44 AM
Amplifier 3000 Wats Rms Power + Smps Higcht Power Bestiality MARAVILLASAUDIO Class D 1 5th November 2004 04:06 PM


New To Site? Need Help?

All times are GMT. The time now is 07:56 AM.


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