F6 Amplifier - Page 115 - 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 26th August 2012, 12:40 PM   #1141
diyAudio Member
 
Join Date: Jan 2012
Location: Pennsylvania
Blog Entries: 1
Quote:
Originally Posted by lhquam View Post
I am not sure what the relevance is for "AC ground". What is important are the bias voltages relative to the bottom of the FET source resistors. We are trying to maintain these voltages at constant levels under varying signal conditions.
The AC drive signal to the upper JFET will be relatively larger in magnitude than for the lower JFET. In your opinion is it or not?

Last edited by Antoinel; 26th August 2012 at 12:45 PM.
  Reply With Quote
Old 26th August 2012, 12:50 PM   #1142
diyAudio Member
 
buzzforb's Avatar
 
Join Date: Oct 2010
Location: Burlington, NC
ZM, Why will it go bottatboom? Dont understand.It is used as Vref for so many bias circuts for transistors.
__________________
...Shape the sound , Man!
  Reply With Quote
Old 26th August 2012, 12:54 PM   #1143
Rush is offline Rush  United States
diyAudio Member
 
Join Date: Sep 2009
Location: Tampa, Florida
Quote:
Originally Posted by Antoinel View Post
The AC drive signal to the upper JFET will be relatively larger in magnitude than for the lower JFET. In your opinion is it or not?
The AC drive signal is the same for both secondaries of the transformer (they don't know how they are being used). If you have a different resistance across one of the secondaries you may change the amplitude.
Please explain how could the AC drive signal be different in the secondaries?

Rush
  Reply With Quote
Old 26th August 2012, 01:04 PM   #1144
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 buzzforb View Post
ZM, Why will it go bottatboom? Dont understand.It is used as Vref for so many bias circuts for transistors.
Quote:
Originally Posted by Zen Mod View Post
.....

you need to change places of leds and CCS
read what I wrote about 6k8 res on bobbo's sch
__________________
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 26th August 2012, 01:11 PM   #1145
diyAudio Member
 
buzzforb's Avatar
 
Join Date: Oct 2010
Location: Burlington, NC
Choice of Rs on output stage has affect on values of bias network. Is it in parallel with bias network?
__________________
...Shape the sound , Man!
  Reply With Quote
Old 26th August 2012, 01:15 PM   #1146
Zen Mod is offline Zen Mod  Serbia
diyAudio Member
 
Zen Mod's Avatar
 
Join Date: Jan 2003
Location: ancient Batsch , behind Iron Curtain
no
, it isn't in parallel

it is important for for needed bias voltage span which you're having on trimpot

without Rs - say that you need 1V5 max

with Rs=0R47 and Iq=2A , you need 1V more
__________________
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 26th August 2012, 01:23 PM   #1147
diyAudio Member
 
buzzforb's Avatar
 
Join Date: Oct 2010
Location: Burlington, NC
Damn, i amignorant. If i use 2sk246, I can run at Idss, correct. Should i use1K resistor above to help with dissipation?
__________________
...Shape the sound , Man!
  Reply With Quote
Old 26th August 2012, 01:36 PM   #1148
Zen Mod is offline Zen Mod  Serbia
diyAudio Member
 
Zen Mod's Avatar
 
Join Date: Jan 2003
Location: ancient Batsch , behind Iron Curtain
you can waste at least 50% of PSU voltage on additional resistor
__________________
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 26th August 2012, 01:54 PM   #1149
diyAudio Member
 
bobodioulasso's Avatar
 
Join Date: May 2008
Quote:
Originally Posted by Zen Mod View Post
now choose Rs value & Iq , and calculate that in.

ZM will allow at least 1mA through trimpot , and 3mA through zenner
Attached Images
File Type: jpg f6.jpg (78.1 KB, 197 views)
  Reply With Quote
Old 26th August 2012, 01:55 PM   #1150
Zen Mod is offline Zen Mod  Serbia
diyAudio Member
 
Zen Mod's Avatar
 
Join Date: Jan 2003
Location: ancient Batsch , behind Iron Curtain
go and build

say tnx! to Pa

if you can't find 3k trimpot - use 2K one , and 1K resistor below

and yes , you can use more than 10uF in series with secondary

__________________
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

Last edited by Zen Mod; 26th August 2012 at 01:58 PM.
  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
New F6 diy coming soon ? Nounours18200 Pass Labs 37 31st August 2012 04:35 PM
Hi Vi F6 box ioro Multi-Way 4 15th April 2012 08:27 PM
Whats happening with F6? jugoslavija Pass Labs 1 1st November 2011 07:39 AM
Hi-Vi F6 kkosiba Multi-Way 14 9th November 2007 08:38 AM
F6 traw Pass Labs 7 2nd November 2007 07:09 PM


New To Site? Need Help?

All times are GMT. The time now is 12:01 PM.


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