F6 Amplifier - Page 138 - 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 1st September 2012, 11:53 PM   #1371
diyAudio Member
 
bobodioulasso's Avatar
 
Join Date: May 2008
Given the moderate (turn on) Vgs of the JFets, i think 0R22 for Rs is enough.
Olg isn't penalised too much allowing more feedback aiming to less distortion and a better damping factor etc...
But i might be wrong.

Last edited by bobodioulasso; 1st September 2012 at 11:59 PM.
  Reply With Quote
Old 2nd September 2012, 12:33 AM   #1372
diyAudio Member
 
buzzforb's Avatar
 
Join Date: Oct 2010
Location: Burlington, NC
Thats what i am going with.
__________________
...Shape the sound , Man!
  Reply With Quote
Old 2nd September 2012, 01:08 AM   #1373
lhquam is offline lhquam  United States
diyAudio Member
 
Join Date: Mar 2010
Location: Olalla, Oregon: Land of the 100 Valleys
Correction: I am using SJEP120R100A JFETs. I do not know how they differ from to SJEP120R100 JFETs, but their data sheet says "High Performance Audio".

Quote:
Originally Posted by lhquam View Post
I do not know if there will ever be a consensus on the "optimal" configuration of parameters. It will depend on personal sonic preferences.

My prototype uses SemiSouth SJEP120R100 JFETs.
  Reply With Quote
Old 2nd September 2012, 01:11 AM   #1374
diyAudio Member
 
buzzforb's Avatar
 
Join Date: Oct 2010
Location: Burlington, NC
I think they are parts that missed the mark for switching purposes which they were made for.....I think.
__________________
...Shape the sound , Man!
  Reply With Quote
Old 2nd September 2012, 01:16 AM   #1375
lhquam is offline lhquam  United States
diyAudio Member
 
Join Date: Mar 2010
Location: Olalla, Oregon: Land of the 100 Valleys
I thank you for that suggestion.

The source resistor has two different effects:
  • 1) degeneration - local negative feedback.
  • 2) bias voltage stabilization - and ability to measure bias current.
Instead of one source resistor, consider 2 in series with the top resistor controlling degeneration (possibly zero ohms) and the bottom resistor supplying the additional voltage drop for bias stability. The node between the 2 resistors connects to the bottom of the transformer secondary (the "modulation node").

Quote:
Originally Posted by Zen Mod View Post
and you can modulate them from bottom of Rs ....... or from top of Rs ....... or one from bottom and other from top ....... or the other way around .........

  Reply With Quote
Old 2nd September 2012, 01:40 AM   #1376
diyAudio Member
 
buzzforb's Avatar
 
Join Date: Oct 2010
Location: Burlington, NC
Like SRPP. Where/how you pull from determines all sorts of things
__________________
...Shape the sound , Man!
  Reply With Quote
Old 2nd September 2012, 02:31 AM   #1377
BudP is offline BudP  United States
diyAudio Member
 
BudP's Avatar
 
Join Date: Feb 2007
Location: upper left crust, united snakes
Nelson, a question for you please.

When you chose the impedance match to the primary of the transformer as input device, what guided you to 600 ohms? Will a higher impedance / inductance/ DCR cause undue distress? I have a pair of 2800 ohm split primary and secondary transformers, 48% nickle core and pin out to match the Jensen parts. I can also have 1200 ohms or 600 ohms or whatever is best. Can you provide some guidance please?

Bud
__________________
"You and I and every other thing are a dependent arising, empty of any inherent reality" Tsong Ko Pa
  Reply With Quote
Old 2nd September 2012, 08:49 AM   #1378
Zen Mod is offline Zen Mod  Serbia
diyAudio Member
 
Zen Mod's Avatar
 
Join Date: Jan 2003
Location: ancient Batsch , behind Iron Curtain
as my , always modest , chip in ..... ( just to mud the water before Pa's answer ) -
those so called 2K8 , instead of so called 600R , will present even more uniform load to input buffer while still having more than enough muscles to fed output gates
__________________
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 2nd September 2012, 11:11 AM   #1379
diyAudio Member
 
buzzforb's Avatar
 
Join Date: Oct 2010
Location: Burlington, NC
Ill let everyone know how they sound.
__________________
...Shape the sound , Man!
  Reply With Quote
Old 3rd September 2012, 02:30 AM   #1380
diyAudio Member
 
buzzforb's Avatar
 
Join Date: Oct 2010
Location: Burlington, NC
Here is MY Franken6. I got most of the way, but alas,not finished. Switched caps to the on hand 220uF. Ill try to throw it together, but things are going to get thick around here for a week or so, so we will see.
Attached Images
File Type: jpg DSC_0107.JPG (660.8 KB, 315 views)
__________________
...Shape the sound , Man!
  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 11:05 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