F6 Amplifier - Page 146 - 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 7th September 2012, 02:51 AM   #1451
diyAudio Member
 
Join Date: Feb 2004
Location: Davis,CA
From post 1425

"The only unfinished part of this design is a way of deriving the V2+ and V2- voltages for the input JFETs from the floating V1+ and V1- supplies."

I remember some 15 years ago or so that a regulated supply was used for the front end of an amplifier and a unregulated supply possibly of a higher voltage was used for the power devices.

Is that possible here?
  Reply With Quote
Old 7th September 2012, 03:28 AM   #1452
lhquam is offline lhquam  United States
diyAudio Member
 
Join Date: Mar 2010
Location: Olalla, Oregon: Land of the 100 Valleys
Default PC Boards arrived - first build

My PC boards arrived a day early! Great service from ExpressPCB.

Here are some images of the boards and a build which includes modifications for floating power supplies.

Also included is a THD vs Frequency sweep with 0R47 source resistors, 1 watt into 8 ohms, closed-loop gain 4.7. Amazing! Except for some issues below 80 Hz, which are to be investigated, the curve is perfectly flat. I do not know why I didn't see the same with my breadboard.
Attached Images
File Type: jpg DSC_0373.jpg (307.2 KB, 431 views)
File Type: jpg DSC_0369.jpg (226.6 KB, 414 views)
File Type: jpg F6-0R47-gain-4p7-1W-fsweep.jpg (122.1 KB, 386 views)
  Reply With Quote
Old 7th September 2012, 03:30 AM   #1453
lhquam is offline lhquam  United States
diyAudio Member
 
Join Date: Mar 2010
Location: Olalla, Oregon: Land of the 100 Valleys
The statement about deriving the V2 voltages was premature. The existing RC filters were adequate. The average of the V1 voltages were fine for supplying the RC filters.

Quote:
Originally Posted by flocchini View Post
From post 1425

"The only unfinished part of this design is a way of deriving the V2+ and V2- voltages for the input JFETs from the floating V1+ and V1- supplies."

I remember some 15 years ago or so that a regulated supply was used for the front end of an amplifier and a unregulated supply possibly of a higher voltage was used for the power devices.

Is that possible here?
  Reply With Quote
Old 7th September 2012, 04:54 AM   #1454
lhquam is offline lhquam  United States
diyAudio Member
 
Join Date: Mar 2010
Location: Olalla, Oregon: Land of the 100 Valleys
Update: The bench supplies were current-limiting in the previous THS vs Freq plot. Try this.

I do not understand why this circuit works this well.

Quote:
Originally Posted by lhquam View Post
My PC boards arrived a day early! Great service from ExpressPCB.

Here are some images of the boards and a build which includes modifications for floating power supplies.

Also included is a THD vs Frequency sweep with 0R47 source resistors, 1 watt into 8 ohms, closed-loop gain 4.7. Amazing! Except for some issues below 80 Hz, which are to be investigated, the curve is perfectly flat. I do not know why I didn't see the same with my breadboard.
Attached Images
File Type: jpg F6-0R47-gain-4p7-1W-fsweep-2.jpg (123.6 KB, 370 views)
  Reply With Quote
Old 7th September 2012, 06:18 AM   #1455
lhquam is offline lhquam  United States
diyAudio Member
 
Join Date: Mar 2010
Location: Olalla, Oregon: Land of the 100 Valleys
I might believe you now about Spice and the transformer models. The measurements with my PCB do not conform to what my Spice models predicted. I am not sure why my breadboard was so much worse than the PCB. Perhaps it was a non-obvious layout issue.

Quote:
Originally Posted by Zen Mod View Post
little patience can't harm

we'll be given with measured performance data , judging by previous experience



btw. Spice is here pretty much useless , just because Spice doesn't know drek about exact xformer
  Reply With Quote
Old 7th September 2012, 07:24 AM   #1456
JZatopa is offline JZatopa  United States
diyAudio Member
 
Join Date: May 2003
Location: Chicago
Quote:
Originally Posted by lhquam View Post
Update: The bench supplies were current-limiting in the previous THS vs Freq plot. Try this.

I do not understand why this circuit works this well.
Considering there isn't an official schematic that performance is impressive. I am very curious to see if what you have built is dead on, close or it's own derivative. How does it sound so far? Any way you can compare it to an F5?
  Reply With Quote
Old 7th September 2012, 07:33 AM   #1457
diyAudio Member
 
bobodioulasso's Avatar
 
Join Date: May 2008
Quote:
Originally Posted by lhquam View Post
Update: The bench supplies were current-limiting in the previous THS vs Freq plot. Try this.

I do not understand why this circuit works this well.

Measurements using normal supply (not floating) and this board?
  Reply With Quote
Old 7th September 2012, 07:34 AM   #1458
The Dastardly Dad of Three
diyAudio Member
 
Join Date: Sep 2009
fab stuff lhquam !! build the other one quick and tell us how it sounds esp vs your F5 build !!!
  Reply With Quote
Old 7th September 2012, 01:32 PM   #1459
lhquam is offline lhquam  United States
diyAudio Member
 
Join Date: Mar 2010
Location: Olalla, Oregon: Land of the 100 Valleys
Quote:
Originally Posted by bobodioulasso View Post
Measurements using normal supply (not floating) and this board?
I made mods to the board to allow the supplies to float by removing one jumper wire. The power supplies are not floating in that THD vs. Frequency sweep.
  Reply With Quote
Old 7th September 2012, 02:33 PM   #1460
diyAudio Member
 
bobodioulasso's Avatar
 
Join Date: May 2008
Wow!
looks like you are there now.
Congrats.
Impatient to read your listening impressions
  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 05:35 PM
Hi Vi F6 box ioro Multi-Way 4 15th April 2012 09:27 PM
Whats happening with F6? jugoslavija Pass Labs 1 1st November 2011 08:39 AM
Hi-Vi F6 kkosiba Multi-Way 14 9th November 2007 09:38 AM
F6 traw Pass Labs 7 2nd November 2007 08:09 PM


New To Site? Need Help?

All times are GMT. The time now is 01:25 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