SS 120R085 Depletion Mode Jfet - Page 13 - 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 22nd July 2011, 12:13 AM   #121
diyAudio Member
 
buzzforb's Avatar
 
Join Date: Oct 2010
Location: Burlington, NC
NYCOne,
check out this thread for possible answers.

J-fet Zen Srpp ???
  Reply With Quote
Old 22nd July 2011, 02:01 AM   #122
diyAudio Member
 
buzzforb's Avatar
 
Join Date: Oct 2010
Location: Burlington, NC
IT seems that the limited triode region of the J-fets, at least the ones i have, are what is causing trouble. The magic of Pass' design must be how he stabilized DC bias with the photo-coupler.
  Reply With Quote
Old 22nd July 2011, 09:44 PM   #123
The one and only
 
Nelson Pass's Avatar
 
Join Date: Mar 2001
It was the Magic Marker that I used to obscure the part numbers.

  Reply With Quote
Old 22nd July 2011, 10:28 PM   #124
NYCOne is offline NYCOne  United States
diyAudio Member
 
Join Date: Jul 2010
Blog Entries: 1
Quote:
Originally Posted by Nelson Pass View Post
It was the Magic Marker that I used to obscure the part numbers.

NP:
A while ago you'd mentioned a six legger turning to an eight legger. Has that been sidelined?

I'm triply handicapped: I know very little about SRPP and IMC, I can barely follow the Aleph CS explanations, and I know nothing about electronics. Besides that, I'm having no trouble with my CXF5, CF5, F5, and J2...

I have to start building more speakers for these amps.
  Reply With Quote
Old 22nd July 2011, 11:48 PM   #125
diyAudio Member
 
buzzforb's Avatar
 
Join Date: Oct 2010
Location: Burlington, NC
I have a LU version of the SRPP working in LTSpice. I figure LU's are cheaper than the R085's, so thats a good place to try to find understanding. Clearly still learning. Unfortunately, I lost my biggest helper this week. Cheers to Bill. Sorry, NYCOne, I thought I was helping. Good Luck with the J2. I hope you get it working.
  Reply With Quote
Old 22nd July 2011, 11:56 PM   #126
NYCOne is offline NYCOne  United States
diyAudio Member
 
Join Date: Jul 2010
Blog Entries: 1
Quote:
Originally Posted by buzzforb View Post
I have a LU version of the SRPP working in LTSpice. I figure LU's are cheaper than the R085's, so thats a good place to try to find understanding. Clearly still learning. Unfortunately, I lost my biggest helper this week. Cheers to Bill. Sorry, NYCOne, I thought I was helping. Good Luck with the J2. I hope you get it working.

Buzz,
I'll take help if you're offering.
  Reply With Quote
Old 23rd July 2011, 12:15 AM   #127
diyAudio Member
 
buzzforb's Avatar
 
Join Date: Oct 2010
Location: Burlington, NC
The major theme of the thread I posted was stabilization of the DC bias point. It would seem, that the 6/8 legged creature is there to serve this purpose. In trying the LU version, I have realized what they were talking about. I did just as Nelson advised and added multiple small value resistors in between the two fets and have palyed with pulling from different points to change gain and bias. All this is of little help to you since you are using enhancement mode devices. I will post a schematic, but have little in the way of distortion numbers as I have yet to purchase a sound card to do measurements.
  Reply With Quote
Old 23rd July 2011, 03:44 AM   #128
NYCOne is offline NYCOne  United States
diyAudio Member
 
Join Date: Jul 2010
Blog Entries: 1
Quote:
Originally Posted by buzzforb View Post
The major theme of the thread I posted was stabilization of the DC bias point. It would seem, that the 6/8 legged creature is there to serve this purpose. In trying the LU version, I have realized what they were talking about. I did just as Nelson advised and added multiple small value resistors in between the two fets and have palyed with pulling from different points to change gain and bias. All this is of little help to you since you are using enhancement mode devices. I will post a schematic, but have little in the way of distortion numbers as I have yet to purchase a sound card to do measurements.
I just finished building my ARTA box as seen on this site:

HiFi Measurement

I'll have a chance to play with it this weekend.
  Reply With Quote
Old 23rd July 2011, 03:59 AM   #129
diyAudio Member
 
buzzforb's Avatar
 
Join Date: Oct 2010
Location: Burlington, NC
Thanks. I had seen the Pete Millet design, but had no idea about this one.
  Reply With Quote
Old 23rd July 2011, 06:01 AM   #130
The one and only
 
Nelson Pass's Avatar
 
Join Date: Mar 2001
I've said it before. The 6/8 legged beastie is just misdirection.

  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
Depletion mode mosfets for 2mA CCS ? mach1 Tubes / Valves 6 29th October 2008 09:50 PM
Depletion mode? CBS240 Solid State 1 4th October 2007 09:52 PM
depletion mode mosfet selection svokke Solid State 0 17th May 2004 09:47 PM
How's about a Depletion Mode / Enhancement Mode CCCS MIKET Tubes / Valves 9 11th September 2003 04:44 PM


New To Site? Need Help?

All times are GMT. The time now is 05:59 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