F5 Front end JFETs substitute - Page 2 - 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 11th June 2013, 01:21 PM   #11
EUVL is offline EUVL  Europe
diyAudio Member
 
Join Date: Oct 2003
> Only the Toshiba output devices show essentially identical transfer curves between N and Pch.

Not entirely true.
F5 power amplifier


Patrick
__________________
xen-audio.com
  Reply With Quote
Old 11th June 2013, 05:46 PM   #12
expert in tautology
diyAudio Member
 
bear's Avatar
 
Join Date: Apr 2002
Location: New York State USA
Patrick, ur pdf is on the input devices? I was talking output devices.
__________________
_-_-bear
http://www.bearlabs.com -- Btw, I don't actually know anything, FYI -- [...2SJ74 Toshiba bogus asian parts - beware! ]
  Reply With Quote
Old 12th June 2013, 03:06 AM   #13
diyAudio Member
 
Join Date: Apr 2011
Thanks for the insights guys, they give me some comfort that there's still possibility of having a working amplifier (although not optimal performance) with the parts that I got, and the prospects of further experimentation is also very interesting. I think I really need to open up my mind and not be afraid of trying or messing with the board, it's really cool to be able to expect the likely outcome of further experimentation.....
  Reply With Quote
Old 12th June 2013, 04:25 AM   #14
EUVL is offline EUVL  Europe
diyAudio Member
 
Join Date: Oct 2003
You're right. My mistake. Apologies.


Patrick
__________________
xen-audio.com
  Reply With Quote
Old 12th June 2013, 10:46 AM   #15
AndrewT is offline AndrewT  Scotland
diyAudio Member
 
Join Date: Jul 2004
Location: Scottish Borders
Since you are open to the idea of experimenting with different semiconductors, then I suggest that you solder tack the Through Hole leads to the top of the pads.
Alternatively, insert the very shortest lead through the hole for effective soldering. This will leave LONG leads on the semis when you come to snip them off ready for the next experiment set.
__________________
regards Andrew T.
  Reply With Quote
Old 13th June 2013, 02:29 AM   #16
diyAudio Member
 
Join Date: Apr 2011
Hey, that is a brilliant idea! I was scratching my head trying to figure out a way to conveniently replace the JFETs without desoldring the MOSFETS that would have been fastened on the heatsinks later....Thanks for the tip!
  Reply With Quote
Old 26th September 2013, 02:50 PM   #17
diyAudio Member
 
Join Date: Sep 2010
Location: Perth, Western Australia
Hi - question for all. What differences need to be made to accommodate a J174/J111 pair in this schematic? Or failing that a piggybacked J174/J111 pair?
  Reply With Quote
Old 26th September 2013, 05:31 PM   #18
The one and only
 
Nelson Pass's Avatar
 
Join Date: Mar 2001
Quote:
Originally Posted by bear View Post
So, I might suggest that there are 4 basic flavors:

- complimentary input + complimentary output
- complimentary input + asymmetrical output
- asymmetrical input + complimentary output
- asymmetrical input + asymmetrical output
To a large extent P3 will trim any of these to resemble the others.

  Reply With Quote
Old 26th September 2013, 05:42 PM   #19
The one and only
 
Nelson Pass's Avatar
 
Join Date: Mar 2001
Quote:
Originally Posted by aspringv View Post
Hi - question for all. What differences need to be made to accommodate a J174/J111 pair in this schematic? Or failing that a piggybacked J174/J111 pair?
The original parts have Idss around 8 ma, and higher transconductance.

You can select these for 10 mA Idss or so, but the open loop gain will be
lower, not that it's a big problem.

  Reply With Quote
Old 27th September 2013, 04:03 AM   #20
diyAudio Member
 
Join Date: Sep 2010
Location: Perth, Western Australia
Cheers Nelson; much appreciated.

However I have a feeling that the batch of 60 J174/J111's I have are going to be somewhat higher Idss than 10 mA. I haven't sorted them all as yet, but the first few measure a lot higher than that.

So I guess the next question would be what to change in the schematic for a higher Idss part?
Attached Images
File Type: jpg F5 simplified.jpg (42.4 KB, 271 views)
  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
Can anyone recommend a complimentary pair of SMT jfets for F5 JZatopa Parts 0 21st November 2012 07:06 PM
Potential mathed JFETs for Balanced F5 build NYCOne Swap Meet 3 22nd May 2011 06:11 PM
WTB matched jfets for F5 ! komigenie Swap Meet 4 16th March 2011 12:54 AM
WTB: 2SJ108 and 2SK370 JFETs for F5 nl Swap Meet 1 24th September 2009 12:31 PM
WTB: 2SJ108 and 2SK370 JFETs for F5 nl Group Buys 0 22nd September 2009 08:06 PM


New To Site? Need Help?

All times are GMT. The time now is 11:24 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