Top ten ways to better a Pearl ? - Page 4 - 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 6th December 2005, 07:10 PM   #31
MRupp is offline MRupp  Germany
diyAudio Member
 
MRupp's Avatar
 
Join Date: Dec 2003
Location: Frankfurt area
Quote:
"Try lowering the voltage over the FETs ..."
Thorsten,

I found te following information in an article from Klaus Boehning detailing his phono pre design, at http://www.klaus-boening.de/html/lab_page.html - check the chapter Determining the lower limit of UDS . Some other references tend to also prefer a higher VDS for the common source transistor but I cannot really say what is better.

Btw., where can I find the Hiraga article, please?
__________________
Martin Rupp
  Reply With Quote
Old 6th December 2005, 09:14 PM   #32
diyAudio Member
 
Join Date: Jun 2004
Location: Copenhagen
The article was about a hybrid amplifier called " le Passific ". Two stages with j-fet/bjt cascode input differential driving two el84 push-pull outputs. I read a photo-copy of the article around 12 years ago. I think it was from "l`Audiophile".
The decision to lower the fet-voltage was made on subjective grounds. The lower gate leakage current was mentioned as a possible explanation for the better sound quality.
I tried it out on a "Monster amp" together with a friend, and we came to the same conclusion as Jean Hiraga.
To Buhl: On the Pearl schematics at passdiy.com, you can see two voltage-dividers each with two 10 kOhm resistors. The middle points connected to bases of bjt´s of the cascodes. To decrease the voltage over the fet, you just have to decrease the value of the lower resistor. For listening tests, just solder another over the existing one. Remember that a new solder-joint takes around 15 minutes of playing to burn in.
Just try it out. But let us know what you think.

Thorsten
( another one )
  Reply With Quote
Old 7th December 2005, 09:53 PM   #33
steenoe is offline steenoe  Denmark
diyAudio Member
 
steenoe's Avatar
 
Join Date: Mar 2004
Quote:
Now this thread has come out of the sauerkraut and back to the technical.
Hans, I am sorry to have caused disruption on your thread! I see now that my post didnt have the impact, it was supposed to, at all! I did read my first post again, and didnt find it expressed, what I meant it to! The tone was too harsh, no matter how I try to turn it I am sorry for that The sauerkraut is all mine, Hans I will try to contribute in a more polite and hopefully enlightening manner for the future

Steen
  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
The New 2-ways. Spasticteapot Multi-Way 16 19th November 2006 01:39 AM
Two ways with a low x over tade Multi-Way 2 20th May 2006 07:22 PM
A30....I still have a ways to go !!! mpmarino Pass Labs 26 14th March 2005 08:52 AM
2-ways + sub OR 3-ways EyalR Multi-Way 12 18th January 2004 05:48 PM


New To Site? Need Help?

All times are GMT. The time now is 08:04 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