Aleph 5 DC offset and bias adjustment - 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 20th December 2002, 12:23 PM   #1
diyAudio Member
 
Join Date: Sep 2002
Location: UK
Default Aleph 5 DC offset and bias adjustment

Sorry if this has been covered elsewhere but I did try and I couldn't find it.

I'm just finishing assembly of my Aleph 5 clone monoblocks and all appears to work fine on the bench.

Two questions, what level of DC offset is typical or acceptable on the output and ho can I adjust it if it's wrong?

Secondly I have read Nelson saying that Aleph 5's work better with higher bias curent. Assuming I have the thermal capacity in the sinks how can I adjust the bias up?
__________________
Bertie
  Reply With Quote
Old 20th December 2002, 01:12 PM   #2
diyAudio Member
 
rwagter's Avatar
 
Join Date: Jul 2002
Location: Netherlands
Did you really search. I asked because it has been covered really recently. B ut here are the links:


Aleph5....it works!!!
DC offset / Bias setting for Aleph 2
Upping the bias on Aleph 2

RALPH
  Reply With Quote
Old 20th December 2002, 04:47 PM   #3
The one and only
 
Nelson Pass's Avatar
 
Join Date: Mar 2001
To answer the questions anyway,

about 50 mv is my standard for DC offset in Alephs. If
you need to trim it you can do so in a number of places,
but adjust the the Source resistance in the current source
which biases the differential input transistors is a good
place.

Yes, you can increase the bias easily enough using the
resistor which feeds the Base of the NPN transistor on the
positive current source. I forget the number, but its the one
which goes from the Base to a capacitor which is charged
by a resistor to the positive supply.

Simply removing this will up the bias without any other
alterations needed.
  Reply With Quote
Old 22nd December 2002, 03:49 PM   #4
diyAudio Member
 
Join Date: Sep 2002
Location: UK
Yes I did search,

and thanks very much to Nelson for the reply.
__________________
Bertie
  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
Marantz 4270 DC offset and bias adjustment The Donk! Solid State 6 8th February 2010 04:53 PM
Accuphase E204 DC offset / bias current adjustment slam Solid State 2 25th February 2009 05:39 PM
Aleph-x bias adjustment bach2800 Pass Labs 31 30th October 2006 11:03 PM
EE-Zee & Chee-Zee bias and offset adjustment idea thoriated Tubes / Valves 0 3rd April 2004 12:16 AM
DC offset / Bias setting for Aleph 2 fcel Pass Labs 24 26th August 2002 06:29 AM


New To Site? Need Help?

All times are GMT. The time now is 11:20 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