Bias increase after components burn in a few days?? - 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 12th December 2012, 05:17 AM   #1
diyAudio Member
 
Join Date: Jun 2007
Default Bias increase after components burn in a few days??

hi all,
since completing my PLH mono's i have to say the sound is very good, it gives great insight into the recordings,
i'm tempted to day detail but i don't mean bright.

but one interesting quirk.
I set the bias to 1.95A total (after a long warm up)
this was happy and stable.
the bias would start at 1.6A and move up to full after warming up.

after several days of using a few hours each day, the bias had increased to 2.1A

I re-adjusted the bias to around 1.8-1.9A (after 5 hours warm up)
and this was stable,
the amps would take over an hour to move from bias at cold (1.6A) to full bias

but after a few days use the bias has drifted up to 2.0A,
now at power on it fairly quickly moves up to 1.9 then slowly increases to 2.0A.

the ambient temp now is about 10 deg colder than the first setup.

it's not a problem, but just wondered if anyone else had seen the bias increase after the components have a few tens of hours on them.

one thing this has taught me is how useful it it to have a bias meter on the amp. (well PSU so measuring actual total current draw per mono amp)
i only threw the meter in as i had them, but i will certainly add them in future when i build an F5.
  Reply With Quote
Old 12th December 2012, 05:08 PM   #2
The one and only
 
Nelson Pass's Avatar
 
Join Date: Mar 2001
Not really. I see bias increases, but I usually rack them before an hour has
gone by, so they continue to heat up for days, and then they get adjusted
again, usually twice.

Keep in mind that ambient temperature and ventilation (location) and
line voltage all play a big role in this.

  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
Technical Q:How to increase Xmax in a woofer to increase loudness. asberrys Multi-Way 12 30th June 2012 11:12 PM
On days like these ... Doz Tubes / Valves 2 20th January 2011 02:51 PM
burn in of components jitter Parts 25 30th April 2009 07:47 AM
Safe to increase bias on factory Aleph 30's? hifimaker Pass Labs 5 18th January 2005 08:18 PM
increase the bias current of an opamp final stage herve Solid State 19 15th September 2003 12:29 PM


New To Site? Need Help?

All times are GMT. The time now is 07:12 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