Bias adjustment for Krell KSA 100 - diyAudio
Go Back   Home > Forums > Amplifiers > Solid State

Solid State Talk all about solid state amplification.

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 August 2003, 10:51 AM   #1
diyAudio Member
 
Join Date: Oct 2002
Location: Germany
Send a message via AIM to Alex helge Send a message via Yahoo to Alex helge
Default Bias adjustment for Krell KSA 100

Hi,


I would like the Bias and the Offset at my KSA 100 to control.

Can you me send the accurate Bias and Offset adjustment for the KSA 100 Mk 1 and MK 2 (KSA 100 with fan-cooler).



Best regards

A.Bennink
Attached Images
File Type: jpg krell diy.jpg (40.9 KB, 973 views)
  Reply With Quote
Old 22nd August 2003, 11:42 AM   #2
Jozua is offline Jozua  South Africa
diyAudio Member
 
Join Date: Aug 2003
Location: Cape Town
Default Bias adjustment for Krell KSA 100

Hi

I have the circuit diagram for the KSA 100 Mk1. Let me know if you want it. It does not give much details re the bias setting.

I enquired if one can set the bias to 50 watt Class A so that the amp does not run so hot and hopefully lengthen it life longer. The advice I received was not to do it and rather to replace the transistors and main capacitors which are well beyond their safe liefspan.

The question is however is it worth it as the these amps are plus minus 20 years old and entering their high risk period for breakdowns. Was it not for the high risk aspect I would love to buy a secondb KSA100 Mk2.

I still like this amp and find it still very much to my liking. It very dynamic and really kicks ***. The modern sliding bias class A amps I have heard just does not have the power and authority of the older more classical class A Krells. I am using the amp with a home build Nelson Pass single ended pre-amp and the combination works better than with the Krell pre-amp.


Jozua
Cape Town
South Africa
  Reply With Quote
Old 23rd August 2003, 10:36 PM   #3
The one and only
 
Nelson Pass's Avatar
 
Join Date: Mar 2001
If you replace the electrolytics, it'll probably give you another
fine 20 years.
  Reply With Quote
Old 24th August 2003, 07:38 AM   #4
Electrons are yellow and more is better!
diyAudio Member
 
peranders's Avatar
 
Join Date: Apr 2002
Location: Göteborg, Sweden
Blog Entries: 4
Alex, what was your problem really? Did you only want to "calibrate" the amp or was something else?
__________________
/Per-Anders (my first name) or P-A as my friends call me
Super Regulator SSR03 Group buy
  Reply With Quote
Old 24th August 2003, 09:10 AM   #5
diyAudio Member
 
Join Date: Jan 2003
Location: Enschede
searched with google for krell and schematic:

http://lightning.prohosting.com/~tedl/
  Reply With Quote
Old 24th August 2003, 10:03 AM   #6
diyAudio Member
 
Join Date: Oct 2002
Location: Germany
Send a message via AIM to Alex helge Send a message via Yahoo to Alex helge
Default bias KSA 100

Hi,
I have a KSA 100 MK1 to adapt at KSA 100 MK2.
My KSA 100 hath the driver board from KSA 100 MK 2, but the power supply is KSA 100 MK1.
How must I the Bias to adjust ?
Is the bias for KSA 100 MK 1 and MK 2 identic ?

Many thanks for your answer
Best regards
Alex
  Reply With Quote
Old 24th August 2003, 11:06 AM   #7
Electrons are yellow and more is better!
diyAudio Member
 
peranders's Avatar
 
Join Date: Apr 2002
Location: Göteborg, Sweden
Blog Entries: 4
The design seems surprisingly conventional so I think you can go by the temperature. If you remember how hot the amp is or was (someone else maybe can tell you?), just turn up the bias carefully and check the temperature.
__________________
/Per-Anders (my first name) or P-A as my friends call me
Super Regulator SSR03 Group buy
  Reply With Quote
Old 25th August 2003, 10:24 AM   #8
Jozua is offline Jozua  South Africa
diyAudio Member
 
Join Date: Aug 2003
Location: Cape Town
Default Bias for Krell KSA 100

Hi


If anybody has rebiased their KSA 100 amp to a lower Class A rating It would like to know how it sounded once it was done ?

Has anybody buildt the KSA100 based on the schematic provided ? I for one would love to take on such a project.

I also have the KSA200s which is much younger than the KSA100 but it has broken down 3 times upon switch on!! Could it be that this design is more unstable than the original KSA 100?

Is it worthwile to repair once again or should I just sell it ?


Jozua
  Reply With Quote
Old 25th August 2003, 10:34 AM   #9
diyAudio Member
 
mrfeedback's Avatar
 
Join Date: Feb 2002
Location: Perth, Australia.
I repaired and biased a KSA-100 recently.
I set bias to 500mV across two output transistor emitter resistors I think.
The original spec is 600mV I think.
Do not quote me on this until I find out the correct figures in the next day or so.
Either way I set the bias 20% or so less than the spec, and the owner informs me that it sounds better now than before, and is reliable.

Eric.

Eric.
__________________
I believe not to believe in any fixed belief system.
  Reply With Quote
Old 26th August 2003, 01:41 PM   #10
Jozua is offline Jozua  South Africa
diyAudio Member
 
Join Date: Aug 2003
Location: Cape Town
Default Bias for Krell KSA 100

Hi

MY KSA 100 has broken down (first time in nearly 20 Years !!) and I took it to a guy who was quite hesitant to work on the amp. I suspect the mere brute power and size put him off. He did some quick test and told me that the Transistors were fine and not leaking.

Visibly there is nothing burnt or damaged on the amp but when you switch it on the fans start and stop after a split second.

I have found another "expert" and would appreciate any advice I can give him as to what he can be on the lookout for. I also want him to set the bias lower - maybe to 500mV. I am also toying with the idea of replacing the flimsy wire running from the RCA input with some Van den Hull wire. Would this be safe to do ?

Any advice would be appreciated.


Thanks.

Jozua
  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
Krell DVD Standard laser adjustment ECM Digital Source 6 1st January 2010 07:18 PM
BOZ bias adjustment help rtate Pass Labs 16 11th July 2008 07:04 PM
Yamaha R-3,RX-300 bias adjustment spongebob-2005 Solid State 1 18th November 2006 01:21 PM
Bias adjustment question n0plb Tubes / Valves 20 5th May 2005 01:21 PM


New To Site? Need Help?

All times are GMT. The time now is 11:32 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