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Pre amp fault
Pre amp fault
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Old 5th January 2008, 07:29 PM   #1
Addolff is offline Addolff  England
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Default Pre amp fault

Need some help here please.

I have a Krell KSP 7B pre / KSA100S power amp which has recently been giving me problems

When I turn the combo on, most times it is fine, everything quiet. After a while though a high pitched 'white noise' type sound is heard - even with the volume muted.

In addition, sometimes there is a hum, apparent on all sources, but worst with the phono stage. It will be virtually silent, then this too suffers with hum.

When I use another pre amp, no problem.

Any help would be really appreciated.
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Old 5th January 2008, 07:56 PM   #2
analog_sa is offline analog_sa  Europe
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Pre amp fault
These symptoms are not sufficient to pin-point a simple cause. What level of experience/abilities in electronics do you have?
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Old 6th January 2008, 11:02 AM   #3
AndrewT is offline AndrewT  Scotland
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Location: Scottish Borders
one channel or both?
does it change channels when you swap interconnects?
regards Andrew T.
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Old 6th January 2008, 01:25 PM   #4
Addolff is offline Addolff  England
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Thanks for your reply.

Very little electronics knowledge - I can use a multi meter to test the simple stuff and can use a soldering iron.

I just wondered if the symptoms may have been a dead giveaway to an experienced hand for a particular fault - leaking capacitors or something.

The thing that is intriguing me the most is that the 'white noise' I described is apparent even with the volume muted.
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Old 6th January 2008, 01:55 PM   #5
Jan Dupont is offline Jan Dupont  Denmark
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What your reply to Andrews question ??
It could brings us closer to the problem.....

Your volume sits in the front end of the circuit, so no mystery there......

I would first suspect a bad soldering, and properly a soldering to ground since you sometimes get hum.........
Free Schematic and Service Manual downloads www.audio-circuit.dk
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