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Dave[_4_] Dave[_4_] is offline
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Default Help! Crackling noise from speakers.

"Matt Kissmann" wrote in message

I'm hoping someone can help me! I have a Kenwood KR-9600 with a pair
of Pioneer speakers. Recently, there has been loud crackling and
hissing noises coming from my speakers (usually just one speaker).
This happens when there is no input and happens when each input is
selected with the selector knob. Any ideas? Suggestions for a fix?

That's a very nice amp, top of the line Kenwood at the time. Definitely
worth repairing.

Did this noise just start out of the blue, worked great one day and not the
next, or has it been steadily worsening? Has the amp sat unused for any
period of time?

I'd start by cleaning all of the controls. Use a cleaner/lube spray, you
can get it at Radio Shack. Some brands are Caig DeOxit or Faderlube. Get
one with a lube component, not just cleaner. You need to unplug the unit,
take the cover off, and using the little straw that comes with the can of
cleaner, squirt cleaner into each knob (bass/treble/balance/volume/speaker
selector, input selector) and work the knob back and forth about 50 times.
Each knob. Then do all the switches. Tape monitor, loudness, subsonic and
high cut filters, speaker selectors, each and every switch. Switches that
don't get used much (like tape monitor) are prone to oxidation. Crackling
occurs as the signal arcs across the oxidized contacts and blows a tiny hole
in the oxidation on the other side. The squirt stuff has to get INSIDE the
switches and potentiometers behind the knobs where the contacts are... on a
few occasions I've actually drilled a tiny hole in the casing if they are
sealed. Soaking the outside won't do you any good. Let the amp dry at
least 24 hours before you plug it back in.

I don't like the hissing aspect of the noise, noisy switches generally don't
hiss. I'd be thinking about a transistor failing, either in the amp or
pre-amp. The KR-9600 has pre-out, main-in jumpers on the back, correct?
You can take them out and replace them with an RCA patch cord for testing...
run the R pre-out to the L main-in and vice versa... does the crackling
change channels? If so the problem is in the pre-amp, if not then the
problem is in the power amp.

Post back with your results.