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Old 12-08-2007, 12:07 AM   #1
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Peavey Valveking 112

I have this peavey valveking that sounds weak and distorted. I've replaced the preamp tubes, phase inverter tube, power tubes, and check for opened resistors. I didn't find anything. I've noticed a defective 4560 IC and replaced it, but it didn't resolve the issue. What could be causing this?
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Old 12-08-2007, 05:36 AM   #2
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Isolate the problem, is it the power amp or the preamp that is bad?

Apply a signal to the input and trace it through the amp, find out where it doesn't make the jumpe from stage to stage.
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Old 12-08-2007, 07:35 AM   #3
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It looks like it's in both. There's distortion coming out the main speaker and distortion on the preamp: going from the send on the effects loop to the input jack of another amp.
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Old 12-08-2007, 11:26 AM   #4
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Well, if the distortion is present at the preamp out, it won't disappear going to the power amp. APply a clean test signal from somewhere else to the power amp input.

As to the preamp, as I said, apply a clean signal at the input and trace it through stage by stage.
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Old 12-08-2007, 10:54 PM   #5
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Thanks! I'll give it a shot.
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