Marantz PM385 left and right sound doesn't equal. - diyAudio
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Old 23rd July 2014, 05:32 AM   #1
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Default Marantz PM385 left and right sound doesn't equal.


My integrated amp Marantz PM-385 sound doesn't balance between left and right channel. The left side is louder than right or the right is lighter than left. Sometimes I should say the right channel is duller than left - less sparkling and brightening. The symptom is more noticeable when press "Loudness".

First, I thought it was just because of a Volume. So I replaced it with a new "Alps". But the problem remains. The other contacts of this amp are bass - still work but treble and balance aren't working. Other switches of source still work. Speaker selector switch is working but sometimes a little loose on right; just press again and it'll work normally.

Please help me what should be checked ?
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Old 23rd July 2014, 07:23 AM   #2
Mooly is offline Mooly  United Kingdom
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Those slider controls would be highly suspect for a start... and you actually say the treble and balance don't work. Fix the known faults first and you may well find the other issue is corrected too.

(And faults like this are easy to trace with a scope and generator)
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Old 23rd July 2014, 08:06 AM   #3
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I've been reworking an amp from 1974 and it had a similar but not as drastic of a problem. Turns out the bias had drifted a lot. Was putting out weak output compared to what it was rated for. Maybe it's that...

Unless someone kicked the speaker wire on one of your channels, accidentally shorting it. I just heard that story from someone actually.
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