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Extreme warm up sound changes in vintage preamp

Posted on December 12, 2012 at 10:38:37

Have a Mitsubishi DA C20 dual mono preamp. Use it mainly as a phono preamp (its MC phono stage is insanely good especially with Denon 103/R carts).

When powered up, the preamp has a fairly loud hum that disappears over 30 minutes of warm up. Also the sound is a little garbled for the first few minutes. This warm up change is the same with tuner, phono or aux channels and is not volume dependent. Once warmed up it sounds great.

Was wondering if anyone has had a similar problem and if there are any easy fixes. Probably something in the power supply- any likely candidates?


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It's a solid-state preamp, you may want to consider just leaving it on all of the time. nt, posted on December 12, 2012 at 12:59:11

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RE: Extreme warm up sound changes in vintage preamp , posted on December 12, 2012 at 13:10:18

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You have a problem with that preamp. Sounds like it's going to blow soon. Could be a cap starting to fail.

I would have it fixed before it goes if you want to keep it.



Leaky electrolytic coupling capacitors. NT, posted on December 12, 2012 at 21:19:09
Alpha Al
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+1, what Al said.~nT, posted on December 13, 2012 at 09:04:39

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Either recap it or lose it...nt, posted on December 13, 2012 at 12:07:08

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