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Doepfer

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Loud ground loop hum

2016-06-12 by Scott Rogers

Hi all

Sorry to complain again but I can’t figure this out. I have a lot of gear in my little studio and everything sounds fine except for my modular synth.

I have 3 Doepfer LC9 cases and there is always a loud hum or buzz coming from them. I’ve tried removing all the modules from one of the boxes except for a VCA and the hum is still there as soon as I connect a cable to the audio output. When I patch something between 2 boxes the buzz gets twice as loud.

I tried plugging the output into a Roland boutique synth powered by batteries and there was no hum at all so it seems to be a ground loop, however there is no hum from any of the other 25 synths in my room.

Everything in my studio comes from the same source, a high quality (pure sine wave output) UPS. I’ve tried a lot of different things but can’t find a way to stop the buzzing coming from the Doepfer boxes. Anyone have any idea why this is happening?

Thanks

Scott

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