Minimoog hum

[elsongs]

My Minimoog Model D makes a hum, not a LOUD one, but noticeable when I turn the volume up. Is this normal, or do I need to do some grounding adjustments on the thing?

[Hybrid88]

Should be in the "Help" section for future reference.

Does the mini have two or three pins on the end of the power cord? If two it needs an earth modification added, though more common with the Japanese plugs like MS-20 etc. Possibly the chassis, or seperate boards aren't correctly earthed? Or you may have a faulty component or something.

[xpander]

it is not normal, my 1970s minis have a great signal-to-noise ratio.

[Cumulus]

Mine doesn't have that problem, either.

[WhinyLittleRunt]

This is gonna sound really stupid, but plug it into one of those gray 2-prong adapters and then into a power strip or outlet, and see if the hum goes away. We had this issue with a Pro One and by doing this unconventional thing we resolved it...

[Hybrid88]

This is gonna sound really stupid, but plug it into one of those gray 2-prong adapters and then into a power strip or outlet, and see if the hum goes away. We had this issue with a Pro One and by doing this unconventional thing we resolved it...

Must have been an earth loop, notorious for causing hum issues in audio gear - if this is the case reassess how you gear is setup plug wise, things like the order certain pieces of gear are plugged into the wall outlets may have an affect. I wouldn't recommend using a two-prong adapter unless your desperate though, by doing that you're removing the earth for the synth, so if there is a fault or short circuit inside the unit then you basically have no protection from the panel / chassis etc becoming live (something I personally wouldn't risk with a synth of that age).

Back to the original posters problem, have you had the capacitors replaced by a tech? Might be something to think about as old caps can increase noise in the circuit with age. But this problem would more be excessive noise rather than a pitched hum.