external amp humming

I have a Yamaha DGX620 and recently purchased a 50w external amp. With very little volume, a annoying humming sound occurs... does not with another keyboard brand connected. I'm thinking its the power adaptor that came with the DGX, the PA 150. Is there another adaptor that would help with this or any other alternatives or suggestions to STOP that humming.

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Nov 28, 2009
by: Andrew Jacob Sahagian

You can try several things.

Keep in mind that these portable grands are not designed for "Pro" use, thus they lack a clean line output, and we're stuck using a headphone amplifier output, which by its nature, introduces hiss or noise to the output to your amplifier.

Yes, hums are usually related to power, but not usually the actual power adapter. It's most commonly a "ground loop" issue, with the infamous 60Hz hum. The solution for this sometimes is to try plugging the keyboard (or amp) into a different power outlet, perhaps on a separate circuit.

Also try an audio cable of higher quality, which may have shielding or braiding in it to reduce external noise and cancel out internal noise. Also, shorter cables tend to produce less noise than longer ones.

Best of luck!


May 11, 2010
You need an isolating transformer with ground lift
by: Anonymous

The same goes for connecting some laptop sound inputs/outputs to mains powered hi-fi/recording gear

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