Hi Chony,

As quietDIN pointed out, lifting the ground by using an adapter or by removing the ground pin is NOT the way to solve a ground hum problem (if that is why you are asking "?")

There is always a reason why hum exists and it is best to find the source and then solve the problem correctly (and safely).

One thing I always keep in my gig bag is a Hum Eliminator by EBTECH. Click HERE to see this device. The Hum Eliminator has helped me out on many occasions. You simply insert it between the keyboard or other audio device and the mixer/amp and it removes the offending hum.
The small unit has two inputs and outputs and requires no eternal power. There is a larger rack mount version with more ins/outs if necessary.

The link I supplied also has some good information on just what ground loops are and what causes them.

I hope this is useful to you.

Best Regards,

Dave


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Wm. David McMahan
Nat'l Product and Support Manager
Generalmusic USA
GEM Community Forums