[LAU] Am I experiencing ground hum or is it something else?

[Ricardus Vincente]

On Sun, 2009-11-29 at 18:44 +0100, fons at kokkinizita.net wrote:

 Are you plugging the devices into different outlets?

 Rich...


> > How can I check if the keyboard/power supply is grounded? The power supply
> > itself is a three pronged one....
> 
> Then in most countries it is required by law to be
> effectively grounded. Next question is if you power
> socket is... It should be if it accepts the plug.
> 
> Since you also have this interference with an amp,
> but not with the headphones it really seems to be
> a grounding problem.
> 
> To only other way to explain it would be to assume
> it's some high-frequency stuff which your headphones
> would just ignore, but any active input such the amp
> or soundcard could demodulate into the audio band.
> 
> If you're using a laptop, does running it on battery
> make a difference ?
> 
> Anyway I'd try a DI box, it's good practice anyway with
> all instruments.
> 
> Ciao,
>