On Sun, Nov 29, 2009 at 6:31 PM, Ricardus Vincente
<wizardofgosz@gmail.com> wrote:
On Sun, 2009-11-29 at 18:44 +0100, fons@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,
>