Do you speak about a mechanical sound (coming from the case, not connected
to mixer/amplifier/loudspeaker) or an electrical noise coming from the
modules

Which power supply is built in (A-100PSU2 or A-100PSU3)

Best wishes
Dieter Doepfer

> Hi I have a P-9 that makes a high pitched sound at the edge of my
> hearing (12-13000Hz or so). I have three others, none of them
> make it. It decreases as I unplug modules, but with half of them
> unplugged, it is still faint. It doesn't appear to be any module
> in particular. The bus board reads version 5/2008.
>
> Any thoughts