[LAU] sortof OT -- ART tube pac preamp and compressor noisy?

[Martin Peach]

On 2013-08-13 11:37, Ralf Mardorf wrote:
> On Tue, 2013-08-13 at 08:08 -0700, Rusty Perez wrote:
>> Also, when I get really close to my ART tube pac unit, I hear a quiet
>> humming from the box itself.
>
> This likely is the normal sound of a mains transformer, especially when
> the plates of the mains transformer aren't sealed anymore, IOW when
> there's air between them, the transformer becomes loud. This hum
> shouldn't be audible by the audio signal.
>
> One of the loudest transformers I know is used for my Matrix-1000 and
> it's one of the devices that IMO do cause completely no audible noise
> and/or hum. A loud transformer shouldn't have impact to the audio
> signal.

If the motion of the transformer plates is vibrating the elements inside 
the tube, the tube could act like a microphone. In the OP's case there 
is a lot of gain, so it might be the cause.

Martin