Paul, I live in a condo, so that's a safe bet! Turns out a 2-wire
adapter eliminates the hum, but now whenever I connect a jack from
the out-board mixer to a module there is a good sized POP. If I
first zero the mixer's input level, this becomes just a slight
"scratch" which is not too objectionable. Once the mixer's plugged
in, everything's pretty quiet. I have to admit that I'm not
satisfied with this non-std setup, though. Now, if I were to have a
nice black ON-board mixer with white lettering and switchcraft jacks,
hmmm, this might cut the gordian knot... :)
George
--- In motm@y..., "Paul Schreiber" <synth1@a...> wrote:
> Try plugging the MOTM AC cord into a 2-wire adapter. I bet it's
your house
> wiring.
>
> Paul S.
>
> ----- Original Message -----
> From: "J. Larry Hendry" <jlarryh@i...>
> To: <motm@y...>
> Sent: Sunday, February 11, 2001 6:14 PM
> Subject: Re: [motm] Ground Loops
>
>
> >
> > ----- Original Message -----
> > From: GeorgeK <george.kisslak@h...>
> > To: <motm@y...>
> > Sent: Sunday, February 11, 2001 4:43 PM
> > Subject: [motm] Ground Loops
> >
> >
> > Well, I just finished building my first modules, the 900, 120, 420
> > and 320, and amazingly everything seems to work (and looks great
> > too!) What a sweet filter the 420 is! (In just a few more days,
my
> > girl gets some flowers, and I get some sound sources - my 2nd
order's
> > in!)
> >
> > I've run into a little problem, however. When the 900 power
supply
> > is installed into a rack with the modules and is powered on, I
begin
> > to pick up some minor 60hz hum; not much, but enough to ruin the
dark
> > background - Bummer. (FYI, the rack is wood frame with metal
rails.
> > A mixer is in a separate all-metal rack. Everything is plugged
into
> > the same power strip. Patch cords are shielded) I pick up hum
> > regardless of which jack/module I plug into. I visually checked
all
> > coax solder joints and ground wires; everything looks ok. Funny
> > thing is that even when I disconnect all of the modules' power
cables
> > from the 900, I still pick up hum whenever the 900 is on.
There's no
> > hum when the 900 is not in the rack, whether connected to and
> > powering the modules or not.
> >
> > Is appears the AC ground is part of the common ground with the
> > modules when installed in a rack with metal rails. This is by
> > design, correct? Is it possible that the mixer being in a
separate
> > rack is a problem? If anyone on the list has some insight, that
> > would be great.
> >
> > Cheers,
> > George
> >
> >
> >
> >
> >
> >
> >
> >
> >
> >
> >