i've got bad 60hz buzzes coming from several i/o processors/effects and
have tried many things to get rid of the buzz--unplugging everything
and plugging in one at a time, lifting signal ground, lifting ac
ground; no luck. the offending equipments buzz even when they're the
only things connected to the mixer; as long as they're connected by ins
and outs, they buzz. just outs going in to the mixer, no buzz. the
mixer is unbalanced and by itself does not buzz, nor does it buzz when
a synth is connected (because the synth only has output, no input)

(btw, i have everything plugged into one outlet, no dimmers etc)

i've searched this forum and the web for info and read in several
places that star grounding is a preferred solution by many to ground
problems.

as i understand it, you attach an equal length 12awg (or thicker) wire
to each piece of equipment. i guess i would use an existing screw/hole
on the chassis for this.
all of these wires come together at one point usually i read about a
copper rod driven into the earth. since i am in a rental apartment in
the city a copper rod into the earth is not an option. I do have a
water pipe in my apartment, i think it goes to the boiler, not sure if
it goes to earth as I don't have basement access.. my reading of
forums and articles on this subject has left me with the following
q's--feel free to answer any of them:

1. Do you think star grounding is the best option for me?

2. Should I lift signal ground and/or ac ground on each piece of gear
if i am doing a star ground system?

3. My mixer has a ground terminal--should i connect the wires to that?
or should i try for the pipe? or something else?

4. Should i connect my non-audio-passing midi controllers to the star
as well? my DAW computer? my LCD monitors? my powered speakers?

thanks all!

antonlamont45 wrote:
i've got bad 60hz buzzes coming from several i/o processors/effects and
have tried many things to get rid of the buzz--unplugging everything
and plugging in one at a time, lifting signal ground, lifting ac
ground; no luck. the offending equipments buzz even when they're the
only things connected to the mixer; as long as they're connected by ins
and outs, they buzz. just outs going in to the mixer, no buzz. the
mixer is unbalanced and by itself does not buzz, nor does it buzz when
a synth is connected (because the synth only has output, no input)

You have ground loops. Read the FAQ on the subject.

i've searched this forum and the web for info and read in several
places that star grounding is a preferred solution by many to ground
problems.

It's one possible grounding configuration.

as i understand it, you attach an equal length 12awg (or thicker) wire
to each piece of equipment. i guess i would use an existing screw/hole
on the chassis for this.

You could do that, IF you also lifted all the signal grounds on every cable.
Go read the FAQ.
--scott

--
"C'est un Nagra. C'est suisse, et tres, tres precis."

as i understand it, you attach an equal length 12awg (or thicker) wire
to each piece of equipment. i guess i would use an existing screw/hole
on the chassis for this.

You could do that, IF you also lifted all the signal grounds on every cable.
Go read the FAQ.
--scott

sorry, forgot about the faq! just read it (read it at
http://www.recaudiopro.net/faq/,
is this the current version?), but still have a question--

are you saying that it is necessary to lift signal grounds on the
unbalanced cables and the ac cords as well? and also, is the mixer a
good central grounding point for my star system?

antonlamont45 wrote:

are you saying that it is necessary to lift signal grounds on the
unbalanced cables and the ac cords as well?

No. NEVER lift the safety grounds on the AC cords. That is a VERY bad thing
to do. No matter WHAT scheme you use for grounding, make sure that it NEVER
involves lifting safety grounds.

If you have unbalanced cables, the easiest thing to do might be to plug them
into a balanced input, with the ground pin on the balanced connector lifted.
This allows you to lift the signal ground reliably and safely at that point.

Grounding problems are more apt to be a case of TOO MANY grounds rather
than too few.

and also, is the mixer a
good central grounding point for my star system?


Sure. It doesn't really matter whether you do star grounds, ground busses,
or any other configuration. All that matters is that there is ONE and ONLY ONE
ground connection from any piece of equipment to any others. If both pieces
of equipment have power line safety grounds, that should be the ground
connection between them. If one of them doesn't, then you should have a signal
ground between them.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."