OK, here's my initial question. How much signal loss can a bad ground
cause?

Here's the background:
I am working on a proposal that I wrote up for a theater at a
college. I am rewiring their sound booth because everything was just
too crazy and random. I ripped everything out of the punch blocks and
then rewired it. I rearranged the patch bays, and I rearranged the
booth. Currently I have everything re-punched in the blocks and I
have everything hooked back up. I'm in the process of testing the
system to make sure everything works because we have a show in two
weeks. Almost everything works. My only problem is the signal loss.
I patch the CD player through to the mixer and try to run it through
the speakers. I end up getting 1/4 of the output that I should. It's
very quiet and muffled. I have tried troubleshooting and I can't
figure out what the main problem is. If there was a bad ground
somewhere, would/could that be the problem or is it something else? I
think that I'm just going to run a cable straight from the mixer outs
to the amps so that it works for this show and then I'm going to rip
it apart and try and fix the problem again, but I want to find the
answer. So if you think you can help, I'd love your opinion...Thanks
-Luther

"Luther Bell" wrote ...
OK, here's my initial question. How much signal loss
can a bad ground cause?

A bad ground would NOT be on my top-5 list of things that
would cause "signal loss". If it were truly a "bad ground"
problem the symptoms would much more likely be something
like hum/buzz.

Trace the signal through the system and see if the level is
correct (or not) at each point. If ONLY the CD player has
a level problem, it seems unlikely that the problem lies
anywhere beyond the mixer.

Unsolicited advice for free...
Be sure to test the system with the dimmers operating
before declaring it launch-ready. THAT will find some
potential grounding/shielding problems!

In , on 10/05/03
at 08:48 PM, (Luther Bell) said:

OK, here's my initial question. How much signal loss can a bad ground
cause?

Here's the background:
I am working on a proposal that I wrote up for a theater at a
college. I am rewiring their sound booth because everything was just
too crazy and random. I ripped everything out of the punch blocks and
then rewired it. I rearranged the patch bays, and I rearranged the
booth. Currently I have everything re-punched in the blocks and I
have everything hooked back up. I'm in the process of testing the
system to make sure everything works because we have a show in two
weeks. Almost everything works. My only problem is the signal loss.
I patch the CD player through to the mixer and try to run it through
the speakers. I end up getting 1/4 of the output that I should. It's
very quiet and muffled. I have tried troubleshooting and I can't
figure out what the main problem is. If there was a bad ground
somewhere, would/could that be the problem or is it something else? I
think that I'm just going to run a cable straight from the mixer outs
to the amps so that it works for this show and then I'm going to rip
it apart and try and fix the problem again, but I want to find the
answer. So if you think you can help, I'd love your opinion...Thanks
-Luther

Having been there both due to my own gaffs and those of others, it
often pays to walk away for a while and come back with fresh eyes.

Since you have recently rewired everything, the obvious place to look
is a wiring error. Consider the possiblilty that you slipped row
somewhere as you punched things down. A very intense visual inspection
is usually worth several times its investment in hours of trouble
shooting.

A stray flake of wire at just the wrong spot could be the cause. Do you
have any unexpected crosstalk?

Also consider the possibility that something failed while you were out.
Are there any gain controls on the amplifiers that could have moved?


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(Luther Bell) writes:

OK, here's my initial question. How much signal loss can a bad ground
cause?

All of it. I've had ground loops so bad I got nothing but 60Hz out of
it. Experiment with where the power amps and mixers are plugged in.

If you don't have hum, look beyond your grounds.

weeks. Almost everything works. My only problem is the signal loss.

I patch the CD player through to the mixer and try to run it through
the speakers. I end up getting 1/4 of the output that I should.

Based on what?

It's very quiet and muffled. I have tried troubleshooting and I
can't figure out what the main problem is. If there was a bad
ground somewhere, would/could that be the problem or is it something
else?

What mixer do you have? Have you experimented with the pregain on
that channel? What are your fader settings?


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