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[Duane Massey]

If it worked before, and nothing has been altered, I would suspect the amp, but you've already tried that.
If the problem has always been there, I'd suspect a wiring error at the speak-on connector(s).

[Robert Sims]

Do you have the amp in the bridge mono mode? This will disable the second input. If you have the input paralleled you would hear aux one feed in both monitors.  


Do you have anything inserted in the Aux feeds? EQ,s ? I've had inserts cause crosstalk in the past. More so on a group inserts, but it might be a mis-wired or half connected insert if you're using them.

[Bob Henley]

OK, new developments today:

1) I have ruled out the amp and everything before it: I connected a pair of speakers directly to the amp and could not reproduce the problem.

2) I was able to reproduce the problem with an iPod connected to the amp.

So, it looks like that speaker cable.

Should I replace both pairs, or just the one that's giving me problems? A quick search for speaker cable comes up with Belden 8477 for a 2-conductor 12 gauge - is that OK, or should I look elsewhere?

Here's the new table:

[Charlie Zureki]

Bob  Healey wrote on Wed, 27 May 2009 18:32

OK, new developments today: 1) I have ruled out the amp and everything before it: I connected a pair of speakers directly to the amp and could not reproduce the problem. 2) I was able to reproduce the problem with an iPod connected to the amp. So, it looks like that speaker cable. Should I replace both pairs, or just the one that's giving me problems? A quick search for speaker cable comes up with Belden 8477 for a 2-conductor 12 gauge - is that OK, or should I look elsewhere? Here's the new table:

Bob,

 Before you replace any cabling/wire, check the  solder connections in the panel (wall or stage pocket?) to the  (NL4) Speaker connectors.

Are they terminated correctly? No solder or wire bridges between these two Monitor connectors inside the floor pocket or Wall panel?

 If you have to replace speaker cable in the conduit... I'd suggest replacing both pair. (maybe leave the good cable in the conduit for spares)  And, pull BOTH new pair at the same time.


Measure the distance of all the conduit length , extra for inside the rack, and add extra for a safety margin. DOUBLE that LENGTH and cut ENTIRE LENGTH from the spool ( example: two 100ft runs = 200ft and add extra, cutting 200+ ft from spool)  ..... fold the ENTIRE length in half and tie middle of cable on to pull string/fish tape and.....make your pulls.

MEASURE CAREFULLY, MEASURE TWICE ....

Any Belden 12 ga should be fine.... use twisted pair.

Good Luck,
Hammer
 

[Charlie Zureki]

Bob,

  Did you find the answer to the problem?

 Keep us advised.

Thanks,
Hammer

[Bob Henley]

Charlie Zureki wrote on Sat, 30 May 2009 11:24

Bob,   Did you find the answer to the problem?  Keep us advised. Thanks, Hammer

No, I found other problems...

Somebody had unplugged the control wire leading to the sequencer from a power strip in the back of the amp rack, then thought the power strip was broken.

They proceeded to plug everything into the other power strip. Meaning we went from four twenty-amp circuits to two twenty-amp circuits.

It's been like that for at least a year. I really don't understand what people think sometimes.

I did take a look at the connectors and didn't see anything amiss, but I'll get back in on Monday and replace them. We'll probably order new speaker cable on Monday if the connector change doesn't fix the problem.

[Mark Mattocks]

Bob -

I've read through the rest of this thread and I have trouble believing that four runs of single conductor 12 ga in conduit are now bad.  Did it work before?

I would now check to be sure that the pair of speaker wires connected to output 1 of the amp are indeed the same pair that is connected to the output in the floor pocket.  Are the runs to monitor output 2 - in the farther box - continuous or are they junctioned in the first box?  The more that I think about this, the more it seems to be a mis-wiring issue or a short in the junction box to a steel plate possibly.

I would also meter all conductors to all other conductors with no speakers or amplifier attached.  Any reading other than infinity between the speaker wires would indicate a short somewhere along the way.

Best,
Mark

[Bob Henley]

OK, I finally got back in.

I inspected all the connectors again and didn't find anything suspicious.

Then, I metered the conductors. One pair returned infinity, the other a value.

It looks like two of the cables were damaged and are now shorted. The cost of cable isn't a problem and we've got lots of downtime this summer, so we'll replace the cables next (as soon as we order new stuff)

Thanks for the help, everybody. This forum is awesome!