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[Bill Beach]

our church uses 2 JBL SRX-715's for the mains each run by one channel of a Crown CE1000 (passive).  we are set up as a stereo system (L&R) but run a mono signal to each side.  the problem we are having is the right speaker cuts in & out at will for irregular, intermittent intervals.  it is mostly apparent when the pastor is speaking as the levels are lower and that is the only thing going on at the time.  I have changed the channel of the amp driving the speaker, and also switched the amp for the left speaker to the right speaker and vice versa.  we are / have been planning to go to bi-amp on the JBL's and therefore ran an additional speaker line to both speaker positions.  I have switched the right speaker from the wire we were using to the additional wire.  none of this has made a difference.
just would like some ideas of where to go now.  any more needed info gladly supplied.

[Mark Mattocks]

Are there two sends to the amp?  Are they a 'Y' cable or separate from board to amp?  Is there an EQ or processor in line?  Is the switch on the input side of the back of the amp on 'stereo'?  Have you tried the other NL4 input on the speaker?  

Based on your troubleshooting so far - as long as each step has been a separate step with the issue verified as still being there after each individual change, the problem may be a bad connection on the crossover board in the speaker.  The crossovers (I believe) are mounted on the input plate and a visual inspection for a cracked solder joint may be helpful or swapping the two input panels/crossovers from speaker to speaker would help verify.

Let us know what you find,
Mark

[Kent Thompson]

[Brian Ehlers]

I agree with Mark;  if you've ruled out all the other wires and connectors in the path, then it is likely the input jack or crossover inside the speaker cabinet.  It could also be a solder joint (or crimp-on connector) where the wire attaches to the actual drivers inside the cabinet.  Either way, it's far from impossible to fix.

If you want to diagnose further before removing the input plate or drivers, then rotate the cabinet to different positions and angles (sideways, upside-down, twisted, etc.) while playing music softly.  If it's a bad solder joint, you will likely find positions where it cuts out full-time or never cuts out at all.  (Of course, this test is not really practical if your cabinets are flown.)

[Jordan Wolf]

Why don't you try to test the system using the Aux Sends for the outputs instead of the Main Outs.  That would tell you if it's at the board end or amp end.

Also, how are you getting the signal to the amp inputs - 1 XLR cable to Input 1, then jumpered over to Input 2?  Or are you running two separate lines into the amp?

[George S Dougherty]

Jordan Wolf wrote on Sun, 14 November 2010 22:53

Why don't you try to test the system using the Aux Sends for the outputs instead of the Main Outs.  That would tell you if it's at the board end or amp end. Also, how are you getting the signal to the amp inputs - 1 XLR cable to Input 1, then jumpered over to Input 2?  Or are you running two separate lines into the amp?

His testing so far, if you read and understand it, pretty much eliminates the possibility of signal prior to the amp being the issue.  As others have mentioned, it appears to be something internal to the speaker.  

[Bill Beach]

let's see if i can cover all the replies / questions without a lot repetitive jabber.
Mark;  there are 2 sends to the amp, 2 separate balanced cables back to front.  from the mixer board, there is a compressor, an EQ, and crossover before making the run to the amp.  both amps are set for mono.  I haven't tried the other input on the speaker.
Kent;  not sure I understand the question  ;o)
Brian; yes the test would be quite difficult to accomplish as the JBL's are flown.
Jordan; question answered in reply to Mark above.
thanks a lot to all who have offered suggestions.  I will be taking a close look at the speaker to try to determine if that is where the problem lies.

[Kent Thompson]

One question about the comment you made about the amps are set to mono. What do you mean by this? Do you mean they are set to bridged mono? You also say there is a crossover in line but only one amp supplying power to the mains. Is the crossover only use to cross over the subs and the mains? I am still not clear on your setup as you can see by my questions.

Well here is what I am thinking.
(If the amp is set to bridged mono then there should be only one cable going to the amplifier so step 2 will not be needed only step one.)

1. Starting at the amplifier speaker outputs switch the cables. Put the 1st speaker cable in the second output and the second cable in the 1st output. Did the dropout change channels? no-then the issue is with the speaker. Yes- the problem is further upstream.

2. move the channel 1 input cable to channel 2 and the channel 2 cable to channel 1 did the dropout change channels? no- then the issue is with the amplifier. yes- the problem is further upstream.

3.follow the cables up to the crossover. take channel 1 output cable and move it to channel 2 and move the channel 2 output cable to channel 1. Did the dropout change channels? no- then the problem is with the cable. yes-then the problem is further upstream.

4. move the crossover input cable from channel 1 to channel 2 and the input cable from channel 2 to channel 1. Did the dropout change channels? no-then the problem is with the crossover. Yes- the problem is further upstream.

I could keep going but, by now you should be able to finish checking everything using this method. When ever you get a no answer you found your problem. Doing things systematically like this will make sure you do not miss anything.

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