Static/interference/feedback issue......

Static/interference/feedback issue...

Posted on Apr 16, 2010 11:52 pm
dustinkrueger
Member Since: Mar 13, 2010

I am a mobile DJ and recently purchased new speakers that required me adding a second amp. Here is my current set up

Speakers:
Peavey SP4's - 4 ohm speakers
1000 watts continuous
2000 watts program
4000 watts peak

Amps – 2 Crown XLS 802D

Stereo, 4 ohms (per ch.) 800W
Stereo, 8 ohms (per ch.) 500W
Bridge-Mono, 8 ohms 1,600W

I was previously running with one amp in dual mode; however, the single amp did not have enough power to push the speakers so it was suggested on this forum to add a second crown amp and run them in bridge mono.

When I connected everything according to the manufactures recommendation, running in bridge mono, there was terrible feedback/interference/static in the speakers when the amps were turned up and/or the master volume on the mixer was turned up. The feedback/interference/static would not be noticeable when playing; however, there was some crackling in the speakers when anything with bass was played.

I began to do some troubleshooting and first tried another set of speakers and had the same problem. This would eliminate a problem with the speakers.

I then switched out of bridge mono and again ran in dual. I hooked up to the new amp and continued to have the feedback/interference/static problem.

I then switched from running everything through the new amp to the crown 802 I had originally, again running in dual mode and the feedback/interference/static problems was gone.

This says to me that there is some problem with the new amp that I purchased. Would everyone agree? Is there some other trouble shooting I should try before sending the amp back?

Any help or suggestions would be much appreciated. Thanks

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pjk
Prince CZAR-ming
Member
Since: Apr 08, 2004

Apr 18, 2010 02:30 am

While not a Sound guy, first thing I'd think is there's a grounding problem. The speakers are eliminated, and you switched back to the original amp, and the problem was gone.

Process of elimination points to a problem with the new amp.

Maybe a loose ground / input ground / etc somewhere in the machine. See if any of the inputs are a tad loose, as the fastening nut that makes the chassis ground may be loose.

I wouldn't open it up though, as that could jeopardize the warranty.

You should eliminate the possibility of cables as well, though I think you already have, if you used the same cables with the new amp, and old amp, into the new speakers.

That's what warranties are for, I'd say.