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Blown 2 speakers at gig Friday.. any ideas? :0
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byronmurphy
Prenoob

Joined: 01/06/2014 10:29:33
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Hi,

I play in a duo and our singer just recently bought a new P.A.
Presonus 16.4.2AI desk with 2 JBL 515xt and a JBL sub.

We use and acoustic guitar, bass guitar, 2 vocals and a stomp box pedal. In the first set about 10 times there was a loud crack sound ( which could be peaking and clipping ) but it's extremely loud and I noticed it was when I was using the stomp that it would happen. So in the break we isolated everything and tested the stomp box and it cracked loudly and the speaker stopped working. The singer tested it again and blew the other speaker :0
The firmware has not been updated since he bought it new 2 months ago and we are pretty new to digital desk with compression. We had a friend come in and set it up for us as he is a good sound engineer so we just load the preset he made for a gig.
It seems to me that it is majorly clipping out with a lower frequency that the kick/stomp pedal is producing. And there is quite a bit of compression on the stomp channel. It also happened with an electronic drumkit that was used in a different channel on a separate night.

Hmm I'm just trying to give as much information as i can and any advice or ideas is much appreciated.

The next set we used the foldback speakers for FOH without the stomp and it was ok. I gave some hard strums on the guitar at the end of a song to see if it would clip out and I thought I heard it slightly but it's hard to tell.

I can explain more if anyone has any ideas...Thanks
andguent
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Joined: 22/02/2013 06:54:29
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Location: Philadelphia, PA
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I'm no expert, but I can describe how I would troubleshoot it.

* Pull down the volume for your speaker outputs or disconnect your speakers during testing.
* On the right side of the mixer, look for the "Meters" section and press the "Input" button. It should light up. This will now change all of your channel LED meters to input volume meters.
* Have someone stand at the mixer watching the LEDs. Play music like normal, one channel at a time.

Your LED meters should generally stay within 1/2 to 2/3rds of full volume. If any meter lights the red clip light up top you need to make adjustments. Be aware that the gain knob up top will turn everything about the channel down, including main mix and aux mix volumes.

Also, with all volumes like normal, the master meters up at the top right of the board should occasionally touch yellow, but not live in yellow or red.
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byronmurphy
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Joined: 01/06/2014 10:29:33
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Thanks anguent that's great I will try that to see if it's clipping out.

So would I be right to say that if something is clipping from the signal to the desk, there will be a large crack sound from the speakers?
There was no minor clipping ( or smaller cracking sound ) it was either...BANG! or it was sounding fine. Anyway sounds like a good way to test it without blowing speakers cheers mate..
sjc193
Presonic
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Joined: 30/03/2012 20:51:58
Messages: 568
Location: Warren, PA
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This really sounds like a bad 1/4 inch cable to me, the very first thing I would have done in that situation is try a new cable (the one plugged into the stompbox).

Did the electronic drums happen to be using the same cable? If it was that would also point toward the cable.

If the cable is ok then yes keep the input gain low, I let mine peak about half way up the meter (input meter)

Steve
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byronmurphy
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Joined: 01/06/2014 10:29:33
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Hi Steve thanks for your help...

Yes it is a 1/4 inch cable and after the first set we changed the lead to the one that was running the acoustic guitar.. Still did it though..
But something in common is that the electronic drumkit was using a 1/4 inch cable too, but a different one.

Hmm so I guess it could be the input gain but I have to wait until this Saturday night to test something on his P.A.

Thanks again guys, appreciate it.
salvadoredelle
Presonic
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Joined: 01/04/2011 17:49:43
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Location: Northern California
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could be your stomp box is funky too... a loose connection or a battery loose in side.. I had 3 D/I boxes I use 48 v phantom power on but have to have the batteries... they got loose and were and cracking... I fixed them and no more... also cheap cables will do more to ruin your sound than anything.. if they have molded ends or are cheap HOSA or the like throw them out or they will keep causing you problems... HOS and other cheap crap cables will also loose sound quality and sound bad... they use the crappiest cable and connectors....
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