I have a sound system in a coffee shop/dance hall (for teenagers in recovery). The system is a windows based computer running iTunes plugged into a NuMark Dm1090x mixer. The amp is a QSC Audio RMX2450 driving two Peavey SP 5xt speakers. All run through (except computer) a Furman PL-8 power conditioner.
Now the problem is that when I turn up the volume and a song plays a loud high seemingly of any kind I get a loud "chirp" or "squawk" like sound that really hurts to hear and I would imagine does damage to the system. I can't seem to figure out what is causing this. I have tried disconnecting the computer and using an mp3 player as a source and it still occurs. Audio sounds fine at lower volumes, only happens when I push for big sound (all within/under range of any clipping) and sound is not distorted. Any ideas what is wrong?
Now the problem is that when I turn up the volume and a song plays a loud high seemingly of any kind I get a loud "chirp" or "squawk" like sound that really hurts to hear and I would imagine does damage to the system. I can't seem to figure out what is causing this. I have tried disconnecting the computer and using an mp3 player as a source and it still occurs. Audio sounds fine at lower volumes, only happens when I push for big sound (all within/under range of any clipping) and sound is not distorted. Any ideas what is wrong?
That busness about the screen going wacky is a real clue. I would suggest that the power amp is oscillating. How long are your interconnect cables? have you moved anything around about the time this started happening?. Check the cables for fraying or loose connections. Try different interconnect cables.
I am using a 1/8th inch stereo plug to RCA (composite) from the computers on-board sound card to the mixer. I have tried switching this cable and tried a different audio source with a different cable on a separate channel on the mixer. I dont see any cables in a loop, I have gone through and unplugged anything non-essential. I will try putting the amp on its own power circuit and see if that helps and report back. Please keep the ideas coming, and THANK YOU for all the help thus far.
just another guess but If you have a scope you can look at line power ,signal and of course the out put,no scope ,The lines on the monitor and squeel from the system tells me maybe the line conditioner is not making enough juice to run it all try taking it out of the system and running it ,if it does it again change some things to a different circuit,A digital sound processor will squell if it has no signal or power if sagging,Those lines on the screen should tell you something ,rolling lines = something oscillating, Post what they look like ,Good luck!
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