Maybe you can figure it out HELP PLEASE!!

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HIFI4EVER
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Joined: Fri Feb 03, 2017 10:29 pm

Maybe you can figure it out HELP PLEASE!!

Post by HIFI4EVER » Sat Jul 08, 2017 2:45 pm

Okay, so I'm having a very hard time right now figuring out why my system has a bad noise to it.

It is ground for sure. I have QSC 1400 amps. I use 2 out of 3. One on top of each speaker.

I run them bridged and when I use different input to each it is fine.

Example: Use RCA left from preamp to left bridged amp XLR in / Use RCA right from preamp to right bridged amp 1/4" jack it will not hum.

Example: Use RCA left from preamp to left bridged amp 1/4" jack in / Use RCA right from preamp to right bridged amp screw post in it will not hum.

Example: Use RCA left from preamp to left bridged amp 1/4" jack in / Use RCA right from preamp to right bridged amp 1/4" in it WILL hum.And same for all. If I use the same input on both amps it humms.

WHY?? Please tell me what I am missing here...

Amps are plugged in to wall behind speakers separate outlets.
Preamp SAE brand plugged in to me as left outlet but on a power strip.

Tried different in puts to preamp.. Not it.
Tried different sources.. Not it
If I turn off one amp still a slight hum, if I disconnect that other rca from preamp fully goes away.

I wonder if I had both channels plugged in on amps would it make it go away? I'm only using mono so only the mono channels hooked up using XLR to rca. I know not the best, but even using exposed wires to different inputs no hum, so it has to be ground right?

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thunda
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Location: Columbia, Tennessee

Re: Maybe you can figure it out HELP PLEASE!!

Post by thunda » Sat Jul 08, 2017 4:29 pm

Maybe the 1/4 inputs are TRS? The xlr would act the same as trs providing extra shielding.
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Enzo
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Location: Lansing, Michigan

Re: Maybe you can figure it out HELP PLEASE!!

Post by Enzo » Sat Jul 08, 2017 6:06 pm

Or you simply have a ground loop.

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