I thought I'd ask this here, in case there's something stupid I might be doing to cause this, or if there are things I should try, before I call on Behringer product support.
My new-in-February QX1832USB sounds OK for the first two minutes or so, but then the output starts to distort - loses high end, gets a bit of "static" white noise in it - and fades in volume considerably. If I change nothing, but cycle power on the mixer, it's all good ... for another two minutes.
This happens with several different input sources - a line-level output from a synth, a drum machine, or an Alesis DM Dock - and almost all the settings on the QX1832USB set to nominal/flat/off.
I could upload an audio capture if that would help.
I can't imagine there's a setting that says "Work OK for 2 minutes, then f*** up", but maybe it's something I'm doing.
This sounds like a power supply issue to me. It sounds like voltage is steadily leaking or declining in some part of the circuit, so it steadily descends into clipping and distortion of the audio. if your system is that new, it should definitely be under warranty - please contact CARE at firstname.lastname@example.org or call at 1-702-800-8290 in the US for assistance!
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