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Audio problems: High freq. hum & USB

Audio problems: High freq. hum & USB
« on: January 25, 2019, 12:48:59 PM »
Hi!
I'm running my Prophet X through an Apogee Duet (all current firmware and software) into Logic Pro X on a mid-2012 MacBook Pro.
Hearing a high frequency hum (about 600) through my monitors.
Also, audio stops when USB is connected. I went through all sorts of 9to5 Mac steps to set up my PX as an external instrument; note info shows, as well as track input levels, but still no audio out.
1/4" outs work fine - as long as USB is disconnected.
I'm ready for good advice.

Re: Audio problems: High freq. hum & USB
« Reply #1 on: January 26, 2019, 04:54:00 AM »
I've experienced noise with long USB cables with other devices. Interestingly, my last keyboard came with some kind of a clamped coil to put on the USB cable to prevent noise. I did not need it in that case, but perhaps this might provide a clue for you.

Re: Audio problems: High freq. hum & USB
« Reply #2 on: January 29, 2019, 10:37:43 AM »
Thanks, Steve. I may not have been clear; I only get signal at ALL when USB is disconnected. I think I'm going to have to call Sequential tech support.