I’ve looked around the internet quite a bit and found a couple topics on this forum that have popped up around this exact same issue, but never resolved. So, I thought I would resurrect it.
I have the Plugable UD-ULTC4K that is hooked up to a 2019 Mac Book Pro via Thunderbolt 3 cable. The video monitors work flawlessly, but the problem is I’m getting this pulsating static from my studio monitor speakers that are connected to an Apollo Solo audio interface via 1/4" TRS cables through a separate TB3 port.
I suspect this is primarily a dock issue, because I’ve isolated the Interface, speakers, and all line cables approximately 5 feet from any computer wire or peripheral. I’ve unplugged all external peripherals and video monitors from the dock and left only the main TB3 cable plugged into the laptop and the static is still audible. I’ve also swapped out cables, both TRS and USB-C, switched around to different TB3 ports, plugged the speaker power cables into separate outlets from the dock, and nothing outside of complete disconnection has had any effect.
The static 100% dissipates ONLY when I fully disconnect the dock from my Mac Book Pro and use the laptop screen.
The static is rhythmic to the point where you could put a metronome to it, almost like the ticking of a second hand on a clock. I’m guessing possible processor feedback? And it has a lower frequency buzz whenever I scroll a page, hover my mouse pointer over a button, or any other movement/input via mouse or keyboard (both are bluetooth, if that matters). Turning off the bluetooth doesn’t alleviate any of the issues, in case you’re wondering. Neither does cycling the power on the dock itself.
Is there some kind of fix or suggested work around to alleviate this annoying static? It’s happening only through the speakers, and not through my monitor headphones.