Denon AVR-X1700H subwoofer hum


Standard Member

A few months back, I replaced my Yamaha RXV-575 with a Denon AVR-X1700H to get support for 4k passthrough for a PS5. All devices are connected via HDMI with the exception of a music player (optical audio) and the TV audio (again optical - I couldn't get ARC to work for some reason). All power connections have remained the same.

Since then, there's been a very pronounced 'hum' from the subwoofer. By complete accident I've just found that plugging in a laptop via HDMI and connecting the laptop power brick, the hum is dramatically reduced. The HDMI cable for the laptop has always been plugged in to the receiver, but the other end generally lies loose, coiled on the TV stand ready for the occasional times where we connect up the laptop. I tried unplugging this HDMI cable completely, and the hum remains.

So it seems to me like there's possibly some sort of grounding issue? The sub and receiver are both plugged in to the same power strip going into a mains socket. Some of the other equipment is on a second power strip in a different mains socket (but all the power connections are the same as they were when the Yamaha receiver was in use). The laptop power is plugged in to a third power strip, again in a different mains socket. I'm a little bit surprised, as the laptop power brick isn't likely to earth the laptop through its connector is it?

Can anyone offer any advice as to how to try to alleviate this? I guess I could just leave a laptop plugged in to the HDMI all the time, but that's a little inconvenient!

Thanks in advance.


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