Hello,

I just bought 5 monitors (Yamaha HS5) for a 5.1 setup and after setting them up two of them have that annoying constant 50Hz buzz.

I tried switching everything except for the offending monitors off and disconnecting the audio cables and the humming persisted, so I figured it would be either the monitors or the power cable.

I switched the power cables of a humming with a non-humming monitor and now the other monitor was humming. So I thought the problem is the power cable or the power strip.

Then however I tried to switch the humming power cable with a third non-humming monitor, but contrary to my previous test, now it was the same monitor that kept humming and the other one didn't start humming.

I tried plugging the monitors into the same powerstrips, into two different powerstrips, plugging the powerstrips into adjacent outlets, plugging the powerstrips into outlets on different walls but nothing changed. Only when I plugged one of the humming monitors directly into an outlet without powerstrip the humming was reduced.

So it all seems pretty random and I am not sure what else to try. I've read that there are some devices to plug into for eliminating ground loop but the cheaper ones have audio cable inputs and the few I found with power cable inputs are very expesive.

Does anyone know if/where I can find reasonably priced devices that are likely to solve this problem, maybe something on Amazon? I am in the EU so my power cables end in schuko / type F connectors. Or is there anything else that I can try?


EDIT:
After some more testing of plugging
the monitors one at a time directly into a few different power outlets and even in different rooms I came to the conclusion that they all hum. Either there is a solution with some filter for the power outlets or I’ll have to return them.