Meridian Unplugged - Powered by MrTechGuy.co.uk Forums Discussion Meridian - Systems Stand-by sound DSP8000.2

A possible reason for the transfor hum - if that is your humming with 120 Hz - is that the main voltage is in practice not a sine wave.
It is a asymmetrical AC voltage/current, so the “upper” and “lower” wave is not the same or equal. Then the summary of both waves are not zero, means an voltage offset or basic say a DC is generated on the main AC lines. This could be caused from different sources, a typical source is a cheap/basic hair dryer and of course other loads on the mains. As that loads are active in random times, that distortion of the main sine waves are also random. And therefore the hum is also random.

MAYBE the transformer in the 8k have less iron in the transformer as other transformer from Meridian, they could be more sensitive to DC / Iron saturation what causes hum. So it could be that one or two Volt offset can saturate the transformer.

To solve the possible hum problem, there are two ways:

#1 Simply replace it and hope that the reason was the transformers.
#2 Is to watch with special equipment, supported from your main line supplier, the main line for that asymmetries and have to known the specification what the main line supplier have to deliver.

I had a hum problem very seldom with my speakers - not only the 8k - about 8 years ago and called my main supplier.
They installed the measuring tools and recorded the line parameters for about one week.
According to them, everything was in specification, but I did not get the measurement data, only the official result...
But “surprising” I have never a hum problem since that time... so my guess is, the supplier have made something, but I don't know for sure.

You should find out if it's a mechanical hum from a saturated vibrating transformer, or something else.
Maybe record that noise and give a link for a download, so the forum members have a chance to hear it.

Also watch, when that noise appear if not in your house a source just have switched on, refrigerator, hair dryer, heating, water pump or whatever. Or try out all your sources maybe to force that problem.

Good luck and tell us what's going on.
Robert