Meridian Unplugged - Powered by MrTechGuy.co.uk Forums Discussion Meridian - Systems Hum / Earth Loop on 541

I wonder if anyone can offer me any advice.
I'm experiencing a loud hum through the speakers from my 541 processor. I'm using this with a 555 power amp, but the buzz is definitely coming from the processor because there's no noise using an Arcam pre amp instead, and it even occurs with nothing else connected to the 541 other than the 555.

If instead of using the front left and right pre outs, I use a tape output to connect to the 555, there's no hum at all, but the volume is deafening because the volume level is fixed. There's also no hum if the power amp is connected to the rear or centre pre outs instead of the fronts.

I've tried different interconnects and mains cables / supplies but this makes no difference.

I'm suspecting a fault on the 541, but any suggestions would be welcome.

Thanks, Jeremy

Sounds like a fault - I use a 541/555 with no problem.

Hi Jeremy.
I have mailed you. I put an earth wire from the Earth stud on the 541 to the caseing of my Nad amp. I put this down to the old Nad, and it worked fine.
I even forgot it ever was there.
Try it, a simple wire to the case of the 555 from the earth stud on the 541.
If it continues to be a problem, mail me back. We must get it sorted for you.

Cheers, Chris

I've tried connecting a lead between the earth terminal on the 541 to the earth terminal on my power block and also to the 555's chassis, but this made little difference.

Strangely, using the 541 with an Arcam power amp gives a much lower volume of buzzing through the speakers than with the 555. I don't think it's the power amp though because the 555 plus an Arcam pre-amp produces no mains hum at all.

Jeremy

Chris, I've got your mails and as ever you've been extremely helpful. I'm confident this will all be sorted out.

Despite its lowly status in the Meridian hierachy, I'm very pleased with the sound of the 555 power amp I acquired yesterday (with a 507 CD as source) driven temporarily via the Arcam pre.

IIRC, the 551 integrated contains much of the 555 amp (to the extent that the 555 is a match to it for bi-amping). I thought the 551 was an excellent amp with plenty of detail and control.