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Question A bit of 50hz hum..


Active Member
My subs are placed in the corners, alas, because that's the only place they can be out of the way.. now, when I was wiring the house (new build) I put 2x speaker cables in the walls to Front Left and Right for biwiring expansion potential. I ended up not biwiring the fronts so I had a spare pair of cores. Having only a 7.1 amp (the second sub came along free with a set, no current plans to upgrade the amp) I figured I'd put a (pair) of phono on the ends of the spare wires at the speaker end and I'd join the cores at the amp end into a single phono and connect to the amp sub out

I thus have from amp to speaker : single phono branching to two cores, each branching to two phono. Electrical continuity wise it all works out- all the phono centre pins are on one core and the surrounds are on another

This works fine, though will doubtless cause me some nuisances setting the volumes of the two subs. Bigger problem is that the tiny signal on these wires is amplified by the sub amp, so any noise gets worse. When all connected up there's a very faint 50hz hum (that massively increases to intense wife dissatisfaction if I unplug the amp end, muha. Sorry darling

Is there anything I can do to reduce the problem? Maybe turn the sub amp down and crank the output volume at the avr amp end in audyssey setup? Or what about using the high level inputs to the sub with the speaker out? (Avr x2000 doesn't have hi level out for sub so I lose dedicated LFE control in that case tho?
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Active Member
I'm guessing that sending the low level lfe signal through speaker wires that are un-shielded is the main reason for picking up your 50hz hum. Not easily cured without re-wiring in my opinion.

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