Hello,

For once, I'm actually posting on here asking for some advice!!

For reference: my amp has a single phono output for the subwoofer and my subwoofer has a L and R input.

When I plug my subwoofer into power with no cable to the amp, and turn the volume right up, I get silence. This is good.

When I connect the double-shielded phono cable from the amp to the sub (into either L or R) the sub starts humming.

If I turn the amp off, the humming gets quieter, but still exists at 50% the volume is was originally at.

I have tried a different cable, I have tried plugging the amp into the same power lead as the amp itself, and I have tried putting one of those magnetic clamps around the power cable at the sub end to stop any power interference.

If the sub remains connected to the amp, with the sub plugged into power and turned on, but the amp has no power whatsoever (i.e. it's unplugged) I still get the same level of humming as when the amp is plugged in and simply turned off (i.e. 50% of original volume).

So... does anyone have any advice??

This humming means I must have the sub volume turned down so low for general use that it's almost not worth having it...

Thanks in advance!

Hi Richard, Thats most annoying! Have you tried the high level input on your sub? Maybe this makes it work better.

Good luck and keep us updated!

Amp has several settings for amp output: 0dB, -1dB, -2dB, etc... I have it set to 0dB (i.e. max volume) already...

Well, it has an "SP LFE" setting under the "LFE LEVEL" menu which ranges from 0dB to -20dB. I have it set to 0dB, as mentioned. Not sure if this is the right setting though.

There doesn't appear to be any other settings related to this in the amp... (a Yamaha RX-V357)

It seems that the output level doesn't match with your subs input sensitivity. That is the only explaination I can think of right now.

Would that mean one or the other is faulty, or just two bits of kit not designed to work together?

If they're both perfectly fine, how can I correct this? The amp has a phono out and the sub has two phono in's... neither indicates what should flow through either socket, but I have always assumed the amp outputs line level and the amp expects line level in... could I be wrong?

No, I would think the same as you do! But I do not think it is a matter of intervention. Somehow your amp and sub do not match. Is there a way you can try another amp? One you could borrow for example? This issue can be solved by trial and error, I expect. Or of course some Einstein , has to come up with a solution :)

I cannot easily try another amp - nobody at work is into this sort of thing and will not therefore be able to lend me anything... quite annoying really! lol

I'd like to know how my amp and sub are mismatched, if you know what I mean... maybe I should phone the manufacturers of each...

Good idea. Maybe the manufactories can tell you what the problem is. And who knows, they have a solution as well!

Good luck and keep us updated!