Small spaces and equipment hummmm

[the-chauffeur]

Hi folks. Newie alert

I've just joined you, although I could've sworn I've been here before. I've had my Aerius I's for a few years now, and with a mostly Musical Fidelity set-up, everything has sounded wonderful. That is until I moved to my current abode...

Living in the UK, space is at a premium, and as a dedicated listening room is a luxury I'm never likely to be able to achieve, my system shares the living room with the usual furniture and grey boxes like the TV. It's a square space, about 12' x 12', with two leather armchairs at the sides, and a three-seater sofa facing the speakers/hi-fi/TV and the walls are painted. The speakers are towads the corners, and are basically in line with a REL Strata II, 36" CRT TV and the hi-fi rack (isolated shelves).

The problem I seem to be plagued with right now is hum. Equipment hum, to be precise. How do I know? Well, I've done some searching and rearranging. To make life easier for myself, I've isolated the electrical circuits feeding the 2-channel audio circuits from any others. And most of those run through a line conditioner.

For the most part, the remaining circuits are switched off when I'm listening to music. So, when everything's quiet, and with only the sources and speakers powered, I can hear a low level hum. Not hugely invasive, but when you're used to absolute quiet, it's very irritating (I've got enough mild tinitus already without additional noises to contend with ).

My first thought was that the mains was contaminated, but having switched each component on and off, it's clear that the mains isn't the problem. The biggest contributor by far is the sub. I took it to a local dealer and put it in one of their isolated demo rooms, and the diagnosis was that the hum eminates from the transformer board. They assured me it wasn't faulty - it's just that being an older sub, the board/chasis isn't particularly well insulated. Checking back over the rest of the system, the amps in particular put out a much smaller hum, which on its own would fade into insignificance but with the sub, it adds to the background noise.

What I'm wondering is how you guys with smaller rooms deal with any equipment hum? I've tried dispersion material behind the hifi equipment, but it's not really improved much. I've also tried switching off all the other electrics in the house (yeah, fridge-freezer too) just to be sure. And of course it's not a problem when watching movies - but I want more music. Trouble is, I have a nasty feeling I've either gotta get used to it or buy a new-er sub.

Any pointers, suggestions or solutions would help greatly. And I'll try to get a photo up in the members section PDQ.

Thanks in the meantime.

Neil

 

[nsgarch]

I'm not clear if you're talking about airborne hum (mechanical) or electronic hum (coming thru the speakers) or both? And thank God your folks knew how to spell!

Neil

 

[the-chauffeur]

Hey Neil

Uhhhh, I think it's mechanical - insofar as it's not coming through the speakers and is present even when they're switched off.

Does that make any more sense?

Other Neil

 

[nsgarch]

Mechanical is a lot easier to deal with. Most likely a transformer, but could be something else. Turn on all equipment and remove tops or covers where not too difficult. Get a tank vacuum cleaner hose or a long cardboard tube (like from a roll of paper towels or longer) and hold one end to your ear while scanning your components' transformers with the other end. If it's mechanical vibration, it will reveal itself quickly. Then it becomes a matter of eliminating it. But see if you can find it first.

 

[SteveInNC]

Auto mechanics often use a stethoscope to isolate the specific source of a noise (and inside an engine compartment, there is alot going on). Nsgarch's suggestion of using a paper towel tube is a good one, and has the added benefit of being non-conductive, in case you touch something electrically live. A small rubber hose is another alternative.

If it turns out to be a vibrating transformer, you might be able to mechanically isolate it from the sub chasis using rubber grommits at the mount points. You'd want to put them on both sides of the flanges that the mounting screws pass through.