When I turn on my Cambridge Soundworks 12S sub, it makes a very loud pulsing sound, regardless of the output level, regardless of whether I have the receiver sub cable plugged into it or not. It does not matter what outlet I plug into in the house. In the past, it has worked just fine and only when I hadn't used it for a few months, then turned it on (either full on or on auto), did it exhibit this. Don't think it's a ground loop problem and it hasn't blown a fuse yet - but I don't leave it on for more than a couple of seconds. Our dog really hates it.

It's out of warranty and CSW folks only tell me to ship it to them and they'll fix it for some undetermined amount of money. I'd take a shot at fixing it myself if anyone has info on how to get replacement parts and directions for installing.

Interesting that I just got the small CSW basscube 8 as a refurbished item.Out of the box it hums everytime it turns on.The hum has nothing to do with outlet,Ive tried 3 different ones and it has nothing to do with cable since I have direct tv but its not hitched up in the room I have set up with this sub which is only to watch dvds on a pioneer plasma.
Very frustrating since I have read other reviews online complaining about this CSW sub hum.Yours seems to have started after a while of usage which is very strange.Im really not into paying return shipping to get rid of this,hoping someone out there has a cure for this hum.If Cambridge told you they can fix it then they must have sent me a broken one?

My case is that the only sound it will make is the pulsing buzz - real loud too. You don't want to stay in the room with it even. Yours sounds more like an irritating low hum?

Yes it is,very irritating because my room is only 10 by 9.Sounds like yours has defective itself out of action if all it makes is a loud buzz.Mine does its job but when quiet moments show up in the material you plainly hear that awful humm.Im calling them today but the prospect of paying to ship it back might force me to keep it.

Got good news from CSW that any humming noise is not normal and they are paying shipping back for it and sending me out a new one.They asked me if i heard a slight pop when the unit powered up for thats a sign of a healthy sub.I did not hear this,only a constant hum.

Good to hear - back when mine worked correctly, it always made the little pop when it autostarted. Not so much any more. Good luck