Axiom Home Page Forums General Discussion Technical Questions Humming coming from subwoofer

Can anyone help me out here? I have a sub that's about 5 years old. I bought it used, but optically and technically it's in good shape. However, no matter where I plug it in, it hums. It's not that loud, but noticeable. It even hums when I unplug the input from the receiver. It has a standby mode when plugged in but not turned on, and it even hums then. I've ruled out a ground loop problem, by bypassing the ground part of the plug.

I've also tried plugging it in in various outlets, but with no change. Is it possible that the transformer inside the amp is simply this loud?

The brand is Elac. A german company. This little 8" sub cost about $550 new, and Elac is a respected company here, so I don't think it's just a piece of crap. I wonder what the deal is.

I would appreciate any input.

Thanks!

As it is humming with nothing connected I would say it is a problem with the amp and it is picking up noise coming off it`s own tranformer or power supply.

Are you still living in Germany, or are you back in the states now? Maybe it is a voltage issue, but I'm guessing it would not work at all then.

I see Elac took the Rubiks cube sub to market......

http://www.geekalerts.com/rubiks-cube-subwoofer-from-elac/

Yes, well with the receiver connected, it hums too. It's just not noticeable until there's a pause in the music....

The noise doesn't come from the transformer itself, but rather from the speaker.

Usually if it only hums with the receiver connected to it then it could be traced to a ground loop back to the receiver but it still makes noise with nothing connected which is why I say it is the amp which really is the only other possible choice.

What Jay is saying is that since it hums when nothing is connected except the power cable (you've ruled everything out), then it is the amp. The noise you hear from the subwoofer driver is from the internal amp.

Barkeep, as Jay and Randy have pointed out, if it hums even when no other connection other than the power cord exists, it can't be a ground loop hum because there's no connection to form a loop. That points clearly to the internal sub amp itself and since it isn't a mechanical hum from vibrations in the transformer, but an electronic hum coming from the driver, there appears to be a fault in the power supply section. The rectifier and filter capacitors do the job of converting AC from the wall outlet into clean DC to be used by the amplification section. It's likely that the rectifier or a capacitor is going bad and needs to be replaced if the hum is too annoying.

Hmm, that's a new and interesting perspective. Thanks. Now if I only knew which component(s) to change out. There are two big caps at 6800 uF, and some other components. Here's a pic. Is there any way to test the components to see which one(s) need to be replaced?

Are you familiar with working with circuit boards?