Hi

I have a vintage axiom subwoofer (model ax500a).

It works great, with the exception that it makes a humming noise. I's not very audible, but if the music or movie i'm watching / listening has a quiet moment you can hear it.

I don't think it's a grounding issue. The symptoms sounds very similar to this posters problem :

http://www.axiomaudio.com/boards/ubbthreads.php?ubb=showflat&Number=276702#Post276702

except my sub is an axiom.

I'm hoping someone has some experience with the internal workings of this sub and can let me know if an easy repair is possible.

Thanks

First you need to do some diagnosing and truly eliminate a possible ground loop. Start with just the sub turned on and nothing connected to it, does it still hum? If it does then the problem is most likely in the sub's amp, if it doesn't hum then you quite possibly have a ground loop problem and usually the subs cable or TV cable or similar feeding one of the components is the problem and removing a cable one at a time with the sub connected will help you find the culprit.

Also check out this article from Axiom for a bit of troubleshooting advice.

Sorry, i thought i was clear with my post.

It's NOT the round loop from the power plug, or from the receivers signal. If i disconnect the sub but still leave it powered on the hum is still there. It's a consistent buzz.

From this i assume it's a problem with the subs internal amp.

Is this an easy fix?

Rui, yes your reference to the previous thread indicated pretty clearly that a ground loop wasn't involved. The same answer as to what caused the problem that was given there would apply here. As to how easy the fix would be, although I have no knowledge of the AX500A, presumably the rectifier and capacitors are standard parts which are readily available. Still, someone with the necessary diagnostic equipment to determine exactly what needed to be replaced wouldn't likely charge less than about $100 for parts and labor.

Thanks for the response JohnK

I guess i now have to decide if the hum is annoying enough to spend $100 to fix. Not quite sure.

I was hoping that since it's an axiom sub there could be a step by step or instructions on how to fix it.

I'd try emailing Axiom itself; most of us here are enthusiasts.

my 350's have a very quiet hum, but I have to get real close to the amp to hear it.

On your 350s does the hum come from the speaker or the amp? If it is from the amp itself, it could be transformer hum from harmonics in your electrical supply. There are sine wave regeneration products out there that may clean it up, but the cheaper ones use stepped sine approximations which may have just as much trouble. Of course since you can't hear it from any distance, you may just not care.

I will have to check, I think it is from the amps, but not totally sure. The only time I hear it is when the room is dead quiet, and I put my ear way down by the sub...