My Sunfire True Sub Won't Stop Humming!!! - Technology Forum - Home Theater, Computer, Televisions, Personal Electronics and more!

ITRocks · 07-28-2006, 08:07 AM

I have tried everything I can think of with this thing. I have tried grounding it, moving the sub cable away from the ac lines, I've tried changing the polarity of the ac input, and I tried moving the sub to another outlet.

Someone please help, this thing is driving me up the wall!

Thank you in advance,

TechBoy · 07-28-2006, 08:08 AM

Does it also hum when no input is attached at all? In that case, it's the sub.
Normally you won't need to ground the sub or a shield around the sub in an extra way.

If it only hums when an input lead is connected, it may be a ground problem. Does the sub use the same power outlet as the amplifiers (receiver) do (does)? Preferably it should.

Also, did you try connecting the sub's connection cable (output from amp/receiver) to another (spare) amp (TV or something)? Sounds terrible, but if that one hums too, it may be the cable and/or the receiver output.

Semona · 07-28-2006, 08:08 AM

I had this problem with mine once, it was a bad cable.

Cyborg · 07-28-2006, 08:08 AM

My true sub had a hum problem also. My dealer recommended a solution which has worked well (no more hum) but goes against all safety rules and i'm sure is backed by none at "home theater forum". Cheater plug. I've used it for 4 years now. No humming, but use at your own risk.

ITRocks · 07-28-2006, 08:08 AM

Thank you for the info

TechBoy · 07-28-2006, 08:09 AM

I find that odd that your sub only has 2 prongs but I believe you, really. A cheater plug is an adapter that has a female three prong plug on one end (that you would plug the sub into) and a two prong male plug on the other. It works but defeats the purpose. There was another thread running around here where the guy used a cheater plug and lightning blew his SVS out.

I did a few tests with my Velo at my old house once. The sub would turn itself on when another device on the same circuit was powered on, causing it to hum slightly. I ran an extension cord down the hall to another room and it went away. I had to replace the outlet then. I thought sure changing the cable would work, it did in my case. Hmm????

ITRocks · 07-28-2006, 08:09 AM

I tried plugging it in to the same outlet as the receiver, still hums. I tried using another cable, still hums. Tried plugging it into the television, still hums. When the subwoofer is plugged in but not terminated with any connection it does not hum, when I plug the sub cable in wiht no termination at the other end it does not hum, but as soon as I plug it at the source, it hums (even if the receiver is off or even unplugged it will still hum).

I feel dumb for asking this but what is a cheater plug?

My sub has a 2 prong non-polarized plug. no ground.

Cyborg · 07-28-2006, 08:09 AM

Is it a loud hum or just perceptable? Is it accompanied by distortion? Does the driver move alot or seem to vibrate? I am no expert but perhaps the amp has gone bad?

Semona · 07-28-2006, 08:09 AM

Just my 2 cents without actually listening to it, it is probably operating normally then. You might have the gain (volume) up too high.
My Velodyne HGS 10 is of the same design; sealed enclosure, high wattage amp, large driver with high excursion, and sometimes in idle I am aware that it is on but I do have to be close to hear it. Other than that,i'm going to step aside and let the real experts here try to help.

ITRocks · 07-28-2006, 08:09 AM

no the amp is probably OK. The hum is very quiet, but like a mosquito buzzing in your ear it is very annoying.