Axiom Home Page Forums General Discussion Advice from Axiom Owners Long Time

Howdy Fellas! I haven't been on in quite some time. I dropped in to ask about my 500. It has a continuous sound emanating from it even when everything is off. I guess the best way to characterize it is very low volume and it sounds like the hum of distant machinery - like something running in your basement. You have to be right in front of it to hear it - or I noticed that you can hear it in the corner. Anyone else encountered this phenomena?

Does the sound go away when you unplug the coax cable and just leave the AC power plugged in? Is it a low rumble bass sound, or more of a hum like a transformer makes?

I think the the humming is possibly pointing to a amplifier that is on its way out. That is one of the first symptoms. I wouldn't leave the sub on standby either until you know for sure what the issue is. It could start making popping noises and then blow (make a big sound) all together which could startle the whole the house especially at night.

Humming can also come from a ground loop which is fixable but they just don't magically appear and the humming is usually present when the HT is on. Ground loops usually come from adding new equipment, cables, room lighting or moving all the equipment to a different part of the house.

My 600 used to make a low rumbling sound that I could hear upstairs, I have to unplug the sub for a few minutes and then it goes away.

The simplest troubleshooting would be to disconnect the sub from your system completely and just have the power cord plugged into the wall and sub with the sub power switch to on/standby. If the hum is still present you need a new amp.

If you haven't already, you could also try removing the grounding screw on the back of the unit.

Ground screw was removed long ago to stop the ground loop hum. The sound does not stop when I unplug the sub cable. The only way to stop it is to turn it off or unplug it. The sound is a lower sound - not like a 60 hz hum. Difficult to describe. It is like the sound of machinery operating far off in a big building. Like background noise. Correct me if I am wrong, but it should be silent when nothing is on? At any rate this is my third amp on the 500.

Hi Argon,

Try re-installing the chassis ground screw which you have removed awhile back. Don't hesitate to dial Axiom's toll free number for assistance. I'll be back on duty tomorrow (Monday) at noon until 8:00 ET.

Hey JC,
I reinstalled the ground screw but it did not stop the hum. I should be free around 4:00 pm ET. I'll call around then.

I recall that you had amp problems in the past, was hoping it was resolved.. Have you tried different outlets, or one on a different circuit just as a test?