Hi blondespot11,

First, good detective work on your part in isolating the source of the hum. You have a classic case of "ground-loop" hum,which is caused by a voltage differential between your incoming cable-box signal and the ground for the electrical system in your home.

You can get rid of it easily with one of these Axiom ground isolating transformers:

http://www.axiomaudio.com/groundisolator.html

Before you order it, you can try plugging your subwoofer and or your/AV receiver into a different electrical circuit than the one for your cable box--try a different AC plug across the room, if possible. That may do the trick. If the hum is still present, you'll need the isolating transformer, which, by the way, will pass all Hi-Definition digital cable signals (and analog video too) with no degradation. It has a bandwidth up to 1.5 Giga-Hertz. If you're interested, here's a detailed article I wrote on ground loop hum troubles and how to remove them:

http://www.axiomaudio.com/tips_eliminate_hum.html

Regards,

Thanks for the quick reply. I just got a call back from Jean Claude from the Axiom desk. He also pointed me to the isolator. I have tried plugging my subwoofer into another outlet with no luck so I went ahead and ordered the isolator. I will let you know what happens once I get it.

Ok. I have received the ground isolator and it cut down the hum significantly, but I still notice a faint hum. When I unhook the cable to the subwoofer there is no hum at all. I have the EP350 v2. Are there some setting on my subwoofer that I should change?

1. Does this isolator that you bought require a ground connection? If so, did you ground it?

2. Does the hum go away when you turn off your amp?

3. Try turning off all the lights and see if your hum goes away. If it does, your sub cable is picking up radiated noise from your lights. You could then try a cable that is more heavily shielded.

does the 350 have the ground screw on the back of the amp chassis like the 500/600 do? If so it is something Axiom has advised you can try (removing the single screw). Check your 350 manual for mention of it, or someone else here can confirm.

Good luck.

I was thinking the same thing Dave. However, if you check the product page for the 350, the picture of the back does not appear to have a ground screw.

Also, to the poster, what type of cable are you using to the sub?

I went thru the same thing, except I solved it in reverse order. Chassis ground on sub first, then the axiom isolator. All the hum is gone, but on weak cable signals I get weird lines in the JVC with every bass hit. Not a problem on HD feed from the cable or DVD (optical), but strange still. I've got the power lines separated from signal lines as best as possible, and using XLR cables from the pre-pro. I'll eventually get it cleaned up... but at least it doesn't hum.

Scott

You are correct, there is no screw to remove on the back of the 350. I ended up just going to Radio shack and getting a ground isolator RCA cable. I hooked that up to my subwoofer. I am now happy to say that I am hum free. Thanks to all who replied.

Jonah, apparently there were two sources here for the ground loop hum; the more significant one came in through the cable TV connection and was eliminated with the Axiom cable TV isolator. Another was coming in by way of the subwoofer power cord and this probably was the RadioShack item used to stop that. One of the cables would be plugged into the low-level sub input(or the receiver sub out, if more convenient)and the other side of the same color cable would be connected to the regular sub cable with a RCA coupler.

I'm curious how this Radio Shack isolator works. Is it a 60 Hz notch filter? If so, that can't be great for bass.