Axiom Home Page Forums General Discussion Home Theater Subwoofer hum

How loud is the dreaded hum ? And at what volume does it usually show up? I just got my Hsu VTF 2.3 today and it sounds fantastic, but... I fooled around with the volume knob and noticed it begins to hum noticeably at 1:00 and beyond. It is not real loud, but when all else is off and quiet it is audible. Is this the ground loop problem? I do not have the cable coax going into the receiver. Maybe a noisy AC line? Maybe defective sub? The sub just by itself makes some hum but much lower in volume -- with the line in connected it is louder but not audible until 1:00 on the dial.
Any thoughts here would be appreciated?
Thanks
MArk

Not familier with that sub but the Axiom EP500/600 have a ground screw on them to help with hum.

I think I read a post by Alan Loft that if the sub hums with no line connected, there might be something wrong with the amp in the sub.

http://www.axiomaudio.com/boards/ubbthreads.php?ubb=showflat&Number=187452#Post187452

No ground screw on the Hsu. Could be a ground loop but it sounds like you have the gain way to high? Have you calibrated the Hsu with the rest of the system? Most Hsu owners find somewhere around 9 to 10 o’clock is about the highest the amp should be.

Mark, as the others have indicated, if the hum occurs without being connected to other equipment, a ground loop can't develop. If it's a faint hum it may simply be that the noise level of the sub amp is audible at that high of a setting but wouldn't be audible in normal use. If it's louder than that it might indicate a defective sub amp.

You are exactly right, the best setting for me is around 10 and there is no audible hum either connected to the recevier or not. I only noticed the hum when it is turned way up -- and not in use since that would knock some walls down...But the hum is a little louder when connected to receiver (again only at the higher amp levels (>2 clock)

I guess I was curious to know if the humming at high amp levels is normal?
BTW - the hsuforum does not cover much of this stuff which is why I am relying on you guys -- thanks for being patient with me.

No they don't see as much traffic @ the Hsu forum as they do here. The people here are a lot nicer too

That's why I keep coming back

In my experience with subs, humming at high amp levels is "normal". I don't know why amplifier manufacturers have such a difficult time rejecting power line noise.

I don't find that to be the case. Sounds like you might need a line conditioner Tex.

I emailed Hsu support yesterady and explained my situation. They responded to say that the hum at high gain levels is normal. It was attributed to the tremendous gain that the amps have. He recommended that I use the 9 o'clock position for the sub volume -- which works fine as there is no hum at all at this setting -- and it sounds fantastic.

FWIW -- It just seems weird that they would design a piece of equipment not to be used for 2/3 of the volume range. If you can't really use the full range then why have the knob able to access it. It would be like having a speedometer that goes to 300mph when most cars can only go 130 mph max.