I send this to SVS support, but thought that I would run it past the "pros" here.

Here is what I sent them (with some modifications)...
I bought my 20-39 PCi sub back in November of last year (when I bought my awesome Axioms), and I just love it!

I have a question though. Last night (actually early this morning around 6AM) for no apparent reason, I was woken up by a loud, low "hum" (not low grounding loop hum) but like something was sending a VERY loud, low test tone to the subwoofer. My sub is in my basement, and we have a 2 story house. It was enough to wake me up, and when I started going down to the first floor, I could actually FEEL the bass. Not that feeling the bass is unusual, but when the system is off, it sure was odd.

I made it to the basement and turned off the sub right away (it was on Auto) I checked everything, and the crossover on the sub was set at 80, the volume as at about 50%. The receiver (a Pioneer Elite VSX-54TX) was off, and there seemed to be no reason for the bass to kick in.

Even though I bought the sub (and actually all equipment) in November/December 2004, I didn't use them regularly until about 2 months ago when I finished my home theater. I am using good quality wiring and have never had anything strange like this happen before.

Any ideas? Anything I should check? I really don't want to have to turn the sub on and off every time I watch a movie, but right now that looks like the only sure fire way to make sure I don't damage the sub.

Nick, I've heard that emergency hot-lines have gotten calls like "Help! I can't hear my sub!!", but your situation is a new one on me. I doubt that even Tom at SVS can help in this case and I suggest that a priest be called in. Seriously, even when the sub is set on auto, a voltage of a certain amount has to be input to "wake up" the sub amp. If someone there wasn't playing games with you it's hard to figure where the power came from. If Tom or anybody at SVS has a reasonable idea, tell us about it.

You know, your story is kinda creepy. I'm with JohnK--call a priest.

not just one priest 2 an old one and a young one.

I had a pair of Definitive Technology speakers with a built in amp that used to do the same thing.I had to send them back to get the amps replaced.

My 20-39PC+ started doing the same thing about a month after I received it. The amplifier assembly had to be replaced -- SVS suspected the power supply. I switched on and off manually while the new amp was being shipped out.

Replacement was a no-brainer and no problems since. Here's the patient in the middle of the operation :

I was thinking very seriously about using an SVS 25-31CS with my plate amp, but the Wife made some comment about placing the new sub out in the utility room next to the other hot water tank....

You would still get pretty good bass...

No response yet from SVS, but it is the weekend, so I am not expecting anything until Monday sometime.

Hopefully they will have a solution for me and it will be under warranty.

Yeah! That's true!

I hear the bass quite well now while in the shower, it would be even better with the sub near the actual water heater!!

Tom from SVS has me doing the usual. Use a different cable, try a different outlet (actually my idea), but of course if the problem was a pure fluke, I am wasting my time. Of course, if the sub does it again, then it localizes it (somewhat) to the sub or the receiver (which is powered of... OK, in standby mode like all receivers).

This could be a long process until the problem happens again...

I just thought of a possible cause for your problem. I have a small powered subwoofer attached to my computer. It has an auto on/off signal sense feature, just like your SVS.

I occasionally notice that it is on even though my computer is off and incapable of generating a signal. I've been able to track this "phantom turn on" issue to two causes.

1. I have a halogen desk lamp plugged into the same power strip as the subwoofer. When I turn the desk lamp on, it triggers the sub to turn on, as well.
2. I often leave my cell phone on my computer desk. If my speakers are on when the phone communicates with the cell network, they pick up the signal and I canhear beeping noises through the speakers. The cell signal also triggers the sub to awaken and make noise.

Does either of these causes match up with your situation?

>>Of course, if the sub does it again, then it localizes it (somewhat) to the sub or the receiver (which is powered of... OK, in standby mode like all receivers).

In my case the problem only happened when the sub's amp had been powered up for a while... I heard it after the receiver was switched off but the sub's auto-on was still on for 15 minutes or whatever the time is.

I was able to repro more quickly by leaving the sub powered on (rather than auto-on) after checking with SVS that it was OK to do so.

Sounds like a different problem though, mine was more like what you would get if you crossed... well, maybe a canary with a subwoofer. Very low frequency chirps

In response to:

Poster: pmbuko
Subject: Re: (Do I dare?) Wierd SVS thing..

I just thought of a possible cause for your problem. I have a small powered subwoofer attached to my computer. It has an auto on/off signal sense feature, just like your SVS.

I occasionally notice that it is on even though my computer is off and incapable of generating a signal. I've been able to track this "phantom turn on" issue to two causes.

I have a halogen desk lamp plugged into the same power strip as the subwoofer. When I turn the desk lamp on, it triggers the sub to turn on, as well.
I often leave my cell phone on my computer desk. If my speakers are on when the phone communicates with the cell network, they pick up the signal and I canhear beeping noises through the speakers. The cell signal also triggers the sub to awaken and make noise.
Does either of these causes match up with your situation?
_______________________________

Mine happened in the middle of the night with no lights on, nothing "powering on or off" (my computer subwoofer makes a click sound when I turn on or off the lights in the room that it is in since it is on the same circuit, so I know what you mean there). It is just so strange. The house was just quiet, and then the low freq rumble (not hum) that was loud enough to wake me up 2 stories above it....

Does anyone in your area have an arc welder?
I had a similar thing happen with my old sub where I use to live.
Turned out it was caused by a guy 2 blocks useing a welder.

Hmmm... Arc welder... Don't know, to be honest. They would have to be more than a couple of blocks away from where I live if that was the case. While I am not 100% positive, I am pretty sure that nobody in our subdivision has one, but maybe it is some other power drawing equipment. It was pretty early, but just like I like to stay up late, I know others like to get up early.

I'm not one of those people.

The up early or up late?

Ask any of my XGFs.
I am not a morning person.
9.00A.M. and I'm ok, any earlier....... make sure there is GOOD coffee.