Subwoofer starts playing randomly even with receiver off

hifigal

Can anyone tell me what could make a powered sub start playing randomly even with the system off? It will just turn on and start making loud noise by itself even if the rest of the system is off. Sometimes it happens in the middle of the night (which wakes up everyone in the house).

ViperZ

Your subwoofer is in stand-by mode, not OFF, there should be a switch in the back somewhere to physically turn it OFF. If the subwoofer 'turns on' in the middle of the night (i.e. it wakes up from stand-by), it means the amplifier in the subwoofer is broken and will require repair. Turn it off and unplug this subwoofer. It is unsafe to keep it in stand-by like that. There are cases like that with older JBL subs (i.e. PB12), which would do that exact thing, then they would catch fire.

hifigal

The sub is in auto mode so it should turn on when it senses a signal. It does do that, and it plays fine. However, it also randomly turns on and starts playing when there is no signal being sent by the amplifier. What is making it do this?

EndersShadow

hifigal wrote: »

The sub is in auto mode so it should turn on when it senses a signal. It does do that, and it plays fine. However, it also randomly turns on and starts playing when there is no signal being sent by the amplifier. What is making it do this?

Perhaps its picking up signal from a ground loop in your system. Do you have cable or satelitte TV and is that cable close to the sub's RCA cable?

jaritta

I think I would try replacing the cable from the reciever to the sub first. If there is a loose connection or bad spot in the wire it can cause a ground loop hum which would bring the sub out of stand by mode into active mode when there is no signal from the reciever.

I think I would replace the cable before I sent the reciever off for service.

just my .02

MADGSF

To expand on jaritta and EndersShadow's idea how about just disconnecting the cable from the sub, the one from the receiver that sends the signal. Then leave it like that for a few days with the sub in stand by mode and see if it comes on during the night. That might point you in the right direction.

zxasrt69

I have same problem sub came on at 3 am and it was loud and was humming had to unplug it

gurot1

I had my computer speaker sub do that in the middle of the night. It turned out to be the wire connecting the computer to the sub that was the culprit in my case

VR3

Skynet