Audiosource Subwoofer "hums" after receiver goes off

[jamesm113]

First time post, so go easy.

Here's the deal - my subwoofer hums after the receiver powers off. If the receiver is on, there is no hum

Receiver: Pioneer VSX-820, mono sub out. 2 prong plug
Subwoofer: Audiosource SW-15. stereo RCA inputs and stereo speaker wire inputs. 2 prong plug.
Sub cable: 10 ft Monoprice RG59 w/ RCA connectors + monoprice splitter

Now I figured it would be a ground loop, so I unplugged everything on the circuit, unplugged all coax lines for cable/internet, and tried some different circuits with nothing else in use. No luck. I also tried using the speaker wire inputs and not plugging anything into the RCA inputs. The hum happened all the time.

The noise persists if I unplug the cable from the subwoofer side.

Any ideas? Thanks!!

 

[TLS Guy]

First time post, so go easy.

Here's the deal - my subwoofer hums after the receiver powers off. If the receiver is on, there is no hum

Receiver: Pioneer VSX-820, mono sub out. 2 prong plug
Subwoofer: Audiosource SW-15. stereo RCA inputs and stereo speaker wire inputs. 2 prong plug.
Sub cable: 10 ft Monoprice RG59 w/ RCA connectors + monoprice splitter

Now I figured it would be a ground loop, so I unplugged everything on the circuit, unplugged all coax lines for cable/internet, and tried some different circuits with nothing else in use. No luck. I also tried using the speaker wire inputs and not plugging anything into the RCA inputs. The hum happened all the time.

The noise persists if I unplug the cable from the subwoofer side.

Any ideas? Thanks!!

The subwoofer is faulty and needs repair.

 

[theJman]

Does the subwoofer have a standby mode? In other words an auto-on function, whereby the subwoofer will turn on automatically when the receiver sends it a signal and then go into a standby mode after the receiver is powered off. If it does, how do you have that set?

 

[jamesm113]

Does the subwoofer have a standby mode? In other words an auto-on function, whereby the subwoofer will turn on automatically when the receiver sends it a signal and then go into a standby mode after the receiver is powered off. If it does, how do you have that set?

Yes, and it goes into standby mode after a couple minutes

 

[j_garcia]

Since it hums with no input then what TLS said is correct. Start looking for a shop to repair it or a new sub.

 

[theJman]

Yes, and it goes into standby mode after a couple minutes

Does it hum in standby as well?

 

[jamesm113]

Does it hum in standby as well?

Once it goes to standby, there is no hum. However, it takes a few minutes to switch over after the signal from the receiver is turned off

Since it hums with no input then what TLS said is correct. Start looking for a shop to repair it or a new sub.

I can do some basic circuit repairs... any common problems I should look for? I do like the sub and would like to keep it

 

[theJman]

Once it goes to standby, there is no hum. However, it takes a few minutes to switch over after the signal from the receiver is turned off

I gotta agree with the others at this point; it does sound as though the amp has a (potentially) fatal issue. There's really no generic fix for amps, so without the schematics I don't know if there's much you'll be able to do. Is it very old? Maybe the manufacturer can provide some insight.

 

[j_garcia]

You might be able to get a schematic from Audiosource and that may help troubleshoot it. It sounds like a failing capacitor, which is a common fail point for older amps. I think you might check with Audiosource and see if they can just get you a replacement amp.

 

[jamesm113]

It's an older sub, I think around 1999 or 2000. Did some simple mods on it and I am quite happy with the sound.

I'll see if I can get a schematic/replacement amp from AudioSource.

I actually looked for some bad caps last night. Saw a couple questionable ones.

 

[jamesm113]

Here is the picture:

 

[theJman]

It's certainly worth a shot. Cap's aren't supposed to have boogers on their legs.