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Old September 17th, 2014, 6:18 PM
Dubious Dubious is offline
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VTF2-MK2 making noises even when not connected

I understand that my sub may be older and out of warranty, but I figured that I would ask anyway.

If I simply plug the sub into a power source (with no audio source connected) and have the power switch to either AUTO or ON it will stay powered up and emit a slight pop/thump/hum continuously, maybe 3 times per second if I had to estimate. It is audible in a quiet room from about 10-12 feet away.

I originally thought that it was a bad LFE source cable or interference but if I move the sub to the middle of the room and power it on with no audio source it still occurs.

I'm assuming that some circuitry in the amp has gone bad after all these years but I figured that I would ask before taking any drastic measures. The sub still plays fine when source material is provided but never shuts off in AUTO power mode and continuously emits slight pops/thumps/hums even with no source connected. Granted, it is slight but I am a perfectionist so I want to troubleshoot these things.

Thanks for any reply that may come.
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Old September 19th, 2014, 6:21 AM
pr@j pr@j is offline
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It could be line interference from the AC outlet, have you tried a different power outlet? Try an outlet on a completely different circuit - ie, if you normally use it in basement, try an outlet that is upstairs on a different line - it could be interference.

The other likely source, could possibly be a grounding issue in the cable, with no source material going to the sub it could be:

a) the sub output on the amp
b) could be the cable
c) could be AC voltage interference (ie almost like a ground loop interference)
d) If the sound is random hard to say, but if there's a pattern to it, could be your receivers output.

e) Try just plugging ANY RCA audio output from your RX into the sub and , and see if the sound disappears - if it does, there's the issue.

f) If in step e) it remains, then the source is in the sub AMP likely - again, could be anything in the amp, worn out transistor, loose connection on the coils in the amp.

g) if it never shuts off, the sub THINKS its receiving a high enough signal from your amp to stay on.

h) it could be just DUST in the RX - try cleaning it out, never know...dust can also cause crackling on the connections - had a similar issue on my VOLUME knob of my RX - every time I turned it, would hear crackling on all speakers...I think they cleaned it first, helped a bit, but turned out to be a defective POT.

Try these and let us know, you have to go through a process of elimination.
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Old September 22nd, 2014, 3:09 PM
Dubious Dubious is offline
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I moved the sub to another room on another circuit. I let it sit for a couple of hours and it still never powered off in AUTO mode with no source connected. It still made the same subtle noises.

So it's pretty much something with the sub amp itself. The thing is that it still plays when connected to source material so now I have to decide if I want to live with it making noises when nothing is being played through it or shelling out for a new sub. $600 is a decent amount to pay to get rid of an annoyance.

Maybe I'll take it apart and clean all of the connections just for grins and giggles and go from there.

Thanks for the extensive reply.
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Old September 25th, 2014, 6:59 PM
Kevin_Hsu Kevin_Hsu is offline
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Hi Dubious,

Sorry to hear that! If cleaning the connections does not help, please call in to our office. We do have some options for you in terms of repair, upgrade, etc.
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