Question about Sunfire True Sub MK II Subwoofer

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Sunfire Mk II hum (different from greekboy post)

My sub will frequently produce a fairly loud hum, it seems to happen most often when it is called upon to deliver some truly loud low-frequency sound effects. I can make it stop only by unplugging it then powering it up again, but the next time it does some loud work, the hum is likely to return. I have tried making sure the power cord is grounded, and also tried floating the ground. Doesn't seem to make much difference. Ideas?

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  • soothsayer May 11, 2010

    My hum is the same. When a loud commercial with deep bass comes on at 3 to 6db louder than the program the sub keeps humming for about 5 min. then stops and plays normal until the next commercial break. I opened it up but unfortunately no visible wires loose. Dylan could you describe where the ground wire was? It works so good other than this problem I would hate to have to spend $450 to send it to Sunfire (ripoff).

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A reply to Soothsayer's request for clarification: My hum starts as a result of a loud, low-frequency "use" of the sub....but the hum does not seem to go away by itself, even hours later. I have not yet had the chance to access the sub's innards and try Dylan's suggested fix, but it gives me hope. I agree that Sunfire's repair fee seems excessive. Best of luck, let me know what you find?

Posted on Oct 01, 2008

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I had this issue a few years ago and the power cable from one of the inner terminals had come loose. It was still touching but whenever the sub would really pound it would jump off the connection and then reconnect causing it to hum. It was the most annoying thing ever so I finally pulled off the amp plate (super easy) and you could clearly see the loose wire. I had to use a good soldering iron to put it back on since it's a pretty fat wire. If you're not under warranty anymore then pop the back off and see if that's the issue.

-Dylan

Posted on Sep 25, 2008

  • under2x Oct 12, 2010

    I just got a blown mk2 from a friend. After replacing the speaker, I tried everything to get rid of this hum... It would occur when listening to a movie or music and was very intermittent. I tried an adapter to remove the ground, even a power conditioner etc etc. Nothing worked until I found a post about tightening the volume pot. I tried it today and it worked! I can't believe it, it didn't seem loose at all but I popped the knobs off and tightened the nuts holding the volume/crossover/phase pots and it totally fixed this problem.

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