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Does the buzzing come from the speaker cone itself, or does it sound like a mechanical buzzing from inside the box, like a buzzing transformer perhaps?
Occasional a Force XL or Titan XL will develop a slight mechanical hum. The windings on the transformer have heated up and cooled down and have shifted ever so slightly and now are causing the hum. It is simple to eliminate the hum. First, unplug the amp and let it set 5 minutes to allow all the energy stored in the capacitors to dissipate. Remove the six screws that hold the amp to the cabinet. You will notice that the round, torroidal transformer is held in place by a bolt that runs through the middle of the transformer and is terminated with a Phillips head in the middle of the heatsink area on the outside of the amp. You will need to loosen the nut with a wrench while holding the screw with a Phillips head screw driver. With the nut loose, rotate the transformer about 1/4" to the right or left and tighten the nut down onto the transformer. Secure the amp back into the cabinet, plug it in and you are ready to go.
Mike, do you think it could perhaps be DC on the user's AC line? I've read this can cause intermittent transformer buzzing (mechanical), I recall PS Audio sells their UPC-HB that they say fixes this problem with transformers. What do you think - would such a thing even be a possibility with the Force XL?
Quote from: NewBuyer on 5 Dec 2006, 08:47 amMike, do you think it could perhaps be DC on the user's AC line? I've read this can cause intermittent transformer buzzing (mechanical), I recall PS Audio sells their UPC-HB that they say fixes this problem with transformers. What do you think - would such a thing even be a possibility with the Force XL? I would agree that this is definitely a possibility. I've noticed that my pair of Force subs (which I believe are electrically identical to the Force XL) sometimes exhibit a slight buzzing from the transformer and not the driver, as far as I can tell. It only occurs during certain times of the day and more frequently during the summer when everyone's AC is running. It is also clearly evident when my wife is upstairs drying her hair ... this drove me nuts diagnosing the problem as the buzz kept coming on and off before I realized it was linked to the hair dryer.The buzz always emanates from both subs, not one or the other, which further indicates that it is not a transformer problem but a mains line issue.BTW: In addition to the PS Audio UPC/HB, diycable.com sells an RFI/DC filter that should also remedy this problem. I haven't tried it yet, but may pick one up in the near future after I've completed a few of the other projects I've got sitting unfinished.http://www.diycable.com/main/product_info.php?cPath=21&products_id=536