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Subwoofer Interference, Popping

Discussion in 'Speakers' started by Stiffy, May 4, 2010.

  1. Stiffy

    Stiffy Well-Known Member

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    I have a new SVS 12" cylinder sub,It is connected to my AVR with a Belkin "shielded" sub cable. I have a dual dimmer switch for a ceiling fan/light. Only when I use the fan side of the dimmer switch (fan speed) I get a loud pop from my sub. This is very startling, and I am afraid not good for the sub. The fan and light are on a separate circuit from the one my sub is connected to. I also have the sub powered through a surge protector. I have changed out the fan switch as it was mentioned this might be the cause. It didn't help. Is this damaging my sub? How do I fix this? Thanks for any help,
    Chris
     
  2. Robert_J

    Robert_J Well-Known Member

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    It depends. Is the driver's cone moving enough to make a metallic popping noise? That would indicate that the voice coil is hitting the back plate of the motor (magnet). Even if you don't hear anything, the cone could move out far enough that the voice coil leaves the gap and gets hung. It's difficult to tell whether or not it is dangerous or just annoying. Also, which driver do you have? Each has a different amount of excursion. Moving 15mm for a PCi driver is approaching the danger range while it would would just be annoying for a Plus driver. It wouldn't even both an Ultra driver.
     
  3. Stiffy

    Stiffy Well-Known Member

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    Robert, This is not what I would call a metallic noise, sort of a very quick brup. I have been told by an electronics friend of mine (who is in a band and also handles the PA) this is a "harmonic RF emission" from the switch that is being picked up by the sub, harmless as long as the emission is not to high a frequency? I am talking over my head, from memory and may be omitting some things. As far as the driver is concerned the sub is SVS PC12-NSD. I have contacted SVS today but have not herd back from them yet. Just trying to pool my resources so to speak. Thanks for any help you can provide,from reading other posts I understand you are very informed in this area. Thanks again,
    Chris
     
  4. Robert_J

    Robert_J Well-Known Member

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    If it is RF (radio frequency), it should happen when your sub cable is unplugged from the receiver but still plugged into the sub. Just try it. I'll bet it is caused by your electrical system though. Does your sub have a 2 prong or 3 prong electrical plug? If it is 3, you might want to try a 3 to 2 adapter to lift the ground. I know that a LOT of people will tell you not to do this. If it were dangerous they wouldn't sell the adapters at Wal-Mart.
     
  5. Stiffy

    Stiffy Well-Known Member

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    The sub is a 2 prong plug, no ground prong. Does not do it with sub line out unplugged at AVR and all systems on. Next step to isolate the AVR power source?
    Chris
     
  6. Stiffy

    Stiffy Well-Known Member

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    Isolated AVR power source (dedicated circuit) still have the problem???........... Gremlins!!
    Chris
     
  7. Robert_J

    Robert_J Well-Known Member

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    Even though it is on a dedicated circuit, it may be on the same leg of the breaker box as the switch causing the issue. I know it is a pain but can you try a different circuit that is on the other side of the breaker box. It may require a heavy duty extension cord to get power from a different room.

    I'm running out of ideas.
     
  8. Stiffy

    Stiffy Well-Known Member

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    Robert, Sorry about the delay I had a pretty intense work schedule last week and could only get to the sub today. Tried a different leg (other side) of circuit breaker. I tried separately as well as together powering the sub and AVR...still pops also tried leaving sub powered, and unplugging the line out from the AVR to see if sub cord was picking up the interference (suggested by SVS) ....no pop, cord is good. This fan switch is a slide switch (I believe called a potentiometer) I think my next move is to install another type of switch or after market remote for the fan that has three separate levels ( no slide) as it seams to be the "sliding of the switch" that generates the interference, fan at level is fine. I have even been able to hold the fan switch between levels and prolong the interference. What throws me off is the light side of the same switch has no problem at all??. Thanks for your help

    Chris
     

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