Did I Do Something Bad?

Discussion in 'Speakers & Subwoofers' started by drobbins, Aug 21, 2005.

  1. drobbins

    drobbins Screenwriter

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    I was working on setting up my BFD on my JBL SUB160. I used downloaded test tones and the sub's volume is set about 1/3. I guess that setting was too high to begin with. It blew out two wall light bulbs and one recessed ceiling bulb! :b After a few minutes I started smelling an electrical meltdown smell. It definitely was coming from the sub. [​IMG] I have a few questions:

    1. Did I damage the sub or was it just "warming up"? Even though the volume is not near the max setting, can the driver still be over powered?

    2. When I turn on the BFD the sub pops. I don't think this is good. Is there an issue with leaving the BFD on all the time?

    3. The SPL levels taper off as the frequencies get lower. Obviously I am getting into frequencies that the sub is not designed for. Will it hurt the sub to increase these levels?

    Thanks,
    Dave
     
  2. Arthur S

    Arthur S Cinematographer

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    That smell is not a good sign. Disconnect the BFD and try using the sub directly from your receiver. If it works, you may be OK.

    Even though the setting on the sub was not very high, you still might have damaged it. The fact that you blew light bulbs shows the levels were way too high.

    Others with experience with the BFD can answer those questions.

    I think the test tones have to be used very, very carefully.
     
  3. billybob_jcv

    billybob_jcv Stunt Coordinator

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    I would like to know why it was possible to pop light bulbs before tripping the house circuit breaker. Could you have other problems in the house wiring? Something is not right.
     
  4. John Garcia

    John Garcia Executive Producer

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    The BFD should be on before you turn on the sub. The pop is normal. One website states to have the BFD either be sequentially turned on before your sub, or left on all the time.

    If you over boost frequencies the sub wasn't designed for, yes you can damage it. I believe most people tend to try to avoid boosting unless absolutely necessary.

    IMO, rather than a BFD, I would have been looking to get a better sub.
     
  5. drobbins

    drobbins Screenwriter

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    Well the sub is still working fine. The lights blew out from the wall vibrating not an electrical issue. I had used the tones at "0" volume where I set my Avia levels. Initially the SPL was 117 @ 45 Hz. I came to the conclusion that they are recorded louder. I am now using "-15" to set the BFD.
    I would like a better sub in the future, but right now the JBL and Sony subs are gifts from my wife. But if I keep overpowering it, a new sub might be in my near future, one way or another.
     
  6. Ryan Schnacke

    Ryan Schnacke Supporting Actor

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    [​IMG] [​IMG] [​IMG]

    I think we have identified the problem.
     
  7. drobbins

    drobbins Screenwriter

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    Is 117 bad? [​IMG]

    Anyway I got it all lined out today. I had one other issue though. I set the crossover on my Yamaha 5740 on 110 but the sound was still coming out of my center until 80?

    Dave
     
  8. billybob_jcv

    billybob_jcv Stunt Coordinator

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    The crossover isn't a cut-off, it is a slope that starts at the crossover freq. Usually, the slope is something like 12, 16 or 24 db/octave - I don't know what the Yamaha uses. The slope allows the mains & center to be sloped down, while the sub is sloped up so they will blend together smoothly.
     
  9. John Garcia

    John Garcia Executive Producer

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    117 isn't too bad at 45Hz, probably just a bit hot. To set your levels, you should adjust the volume of your first speaker so it gives the reading you want and adjust everything else relative to that same point.
     

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