Hearing voices in subwoofer?

Discussion in 'Speakers' started by Steve Zimmerman, Jan 28, 2002.

  1. Steve Zimmerman

    Steve Zimmerman Second Unit

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    Just for kicks this morning I played a rather bass-heavy CD with the separate amp to my main speakers turned off. Thus, my receiver and subwoofer amp were on but my mains were not.

    As expected, I could hear the throbbing bass when listening to the CD at what would have been a hefty volume (-15 dB) if the mains were on.

    What I was *NOT* expecting was that I could hear the vocals--albeit at low volumes, but definitely audible at the listening position--coming out of the subwoofer. Since my receiver crossover is 80 Hz, I wasn't expecting this. Am I hearing low-frequency harmonics in the voices, perhaps? The vocals coming out of the sub don't sound to my ear like they are really as low as 80 Hz, but they could be.

    Or perhaps I'm hearing sounds as high as 160 Hz (or even higher?) due to the fact that the crossover is not a brickwall?

    Or is my receiver (Denon 2801) not doing as good a job at the crossover as something like the dedicated Outlaw ICBM unit?

    --Steve
     
  2. Jonathan T.

    Jonathan T. Stunt Coordinator

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    Okay im gonna bring this thread back from the dead because he asks a very interesting question that never got answered.
     
  3. John Garcia

    John Garcia Executive Producer

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    The ICBM probably has a steeper slope and filters out the lowest of vocals. What are the two x-over points set to?
     
  4. Jordan_Brulotte

    Jordan_Brulotte Stunt Coordinator

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    I asked this question too when I was new to the diy scene. I had my crossover set to 80hz as well and could hear "voices" coming from the sub. Back then I didn't know too much about DB slope and the order of crossovers. Since I had a 2nd order crossover with it set to 80hz it would play to 320hz at 24db down, which can still be easily audible.
     
  5. JeremyErwin

    JeremyErwin Producer

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    some graphs of a thx crossover scheme. The source is a review of the high end Denon AVR-5085, so they may not apply to your situation, but one might note that the filters are not brickwalls.
     
  6. ScottCHI

    ScottCHI Screenwriter

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    contact an exorcist
     
  7. Wayne A. Pflughaupt

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    It’s not an unusual problem, Jonathan. As you may know, crossover frequency settings aren’t a “brick wall.” They taper off at a set rate, typically given as so-many dB per octave. For instance in the situation Steve mentioned with the crossover set at 80 Hz, if the crossover had a 12 dB/octave slope, that means the sub’s level would be 12 dB lower one octave above 80 Hz – i.e., at 160 dB. At two octaves, 320 Hz, the level would be 24 dB down. And so on.

    So as you can see, it’s generally better – for this problem at least – to have a steeper slope say, 24 dB/octave.

    Aside from that, there’s another problem in that it’s not unusual for voice response – especially male voices – to naturally extend to 100-80 Hz or even lower.

    To compound that problem, it’s pretty common for program material have the lows in male voices boosted.

    And adding to both those problems is the situation that it’s common for people to run their subs at a higher level than their mains.

    When it all adds up, it’s pretty common to hear voices in the subs. In fact, it’s difficult to eliminate them entirely. My system’s set up pretty optimally and I can hear it occasionally, with the right (or perhaps I should say wrong) program.

    Regards,

    Wayne A. Pflughaupt
     
  8. Jason Dalton

    Jason Dalton Stunt Coordinator

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    Look in the port, maybe there is an oompah lumpah in there.
     
  9. james_stewart

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    I had a similar problem with my H/K 635 I noticed it when I had the surround off and the "DSP" was turned on. As soon as I disabled the dsp the voices went away from the sub.

    ~james
     

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