Question about frequency response on my new PB12

Discussion in 'Archived Threads 2001-2004' started by Brian Cal, Jul 18, 2001.

  1. Brian Cal

    Brian Cal Stunt Coordinator

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    Just got the JBL PB12 sub a few days ago, and pretty happy with it so far.
    However, the specs state the frequency response is from 25 - 150Hz, and I'm thinking mine doesn't go all the way down to 25. When I run the low frequency sweep on the Avia disc the sub seems to cut off dramatically around 36Hz, and I'm wondering if I'm just expecting too much or if there's a problem.
    FWIW, I'm running the Subwoofer Line Level out from my receiver to the left input on the sub's line level inputs, and the "LFE toggle Switch" on the sub is set at "LFE", which I'm told bypasses the sub's crossover and uses the internal one on my receiver, which is set at 100Hz (damn you Pioneer!). All my main speaakers are set to "small". I played around with the phase switch on the sub which didn't make a drastic difference one way or the other.
    The sub does sound very good for both music and movies, but I'm wondering if it shouldn't go deeper based on the Avia results. Do I have something hooked up wrong, or am I just expecting too much from the Avia low frequency sweep?
    Thanks for any help.
     
  2. Saurav

    Saurav Cinematographer

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    Are you measuring from your listening position? It's possible that either the sub, or your listening position, is in a suckout region for that frequency. Since this will be room-dependent, try moving the sub or the SPL meter around and see if anything changes.
     
  3. Bob McElfresh

    Bob McElfresh Producer

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    I agree with Saurav.
    The speaker manufacturer typically measures the sound with a meter 1 foot in front of the speaker. Yes, this allows them to make somewhat exagerated claims, but how else could they do it?
    I think they allow for a drop of 15 db and then advertize this as the lowest-frequency.
     

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