boosting below tuneing freq.?

Discussion in 'Home Theater Projects' started by PatrickMiller, Feb 28, 2004.

  1. PatrickMiller

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    Im assuming I shouldnt boost the frequencies below the tuning of my ported sub as tempted as I am? My sub goes to about 34Hz (+/-3dB).
     
  2. Bob Kavanaugh

    Bob Kavanaugh Second Unit

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    It's a good way to unload and possibly damage your driver.
     
  3. PatrickMiller

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    If my subs response is 34-150(+/-3dB)is 34 the tuneing of my port?
     
  4. AndersP

    AndersP Stunt Coordinator

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    I think it´s more like 40 Hz, but it´s impossible to know without some measurements.
    Take down some bass test signals from the net with like 1 Hz increments in the area 30 - 50 Hz and burn a test CD.
    Get a RS sound level meter and measure very close to the speaker cone at low level without touching it with the mike.
    The frequency with the absolute lowest output is the tuning frequency. At this frequency you can also feel the "wind" from the reflex tube at its strongest.
     
  5. Dustin B

    Dustin B Producer

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    Another less accurate, but easier way to get a decent approximation of the tuning frequency would be to provide us with the outer dimensions of your sub (excluding any feet or grilles), the diameter and length of the port, whether the port is flared or not and how much the sub weighs (so we can guess wall thickness). Then one of us or you can use LspCAD or UniBox to model the enclosure's tuning frequency.
     
  6. PatrickMiller

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    Well I already have a meter and have measured down to 20Hz.
    There is some output there but it cant be tuned that low, so how can the frequency with the least output be it?
    It is an Infinity 10" Entra 150w. 14.5"x16"x15".Port is flared from what seems to be 2" to 4" and 11" long.Weight is
    47lbs. Thanks!
     
  7. Dustin B

    Dustin B Producer

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    From that I'm guesstimating a net internal volume of 40L, with a 2" port that is effectively 10" long it works out to a ~22hz tune.
     

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