Question on SPL calculations from another forum

Discussion in 'Home Theater Projects' started by Brian-K-Owens, Feb 27, 2004.

  1. Brian-K-Owens

    Brian-K-Owens Stunt Coordinator

    Feb 6, 2003
    Likes Received:
    I am trying to figure out the truth to a discussion I am having on anthoer forum.

    Something like this:

    Talking about SPL ratings for 1 watt/1 meter. Got into the ratings of 2.83 volts/1 meter. Explained that 2.83 volts is 2 watts @ 4 ohms and 1 watt @ 8 ohms.

    I was told this was not correct, that power to the driver would vary when you use the 2.83 volt rating, because Re varies for different drivers.

    The arguement now is do we use the DC resistance, or the actual impedance to determine the wattage when we feed a set voltage to a driver.

  2. Jerry Parker

    Jerry Parker Stunt Coordinator

    Jan 15, 2001
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    No, you are correct. I don't see why you would use Re, since it isn't going to affect the output of the speaker when fed an AC waveform.

    The 2.83v sensitivity specification is around so that you can compare the output of drivers with different nominal impedences. If you are trying to find the wattage for an audio signal, you will want to use the impedence value at the frequency you are mesuring, as impedence will vary with frequency.

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