Multiple port dimentions for single cab.

Discussion in 'Amps and Cabs [BG]' started by MuzikMan, Sep 30, 2004.

  1. Does anyone know what using 2 different sized ports would do to a cab? I can think of 2 possibilities.

    1) Cab would be tuned to the total area of the ports.
    2) Cab would be blurred in its tuning and the ports would unload the speakers at different frequencies.

    I haven't found any sources to research this topic. It seems that all cabs are tuned with 1 or more ports of the same size. Obviously that would be the easiest way to calculate the results but I wonder if there is more to it than that.
  2. BillyB_from_LZ

    BillyB_from_LZ Supporting Member

    Sep 7, 2000
    Each port would have its own tuning frequency. I suspect that depending on how this was done, it could help or hurt.

    You might have big group delays at two frequencies creating lots of mud...maybe not.

    Since a speaker never reproduces just one frequency when you're playing music through it, I don't know what would happen.

    Rumor has it that Vanselus is planning on a cabinet version of basstasters preamp shootout. Perhaps someone (hint, hint) could build one and let them have at it...
  3. billfitzmaurice

    billfitzmaurice Commercial User

    Sep 15, 2004
    New Hampshire
    Owner, Bill Fitzmaurice Loudspeaker Design
    The tuning of a cabinet is accomplished by the sum total of the air mass contained within the ducts/ports, and it doesn't matter how many you use or if they are different sizes. In fact it's a common practice in the DIY speaker community to install more than one duct and do the final fine tuning of the system by altering the length of only one of them. You can only achieve two different tuning frequencies by using a dual chambered box, as in the case of a 6th order bandpass.
  4. BillyB_from_LZ

    BillyB_from_LZ Supporting Member

    Sep 7, 2000
    Thanks Bill!

    I stand corrected...but I'll have to think about that one...