Some port simulations in-room for a Tempest

Discussion in 'Archived Threads 2001-2004' started by Darryl_St, Feb 13, 2003.

  1. Darryl_St

    Darryl_St Extra

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    Hi all,

    I'm about to build two Tempest based subs and was going to use a 190L tuned to 19Hz with 1-4" flared port.

    When I sim this box in LspCAD it looks good, but if I turn on simulate nonlinearity I lost a lot of the low end in-room.

    Should I expect this sim to be correct?

    All these have about the same group delay.

    Can I just have some tubes half-way out of the box for maximum low end? ( They will be behind a false wall out of site ).

    Will tube lengths cause other anomalies that I will hear?

    I can tune slightly higher say 22Hz, which will shorten them and only increase group delay slightly, but will give me even greater low end.


    Have a look,
    ( oops, I can't post the pic )

    190L 19Hz 1-10.5x26.9cm port 114.8db @ 20Hz Nonlinearity off
    190L 19Hz 1-10.5x26.9cm port 109.3db @ 20Hz Nonlinearity on
    190L 19Hz 4-10.5x129.4cm port 112.1db @ 20Hz Nonlinearity on
    190L 19Hz 1-15.2x62.7cm port 110.8db @ 20Hz Nonlinearity on
    190L 19Hz 3-15.2x208.5cm port 112.7db @ 20Hz Nonlinearity on

    Thanks

    Darryl
     
  2. Jeff Rosz

    Jeff Rosz Second Unit

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    well for starters, you could (i would) rule out the 4" ports, go with 6". yes you can have the tubes half out of the box.
     
  3. Darryl_St

    Darryl_St Extra

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    Thanks for the response,

    Have you ever seen or heard of an example of a box with the ports half out?

    Do you know if the nonlinearity in LspCAD sim is correct?

    I just looked at using an 8" ( 21 cm ) port 101cm long tuned to 21Hz will give me 112.7db @ 20Hz.

    That's 3db more @ 20 Hz then a 4" ( 10.5 cm ) port 26.9cm long tuned to 19Hz.

    These are all with 125W into 8 ohm.

    Darryl
     
  4. Darryl_St

    Darryl_St Extra

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    Just wondering if anyone had any real world experience with a LspCAD sim and a test done on a real sub,

    Do you know if the nonlinearity in LspCAD sim is correct?

    Will longer tube lengths cause other anomalies that I will hear?

    Thanks



    Darryl
     

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