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Porting a 2X12 Cab

Discussion in 'Amps and Cabs' started by timc, Jan 11, 2008.

  1. Jan 11, 2008 #1
    timc

    timc Silver Supporting Member

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    Mount Pleasant, SC
    I have a Tophat 2X12 cab, speakers are semi diag. I am wanting to open part of the back to open up the sound a bit, make it less directional. It does have what I've always called a sound post, or a brace like the Marshall 4X12's in the center, so I did not know if I would just 1) cut two boards, 2/3 of the back and leave the center section open, and either just remove the sound post or leave it hanging, or 2) cut 2 say 12" round holes on each side of the cab, centering the holes on each side, leaving the sound post to make contact with the center. Any thoughts?

    Edit - When I say port, I actually mean just opening part of the back.

    Tim
     
    timc, Jan 11, 2008
    timc, Jan 11, 2008
    #1
  2. Jan 11, 2008 #2
    pfflam

    pfflam Member

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    Just cut nice round holes back there . . . do it from the back if possible so that you can remove the tolex and fit it around the holes.
     
    pfflam, Jan 11, 2008
    pfflam, Jan 11, 2008
    #2
  3. Jan 12, 2008 #3
    beej

    beej Supporting Member

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    In an older thread, John Suhr cited a software package that's ideal to determine the characteristics of a port/cabinet so that it's tuned properly. Might want to do a search and look into that.
     
    beej, Jan 12, 2008
    beej, Jan 12, 2008
    #3
  4. Jan 12, 2008 #4
    timc

    timc Silver Supporting Member

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    Thanks. I am actually going to buy a piece of wood ( same type, dimen as the orig back panel) and use that. This way I can switch back if I don't like it.

    Tim
     
    timc, Jan 12, 2008
    timc, Jan 12, 2008
    #4
  5. Jan 12, 2008 #5
    FFTT

    FFTT Member

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    Before you cut anything, try removing one speaker
    and rewire for that one speaker and of course switch
    your amp to the correct impedance.

    In other words, try running it as a detuned cabinet first.

    As far as porting, remove the back panel and use it as a template
    for a completely new semi open back.
    The original back can be clamped to the new back so you can line up all the holes
    for drilling.


    This set up gives you 3 variations from the same cabinet

    Closed, detuned and semi-open back.
     
    FFTT, Jan 12, 2008
    FFTT, Jan 12, 2008
    #5
  6. Jan 12, 2008 #6
    jay42

    jay42 Member

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    Also, try DIY beam blockers, like a couple coffee can lids stuck to the grille cloth with a bit of duct tape -- nothing permanent. Evaluate what you mean when you say too directional. It helps soften the on-axis peakiness and may be enough.
     
    jay42, Jan 12, 2008
    jay42, Jan 12, 2008
    #6
  7. Jan 12, 2008 #7
    rockon1

    rockon1 Member

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    +1 Beam blocker will do the most to affect a directional problem. I use them on all my cabs/amps for sound dispersal. You could do both but I'd definately explore the BB option. Bob
     
    rockon1, Jan 12, 2008
    rockon1, Jan 12, 2008
    #7
  8. Jan 14, 2008 #8
    timc

    timc Silver Supporting Member

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    I'll try two approx 12" holes, so I can keep the sound post (not sure why) then go from there (larger oval, rectangle, BB's).

    Thanks for the respones.

    Tim
     
    timc, Jan 14, 2008
    timc, Jan 14, 2008
    #8

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