Discussion in 'Amps and Cabs [BG]' started by Captain Freedom, Mar 7, 2002.

  1. I have a good sized cab i pretty much built.

    It is lined with fiber glass insulation on the inner sides and back.

    It also has 4 - 6x1" vents, 2 on top, 2 on bottom,
    and 2 8x3" vents on the left & right of the front panel, between each speaker.

    2 - Eminance delta 15's Wired as 4 ohm's (should handle over 600watts)

    When i crank that bad boy up to 450 watts. It sounds all distorted like the cab is ready to blow apart.

    Should i put some air relief ports in the BACK where each speaker pumps the most, Or is it bad to have ports front AND back?
  2. Cap'n - port dimensions and quantity are inseperably tied to the Thiele parameters of the speaker used and the cabinet dimensions. These ports are designed to tune the cab to a particular frequency so that the cab matches the speaker. Pardon my assumption, but it looks like you've got a pretty much random assortment of ports and sizes. I've seen cabs containing 15's with far less area of port than what you've described. Another important dimension is the length of the port. Ports can have the same cross-section dimension but be longer or shorter and this will have a huge effect on how a driver sounds.

    I am not an expert in these area's but I have learned enough to guess that your particular cabinet is NOT tuned to the speaker. Adding more ports is not going to help as I suspect you've already got more port volume than required.

    There will be a real expert along directly that will explain this better.
  3. Thanks for the input, makes sence.
    Although, the cab was a PA cab with 2-15's in it. and all the ports were already there. i just removed the PA speakers, and installed bass speakers. i also remove this giant horn, and lowered the top about a foot.

    Captain Freedom
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