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What Do You Think About These Box Specs?

Discussion in 'Subwoofer Box and Custom Fabrication' started by texcon, Jun 17, 2004.

  1. texcon

    texcon Full Member

    First, here are the T/S parameters of my sub:

    Driver Properties
    Name: S-12-4a
    Type: Standard one-way driver
    Company: Kicker
    Comment: Solo-Baric series
    No. of Drivers = 1
    Fs = 16.7 Hz
    Qms = 7.49
    Vas = 231.2 liters
    Mms = 4.885 oz
    Xmax = 8.51 mm
    Sd = 79.21 sq.in
    Qes = 0.327
    Re = 3.38 ohms
    Le = 0.589 mH
    Z = 4 ohms
    BL = 2.79 lb/A
    Pe = 600 watts
    Qts = 0.313
    1-W SPL = 87.7 dB

    I pumped these into WinISD and it gave me a tuning frequency of 21.65 Hz, which seems pretty low, and a volume of 100.1 liters = 3.535 cu ft.

    Port diameter given is 0.102 meters = ~4 inches with a port length of 0.438 meters = 17.3 inches. What I am unfamiliar with is the "Vent mach" value given, which is 0.17 in this instance. I can adjust the diameter and length, but that affects the Vent mach - my question is what the hell is the Vent mach?

    Now I assume that when I give WinISD the TS parameters, it gives me the "best" design, i.e. the box that has the flattest response? I am new to messing with this, so any help on how to appraoch using this software would be great. I notice that I can mess with the tuning frequency and the box volume, which affects the curve.

    Thanks in advance!
     
    texcon, Jun 17, 2004
    #1
  2. texcon

    texcon Full Member

    I wanted to add that someone from CAF kindly helped me out with some ported box specs for this sub and made an interesitng comment. He said with my sub's xmax being relatively low, I would only be able to push 200-300 watts in a ported enclosure. Perhaps this is why Kicker did not recommend this sub being used in a ported enclosure? Anyway, he suggested I make a 3 cu ft box with a 4" diameter round port at about 10" long. That would give me a tuning frequency of ~30 Hz which seems fine. I may or may not try this, since that is a pretty big box and I am not sure I would want to just suck up that much trunk space.
     
    texcon, Jun 18, 2004
    #2
  3. geolemon

    geolemon Full Member

    Hoffman's Iron Law.
    There are three mutually exclusive items in any subwoofer/enclosure alignment:
    1) small enclosure size
    2) high efficiency
    3) low frequency extension

    Simply put- you can't have all three.
    With a sealed box, all you can trade off is enclosure size...
    As you go larger (sacrificing 'small enclosure size'), you gain low frequency extension, and efficiency... it takes fewer watts to reach the same output levels.

    IN a ported box, you can trade off all three individually, because you can manipulate encloure size and port tuning separately.

    It seems like the box you've been given IS very large with respect to these small box subs... sacrificing "small enclosure size", basically.
    ...maximizing either "high efficiency" or "low frequency extension".

    It sounds like it maximized "high efficiency", if the sub is reaching it's full output with 200-300w rather than ???w.

    Is that really a problem?
    Turn your gain control down, and enjoy the wonders of high efficiency. B)

    Hell, for years I had my three 10W6's on a 400w amp, reaching full output, always blowing minds in the process.
    That's just great fun.. particularly today, when 1000w+ amps are so so so so common. :lol:
     
    geolemon, Jun 18, 2004
    #3
  4. texcon

    texcon Full Member

    Basically, it is my ignorance that is at hand here. I am amazed that this sub could reach full output in a ported box at only 1/3 to 1/2 of its RMS wattage requirements in a sealed box. But I have no problem with that, it's just pretty...well, cool. I suppose that is the magical thing about car audio. I will probably build a few boxes just because I am curious and because MDF is cheap.

    On as aside, I was giving my bro in law a listen to my install and we were playing some old bass CD he had and it sounded great. But he wanted to see it in the trunk while it played and he was amazed at how it really didn't sound that loud when listening to it outside the car with the trunk lid open. That's just the dynamics of car audio, which I honestly cannot explain in scientific terms...not yet anyway.
     
    texcon, Jun 21, 2004
    #4