/ Register

Competition Enclosure

Discussion in 'Subwoofer Box and Custom Fabrication' started by aznboi3644, Mar 2, 2008.

Page 1 of 4
  1. aznboi3644

    aznboi3644 Full Member

    Well there is a competition FINALLY in my town on April 26.

    It's a MECA competition. Trying to think of a few enclosures to build. lol.

    I'll post up some sketchups of some ideas.

    One of them I might build during my spring break this week since the damn temperatures are up in the 60s finally.
     
    aznboi3644, Mar 2, 2008
    #1
  2. cccullen

    cccullen Full Member

    Are you thinking another T-line? What are you planning to use for the competition?
     
    cccullen, Mar 2, 2008
    #2
  3. aznboi3644

    aznboi3644 Full Member

    Well...I want to build three different types of enclosures...ported, bandpass, and t-line

    bandpass probably won't happen though. It would be the last enclosure built.

    Heres a sketchup of the ported competition box.

    6 cu ft tuned to 46Hz with 180in^2 of port...strictly burp box though

    I'm trying to figure out some different ways to change the tuning by sliding in some boards

    Not sure if this is enough port area though lol

    [​IMG]
     
    Last edited: Mar 3, 2008
    aznboi3644, Mar 3, 2008
    #3
  4. cccullen

    cccullen Full Member

    Damn, that's a HUGE port!! is that going to be for your w6?
     
    cccullen, Mar 3, 2008
    #4
  5. aznboi3644

    aznboi3644 Full Member

    Nah..more for the 19Ov.2
     
    aznboi3644, Mar 3, 2008
    #5
  6. Ranger SVO

    Ranger SVO Full Member

    I really think the woofer should be on the baffle board with the port.

    Remember to make sure the box peak is close to the resonant frequency of your Explorer.

    Lots of power.

    Love your box software, what are you using.
     
    Ranger SVO, Mar 3, 2008
    #6
  7. aznboi3644

    aznboi3644 Full Member

    Ranger...well I use WinISD to come up with a response that I like.

    Then I use Google SketchUp...its a free modeling program. Basically you can model up anything you can think of. Just google "sketch up" and you can find it.

    BUT...I still use paper and pencil to get the first rendition down..then do the final on sketch up.

    Well this box peaks in right at 50hz...like my exploders resonant frequency.

    Well...MECA rules state the enclosure must be below the rear seat...my rear seats are only 18 inches from the floor to the top of the rear seats.

    I had a sealed box with an 18inch tall baffle board...the cut out basically cut the baffle board in half...the cutout went all the way to the top and bottom boards.

    I have also asked around and it seems like sub up port back is loudest on the meter for explorers...But I plan on building a few test boxes until the competition.
     
    Last edited: Mar 4, 2008
    aznboi3644, Mar 4, 2008
    #7
  8. electrolytic

    electrolytic Full Member

    Azn, how can i find the resonant frequency of my taurus? I play tones 20hz and up until i find which frequency rattles the inside of my car the most? lol, can you explain with some detail
     
    electrolytic, Mar 4, 2008
    #8
  9. aznboi3644

    aznboi3644 Full Member

    Well I'm not sure if the formula Ranger told me works for cars. I forget.

    I asked around on some forums and Explorer's peak right at 50Hz give or take a cycle or two. Using the formula it came out right at 50Hz like others with Explorers have said.
     
    aznboi3644, Mar 4, 2008
    #9
  10. electrolytic

    electrolytic Full Member

    ok, i found this. So if this is true i can just play tones and see which is the loudest or vibrates the most to get an idea. Or get the meter too.

    Theoretically....get a radioshack meter for like 20 bux and since it only goes to 120dB, find what you think is your loudest note area on a test tone cd. Then start with the meter on and the music at 0, turn it up until the meter goes 3/4th of the way up but not all the way. Because they max out real easy, and you can play your deck at the same volume through-out the cd and find out which tones push the meter just a little higher then the rest.
     
    electrolytic, Mar 4, 2008
    #10
  11. pedro quiroga

    pedro quiroga Well-Known Member

    hmm i guess some suvs are close cause my truck peaks at 48hz.
     
    pedro quiroga, Mar 4, 2008
    #11
  12. aznboi3644

    aznboi3644 Full Member

    your truck peaks at that or your enclosure peaks at that???
     
    aznboi3644, Mar 4, 2008
    #12
  13. pedro quiroga

    pedro quiroga Well-Known Member

    hmm dont know.my kicker wouldnt go any higher than a 135.8 @ 48hz.

    the judge said thats my resonant freq.not sure with the new box now either.


    so if the spl stopped increasing with differnt freqs then is the peak spl my resonant freq?
     
    Last edited: Mar 4, 2008
    pedro quiroga, Mar 4, 2008
    #13
  14. aznboi3644

    aznboi3644 Full Member

    well usually to try to find the peak frequency you build a sealed box that has a flat response...then you play a sweep and the resonant frequency is the peak.
     
    aznboi3644, Mar 4, 2008
    #14
  15. electrolytic

    electrolytic Full Member

    electrolytic, Mar 4, 2008
    #15
  16. Ranger SVO

    Ranger SVO Full Member

    Resonant Frequency = Speed Of Sound (in inches) / distance from right front corner to the rear left corner.

    Speed of sound in inches is 13560 in/sec, so if we have an interior length of 80 inches, then we do 13560/80 and get 169.5 Hz.

    I know, nobody wants a box that peaks at 170 Hz (yes I'm rounding off). So divide by 2 and you get 85 Hz divide by 2 again and we get 42.5 Hz

    So our imaginary vehicle has resonant frequencies of 170, 85 and 42.5.

    So pick one. Any division of 170 by 2 raised to some power will be a resonant frequency.

    Any questions?
     
    Ranger SVO, Mar 4, 2008
    #16
  17. electrolytic

    electrolytic Full Member

    I do, I do lol, so are you saying to take a tape measure and measure inside my taurus diagonally from the corner of the front window to the corner of the back window?
     
    electrolytic, Mar 4, 2008
    #17
  18. Ranger SVO

    Ranger SVO Full Member

    Yes thats right. Remember that this is an approximation, but it will get real close. One other thing, if your back seats fold down, add about 12 inches to your measurements, only if you drive around with the seats folded down
     
    Ranger SVO, Mar 4, 2008
    #18
  19. electrolytic

    electrolytic Full Member

    Sweet! So i have 108 inches so my car's resonant frequency is 31.888888888888 hz roughly and 62hz, hmmm, maybe i should tune my box to 35hz, cerwin vega has one recommendation for a ported 2.5 at 35hz.
    I don't usually put the back seats down, it sounds good with them up.
     
    electrolytic, Mar 5, 2008
    #19
  20. pedro quiroga

    pedro quiroga Well-Known Member

    ok so mine is 55hz.
    123in.is that right?
     
    pedro quiroga, Mar 5, 2008
    #20
Page 1 of 4