Help me redesign my SP4's box

[Smoove]

Here is a sealed off trunk with one SP4 doing hair tricks. He is running 17sqin of port per cube. THis should give you a idea of how to get to your goal

http://www.stevemeadedesigns.com/board/topic/158900-removable-rear-door-brace-started-06-altima-6k-trunk-build-fi-15-sp4-hair-trick-vids/

[Shigshwa]

Jesus.. Never mind, the 4 seater hairtricking sedan on a relatively low budget is a myth then, lol. So... I think right now, to gain more output, I guess I can put dampener on the entire trunk and perhaps reduce port compression by making the port wider? I feel like these would only result in small increases numberwise and wouldn't really be cost efficient... guess I'm approaching the ceiling for spl for what I can afford.

[slowfkncar]

No, the enclosure plays the biggest part in your output and sound. If anything,you would be wasting your money on deadener if your not happy with the enclosure yet. Usually if your tight on space,you will sacrifice a lot of upper frequency output for low frequency output.

If you can get 6-7 cubes gross in your trunk, woofer & port firing into the cabin with no air holes whatsoever from the trunk into the cabin that will give you a nice jump start on doing hair tricks.

[OBI]

Off the power and size of box you should be fine. What is making you think that it wants a smaller box? Unloading?

[Rail]

45 sq inches of port is far to small for the SP4. I hope you guys realize that the sq in per cubic foot "rule" is a myth that is completely false. You should have had at LEAST 76 square inches of port with your box that was tuned to 32 hertz (Small's minimum port area formula).

The guy other people are mentioning that can do hairtricks with a 15" SP4 and an AQ3500D.1 is "jcplaya3" on youtube. His box is 4.44 cu feet, tuned to 31.37Hz, with 77.5 sq in of port. Here is a video of him doing a hairtrick.

http://www.youtube.com/watch?v=hq7LKYBigsg

I have the same sub and amp, but my enclosure is 4.5 cu ft, tuned to 26 hertz, with 91.13 sq in of port. I have a Tahoe though so there is a lot more air that needs to be moved to do a hairtrick. The vehicle flexes pretty good but I could only do a small hairtrick, if that. So it also depends a lot on what vehicle you are trying to do this in. The larger the enclosure the larger the peak will be at the tuning frequency, but at the same time, the mechanical limits of the sub will be reached faster with a larger enclosure. So a large box tuned low will help make a peak at low frequencies to get your hairtricks.

[Shigshwa]

I think my box is good as is, and the sub moves some mean air in the 20 hz range (noticed I could actually flex my mom's Acura's door in the garage). I could add extra port area at the expense of box volume if that'd help it move more air at those low frequencies. If I can't get it to the point where I can hair trick, then I wouldn't mind fixing up the port in the box to get closer. I think the air velocity gets high sometimes when I'm messing around with paper at the port, but I don't know if that has any effects.

I wish I could build a box or 3 to test, but my budget is limited.

[Rail]

I think my box is good as is, and the sub moves some mean air in the 20 hz range (noticed I could actually flex my mom's Acura's door in the garage). I could add extra port area at the expense of box volume if that'd help it move more air at those low frequencies. If I can't get it to the point where I can hair trick, then I wouldn't mind fixing up the port in the box to get closer. I think the air velocity gets high sometimes when I'm messing around with paper at the port, but I don't know if that has any effects.

I wish I could build a box or 3 to test, but my budget is limited.

If you are happy with the results then that's all that matters, its your system. There is a compromise of how much port area you can get, you want enough to allow the sub to perform correctly while still having enough internal volume to create the frequency response curve that you want. My first sub box that I built I did not know how to find the correct amount of port area and only had 46 sq in of port area on my 15" SP4. After a building a new enclosure with the proper amount of port I am MUCH more satisfied, the sound is much cleaner and the port noise is gone. Also I lowered the tuning frequency by 8 hertz but still maintained a lot of the upper end, possibly just due to cabin gain, but overall it performs far better than before.

[Brandonbkd]

Seal it and it'll sound a TON louder

[Shigshwa]

Tried keeping things the same, got a bit more box volume. The box now has 60 sqin of port area. Added some bracing as well.

[Smoove]

^^^^^^^ Thats right around where I would build. Not sure if you gonna do hair tricks, but it should perform nicely in that box.