Discussion: Sub boxes

[POS carb]

I was wondering what everyones setup for boom is...

I found one of the loudest setups is when I had my 2 12s in a ported box up against the trunklid but this was kind of annoying due to the lost trunk space. It was a single chamber with 3 14" long ports and a volume of about 3.5 cubic feet. It got down too but it was a lot quieter outside the car

Right now I have 2 15's facing back in a sealed chamber. It's loud, it makes your eyeballs shake but it doesn't drop down low like my 12 did, if anything they should be rocking like 20 hz no problem. I think it has to do with the box, it's only 1.3 cubic feet per sub, individual chambers, sealed. It helped when I stuffed it with polyester fill (2 lbs) but still, I'm wondering if a bigger box would fix this. The 15's sound great overall, very tight, defined bass, I was very surprised. Also the box is a little smaller than the one for my 2 12's so I get a lot of trunk space.
The factory specs are:
sealed 1.25 ft3 box for SQ or 1.75 for SPL each sub
ported was some obscene ammount like 5 cubic feet per sub but I guess that shit would be heard from 5 blocks ionside a bigass Yukon or something


Some questions to ponder:
What difference would it make acoustically if I were to simply create a single chamber of 2x the volume... is this something that would work? I'm not sure how the box affects the sound coming out the front in a sealed box setup but I guess it has to do with wavelength and cone control (inside pressure) and if it's 1 giant camber with 2 15's pushing it, I dunno, I'm guessing the box will handle lower frequencies better but maybe create too much pressure inside? It worked badass for my 2 12's, I only went to a single chamber once when I tried it out in my friend's 2 chamber sealed box and I wasn't too impressed.

If the rear of the trunk (woofer cones facing back w/ the cones close to the tag) offeres the loudest sound (cancelling waves or something?) what would be the next best? I'm looking for what worked for you! Let us know, o and if you have any REAL dB readings let us have em! When I had the cones facing the back seat it used to rock hard but only w/ the seat down!

Right now I have the 2 15's in a sealed box running 500 watts each and it's enough to make the mirror start turning (the 12's never did that!) and make evey screw on the carb come loose every 2 weeks. I just wish it would drop down a little lower frequency, it seems to muffle out like @ or below 40 hz.

Is there a [cough, free] program available that can be used to measure RTA?

Is the Accord any good for low frequencies? I may be better off with 4 10's, no?!

[89AccordLX2dr]

I'd run a single 15. That enclosure is way too small for 15's hence the reason for the lack of deep lows. Try the single 15 bridged in an enclosure around 3.5cu' internal, ported with a single 4" tuned to your preference. I'd start it at about 6" long.

I was going to try a pair of free air 15's on a panel bolted to the back of the rear seats firing forward. No box is needed there and would save the trunk. I only have the one 15 now since I sold the other for the cash. So I guess I can't try that now until I get ahold of another set of free airs.

[AccordEpicenter]

firing forward invites alot of cancellation. The best is firing backwards or straight up, i can tell you from personal experience. Also if you wanna be loud, 15s in a small or moderatley small box seems to be the loudest but really cuts down on extreme low frequency production, the bigger box you go sealed, the less efficient the sub will be but the lower and flatter frequency response makes it worthwhile for sq apps. My ported 12s peaked at 33hz and would go down to maybe 26hz or so... its all about tuning frequency in a ported box. At 33hz i broke all the 6x9 mounts in the rear deck (broke em right in half) and shattered my already cut down 3rd brake light. all this with the back seat down and the woofers firing backward, and you couldnt read the cd player faceplate because it shook you sooooo much, im not kidding you guys, my roof/door panels moved, you could see my hood move too... At 1/4 volume any mirrors on the car are completely useless, 146-147db is LOUD in a daily driver.

[Vanilla Sky]

find and download a program called WinISD... i use it when i'm looking into a sub because i usually have size constraints when building a box... it'll help you size the box and aid in the decision to comprimise what for what, and really gets you to an optimal design fairly easily... i don't know what subs you're using, but try playing with placement... epicenter is right... foreward facing subs seem to cancel out a lot of times... just experiment with placement until you have what you like

[89AccordLX2dr]

Well the optimal position is box as far back as possible firing back, but this takes up half the truck area. I liked the free air idea because it saves the trunk for it's purpose. Pair of 15's that cancel a bit yet save the trunk is ok in my books. I'll try it someday and share my experiences. Can't be that bad

[Vanilla Sky]

actually, that's not always optimal... may be loudest, but may sound worse than shit

[dXsquared]

i just built 2 boxes for my friends 15 inch Resonent Engineering HC sub... 1200 watt RMS... big bad sub...

anyway, he wanted an SQ and an SPL box... the only thing is that it was going in a NEON trunk...

i went with a 1.75 cube sealed box for SQ... it sounds very tight, doesnt hit super low, but its very acurate for a massive 15" sub...

for SPL, i naturally wanted to go 3.5-4 cubes with a massive port, but for size reasons i went with a 2.5 cubic inch cube (17X17X17) with no port... it hits super low and its kinda sloppy... he's feeding it twin Profile California 600M blocks.. its getting 840 watts RMS and its pretty fuckin loud... we also ran it free air into the trunk, but it was way too shitty sounding...

Travis

[POS carb]

i'm gonna build a 2 ft x 2 box and try that, if it doesn't work out I'm selling this f'in car!!

my friends hook up the ghettoest rigs in their cars and they always sound good! They are the type to hook up 4 subs to 1 ch.; I don't get it!!!!!!!!

[NXRacer]

theres a local shop here in town that the guy is a total audiophile. He builds these boxes that have rounded ports on them and he can seriously get any sub/speaker to sound hellacious with his boxes. I"ve seen him use $10 6x9's hooked up to a $5 deck and they'll bump harder then a set of expensive 10's.

do a little research in what your speaker needs and a good box design and you'll get good results.

[Vanilla Sky]

hey, NX... i'm kinda like that, but i can't do it on my own... i use that WinISD program, and build from there