Box design help

[KoolDrew 0]

Recently I've been thinking about trying to fit a 15" Icon in the trunk of my Sunfire as opposed to the 12" I've planned. I typically would just use a slotted port, but the amount of displacement taken up by the port would bring the box pretty much all the way down to 3cft as opposed to the 4 that's supposed to be optimal. So I've been reading a bit and the idea of using Aero ports kind of interested me. However, does the recommendation for port area remain the same (12-16 square inches per cubic foot)? If so, I would need 2 6" ports or 4 4" ports, and in both configurations the port length would have to be too long.

Is my only bet for fitting a 15" is to settle with something like a 3cft box and making up for it using polyfill? How much polyfill would be necessary? The dimensions I'm working with are probably somewhere around 32x16x19 (WxHxD). I'm hoping 16 would be enough for the height since the trunk isn't too high. I figured I'd double up the MDF to allow me to mount the sub so close to the edge. I guess I could mount the sub on top, but would I lose ouput as opposed to facing it to the rear?

[rushnrun 14]

no matter what style of port the cubic inch of cross sectional area should remain the same

Slot ports offer the smallest vent length for surface area

The last sunfire with a 15 that I did the box was 36x16x18 it was an 05... you pretty much choke off all the foward airflow with a box that big.. there still is room to the rear.. (i.e. the 18" could have been a little bigger..)

[KoolDrew 0]

you pretty much choke off all the foward airflow with a box that big..

What if the sub and port faced inside the car? Or if the sub and port were on top allowing me to make the box not as tall?

Edited January 17, 2009 by KoolDrew

[rushnrun 14]

I'm a big fan of just building and testing.. I know it's not real feisable for others. Normaly I just build a few different cheap boxes out of .5"mdf and throw a junk 10" in and see what box is closer to the sound and output I'm looking for...

If you make the box a little shorter say 2-3" shorter, you can make it a little deeper, fire the sub up and the ports off to the Passenger or drivers side.. that designs works ok in some cars... firing foward can be ok.... if it's not sealed up good I don't think the performance is all that great..

What are you going for anyway??? High SPL or just loud and decent sounding??

personally with your space I'd suggest a rear firing 12... I did another 99 sunfire with two CHEAP 10's on just 500 watts and it was almost as loud as the other guys single 15 (the whole setup cost 250 bucks..) he did low 40's on the dash....

The 2-10 were 2.25 cubic feet tuned 28hz and the 15 was 3ish cubes at 35hz

**the dual 10 box was 12x32x18 so there was plenty of "breathing room" around the box.. He had his small MTX amp mounted to the back of the seat

*********************************************

Some other trunk car builders should chime in... My personal builds are all hatches of some sort, SUVs and HB cars.. so I have no testing experience with trunk cars other than the random builds I've done for others..(there wasn't any testing involved in those builds, just built what the person wanted)

[Aaron Clinton 2,372]

I think I mentioned on CA-F, that I am one that usually leans towards the smaller size driver in favor of knowing its in the proper box.

[KoolDrew 0]

What are you going for anyway??? High SPL or just loud and decent sounding??

My goal is to be loud but sound good as well. I'm not going for numbers.

personally with your space I'd suggest a rear firing 12... I did another 99 sunfire with two CHEAP 10's on just 500 watts and it was almost as loud as the other guys single 15 (the whole setup cost 250 bucks..) he did low 40's on the dash....

The 2-10 were 2.25 cubic feet tuned 28hz and the 15 was 3ish cubes at 35hz

**the dual 10 box was 12x32x18 so there was plenty of "breathing room" around the box.. He had his small MTX amp mounted to the back of the seat

Originally that was my plan, either get a single 12" or two 10's. The only problem with the two 10's is that it would be pretty expensive so I decided on going with a single sub setup. Since the price difference between a 12" and 15" Icon is so small that's why I wanted to try to fit a 15".

[Duran 387]

I think I mentioned on CA-F, that I am one that usually leans towards the smaller size driver in favor of knowing its in the proper box.

Denim and I are on the same page, if you take a big driver, and but it in a small box, you will get small sound.

Figure how much space you have to work with including your port, and choose the driver accordingly.

[Aaron Clinton 2,372]

Could you invert the driver? If so, then you would gain a little bit of internal volume back from no driver displacement. Just trying to think of another way for you to fit the 15.

[nick_19 1]

I had extreme difficulties finding a way to get my 15 in my trunk with the 4.5 cu ft net I wanted and 60 sq in of port area... My solution was the box design I now use. Try sub facing up with port firing to the side. (either side will work, although from what Trevor from PTS said, firing to the driver's side is "mic friendly" and lowers your peak freq a little bit)

Building the box like this is nice. I too had height problems, but now my box is only 13 inches high, but I could make it sooo much wider and deeper. Here is a pic of my box and plans for ya to look at.

[rushnrun 14]

^^^^^^^

The exact style of box I was reccomending for the single 15

[Aaron Clinton 2,372]

Looks like a solid idea worth trying.

[KoolDrew 0]

Could you invert the driver? If so, then you would gain a little bit of internal volume back from no driver displacement. Just trying to think of another way for you to fit the 15.

It's worth a try, but the only spot I'd even have room is maybe towards the front of the box (towards of the edge of the trunk) on the side. nick_19's suggest would probably work since height is the main problem. Doing that will alow me to make it deeper and wider without having any problems fitting it in the trunk. What would be the optimal configuration for the port though? You mentioned facing it towards the side. What sort of advantage would this offer as opposed to rear firing?

I also mentioned on CA-F how I wanted to do a plexiglass window with my box, but the port would be in the way and I didn't want to do one where the sub mounted. If I end up doing a box like that, I'mm end up putting a window on either the side facing inside the car or in the rear with blue LED's.

[nick_19 1]

Could you invert the driver? If so, then you would gain a little bit of internal volume back from no driver displacement. Just trying to think of another way for you to fit the 15.

It's worth a try, but the only spot I'd even have room is maybe towards the front of the box (towards of the edge of the trunk) on the side. nick_19's suggest would probably work since height is the main problem. Doing that will alow me to make it deeper and wider without having any problems fitting it in the trunk. What would be the optimal configuration for the port though? You mentioned facing it towards the side. What sort of advantage would this offer as opposed to rear firing?

I also mentioned on CA-F how I wanted to do a plexiglass window with my box, but the port would be in the way and I didn't want to do one where the sub mounted. If I end up doing a box like that, I'mm end up putting a window on either the side facing inside the car or in the rear with blue LED's.

So funny. Check the box in this video out. It is the same box I just posted a pic of... It has a plexi window in it w/ blue LED's!

I don't know how other setups sound, but I have just heard that you get a dB boost and lower peak freq by firing it to the drivers side. You can always move it around and try diff setups. Any questions just ask... Sounds like you'll end up building a box exactly like mine haha.

Edited January 18, 2009 by nick_19

[KoolDrew 0]

haha, that is funny. Yea, I'll probably end up building it just like that but I plan on carpeting it as well. I never thought about firing the port to the side, but it would also allow me to make the box deeper and the port won't get in the way of the plexiglass window.

Thanks for the help. I'll have to do some measuring to see what dimensions will work, but considering height was the problem I don't think I'll have any problem getting it to fit. Height is mainly a problem because of the opening of the trunk. Here's a pic:

By making the box shorter those little triangle peaces won't get in the way and I'll be able to make the box a lot wider and deeper without having a problem getting it through the opening. The only hard part may be getting it through the door since it's a 4dr and the openings aren't that large. Maybe I'll take some boxes home from work and make a cardboard box the same dimensions and see how it fits.

Edited January 18, 2009 by KoolDrew

[nick_19 1]

Cardboard boxes will save you a lot of time and wood.

I can get my box in and out without a slight problem through the actual trunk... But yeah good luck with the build.

[KoolDrew 0]

The box I have now is about 2.4 cubic feet IIRC and that won't even fit through the trunk opening. I had to go through the car. I'm probably not going to start the build until spring time since it's way too cold out right now and it'll give me time to save up a bit more money, but I'll be posting a build log when I do start.

[BigDaddy13440 3]

I did a box for a Beretta a few years back, I mocked it up with cardboard inside the car, one panel at a time, used every square inch I could get. Only problem was, I couldn't get it in through the back seat, or through the trunk opening.

So, what I did was make the box in two pieces - I made the box, cut it dead in half, and made a 1x2 "flange" on the inside of each half. Put the first half in through the trunk, up against the back seat, then dropped the second half into the trunk. Crawled inside the box, and screwed the two halves together through the flanges (yes, I sealed it with silicone before joining the two halves).

Netted me almost 8 cubes!