00 ext cab sub box

Hotwire · January 18, 2005

Hey all,

I have 2 jbl 12" gt1200s that i have run forever, they seem to be holding together quite well. Wanting to build a box for my ext cab and keep the functionality of it as well.

The subs need 1.2 cu ft per sub (sealed), was wondering if anyone has built a box to this spec and if they ran into any issues.

I'm using an ancient hercules hiphonix (500watt into 2 ohm) to run them and it sounded decent in my little ext cab s-10. now that i'm used to the fullsize, it's time for some noise!

I won't rule out buying new subs or amp, but would like to use what I have to keep the funds in place. Should I move to 10" subs?

Just for comparison, those subs hit 137.5 db back when I first built the box in my s-10, i know the fullsize cab is larger, but just giving everyone a general idea of what I'm used to. I've got boston acoustic fs60s to go in the doors, just need time to install them.

Thanks,

Jeff

Wingnut · January 18, 2005

Here is my setup. I didn't like the way 12 inchers sounded back there. So I went with 10's.

Click here.

Hotwire · January 19, 2005

preciate the reply man, i've seen you posting that around elsewhere and have read through that already.

I was going to attempt a box similar to that in order to get the volume needed for one sub. Just went out and took measurements.. thought i had a good plan going, thinking the little ridge on the floor that's even w/ the end of the seat would provide enough space for the sub to fire downward until i looked at your post again. schnit. the sub would be traveling straight into the carpet if i did that.

man, i don't want to get something for nothing, but is there any possible way you would measure your box for me?

The measurements i have right now are a full 55" across the full floor pan, going 15" deep, so they are a little past the end of the seat, but people's feet don't really occupy there, 20" across under each seat, and was going to go 9.5" high, but was worried about the compression of the seat / carpet to make it fit ok, then was going to recess the box 5.5" for the hump and allow it 15" across. so the little "crossover" on top of the tranny hump is 4". All these are outside dimensions, I can draw up a diagram to show these measurements if this doesn't make sense.

I was figuring I could get both subs in there w/ barely enough volume for each, but then I saw your subs pokin out the bottom of the box and said, dam, no room for the offset of the rim or the firing of the sub.. I know..

so now I'm dropping my expectations down to one sub on the driver's side, pulling the box back some on that side to allow for the sub and firing room, but now am off to check the mounting depth to see if it'll work.

thanks again,

Jeff

Wingnut · January 19, 2005

I'm pretty busy for the next couple of days, but send me a PM around Friday or so if I havn't sent you the measurements.

And 2 12's will work (depending on the subs requirements of course), I just didn't like the couple that I listened to.

I know that the place that I bought my box from has boxes for 12's. They just come a little closer to the front edge of the seat. And you would have to buy subs that are built for smaller enclosures.

Wingnut · January 19, 2005

BTW, I had a HiFonix Hercules in my '89 reg cab pushing two 12" MTX's. That's a pretty good amp there.

Hotwire · January 19, 2005

Yea, that amp has taken some beatings and is still kicking pretty good!

I haven't really looked at it, but what about turning the middle seat in my 40/20/40 bench into a box? Heard of anyone doing that / pictures / results?

Halen5150 · January 20, 2005

If you're going to stick with 12s, go with a forward-firing box to allow for more airspace. You may not get the full 1.2 cubic feet per chamber this way, but you'll get pretty close. The box may stick out past the edge of the seat some though. I'd say go with 10" subs in a downfire box like Wingnut's. You'd be lucky to get .85 cubic feet per chamber in a downfire, which is why I'd go with 10s for this application. Just my thoughts....

Hotwire · January 20, 2005

I appreciate the reply Halen, but I already have the 12s, so you know how that goes. If I went out and got new subs and left those laying under the bed, my wife would probably bobbitize me. She's cool as hell, but when it comes to $$, I had better leave it for her to shop with.

I've come up w/ a design that will allow 1.16 cu ft per sub, not subtracting for the sub's volume itself. I'm going to go ahead and hopefully get the box done up soon, line it w/ polyfill and all the goodness of liquid nails and see how it sounds. Yes I will be making cardboard templates to start out with to make sure it will fit and everything work ok. I'll try to take pics while doing it but can't spend much time on it, I've got a 2 month old little girl, so she demands my attention too.

I've ran all the numbers through blaubox, winisd, and winisd pro, looks like i'm only going to loose .5-1 dB overall so it shouldn't sound too bad, the box will be tight, I'll keep everyone posted on the progress / finished impressions.

Hotwire · January 22, 2005

went out today and got a Infinity 7450a or 7540a, something, to power my front and rear speakers, can't wait to install it and see how it does. 111w rms x 4!!! I also couldn't resist the urge to also get a set of boston acoustic 4x6 746 plates. I had a pair back in the day and they were the sweetest sounding speakers I ever owned, I can't wait to get this system done!!