JasonWW

iTrader: (2)

I'm trying to find anyone who has used the back seat area for a big sound system. Or if you have some pictures of other peoples cars, post them up please. I just need ideas mainly.

I was going to use some older 12's in the far back but they are about 9 years old and probably won't last much longer. So I was thinking of getting some new subs with long throw cones. I have 2 600w amps to use on them. I was thinking of making a big 4-6 cu. ft. sealed box for a pair of 15's. I want some real "building shaking" bass.

I was thinking I could build an L shaped box that is mainly in the rear seat area and extends over the gas tank. The subs can mount under the rear window so you still get the horn loading effect. The amps and stuff can mount to the box in front or on top of it in the front area. The back well would be used for tools and storing junk as I have to have some space for that.

Anyone have any ideas or pics?

ROCNDAV

iTrader: (100)

I'm older now, so I havent attempted this in my 4th gen. But my 3rd gen I had 15's in the rear hatch area with the box extending into the cargo as you are describing. I also removed the seats and built a custom fiberglass box where the two rear seats were.

unfortunatley I dont have any pics. The rear hatch box hit better IMO.

JasonWW

iTrader: (2)

So something like this pic below?

That's a good setup, but I really want that rear space for storage and will easily give up rear seat space for enclosure volume.

I've experimented with the subs mounted in the rear seat area and did not like it either. They sound strange and the output is reduced. That's why I want to have them as far back as I can with the box extending forward.

JasonWW

iTrader: (2)

Since going through my pic I figure I'll post a few that are pretty cool.

First, here are a few of the JL Audio TA.

JasonWW

iTrader: (2)

Here's a few misc pics:

JasonWW

iTrader: (2)

I'm thinking of a box starting out similar to this pic below. Have 2 15's in it and make the box extend forward and downward to give it more airspace. The amps and other gear will mount on the front end on the box. Firing the subs straight up into the rear window should sound pretty good plus I can seal the box off around the window and hatch so all the energy gets directed forward.

I shouldn't need to dynomat the rear storage area and it will keep other noises from back there away from my ears.

ROCNDAV

iTrader: (100)

Yup, pushing two 15" Fosgates

JasonWW

iTrader: (2)

I did some measuring and found that a 9x18x38" box right on top of the gas tank would work out to 2.2 cu. ft. give or take. Perfect for a pair of 12's and won't obscure the rear view. I honestly didn't think there would be enough room there.

So now I'm trying to decide whether to do that and then use the backseat area for amp racks, video monitors and all that crap or if I should extend the box forward and down and make it a 4 cu. ft. box to fit a pair of 15's. Either way I think I'd have room for all the amps and stuff and still have some storage right behind the front seats (plus the whole back of the car).

I was thinking I could build the one box on the tank and then 2 smaller boxes in the rear seat area on either side of the hump then connect them together with bent large diameter 8" PVC pipe. In theory that would work, but sealing it my be a real headache. It would look cool though and I could weld up a amp rack out of square tubing and have my 3 amps go right across from left to right.

I'm wondering how much weight would be a factor as well. The 12's I was looking at were 25lbs. each plus the smaller box isn't that much. If I go with the 15's the drivers go up to 56lbs each plus double the box weight. So pretty much everything doubles in weight.

Can anyone tell me if they think the increase in output is going to be really big between the 12's and the 15's? I haven't tested any subs in like 9 years so I'm out of the loop.

JasonWW

iTrader: (2)

Here is a quick drawing of what I'm talking about.

JasonWW

iTrader: (2)

How about a pair of 15's?

JasonWW

iTrader: (2)

I did some testing by moving my 12" sub around in the car. It's a cube box so it's pretty easy to move around. I did a base reference level with what I had at the time which was a 40hz sine wave. I set my SPL meter on the dash and looped the track.

With the sub in the far back and firing up=111dB
on rear deck and firing to the rear=111 (surprised me)
on rear deck facing forward=109
on rear deck facing up=108 (kind of disappointing)
in the back seat area facing up=106
in the back seat area facing forward=106

I'm going to try an experiment and have the sub in the back seat and facing up and then get a rigid PVC tube about 12" and have it go up and over the back seat to the rear. All the output will exit to the back of the car in front on the storage well. If the output is real close to the highest levels I got above then I can build somthing like this:



Due the the longer path length the bass may play even lower than in the far rear which would be a bonus. I'm real curious how it will work out.

Aside from the higher output I didn't notice too much difference in the overall SQ. Firing into the seat backs you can feel them, but as far as SQ is concerned, the differences seem pretty small. I didn't listen to much music in that configuration.

5dB is pretty big to me, that's like what, more than the difference between one and two subs? I'm going to try an harness that extra output if at all possible.

Funny thing. When I was doing those tests the output stayed at 111 even when I rolled the windows down (temporarily), so maybe the car wasn't being pressurized very much at that low SPL. Then, when I hit the latch release, the hatch pops up a little bit and the SPL drops to 105. That surprised me the most.

wickedwarlock

iTrader: (4)

What are you using to test the spl rating?

JasonWW

iTrader: (2)

Do you mean measuring it?
I used a Radio Shack digital SPL meter.



Very handy device.
http://www.radioshack.com/product/in...entPage=search

ROCNDAV

iTrader: (100)

You may want to try it at different frequencies as well. Depending on the cabins resonant frequency and location of the test sub, you may get some difference from your final box. I did bot hthe rear hatch and back seat area (on a 3rd gen) and it did sound better in the back hatch area.

If you decide on doing it in the back seat area, try making a box out of fiberglass instead of the pvc pipe. you can wrap everything in tin foil and have a custom, tight fitting box.

After moving from two 15" to two 12", I did notice a little loss in lower end frequencies. I like you am old school and really haven't tested anything in over 10-15 years. I just recently put an 8" bazooka tube in my Montero that I am currently driving and think that sounds good Damn, Im getting old.

JasonWW

iTrader: (2)

I wasn't making a box from PVC pipe, I have a cube shaped box already with my old 12 in it. I was going to get some big PVC tubing to make the "duct" to direct the sub output to the rear. I figure that's easier to throw together for testing purposes, but since the round shape might effect the sound and I would build the "actual" duct in a rectangle shape, I figure I should whip up a proportionately sized, rectangle shaped duct for the 12" just to be on the safe side.

The actual sealed box in the back seat that I would make would be all fiberglass to make it really rigid and save weight not to mention fitting around all the complex curves. I would probably take a big block of foam and carve it to shape slightly undersized and then wrap it in fiberglass, carve all the foam out and fiberglass the inside as well. I could mix bondo and fiberglass resin in a "milkshake" that I recently heard about and pour in a thick layer and spread it around to add stiffness quicker than layering the fiberglass down layer by layer.

Check out Mike's (DJSexay) install. His latest has 2 12's in the back seat. He's focused only on SQ and not being really loud to annoy people so he doesn't mind the loss of SPL with the subs there. It's a great looking setup.







http://www.djsexay.com/gallery/albums.php

kyles2000z

iTrader: (8)

why use all that CF and cover up the majority of it? that stuff is too expensive to lay down and then cover 80% of it up!

JasonWW

iTrader: (2)

That's not what he did. He just did the area seen around the subs. Look closer, you'll see.

MikeFbody

iTrader: (2)

yes, the CF is only the outer layer on the baffle, done for cosmetic reasons only.

After having made the box using that method, I must offer words of caution.

The only reason I did it like that, was to try and build my box so that it was foam core fiberglass, not just solid fiberglass. What I mean, is that the box is actually several layers thick of fiberglass, then about 1/8" thick foam, then several more layers of fiberglass. If you notice in the one pic where I removed all of the foam from the fiberglass shell, I actually left some of the foam intact.

It sounded like a good idea, as my experience with building flat foam core panels has resulted in much more superior strength with less weight. But for the sub box, you still need to build it thick enough to keep from resonating, that I feel the benefits of this construction method were not worth the extra headache.

For my next enclosure, I'm going back to just laying fiberglass directly over foil to get the shape I want, and am not bothering with the foam.

kyles2000z

iTrader: (8)

oooh i see now. haha my b.

JasonWW

iTrader: (2)

Here's a few diagrams with the single sub idea. I may go with a more common Rockford T115D4.