Starting with a little backstory, 1985 Fiero GT, no AC (smaller air box), I've already upgraded the dash speakers with Rodney's 2 way speakers, I've upgraded all the headrest speakers with pioneer 4" 2 way speakers, and I got a "Dual 10 inch powered subwoofer" from Walmart. It was small enough to fit behind the passenger seat, but being tall, and from a tall family, I decided it pushed the seat too far forward, so I was going to build a larger, thinner enclosure for behind the seat. I then decided, out of curiosity, to look under my dash by the air box, and see if I had space under there, and much to my surprise, with a very... Specifically... shaped box, it would theoretically fit. So then I made a calculation to see if there was enough total volume for the subwoofer, the original Walmart enclosure was 820 cubic inches, my calculation on total available under dash space was 1100 cubic inches. With that, I started measuring, drawing, cutting, glueing, repeat. Took the dash out and reinstalled a few times, each time getting better and better.
The end result was a very oddly shaped box, made up of 18 pieces of plywood, then painted, then partially covered with the carpet stripped off the Walmart enclosure. New box volume is somewhere between 800 and 860 cubic inches, but due to the impossible shape, hard to calculate. As you can see, the subwoofer is as big as it can possibly be, and the integrated amplifier board is screwed into the side, just as in the original from Walmart. Walmart original: After these pictures, I installed it, and it didn't quite fit, it pushed the dash out a little too far, so today I removed it all again and trimmed the upper portion (that was hitting the passenger vent tube running across the dash), didn't affect the actual subwoofer mounting, but I just finished reinstalling everything, and it fits perfectly. To mount the subwoofer, I have it strapped to some of the standoffs on the frame of the car (for holding cables, etc.), and it is very tightly fit between the dash and the firewall. I had to relocate the blue dingy thingy along with the horn relay and hazard flasher and I zip tied it above the gas pedal, way up above the firewall front compartment electrical pass through, still audible and accessable, but out of the way. Final result is a straight dashboard, nothing behind the seat, and way more bass then I need (only have the 10" because it was on sale, for $50 Canadian) I have it turned down to a reasonable level, and can further control it via the eq on my radio. It sticks down about 1-2 inches from the bottom of the dash (air box sticks down 3-4 inches, so from the perspective of the passenger, it is invisible, the speaker itself is directly above the passenger dead pedal, but as long as they don't kick up, there's room for size 12+ feet, so should be fine, sound is very well distributed, much better then from behind passenger seat, no rattles, etc. I don't have pictures of it in the car installed yet, as I finished at 10 pm, to dark and cold. But it fits perfectly, and while the enclosure is absolutely horrible to build, it took a whole tube of pl premium max to seal all the gaps between the pieces forming that complex curve, then some silicone caulking to seal around the actual sub and the amp board. Total cost was 1/4 sheet of plywood (already had it, so free for me) 1 tube of pl premium max (again, already had it, so free), and half a tube of silicone sealant (free again), and the subwoofer that I bought in the first place, $50cad. Total cost to buy would be around $40cad material+subwoofer and amp, and a lot of hours of work.
This will NOT work on cars with AC, as the air box extends a few more inches into the free space, and due to the shape, 10" will not fit in an AC car, but 8" probably will and 6.5" will. Also with some of the complex curved space taken up, an enclosure for cars with AC, or non AC cars that just want a smaller sub, would much more closely resemble a simple box, and be easier to make.
So has anyone else gotten a 10" sub to fit under the stock (no AC) dash. I know I had searched for pre built alternatives before, and as far as I know generally the largest that had been put under there is an 8", even then it is tight, most people who have done large subwoofer builds also have AC, which is why basically every site that talks about aftermarket subwoofers says 6 1/2 or 8" is the biggest possible. Anyone else use a 10" in that location, anyone else use plywood and pl premium max to construct a box? I am certainly not a bass enthusiast, and would have probably found the factory sub adequate, but for 50 dollars and some labor, it was too good to not get. I don't know whether this thread will be helpful to anyone who is an audio enthusiast, but it is something I haven't seen anyone do before.
I have the stock subwoofer (well, not completely stock since I replaced the subwoofer which was broken with an aftermarket one) and although music sounds better than without subwoofer, it can't really keep up with modern (house) music. Bass gets distorted really fast if I play a nice techno stomper. 😁
I have the stock subwoofer (well, not completely stock since I replaced the subwoofer which was broken with an aftermarket one) and although music sounds better than without subwoofer, it can't really keep up with modern (house) music. Bass gets distorted really fast if I play a nice techno stomper. 😁
Yeah, this is much bigger then I need haha, but for 50 dollars, I can't complain, it does mean there is basically no distortion until it is much louder then I'll ever want!
The other thing is it is very high up, about 1" above where the carpet ends, I've been in and out a few times and it is no problem, unless they intentionally kick up. I think the factory subwoofer sticks farther down then mine does!
Also, come to think of it, the cone is very solidly built and it didn't have a grill to start with, there is a version of it that does, but the cone looks different, so they likely reinforced this one a good bit, nevertheless, I will look into putting a grill on it before winters end.
Man... it is amazing how well that fits. It literally fits better than the stock subwoofer, and you literally don't even see it.
But x2 on installing a grill. Just looking at it makes me nervous. Like... I think the first time someone sits in the passenger seat, they're going to kick that speaker and put a hole in it! It must sound really nice in there though!!!
Man... it is amazing how well that fits. It literally fits better than the stock subwoofer, and you literally don't even see it.
But x2 on installing a grill. Just looking at it makes me nervous. Like... I think the first time someone sits in the passenger seat, they're going to kick that speaker and put a hole in it! It must sound really nice in there though!!!
Thank you, it does fit very well, but it was a chore to make, literally my 3rd wood project ever (adirondack chair and little desk extension 5 or so years ago). I do fully intend to find some form of grill, but like I said, the original subwoofer specifically came with no grill, as a ready to use unit, with a different (very thick and hard plastic) cone design to the version with a grill, best this had was a small ridge of dense foam all the way around the surround, basically to keep the sub from hitting stuff if placed against a flat surface like the back of a seat, and to protect the surround itself, but im not worried on the durability of the cone, it is very thick and hard. Size 12 feet, with heavy winter boots on are still a few inches away. For example, the fusebox on the drivers side sticks down similarly or farther then my subwoofer, I'm sure some people have kicked it at some point in time, but I never have, even with a manual (I've hit my head on it more times then kicked it!)
seems to me you're trying really hard to get murphy's law to show its head haha
Haha maybe so, but I've said I intend to get a grill before spring, and considering my Fiero doesn't have wheels on it, it isn't exactly going to have any passengers until spring, so I can well afford to wait, I'm done all my interior work now, so if I'm getting in or out, it's in the drivers side to start the engine or something. Just saying it doesn't need a grill (cone is thicker and much stiffer then the plastic of a pop bottle), but I'll be getting one anyways.
[This message has been edited by 1985 Fiero GT (edited 02-26-2024).]
I have ordered a grill for it! Chinese special, $0.99, should be here sometime before spring. On another note, I've finished all my winter projects on the inside, and bit the bullet and drilled a hole in my cigarette lighter surround for my aux port, got it all glued in, and it works perfectly, while looking factory, and being out of the way.
My custom sub box I made with a 6.5" JLA sub sits down lower than that and I don't have a problem with no grill. I'd say you could get more volume by making that box a bit larger by doing the same.
My custom sub box I made with a 6.5" JLA sub sits down lower than that and I don't have a problem with no grill. I'd say you could get more volume by making that box a bit larger by doing the same.
yeah, likely, but I'm no expert on audio stuff, just wanted a little bit of bass to compliment the 6 tweeters on my main speakers, it was cheap and i made it work. as for internal volume, I made it the same volume as the original box the sub came with, I have big feet, and I really didnt want anything that would stick down much more then that, in my case unless you know it is there or I turn on the radio, there is no way anyone will see or notice it, if it stuck down any more, it would be visible. also most people who would do this have an A/C car (they are more "desireable" and fairly common) which gives them substantially less space in the width and depth, meaning to get any kind of volume, it needs to be much taller. I'm happy with it, it is exactly what I like how I have it tuned, it can be turned up a lot more then I have it and still sound good, and likely with a slightly taller box, could have a really high end 10" setup, but that isn't what I'm going for, I just got the first (cheapest) thing I saw, and found a way to incorporate it in a way that was basically invisible, and basically free. As for the grill, I intended to get one anyway, it was $0.99 shipped with some other stuff from china, metal mesh, seems high enough quality, and will keep the sub itself clean.
[This message has been edited by 1985 Fiero GT (edited 03-25-2024).]
