I am building a fiberglass stealth subwoofer box and thought I would share the construction process. The car I am making it for is a 1995 Miata. I am working on making the plug which will later become a mold to make the actual box from. I will add pictures as I make progress. This is my own design but ended up looking a lot like the JL audio box. It will hold a pair of 8 inch subs. I feel anything smaller than a 8quot; sub just wont do the job very well. My first post but that dosnt mean Im new to Miatas or making composite speaker boxes. Pictures to follow. Let me know what you guys think.
Here is the basic box not done checking fitment. Its still in bare MDF here. It will later be coated with gelcoat and a mold will be made from it. Under the box I have 1 inch of space for the woofers to move. I am happy with the fit and am wondering what other years this may fit? This car is a 1995 in rough shape being fixed up.
Heres another view. The bump on the top of the box gives it extra air space and a place for the magnets of the woofers to go. It also functions as a wind deflector when the top is down. I am hoping to be able to fit in a pair of the kicker square woofers model S8L5.
Last picture for now. Making that bump smooth and the correct shape was a ton of work. Let me know what you guys think.
Looks pretty good, I added 2(two) JVC CS-BB2 powered subs one under each seat, can get much more stealth than that.
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I agree thats a good idea. I am hoping to squeeze in a pair of kicker square S8L5's in this box. If I can make that happen this will perform excellent. The square woofers are really nice because of the extra cone area,they are more like a 9 inch woofer. I use the S8L5 in my Honda Insight box and they really perform well. Im also looking at different class D amps because they draw less amperage. Im looking for a small mono class D amp thats stable into 2 ohms or better yet 1 ohm. Here is the box again a little closer to being done. The gray coating is gelcoat,it will be wet sanded next. I found more imperfections of course and will have to fill those. The box has to be super smooth and near perfect because it will become a plug for my mold and I plan on making this box gloss black gelcoated on the exterior. Gelcoat is superior to paint for a lot of reasons. My concern is the UV resistance and also the top sliding across the box and zipper for the back window scratching/vibrating against it. I dont like doing things twice,so if I do it right the first time hopefully I wont have to do it again. I also think black blends in better with the interior. I want this to look like it came with the car.
I like your idea. I did something similar using a single 10quot;. With your volume, why not step up to 10quot; subs ?
2 things I want to suggest for you.
- Step the underneath 1quot; of space to 1.5quot; because the carpet padding will compress where your spacers are but not in the cone area and under hard bass hits your woofer's travel will be limited by the carpet. Only found this out with experience, after building the box.
- To cheat on your added spacing, put some fender washers under the cross brace before bolting it back down. Look at my box here in post #3. Note that the brace is higher than the seat belts. Normally it's the other way around, but most people can't tell unless I point it out.
Looks like you are doing a great job. IMO since you are going to this much trouble ...you can do MUCH better than those Kicker subs and a Class D amp. (unless you are just looking for 'boom and doom')
OTOH ...are you aware that a 'real' Stealthbox is still available for lt;$400
product/par....6921.6507.0.0
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I've read that a good cheap sub can be had in the JBL GTO804. It's more efficient (the L5s are power mongers) and is a bit more relaxed in the box's minimum volume. I take it you're leaving the box sealed?
Is that web site current? Thats a good deal! I agree 1 inch is tight,I plan on using my circle cutter on my router to recess mount the woofers about 3/16quot;. I also thought of the washer idea. I dont think I have enough space for the magnets of 10 inch woofers. Once I make the first box I will know more as to what will fit and what wont. If I can get a 10 inch woofer in there I will. I make fiberglass products for a living so making this isnt as big a deal to me as it would be for someone else. The materials would be way too expensive for someone to make just one for themselves.
Thats about 425.00 shipped,a bit more than I want to spend. I also dont like the light grey carpet on the JL box,it dosnt match the black interior. I think the JL box is discontinued but they have new old stock and thats why its discounted. I could be wrong.
Oh yea, welcome to the forum. I think you'll like it here.
Look into slim subs to get a 10quot; to fit.
I have this
one which is the same as this one.
Yes I plan on keeping this box sealed. I like the sound os sealed boxes when the displacement is toward the minimum for VAS. I may have to use shallow mount 10 inch woofers to get a pair of 10's in there. Can you imagine a pair of 10's mounted in this thing inches behind your head? I am going to make sure when I design the feet bass can radiate out in every direction possible. I don't want what little hair I have left being fluffed by bass. I agree all the kicker square woofers are fairly inefficient look at there lousy 83 db sensitivity rating. Thats how they achieve 400 watts RMS power rating on a 8quot; woofer,make it so stiff it takes 250 watts to get it too move. But if a 10 wont go then I will use 2 square 8 inch kickers because of there cone area. To make bass you need to move air. The more air you move the more copious the bass appears. Those little 8 inch kickers have about 20 % more cone area than a typical round 8quot; woofer.
I also am sold on class D amps for several reasons. Number one they draw less amperage. Two they are fairly inexpensive and can make a lot of power for the size on the amp. Also a lot are 2 ohm stable and mono. Regardless of what people say it is difficult to hear distortion through a subwoofer that only produces 30HZ - maybe 400HZ. A lot will argue with me on that,and go right ahead. I have measured THD% with RTA's scopes and my ears. I even had a wave analizer for a while. Its simply not needed to buy a expensive amp to drive a sub,look at velodyne,definitive technology and many top names..pull off the subwoofer plate amp and there is not much to it,many are class b,c or even d. I will not spend over 200.00 on a sub amp for any of my cars.
What ever argument you will get, the point will be killed as soon as you start moving. The maita is a noisy vehicle, top up or down. As for the dual 10quot; behind you, I'm actually thinking of upping my 1 10quot; to 2 10quot; and rebuilding the box.
Don't get me wrong, it sound really good as it is, but all bass is lost with the top down.
Thats what I was afraid of. No bass with the top down and driving,I mean its a convertible my top is always down. Its summertime everyone should be topless right? Anyways I am going to really try and get a pair of good 10 inch woofers in there. I think that will do a good job at a reasonable cost. Another reason I didn't buy a box,I want to make this my own. I think with a slick gloss black gelcoat finish on this will look sweet. Any hardly anyone will even know its a subwoofer. Bonus it really cant be stolen,that bar holds it snug in place. You must unbolt the bar to remove it. So parking with the top down wont be a concern for the security of the sub anyways. I have made more progress and will post more pictures tomorrow.
A really excellent job!
Originally Posted by Audionut
I think with a slick gloss black gelcoat finish on this will look sweet. Any hardly anyone will even know its a subwoofer.
Not saying your thinking is bad, and I don't know your area, so my info is lessons learned from my area.
A slick gloss black will look really sweet, no doubt, but it will NOT blend in with anything in the car, especially top down.
Anyone who will hardly know it's a subwoofer will be a regular Joe. People into car audio aren't exactly stupid when it comes to identifying a sub woofer box.
Originally Posted by Audionut
Thats about 425.00 shipped,a bit more than I want to spend. I also dont like the light grey carpet on the JL box,it dosnt match the black interior. I think the JL box is discontinued but they have new old stock and thats why its discounted. I could be wrong.
The Stelathbox for Miatas ONLY came in BLACK and TAN ...not sure where you are seeing grey. The Stealthbox is worth the $$$ ...personally I hate most JL products ...but that enclosure is nice and thick and DEAD. I agree with Calata ...a gloss black hump will look out of place ...carpeted is the best bet.
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Hm...I like the idea, but when I clicked on this thread I thought you meant something more stealthy. This thing is in the way of roll bars, glass windows, etc.
Someone made a sub for 3rd gen MR-2s that goes in the dash...somehow. I don't know much about it, but that sort of thing sounds cool. Of course it wouldn't be as effective as what you have here, but frankly I don't have the room for that sort of thing.
Yep no roll bar or rear glass will work with any sub that fits in this space. Basically you have to decide what you want,cant have rear glass and a sub or a roll bar and a sub etc etc. Well once I make this I can easily carpet it if I want. Thats a personal choice,like a brand of favorite woofer. The original JL box is a dark grey I have seen one. Yes they are well built,but they dont match the stock black interior at all. They are several shades off and stick out IMHO. Black speaker carpet is cheap and readily available. I also didnt just go and buy the JL sun because I want to try and get 2 ten inch woofers in mine. My box will be dead I have built hundreds of boxes and have been around the block with this. Heres a shot of some of the bigger stuff my friends composite shop makes which I sub contract for. Most of this ends up at amusement parks,the details are hand painted on after molding is complete.
I think that a gloss black finish would look nice, who care if it is not stealth. It is your car, do what you want.
Yep,I agree. Also if I change my mind or the gelcoat dosnt come out as nice as I hoped I can always carpet it. Gloss black is not very forgiving. Thats why I spent several hours wet sanding my plug last night trying my best to get rid if any imperfections. I will be laying glass on it sometime today and hope to post pictures of the plug and finished mold very soon.
As I have posted before, here is my solution to the problem of getting good bass in my 1990 NA. It's a 12quot; slim subwoofer (3quot; deep) mounted in the passenger side footwell. The enclosure is about .5 cu ft sealed, and is powered by a 500 Watt Class D amp.
This offers a few advantages:
1. GREAT bass with the top down OR up.
2. Totally stealth appearance. With the floormat in place, the sub is invisible.
3. Total access to the top area, as well as trunk for maximum cargo space.
Of course this comes at the expense of some legroom for the passenger, but depending on who's riding with you (my wife is only 4'10quot;!) it may not be an issue. For the record, I have had 6 footers ride in my car amp; not complain.
As for sub amps - class D is definitely THE way to go when you take into account efficiency, power output, size, amp; sound quality. While it is true that Class D may not be the best quot;on paperquot; (THD, TIM, etc) - these specs simply do not matter when used for subwoofer application in a car environment.
Class D amps have absolutely revolutionized the car audio subwoofer industry.
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Thank you for confirming my opinions on class D amps! Cars are noisy anyways especially a convertible! Today I installed a new robbins top! Anyone needing a top should check into robbins,very affordable and fit perfect. I am very happy with it and it only took me 4 hours from start to finish first time ever doing one. I am very handy though. Sorry no updates on pictures I have been so busy I havnt had time to take fresh ones. |
Post at 2-7 07:33 AM
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