So...putting together a system for a buddy of mine in his 91 MR2. Space is very limited since any install would have to be in-cabin and directly behind the front seats. So far, he's debating on either four Ascendant Audio Assassins 8's or four RL-i 8's. Whatever he chooses will be powered by his Kar 900.1.

Now...I can't fiberglass (more like I don't know how ), So if I used 1/2" MDF, instead of 3/4" to get the most airspace as possible, will it be OK if I braced the insides with some 1/2" wooden dowels to minimize flexing? Or can I just cover the inside with a layer of resin?

 

1/2 inch is gonna flex quite a bit you would have to do some major bracing, but I don't see why its not doable.

 

So it should be ok if i say...glued some wooden dowels from the top to the bottom, then from the back to the front panels eh?

 

I like the resin idea myself

 

why not just use 1/2" Birch?

 

birch that much stronger than mdf?

 

Ummm yes it is. 1/2 = 3/4 MDF.

 

Hmm...interesting. guess i'll just go the birch route then.

 

Lighter too.

 

Whats the cost difference in birch/MDF

 

It is substantial, but dependant on where your located.

 

it's roughly twice the price of MDF no?

 

eh prolly a bit more..

 

well whatever works the best in that tight area. wish i could 'glass.

hard part is trying to see how i can orient 4 eights.



that was Mike's (of Sound Splinter) MR2 before he changed vehicles. that's one 8...

 

Look into Pioneer's slim 10" subs. You could mount a pair of those in the cabin quite easily. Elemental Designs has also created a slim 10" sub that is said to sound almost just like their "k" series 10" sub.

 

If you can't find any resin for the inside, just use stamps.

 

Hahahahahaha

 

birch is definately the way to go. I've seen home depot have it at times and not have it at others, or you could go to a lumber yard and get some specialty stuff, called marine grade or baltic birch.

Resin itself will add no structural integrity. You'd need resin and mat, or better yet for a sub box woven roving or knytex. Also keep in mind with fiberglass, bends are stronger then long flat surfaces, again why birch is a better bet.

Now building an "all glass" box is definately an alternative, or at least a box where the flat parts are birch and the rest is glass. I bet with all the tutorials around on the net you could figure it out and do well.

 

Just make sure when searching for Birch you dont end up with Birch veneer core. This is simply generic plywood with Birch veneer on both top and bottom. Generally what youll hope to find would be Baltic, although Russian and 'Euro' are along the same line and usually 9 ply.

 

4 8's in a MR2. Good lord. Hope he is goin with a sealed box, a ported is gonna be pretty damn huge. I've never built a box with birch. Huh, never thought of using it. Last place I used birch was in High school woodshop class. I never recall birch comming in 4' by 8' sheets though. If hes limited on space, and its going to be in cabin why not go 1 12. should be more then sufficient for that cabin size. Put the sumb behind the drivers seat, and build a amp rack behind the passenger. Just my idea. Good luck though, would really like to see pics of the box u make to fit that cabin space.

 

You can find em in 4 X 8, but more typically will be 5 X 5

 

Well, he likes the idea of a loud setup...but not the typical 12s etc. So he opted for some 8's, which is pretty cool in my book. Those 8s will get pretty loud, and sound good at the same time.

Don, how many amps do those 900.1 pull? He'll end up getting another one down the road...he's wondering if his alternator can take the strain.

 

I have 2 Ascendant Assassin 12's in my Max and built the box myself. I'd say go w/the tried and true 3/4 mdf. The ONLY thing you'll gain from birch is it's weight... it's NOT more dense then mdf. (density is far more important than if the wood is stronger then mdf or not)

With my box I only used one solid brace with a double thick front and it's more then enough for these subs (it's in a 3.5 cubic ft. enclosure tuned to 32hz). If you build it with anything less then 3/4" mdf or birch, your enclosure will end up being around the same size because of all the bracing you'll need to stop flexing. In other words don't bother!

and sorry rein on your buddy's parade, but those assassin 8's in a sealed box won't hit low notes for the life of 'em. You need to port the 8's. Two 12's would destroy 4 8's... but the 8's will look cool!

 

Where do you get your info about Birch being inferior to MDF? This I would Really love to know..

 

he's not getting the assassins, he's going for the RL-i's, which will work very well in .4 cu ft of airspace.

went to home depot with my buddy awhile ago to look at some birch. the stuff is pretty solid. i'm not too worried about it being too dense. main concern is flexing from the thinner material.

 

What you have to worry about isn't density. It's flexing. Density is what makes the MDF weight more, but MDF flexes WAY more than birch as birch is stronger wood. I've STOOD and JUMPED on two identical sized pieces of MDF and Birch with cement bricks on the ends (both 3/4" thick, 2 x 4 ft). The MDF you could easily flex by standing and jumping on it, to the point that I thought if i really tried I could have snapped it. The Birch did not flex a bit. I bet a lot of people here like me, when we're done using a sheet of MDF to make baffles out of, simply kick the remaining mdf with the holes cut in it to break it down. Makes my weak azz look like a blackbelt. Trying that with birch would hurt me, not the wood. MDF is tried and true for car audio because A it's cheap\readily avaliable, and B it's real easy to cut/router (just turns into sawdust). Birch is expensive and not always at your local home depot. I had to drive accross town (twice, long story) to get my sheet of Baltic Birch and it cost me waaay too much (ummm for me it was more like 3x the cost of a sheet of MDF). Thats why it's hardly used. Oh, I haven't mentioned resistance to water/moisture as an advantage Birch gives either and of course less weight....When you use a router on it, don't try to take off too much at once or you'll need a new bit

Ascendant. Listen to Don if you have a shot at getting good Birch. It's real good stuff!




Edit: If your blessed enough to have a local Woodcraft, which I am, stop by there and see if they have some. Mine didn't, but they were the only people knowledgeable enough to guide me to a few select lumber yards that might have it, and one of them did. Or you can order from them, but I couldn't imagine how much shipping would be....

http://www.woodcraft.com/family.aspx...0&FamilyID=669

Editing yet again...if you order more then $75 worth, ground shipping from woodcraft is free. Thats a significant savings. May be worth considering....

 

Where did I state Birch being inferior? The only advantage it has over MDF is weight and stiffness. MDF being more dense/evenly dense, plus much much cheaper in MY OPINION makes it the hands down pick here. Birch is great and all, but I've never seen a board being that much stiffer. The only situation where I'd use birch is in a Home Audio environment where many layers and braces are being used...and even then, MDF is much better to finish, so who knows. I just don't like birch.

 

Please see the post right above yours.

 

You said " The ONLY thing you'll gain from birch is it's weight". this is incorrect...read my post.

You said "density is far more important than if the wood is stronger then mdf or not" This couldn't be further from the truth. Density lowers the resonant frequency of a box, lack of flexing (strength) stops resonance altogether.

You said "If you build it with anything less then 3/4" mdf or birch, your enclosure will end up being around the same size because of all the bracing you'll need to stop flexing". this would be true of MDF, but not Birch cause it's that much stronger, and like Don said, would flex maybe as much as 3/4 MDF. I've never played with 1/2 birch to compare to 3/4 MDF, but it definately flexes much less then the same sized MDF.

It's cool if you don't like Birch. It's a PITA to work with compared to MDF and is hard on your tools, but for an application where space or weight is an issue, it's a good call. I chose it for my rear deck because I wanted it up there for years without having to worry abou moisture or chipping or anything, as well as I wanted a SOLID rear deck that wouldn't flex under any circumstances without bracing.

Edit: djfrestyle beat me to it....

 

Steve +1
Noobie -a lot

 

...



Ascendant, why don't you give fiberglassing a shot?? theres tons of information out on the internet, and im sure some of the guys on here will help you, Metal Maxima, and im sure others have FB'd before.

 

i wouldn't mind learning, but i rather fubar my own cars before i attempt to fiberglass a friend's car.

 

Just use a LOT of tape. You should be fine.

(I've never glassed but I've read/watched/seen a lot to be able to)

 

should cost you about the same as a birch set up, i would think.. especially if its nothing too fancy and you make the front just a flat surface out of a piece of MDF or birch..

it would be the best way to get the most airspace out of the curves and the space back there.

 

MR2's are small *** cars with very little interior airspace to work with. 4 8's will be hard to fit, why not 2 10's. Hell, have you thought about fitting a sub in the passenger footwell? Put the bass right up front where it's meant to be on the sound stage.

 

not practical due to the fact he does take passengers around quite often. plus bass is non-directional. but thanks for the suggestion non-the-less.

he thought about 10s, but enjoys the idea of 8s much better.

 

He likes the unique-ness about it.
Well, yeah, I'd say your best bet would be to use MDF (or whatever wood you decide) for the bottom and back of the enclosure. Then position some speaker rings, attach them, stretch some cloth, and then you'll be able try your hand at glassing the rest of the enclosure outside of the vehicle.