guardsred944s

Ok so I'm done with the first step of doing a new sound system. The goal is, good sound, invisible system. The next step is selling my miata, then pressing the "checkout" button on my crutchfield shopping cart.

So today I mocked up a sub woofer cabinet for a Polk Audio db840 8", to fit in the right rear cubbie. I went through a couple of designs, calculating volumes, etc. I considered have a sub cabinet behind each passenger but the only way I could have done it (while still being super classy "invisible") would be to face the subs towards the back of the seat. I finally settled on a trapezoidal box which fits in the cubbie and has a volume of approx 533 in^3, the sub calls for 600ish in^3. Not bad I think!

dillon410021

pretty nifty

Andy1212

Nice build, but you should have used mdf. That ply is nowhere near strong enough, you will have some severe flex problems.

supes6

Sounds like it's just a mock-up.. I hope.

JohnKoaWood

You don't sound mat a moc-up... but it does look nice...

guardsred944s

Well I used 3/8 inch ply, i know this isnt the "proper" way to do it, but ill explain why I did it. Firstly, all the material used were from stuff "just lying around". So basically "from scratch".

The second is that I seriously doubt that sub enclosures are subject to to failure because of the material used... instead I assume that it is from improperly joined joints. From my research, the only thing I found as a reason for using MDF is that it is less susceptible to cracking when screwing joints together. All joints have been glued as well as predrilled and screwed using wood screws.

I too am critical of using this material as I know it is not the norm, but I will provide updates when I install the sub as to, whether or not this works...

Thanks for the thoughts!

75ohm

Trial and error for improvements... do it until your satisfied with how it sounds!

You may consider using some backing pieces with glue and air driven staples if you have it to get a tight seal. The tighter the box the better off you'll be regarding rattles...

pontifex4

One of the main reasons to use MDF is that it is about as acoustically-dead as any cheap material which you can cut and shape. Its shear strength is terrible, though, and it LOVES to soak up moisture.

Your plywood may have been a fair choice, considering the environment (my storage bins are always a little damp from the rain which leaks down my hatch). If you're finding that it doesn't seal well, though, it may be worth pulling the box out and epoxying the seams with some fiberglass cloth for a bit of added strength.

guardsred944s

Yea, another thing I was thinking about when I was taking measurements... TG Porsche dipped all their cars at this point, because there is always a moist spot at the bottom of that little cubbie. (Gentlemen: start your euphemisms...)

V2Rocket

MDF is better for sound boxes as it is so heavy with all the glue and moisture that it will vibrate less due to the speakers.

dillon410021

lol, Just wrap it up in some duct tape.

carlege

also its more sound proof= a better sound quality for subwoofers. and its really not all that expensvie. But good luck

Dougs951

What are you planning to put in the rear quarters? If you wouldn't mind could I take a look at your shopping list?

guardsred944s

http://www.crutchfield.com/p_107DB84...dio-db840.html

and

http://www.crutchfield.com/p_236TN25...r-TN250-1.html

but i plan on getting a another 8" when I have the money.

Also a new head unit and some infinity references for the rear side panels eventually.

Dougs951

The speakers in the doors and quarters of my car were blown so I replaced those first. Are your speakers the original paper ones?