dual mdf box or form-fitted fiberglassed box in trunk?

[sumone 10+ year member]

which would you prefer? I'm either gonna have to buy a dual box for 12s or make a box on each side of the trunk. I'm leaning towards making the fiberglassed boxes cause it'd free a lot of space up and would look nicer....not that I'm one for looks, but I wanna know some disadvantages of making the fiberglass box over buying a dual box OR advantages of buying a dual box overmaking a fiberglass box.

Just which would you guys prefer (if price was not an issue)?

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[Germanlookt2 10+ year member]

Oh, heres what i would do, I make these for people I do installs for all the time, First, dont buy a box, make one, use thick mdf, the thicker the better, Ive made boxes where the outer wall was just fiberglass supported by ribs, very tough. What i like to do now which is easier and looks nicer is build the box, to the exact specs for the sub(s)make sure that each sub ahas its own chamber or itll screw the waves up. Then make a ring to raise the sub up an inch or more, Then get soem cloth or fiberglas mat, people use like some kind of resin absorbing mat that you can stretch over the rings and staple on the sides. Soak in resin let it dry, sand, bondo the small imperfections. This way is the easiest for someone new to glass. Since its purely appearance and not a structural part of the box, I carpet boxes, but I painted my own. If you paint youll def need bondo or some glazing compund to make it really smoooth, all the imperfections youll see as most of the newb boxes will have. Take it slow, I can make one in 2 weeks, with carpet looking nice, ill need up to 4 to make a small paineted one. but im soo busy. Planning is everything. THe good thing about this is you can test your box for leaks before you even neeed to glass And if you ever decide to stop you have a box, just staple or glue some carpet to it. Oh and Remember to seal the MDF, its good to coat them in resin ater its all together, the hardest part youll find is not so much the glassing but sealing the box, porting is hard to tune, there are plenty of designs on the web. hope this helps

 

[req 5,000+ posts]

GLASS IT! =D

problem is if you want SPL, you will want a ported box. im thinking of making a ported box myself... and a fiberglass + ported isnt for a newbies first fiberglassing job.

make the box to the specs of the subs via the info from the manufacturer... you can make a sealed box if you like, but you wont get as loud as you think most l ikely....

so you can make the box and carpet\paint it

or you can most likely do a sealed trunk corner pod like i did

not too hard at all. just use the sticky on HOW TO FIBERGLASS in this forum, and ya cant go wrong!

 

[sumone 10+ year member]

No all-MDF box-making for me. Don't have the tools and don't feel like using elbow grease to suffice for the lack of tools...

I'm not worried about the actual process of glassin per say cause I've made kick panels, but the actual disadvantages of having a fiberglassed box.

Like for instance, FG'd boxes are usually at the far ends of the trunk; this leaves you with only one position to place the subs and what if you don't like the sound at that position? You're stuck.

Well I guess the only thing I'm worried about is not having enough volume...

 

[Germanlookt2 10+ year member]

Well sorry to break the bad news, youll spend much more making that glass box, and making it purely out of glass is a beast. trust me youll need a variety of tools to sand cut and work on that glass, as much if not more than making a mdf box.

heres an idea what bare bones tools youll need

Decent drill, preferably rechargable portable ( i have 3 dewalts)

sawsall saw or a zigsaw, I like the zigsaw, b/c more accuracy, but its slow)

table saw orcircular saw for the best long cuts, but with time a zig saw can do it all

a grinder. nothing fancy, but cutting layers of fiberglass is hard, and saws can crack it fast

Stapler, heavy duty one, I like to staple screen as a base when im shaping the box, it kinda gives the glass more strength when it is on it. I use like 100 staples in the process of holding screen on each box lol.

Nice sanders sanding glass takes forever, not like wood. Can use orbital, cheap vibrating, or air (what i use) I do alot of car and body work so im always using them.

If your thinking that fabbing a glass box is easy, well its not. Most people end up scrapping their jobs because they get frustrated glassing them. Its tricky, you have less than 10-20 min before it starts to gel up, Its more around 5 min for me since i use alot of hardener to cure it fast. quick hands, big mess, lot of planning. Start small then see if you can do it...thats my 2 cents.

If you wanna see another nice box im working on i should have it done installed in this guys f150 custom tonight with pics later this week.

As far as disadvatages are concerned SPL needs ports, thats very tough on an all glass box, sealed, glass boxes (when done right can be fantastic.) The reason I suggested the MDF box is because its easy to find a plan thats tuned, the all you need to do is modify the outisde to make it have a smooth all glassed look. Similar to what im doing on this current f150 install

 

[sumone 10+ year member]

basically the only reason I like glass boxes at the ends of the trunk is cause it's outta the way, period. And the reason why I wanna avoid making an MDF box is just cause I can't cut straight lines with the jigsaw. I know MDF is cheap but I just can't make straight lines with my jig. And I know you HAVE to have straight lines when making boxes.

So if I were to make a box, I'd spend about 20 for a 4x8 sheet of MDF, and probably a lot ($50+) for a circular saw, when I could just grab a full box off eBay for less than 70. Unless someone has a super easy alternate way of cutting lines with a hand-jigsaw...

Also, as far as going ported or sealed, I would either want a mid-high 20s hz tuned box cause I'm an SQ-advocate. I don't need loudness; I need tight and versatile output. The 300 watt amp I have hooked up right now is sufficient so the 750 watt one I just bought should be more than enough, so porting to get extra SPL is not necessary.

 

[Germanlookt2 10+ year member]

well you dont need to make straight cuts, especially if your making a box shaped to a trunk. Fiberglass Can be made by itself, but it will take alot for strucktural integrity, you could coat the whole trunk in aluminum foil, then lay glass down, so when it dries the foil just comes off the glass and the box is perfectly formed to the trunk, but depending on the size, it might not come out b/c of its width. And If you have any friends im sure one of them has a circular saw. its one cut, you might even be able to go to lowes or a similar hardware store, they have these uber huge table saws, I sometimes have my mdf cut there for free, and its straighter that i could ever cut it. Just a suggestion, itll take alot of planning, but Id say i never really use my circular unless its a Big box, use the edges that are already on the board, more often than not youll be cutting a curved piece to follow the lines of the trunk. If you think youll save yourself the headache if you do it all in glass I think youll just have more aggrevation.

 

[ss3079 5,000+ posts]

Straight edge. Clamp it in place. Use as a guide. Straight lines.

- Steve

 

[iamamp3pimp 5,000+ posts]

yup

3 inch deep 3 inch c clamps can be had for like 4 bucks at home depot.

you need 2 of em. i also use some old iron metal thing as my str8 edge.

it looks like an old railroad spike, a 48 inch railroad spike