Box Building - Light weight
 

I am going to begin the plans for my box for the trunk of my Skyline (to coincide with the full custom trunk, jigsaw puzzle style), to house a single 12" Woofer. Hertz Mille ML3000, 4ohm 12" Sub. Power will either be from the sub channel of an Audison LRx5.1k (750w RMS @ 4ohms) or a bridged LRx2.9 (900w RMS @ 4ohms).....once I finalize my 'power-plan'.

I am looking for suggestions from anyone who can offer advice on what materials to use in order to keep the overall weight of the box down as much as possible, while keeping it as strong/rigid as possible.....kind of an oxymoron of sorts - super light, but strong.

As far as the box design, I am still on the fence. At this point, I would like to focus on materials more than anything.

To begin....
I can't ever recall building an enclosure, when using MDF, with anything thinner than 3/4", as I've never really had to take overall weight into consideration.

Could a properly built, internal-braced 5/8" MDF enclosure suffice ? I realize that 1/2" might be pushing the limits a bit, so I won't even bother considering it.

As I am not a Carpenter, I have to ask the following with great humility:
Is there a suitable hardwood/plywood that is physically lighter than it's dimensionally-equal counterpart in MDF ?

Thanks to anyone who has read up to this point.

My main concern is that every pound that I sacrifice to bad planning goes right against the car's final performance. In the end, I still want a decent handling car and not having to build 800HP just to haul the entertainment setup around.

So, STRONG & LOW WEIGHT.

Thanks in advance for any advice that builders can offer.
Allan

your 2 options really would be fiberglass ( if done correctly can save weight) or birch ply. just make sure to buy the good voidless stuff. cabinet grade or something like that. It is much more expensive then MDF but lighter and just a strong if not stronger.

With Birch, If I double-layer the baffle, do you think I can get away with 1/2" for the other 5 sides if I also use good internal bracing and gusseted joints ?

A box should always be properly braced. Trying to add more bracing to thinner material will probably wind up heavier than just using the thicker material.

Any plywood I have ever used was lighter than MDF. As mentioned, get void free, cabinet grade, or just a good grade. Cheap plywood has so little glue it will delaminate when you work with it, let alone when built into a box

3/4" styrofoam with fiberglass on both sides. Strong and light, just takes some time figuring out how to do it.

Infinite baffle would be the lightest, no? What about mounting in the rear deck?

Before you do all that, I would find a way to measure the weight of the mdf vs the fibre glass or plywood and see what the real difference is. It may not be as much as you think. You may be able to save weight elsewhere to offset the difference and save yourself a lot of hassle.

I actually had planned that, but the Hertz Mille Air 15" that I bought didn't survive shipping from Italy unfortunately.......it would have been PERFECT, but ya can't win 'em all.

If you have a daily driver and you're concerned about weight, it might be something to consider (lighter box). I mean, in the grand scheme of things, it's minimal weight change, so the benefits might not even be there, but ... it's something to consider.

Why Italy? Don't they have them in Canada?

I would say go with The birch plywood, my last box was built with half ply and half mdf but it was still heavy as ! If you're building the car to race just take the box out when you're at the track instead of compromising build quality to save 10-20 pounds which on the track is only going to save you very small fractions of a second, as a daily driver you'd never notice the extra 20 pounds on the streets especially in a 400hp car, it's small peanuts for a lot of extra difficulty in building the box