box material selection

[tru]

What is it that makes the materials used for a box "good" both structurally and sonically?

I know MDF is kind of the standard, I guess b/c its cheap and it works.

but then theres fiberglass boxes, the material properties are very different from that of MDF, and from what i understand, all that matters is that the box doesnt flex and it should sound good.

do certain materials "reflect" sound more, making them sound bad?
do the materials need to have a certain amount of mass behind them to make them sound good?


The reason im asking is I'd like to use a different method of building a box that would be "Stronger" and more rigid then MDF, require less time then traditional fiberglassing, and ultimately be very light. I just dont want to put in a lot of effort developing something thats not gonna sound decent.


-sorry in advance for asking noob questions

[TazDevil]

no such thing as a noob question.

my knowledge ends after mdf, birch, and fiberglass. from what i believe i understand, the reason you dont use plywood or particle board is because of 1-air leaks, and 2-less strength. besides that.. idk.

[JBLCAMRY]

Equal panel density is the key.

[leamangriffin]

Equal panel density is the key.

You are a jedi master, my friend.

Carbon fibre would be sick, but I doubt you would have that kind of budget. Plus it would prolly flex still.

[TazDevil]

You are a jedi master, my friend.

Carbon fibre would be sick, but I doubt you would have that kind of budget. Plus it would prolly flex still.

supposedly carbon fiber boxes sound like crap.. from what ive heard. looks sick though.

[JBLCAMRY]

I would love to try some of this stuff.

But it cost ~$300 for a 12"x24" piece.

Carbon Fiber Nomex Honeycomb Core

http://www.dragonplate.com/images/photos/CF-0.75Nomex-lrg.jpg

[tru]

Equal panel density is the key.

IM not sure what you mean by this? could you maybe expound on that?

the "honeycomb core" stuff you linked up is very similar to what i would be doing, just on a much cheaper scale, and utilizing different materials

[JBLCAMRY]

IM not sure what you mean by this? could you maybe expound on that?

the "honeycomb core" stuff you linked up is very similar to what i would be doing, just on a much cheaper scale, and utilizing different materials

You will be looking for a material that is equally dense. Meaning there are no variations in the density of the material. IE voids in cheap plywood, or large chunks of differing density material like particle board.

[PEDRO MODEAN]

you could look into EFS but it might cost more than MDF. or just use mdf and then glass it for more strength.

but if your goal is a light weight box then fiberglass would be it.
http://www.edesignaudio.com/elementaldesigns_efs.php

[tru]

You will be looking for a material that is equally dense. Meaning there are no variations in the density of the material. IE voids in cheap plywood, or large chunks of differing density material like particle board.

would uniform density be as important in a subwoofer cabinet that plays 80hz on down? or is it more important for midbass/midrange areas?

it sounds like the coring idea wont be as good as i thought.

[JBLCAMRY]

would uniform density be as important in a subwoofer cabinet that plays 80hz on down? or is it more important for midbass/midrange areas?

it sounds like the coring idea wont be as good as i thought.

Not as important (but still important). Only because of the frequency. The resonant frequency of most materials suitable for this application is very high.

In the application you are going for, is internal bracing an option? Or is that something you are trying to steer clear of?

[CBFryman]

do certain materials "reflect" sound more, making them sound bad?
do the materials need to have a certain amount of mass behind them to make them sound good?

You want your box to be able to reflect sound waves, that is conserving energy.

A non porous material that doesn't flex is best.

supposedly carbon fiber boxes sound like crap.. from what ive heard. looks sick though.

People like to put pseudo science into their stereo ideals. You could make a box out of paper mache and as long as it is strong and designed well it will sound fine.

[tru]

In the application you are going for, is internal bracing an option? Or is that something you are trying to steer clear of?


Its certainly an option!
Im just trying to save weight and time over a traditional mdf or fiberglass box.

[signguy]

I really wanna try this stuff but good god at like $350 a sheet 30x96x1 1/2" gotta hit lottery before I can try

http://i1027.photobucket.com/albums/y333/signguymick/amber20edge20bamboo.jpg
http://i1027.photobucket.com/albums/y333/signguymick/Plywood2.jpg

[iiaudiodesigns]

anyone rember Dynaboard it was dynamat between 2- 1/2" mdf sheets

[Themgators511]

I use cardboard....FTW

[CandeShop]

wow cant believe no one said this...lighter than mdf and not quite as flexible as fiberglass is BIRCH...fiberglass really isnt that flexible if you do it correctly...but of course many beginners try and use sheets of mat instead of chopping it up into smaller easier to use pieces and over lapping them by 50%. makes for more time and work but comes out stronger than just laying a standard 1yd sheet of mat down.

[Wonder_Bread]

I use cardboard....FTW

thats funny I use styrafoam and then i shoot one of the sides with a shotgun for a port and that puts my port at ~32hz if i use a 12 guage

[TazDevil]

ranger board ftmfw.

[Chuck]

What you described in your original post is 3/4" Birch Ply. More money at $50 a sheet though.

[gstrendkill]

lol @ old thread

[Themgators511]

thats funny I use styrafoam and then i shoot one of the sides with a shotgun for a port and that puts my port at ~32hz if i use a 12 guage




lulz, Never thought of that, to tune my enclosures I just cut a hole in the box and what ever I want it to be tuned to if I think hard enough it will be tuned to that exact spot.