An experiment in box materials

[Triticum Agricolam]

There is more then just how much a piece flexes that goes into it.

I would love to use nothing but Baltic, but the reality is not everyone is willing to pay that additional price tag for the material

True that. Baltic birch is heavier than I prefer for car audio too.

I'm not sure what I want to use for my next build. I would like to use BB but I don't think I'm confident enough in my wood working skills to ensure I don't mess up a cut and waste wood considering that stuff is fairly expensive.

I would see if you can get Arauco plywood or a decent "birch" style plywood. Baltic birch really is overkill for most car audio applications. The only time I use baltic birch is when its going to be stained.

[Jessica]

i know that if you cut plywood in with the grain vs against it make a huge difference in strength.

[audiofanaticz]

There is more then just how much a piece flexes that goes into it.

I would love to use nothing but Baltic, but the reality is not everyone is willing to pay that additional price tag for the material

True that. Baltic birch is heavier than I prefer for car audio too.

But but but every one uses it because its half the weight of mdf, and then when you try to tell them that what they are using is not baltic birch they call you an idiot!

LOL

[audiofanaticz]

i know that if you cut plywood in with the grain vs against it make a huge difference in strength.

I dont think thats true, unless your wood is a solid piece of wood that has no plys.

Because if you ever look at the edges of the plys they are alternating so one layer will be going north to south while the layer below it will be going east to west (at least on your higher end woods).

I noticed this when I was removing material to counter sink objects in the wood, but I did only remove a small amount so it was kind of hard to tell.

However I didnt notice no difference in how hard it was to feed the material through my sawblade when going with the grain or against it. It was equally as hard.

Maybe for basic cheap plywood that may hold true.

[Jessica]

i know that if you cut plywood in with the grain vs against it make a huge difference in strength.

I dont think thats true, unless your wood is a solid piece of wood that has no plys.

Because if you ever look at the edges of the plys they are alternating so one layer will be going north to south while the layer below it will be going east to west (at least on your higher end woods).

Maybe for basic cheap plywood that may hold true.

go buy some 1/4" cheap plywood and bend it in various directions.

[audiofanaticz]

re-read my edit.

[Jessica]

i read it lol

[Triticum Agricolam]

i know that if you cut plywood in with the grain vs against it make a huge difference in strength.

I dont think thats true, unless your wood is a solid piece of wood that has no plys.

Because if you ever look at the edges of the plys they are alternating so one layer will be going north to south while the layer below it will be going east to west (at least on your higher end woods).

Maybe for basic cheap plywood that may hold true.

go buy some 1/4" cheap plywood and bend it in various directions.

Yeah I can see how that would be true with plywood that has low ply count. I've seen 3/4" roof sheathing with like 3 plies in it. I'm sure that stuff is stronger in one direction than the other.

Anything I'm going to build a box out of has to have at least 7 plies though.

[Krakin]

Isn't the whole point of using MDF is because it has enough deflection to be essentially an acoustically dead material?

I think the main reason MDF get used is because "that's what other people do" and because its cheap, at least when it comes to vehicle subwoofer boxes.

For full range enclosures I know MDF is really well like because its well damped and "acoustically dead" like you said, but I'm not sure it gets that attribute because it deflects easily. This is outside my area of expertise.

Well one thing I suggest doing is also finding the resonance of a 1ft by 1ft square of each material, if within reason of what you have or care enough to do.

Acoustically MDF is "Dead" because the fibers are small is relation to a ply in the other materials and can move around without pushing other fibers. You then also get the added benefit of the density of MDF.

If you look at this equation it is fairly simple to theoretically understand the resonance of an object.

Where k is the spring constant and m is the mass.

Where K = F/x ; F = force, x = unit of deformation

When you implement you findings on stiffness that directly correlates to a higher spring constant and you already know the mass of your piece of wood based off the density you listed.

TL:DR

My point is when you have a higher spring constant you increase your resonance frequency and when you have a lower mass you also raise the frequency.

Therefore my reason for preferring MDF is because it has a low spring constant and a high mass, making the resonance lower than the other choices.

[Jessica]

you know, i think its great you are doing all this research. People who appeciate it appreciate it. nice work, but it makes me so mad that so many idjuts will just go buy some shitty prefab regardless.