MDF vs Plywood

[tylerthecanadian]

Why use MDF instead of plywood. Isn't 3/4" plywood sturdy enough?

[IanJohnson]

i did my research and went with 3/4 birch plywood for my builds.

Just my 2 cents

[Socky]

regular plywood has too many poors in it, birch is compounded same as mdf, but birch is stronger and lighter.

[727Designs]

If you can find voidless AC Ply it will also work, but I prefer 7+ ply Birch. I typically use 11 or 13 ply cabinet grade.

[Blackedout]

The typical AC plywood flexes a little more than desirable to be used on boxes. Not to mention, the "C" in AC represents a side of the plywood that can have defects and voids, knots, etc.... A characteristic that wouldn't be used in cabinets, and shouldn't be used in speaker boxes.

Birch is normally grade A front and back, and is hands down the best plywood to go with when it comes to our applications. ~1/2 the weight of a normal sheet of MDF, a little more resistant to water in comparison to MDF (for marine applications especially). The more plys the better.

The plys (the grain of the wood) are cross laminated to increase the strength.

MDF is half the price of birch, double the weight, and is pretty stout. Flex is minimal in most applications and can be reduced to almost none with a little bracing.

A few definitions

Plywood Grades:

A - One of the highest possible face grades available. It is typically sanded and it may contain seamless wood patches or inlays.

B- This face is unsanded and has a consistent surface with the possibility of some minor open splits

C plugged - This face is unsanded and can contain limited size knots and other defects that are plugged and touch sanded.

C - This face is unsanded and can contain limited size knots and other defects

D- This face is unsanded and can contain large voids and other defects.

Knowing those grades, you should be able to put two and two together. When you ask for A-C, A-B, etc...

If you're really looking for a substitute to birch, make sure its a high ply grade A plywood.

[87regal]

Baltic Birch>Arauco(or similar) pine plywood>MDF

I can't stand MDF.

[lukaQ]

mdf is ultra easy to work with

[RCP Audio]

i found ply wasnt nearly as strong as mdf and had to double up my entire box when it was made out of ply. but that may of been because it was rubbish stuff hah

[tylerthecanadian]

Good information. I am not building a box with plywood though. I am stiffening my rear doors and am only using small pieces here and there. I was using AC fir plywood because I have it around but was having mixed results with sound quality. It's for 6x9s and 6.5s. Am I going to hear a difference by switching to MDF?

[bigmescan]

Plywood is also graded by a person and their determination of A or B can vary or even C. I use to work at a plywood plant. And the 3/4 cross sections may have voids. I've used birch and is superior then regular plywood. If you ever have a piece of 3/4 ply and 3/4birch and tap with a hammer the plywood will sound hollow is some areas and I've yet to hear that with birch. And plus the birch is just lighter than MDF.