Why MDF? (1 Viewer)

[Brae]

Ok, I know I'll get at least one response out of this post, but since I have never built, and have not immediate plans to built, a speaker or subwoofer I still wanna know why MDF seems to be the choice of cabinetry materials, which is then covered in a veneer.

Wouldn't it be easier to use solid wood? Is there something about the uniformity of the manufactured MDF over naturally grown choice wood products? Is it acoustical properties that MDF exhibits to be better than natural wood?

Please enlighten this ignorant soul.

 

[Anthony_Gomez]

it is cheap, consistant, easily machinable, and dimentionally stable.

 

[Brian Bunge]

Tony pretty much hit the nail on the head! Of course particle board is cheaper, but no self-respecting DIY'er would use that crap!

 

[Dan Hine]

Also, cheap plywoods have voids and loose layers that can rattle. Even nice 3/4" Birch at Lowes and HD have these issues. Quality plywood gets very expensive. Solid wood looks great but you have to line the interior with another material anyway since as solid wood ages it can warp, shrink or split. So again is seems wiser to use this inner matieral and just cover it with a real wood veneer that you can finish to your liking.


Hey Brian, I have some speakers from Radioshack that use 1/2" particle board and they happen to sound .....oh, wait...:b And the crossover for this "3-way" speaker is about the size of a book of matches. It's fun to take speakers apart and see just what is going on inside them.

 

[Brian Bunge]

Dan,
Ah, Rat Shack speakers! What fun!

 

[Chris Tsutsui]

I'll tell you that MDF can warp plenty if you manage to get it wet or use too much glue. Then again, hardwood and plywood warps too.
I think it's fairly cheap because a majority of the wood is Pine dust and the rest is essentially glue. However, I think that good void free plywood is not only lighter than MDF, but is also just as strong. The plywood is also easier on the cutting blades as MDF supposedly dulls equptment faster.
MDF is not only used in speakers, but a majority of high end cabinets use laminated MDF. Each laminated sheet usually has both sides laminated with one side as the A grade, and the other side laminated with C. I think this is to prevent warping.
I wonder if dual laminated cabinets are better than one sided veneers?

 

[Brett DiMichele]

I think everyone has summed up the benefits of MDF or HDF
over Ply, Partical, Birch and Maple
1:It's acousticaly "dead"
2: It's "Uniform" in it's thickness, no air pockets
3: It cuts and machines very well, almost like a metal.
4: It's affordable at $17.00 for a 4x8 Sheet of 3/4" (Give Or Take a dollar or two)
That's about it...

 

[Hank Frankenberg]

Void-free plywood has the weight advantage, but the density of MDF is better for full-range speaker cabinets. For subwoofers, void-free plywood is fine as the density/resonance aspect of MDF doesn't come into play at such low frequencies. Also, due to its longitudinal strength, good plywood is better than MDF for internal braces in speaker cabinets. Man, that MDF is heavy. I recently bought 5 sheets of 3/4" at Lowes, rented their pickup (good deal at $20), drove it home and unloaded it. Had to have an extra beer and tequila to recover.

 

[Brae]

think everyone has summed up the benefits of MDF or HDF

HDF? High-density Fiberboard? I've never seen this at any of the home improvement stores. Where does one typically find this material?

Also, I was not considering plywood or particle-board. I mentioned the comparison to solid wood of quality, and expense. I was wondering that unless money was a strong factor, why quality wood (not manufactured wood products) would not be worth considering.

I can see that costs seem to play a large factor to most DIYers, but somehow the added pain of applying a veneer in order to stain seems trivial to the ease of staining quality wood stock.

Now, if the milling is a lot more difficult with stock wood compared to MDF ... then that's an altogether different story. Since I've not any experience with routering either stock wood or MDF I cannot judge. BTW, what blades are all of you using on your table saws, circular saws, etc, and what routers/router-tables are you using?

I do not have a table-saw, but I do have a DeWalt DW369 (7.25") circular saw that I just bought an Oldman 60-tooth carbide-tip blade for. Would this work for chopping down MDF? Any recommendations for a router & table?

 

[Brett DiMichele]

From my experiance Carbide Toothed Blades cut best.
It's not a cost aspect for MDF vs wood it's the useage.

MDF routes, cuts, shapes like working with metal, it's
a very neat product to work with you would have more
problems doing complex recess work with a natural wood
product due to real woods having grain to contend with
etc.

I have no idea who would stock High Density Fiberboard
you would probably have to order it from Home Depot or
Lowes.

 

[Dan Hine]

It takes more energy to move a high density wall, BUT the greater the density and mass, the slower the energy is released again. This stretching of pulses can blur transients.

I take this to mean that there is a point where the cabinet can become too dense. Therefore using HDF may be less than optimal.
I use a friends Jet table saw. It works well enough and it's free. I use a Dewalt 625 router...no router table at this time. A circular saw should work fine with MDF. Just make an investment in a decently long straight edge as a guide to make straight cuts.

 

[Patrick Sun]

Plywood can be subjected to chip-outs during the cutting phase, or routing phase. That means more work fixing these problems with wood putty later.

 

[Brae]

Why is everyone continuing to mention plywood? I never mentioned I was even willing to consider it. I'm not considering plastic either, but would anyone like to comment on it, too?

 

[Patrick Sun]

Well, good luck finding "hardwood" for cabinet building. I'm sure you can, but it might be cost prohibitive.

 

[Brian Bunge]

Brae,

To keep it simple, solid wood will expand and contract with heat and moisture. Do you want your speaker cabinets splitting apart within a few years? I'd think not. Also, I recently bought 6 3/4" oak boards that were 12"W x 4' long. It was well over $100. MDF and a little veneer is a lot cheaper.

Also, have you ever tried staining hardwood? The end grain will soak up a lot more stain and be darker than the rest of the board. This necessitates using 45 degree miter joints which creates even more work.

If solid wood was easier to work with (in other words, cheaper in the long run) don't you think speaker companies would be using it?

 

[Dan Hine]

I'm not considering plastic either, but would anyone like to comment on it, too?

As a matter of fact, I am considering using some plastic pipe for TL experiments. It is cost effective, easy to work with, and can actually make some cool looking speakers.
People on this forum just like to hit EVERY angle of a question. They're just being thorough. So it's now been mentioned 3 times why using hardwood is not optimal/easier. High grade plywood CAN wook well, so it was mentioned. MDF does work extremely well. Everyone is just offering advice based on experience.

 

[Brae]

Brian, I do now understand the benefits of MDF over hardwood, but it was just confusing that someone started talking about plywood and then kept one talking about the negative aspects of it. Just thought it was amusing, that's all.

Dan, I was kidding about the plastic knock, as I think either, or both, SVS and Hsu are using it in their tubed subwoofers. Also, I would tend to think hardwood would not be so open to expansion and contraction via heat-change as it would to moisture, which could be dealt with via proper sealing (of the wood, not the box).

 

[Pete Mazz]

The real long term problem, IMO, in using solid wood for an enclosure is the cross grain construction you'd have to do to make the enclosure. Wood expands and contracts much more across its grain than along it. If you have the grain on the top, bottom and sides going one way, the front and back panels would be going with the grain to the sides and across the grain to the top and bottom. This is where you'll have problems. Now, if you used MDF or ply for the front and back, then you eliminate this problem. Correctly dried and dimensioned wood could be used if sealed and built properly.

Pete

 

[Javier_Huerta]

What's the difference between particleboard and MDF?

I'm asking this because all I've ever seen sold around here is particleboard. We do have Home Depots around here, so maybe I could go there and buy my MDF. BUT... how would I know it's not particleboard? How to tell?

Thanks.

 

[Pete Mazz]

Particleboard or flakeboard has small bits of wood chips that are glued and compressed to make the panel. MDF or fiberboard is made from hardwood fibers (usually), glued, heated and compressed. When you look at it, it looks very uniform. You can see no individual fibers. It's darker in color than flakeboard, and heavier.

Pete