Why not MDF?

[Zack Brock]

So why do you feel so strong about not using it? Why would I be sorry later? These are the answers I seek! Please pardon my ignorance.

If it doesn't effect the final sound of the cab (and could possibly be a denser material) then I consider it an option, and not corner cutting in any way.

Again these are permanent install cabs. If I save money on construction, I can buy the more expensive woofers and the nicer duratex coating. Or so I'm thinking.

[bgavin]

The disadvantage to MDF is the weight. I have intentionally left scraps outdoors in the California rainy season for two+ years now. MDF does not turn to oatmeal like particle board. It looks crappy, but so does plywood left outdoors for two years.

One advantage to MDF is less warp. It does machine very well, but is hard on blades and bits. I have built projects from 3/8, half, and 3/4 inch MDF. They go together well and are quite sturdy. And heavy. Every one of my MDF projects has been thrown out, due to weight. I hauled around a pair of 1x15 subs made from 3/4 MDF and they survived well. Yes, the corners get rounded, but so does plywood without corner protectors.

MDF is more dense than plywood, and less prone to resonance. It certainly has no voids. It glues up well, and is less costly for permanent (built in) installations. It is heavy. I keep repeating myself intentionally about the weight. MDF is 10 pounds per cubic foot heavier than baltic birch. Both are much heavier than the light ply such as Italian Poplar and other plywoods. A sheet of 4x8x3/4" is 2.0 cubic feet, or 98 pounds in MDF.

[Sydney]

That was a pretty good summation by BGAVIN
The 1st speakers I ever built ( Klipsch Rebel copy ) was built with particle board ( almost 40 years, before good ply & MDF was available )
Terrible stuff - but car boxes are still made of it. Guaranteed to disintergrate.
All my BF builds so far ( 2 completed - 2 pending ) were initialized before the web forum or plans were sold, based upon the published articles in the late great SB (r.i.p.).
Bill recommended plywood for those designs meant for the road ( ie T24, DR200, DR250, DRxxx... ) 5 ply or better and he said use BB if available, but issued a caveat about additional weight incurred. BB is denser, and therefore heaver than 5 ply.
For the home/nonroad designs ( T18, David, Table Tuba, etc... ) MDF was acceptable.
Cabinets made for road abuse have traditionally been made from plywood ( for over 50 years ).
Not all ply is alike and not all MDF is alike. There are new products being introduced all the time.
No one has made a perfect building material for cabs that doesn't have disadvantages.
I have discussed the possibilities of creating molds to cast the curved sub assemblies in DRxxx designs.
And I started a DR200 inner horn assembly ( 2004, after the SB article came out ) that uses fiberglass, instead of bending ply and also uses pieces of MDF and plywood.
Total weight of sub assembly w/o speaker baffle is a little over 2 lbs.
Re bassbrock: A solid dense material is not necessarily better. There have been tests of cabs constructed with panels, made of mixes of dense and lighter material that are superior to ply and MDF in sonics.

[Tim A]

...I consider it an option, and not corner cutting in any way...If I save money on construction, I can buy the more expensive woofers and the nicer duratex coating. Or so I'm thinking.

So then it is corner-cutting, correct?

Regardless of how Bruce feels about MDF, it is for all intents and purposes not much more than glorified particle board. It was designed as an alternative to particle board to withstand weather, so the result of putting it outside is no surprise and is to be expected

I've been a carpenter and woodworker for well over 30 years. I've used everything there is to use, from the finest hardwoods to the crappiest particle boards. I would never consider using MDF for anything to do with woodworking. Yes, it has it's place in carpentry and construction. It doesn't have a place in woodworking.

The only advantage MDF has over plywood is density, and any gains there are questionable. Speaker companies use it because it's cheap. Dare I say, they use it for cost cutting?

These are for a permanent install, correct? If you're going to fly them or put them on stands, you're going to have probems with the added weight.

If it's simply a matter of being able to afford a better driver or a duratex finish, save your money and do it right.

[Turntablist]

MDF is a heavier, it cracks easier, it sucks water like a sponge and doesn't bend at all.
Birchply is light, durable, water-resistent and bends well.
Most BF cabs require plywood..

As Tim said: Buy once, cry once.

[fender3x]

It's all good fender, I miss detail in posts all the time.


By the way, we are neighbors! You are in Miami, and I'm in Jacksonville. LOL

<snip>

So if I can save some cash on the Omni 10 and the Wedgehorns, then nice!

Glad to have another Floridian. Bienvenidos! (as we say down here )

One thing I have learned here is that you ignore the advice of BGavin and Tim Ard at your peril! That said... If you are sure that you are not going to move this stuff, then Maybe MDF is fine. There's a difference between cutting costs and cutting corners. If it's cheaper but won't effect the design's sound or durability, OK!

Now...my experience... for what it's worth. I built my Omni 10 out of leftover 5/8" CDX that I had left over from making hurricane shutters (there's that FL connection ) for my house. The result is an O10 that weighs as much as the T39 I built next using 1/2" plywood.

If I had it to do again, I'd have built the O10 with 1/2" plywood. These really versatile cabs. You can use them for bass, PA, standalone or with subs. The point is that even if the subs are left permanently in place, you may want to take the Omni's out occasionally. I can tell you that almost from the instant I finished mine, I have been thinking about re-building with better materials.

[gdougherty]

Consider manageability during fabrication as well on the weight front. You mention Full-range wedgehorns, I'm assuming you mean the W10's. Don't forget monitors do get moved around. My wedgehorns weigh 28lbs constructed from a lightweight plywood that ran $25/sheet. Previously I had 50lb monitors made from MDF with about as much material as a wedgehorn in a 15" and horn design. They were a pain to move around on stage when I did move them and I'd take a lightweight speaker over a heavyweight speaker anyday especially when the cost difference is so marginal by comparison. If it were 80% of the construction cost that'd be one thing to shave down, but when you compare the cost to something commercially made at the same quality level it's a no-brainer in my book to go with the most manageable material.

[Zack Brock]

Good points all, thank you for your responses!

So I'm glad to hear that it is simply a matter of two things - weight and durability.

But yep, those are indeed two major issues.

I'll have to consider if they 'outweigh' (no pun intended) the possible advantages of MDF.

So far I've partially completed my Tuba 24's out of 1/2" Sandeply from Home Dept. that was $29 a sheet. I chose to build the 24" wide versions so I had to use three sheets.

Thank you again for your responses, you've all made me think.

[gdougherty]

No Lowes with Arauco in the area I take it?

[fender3x]

...when you compare the cost to something commercially made at the same quality level it's a no-brainer in my book to go with the most manageable material.

This is a really good point...even in a DR, the most expensive part is the driver. The wood is cheap by comparison...and I am taking into account that we get ripped off for wood here in FL compared to the rest of the US (judging by what I read here). Recommended eminence drivers are $120-200 for on O10. Wood will cost you under $30 even in MIA...might be even cheaper in JAX being closer to the mills in Georgia.

[Tim A]

So far I've partially completed my Tuba 24's out of 1/2" Sandeply from Home Dept. that was $29 a sheet. I chose to build the 24" wide versions so I had to use three sheets.

This is a really good point...even in a DR, the most expensive part is the driver. The wood is cheap by comparison...

There it is, my point exactly.

I haven't priced MDF in so long I have no idea what it sells for. I'm going to assume around $12/sheet.

So, $29 x 3 = $87 for wood for two(?) cabs, or $43.50/cab. MDF would've cost $12 x 3 = $36 or $18/cab. That's a difference of $25 per cabinet. Hardly seem worth worrying about when you consider all the other costs. Even if you multiply that by 4 cabinets, you're saving only $100. Not enough money to compromise some truly fine cabinets in my book. It's not even enough to cover the cost of the Duratex for 4 cabs, let alone better drivers.