MDF or Quality Plywood

[vandyman]

Need the input,

Question for all who have traveled down this road. I am intending to make some modifications to some Forte's and Quartets for home theater purposes. I will be constructing to new boxes and would like to know the pro's and con's of both Baltic Birch, Apple Ply and MDF as far as affecting the sound quality. I have read tomes on the subject and I'm still looking for more guidance on the matter

My Vandersteen 3A signatures are all MDF, but they are covered in cloth and very little veneer is visible on most of Richard Vandersteens creations. His ultra expensive offerings have exotic MDF/Fiber Carbon materials along with beautiful veneers and paint jobs, which he can do in his shop. I have a very basic shop to work in and would appreciate any and all advice. I do know that bracing will impact the flexing cabinet issue and intend to use bracing to help stiffen the boxes. Thanks in advance for all suggestions and help in this matter.

Todd (Vandyman)

[mustang guy]

The disadvantage to MDF in my personal opinion is the dust, and lack of water/humidity resistance, and weight. If you are gonna veneer, it works up beautifully. Very straight and rigid. Baltic Birch is great material. The disadvantage of it is price. It is pretty heavy stuff too. As for sound quality, I haven't run tests, but I would say there isn't a big difference in these two materials. I have no opinion on Apple ply. Never used the stuff.

[Don Richard]

MDF is dense but not as stiff or strong as plywood and requires more bracing. Baltic birch is denser than other types of plywood, nearly as dense as MDF. One can drive screws into the edge of plywood and the joint will hold securely. That's not the case with MDF. For that reason the home builder is better off with the plywood.

[Pete H]

MDF is dense but not as stiff or strong as plywood and requires more bracing. Baltic birch is denser than other types of plywood, nearly as dense as MDF. One can drive screws into the edge of plywood and the joint will hold securely. That's not the case with MDF. For that reason the home builder is better off with the plywood.

+1, the Baltic birch is a better choice than any other plywood I have used because it is void free and is readily available with a lot more plys than your other choices which make it stronger and as stated above, will accept fasteners better than anything else (that I have used).

[John Warren]

His ultra expensive offerings have exotic MDF/Fiber Carbon materials along with beautiful veneers and paint jobs,

If you think that's exotic, Wilson uses phenolic plate,

FWIW, it's the IDEAL material for loudspeaker enclosures, very high strength, high stiffness and high density with excellent self-damping characteristics. It's total high end and good engineering which is almost unheard of in that world. The fact that Wilson goes down this path is a statement of their passion for getting it right and I don't even work for them.

[Marvel]

Appleply is possibly more uniform with the veneer plys than a lot of the birch you will find. I've just found it hard to locate. I would choose either Appleply or Baltic/Russian Birch over MDF. Appleply is made from Alder and Birch veneers, too.

Bruce

[JJkizak]

As I recall about 20 years ago the very good furniture grade 7 ply plywood available in most flavors at 3/4" thickness was available for about $470.00 per 4' x 8' sheet. Now it probably costs about a grand.

JJK

[Marvel]

The good Baltic Birch and Appleply is made with 1/16 inch veneer plys and is void free. Usually around$50 a 4 x 8 sheet of 3/4 inch. Location can cause this price to vary a LOT. Certain Lowe's can order the Appleply sizes.

[tromprof]

Not all birch plywood is equal. Beware of the kind they sell at Lowes, it is junk. The veneer will splinter when cut, lots of voids, and they all seem to come warped and twisted. I cheaped out and bought some to use with my Cinema 20 sub and was sorry. I am fortunate to have a Paxton lumber store in Cincinnati to get good stuff, about $70 a sheet in 3/4.

[Marvel]

Perhaps I should have said 'select' Lowe's stores. I've purchased excellent material from the Lowe's near me.

Try the appleply from here:

http://www.buyappleply.com/default.asp

[DizRotus]

The question seems somewhat loaded. Nonetheless, the best answer appears to be, it depends.

The issues presented to a DIYer are different from those confronted by a manufacturer. A DIYer is less concerned with small cost differences or factors that contribute to ease of repetitive commercial production. In a commercial setting, a small cost increase multiplied over an entire production run could mean the difference between commercial success or failure.

The one time I met PWK we briefly discussed the Speakerlab SKhorn. PWK spoke disparagingly about Speakerlab's use of MDF (its inability to take edge screws) and non-metal squawker horns. It’s worth noting that post PWK Klipschorns use MDF and composite squawker horns. That doesn’t make current production Klipschorns inferior to older versions, but different. They are produced to the economic conditions of today’s market.

A DIY enthusiast is not similarly constrained. MDF and so-called Baltic plywood each has strengths and limitations. Each could be the correct choice for specific projects. The “best” choice depends upon each individual’s unique situation, such as budget, tools available, skill level, intended use, etc. The cost should not be a deterrent.

Under most circumstances, I would use the highest quality void free plywood available. A complex enclosure, such as the Klipschorn bass bin, with numerous angle cuts would scare me away from the weight and screw holding issues with MDF.

That said I’m getting ready to build small simple bass reflex enclosures for single drivers (RS 40-1197 or FE103) from MDF. The weight and relative acoustical deadness of MDF are advantages. The glued construction makes the screw holding issue irrelevant. Cost is not important.

YMMV

[tromprof]

Perhaps I should have said 'sleect' Lowe's stores. I've purchased excellent material from the Lowe's near me.

I am sure it depends on your area. Supposedly Menards has decent Baltic Birch in my area, though I haven't checked it out. I guess my point was "buyer beware" when dealing with big box stores, sometimes it isn't what they claim it is and the average employee doesn't know the difference.

[Marvel]

I have seen made in china birch ply that has the veneers overlapped and ugly when looking at the edges.It still costs too much for the quality. Then they surprise you and get a shipment frmo someplace and it is really nice, so yes, buyer beware.

Bruce

[mustang guy]

I have seen made in china birch ply that has the veneers overlapped and ugly when looking at the edges.It still costs too much for the quality. Then they surprise you and get a shipment frmo someplace and it is really nice, so yes, buyer beware.

Bruce

The quickest way to tell the good stuff from the crap is to pick up a sheet. That China stuff is lightweight and flimsy. BB is very heavy and rigid. Sometimes they close the voids around the edges to make the asian birch look good. And sometimes they have just as many plys.

Yes, buyer beware... I pay about $70/sheet for 1/2" BB, and $85 for 3/4". If I were located nearer a coast, I could no doubt get it cheaper, as it is all imported from the Baltic Sea region.

[The Dude]

I can only get 5x5s of Baltic birch from local lumber yards, it runs about 30-35. I can get arauco 4x8s for about 35.00 at most big box stores. Depending on the project and how much I need depends what I use. If the box is small enough like the custom drift/surround speakers I made I used mdf. To me it looked as if the Fortes I had were mdf veneered but I could be wrong, I would think if that was true then sticking with mdf would be just fine. Since they don't have that many weird angles, I would use one of those kregg jigs and a good glue they seem to help with making solid boxes.