MDF vs. Ply

[Chopper Greg]

Which is better for speaker/woofer enclosures and why?

 

[fredk]

Do a search here and at hometheatershack.com and you will come up with two very good threads on this topic.

Each has their own advantages.

 

[Chopper Greg]

I did, and while it took some time to find them, I ended up with the feeling that it wasn't a settled issue.

What about alternative materials, like Homasote? There is a variety called '440 Soundbarrier' it's supposed to be a little more expensive but stronger that either ply or MDF and have better sound dampening qualities and lower moisture uptake than either of the others ( http://www.homasote.com/products/440-Soundbarrier.aspx ).

 

[abjonesiii]

i don't know about the science aspect but I've built my own enclosures before with what I thought to be great success. The only material I use is MDF. I work with plywood daily (general contractor) and it just doesn't seem like the kinda stuff i want in speakers. But like I siad no science just my gut feelings.

 

[TLS Guy]

I did, and while it took some time to find them, I ended up with the feeling that it wasn't a settled issue.

What about alternative materials, like Homasote? There is a variety called '440 Soundbarrier' it's supposed to be a little more expensive but stronger that either ply or MDF and have better sound dampening qualities and lower moisture uptake than either of the others ( http://www.homasote.com/products/440-Soundbarrier.aspx ).

If you use plywood, I would use cabinet grade plywood, so there are no voids.

I think in some ways plywood can be easier to work, as the edges don't break out and the dust is not so unpleasant.

However overall I prefer MDF. The edges are good and straight and the boards do not warp. You can make nice dado. MDT takes tight bond well.

I use pre veneered MDF. I use the type veneered both sides so it does not warp. I do extensive dado cuts. I do not use any fasteners, but clamp the enclosures together, after applying Tightbond.

Before the mid eighties, I wasted a lot of time and money on veneer. A professional cabinet maker showed me how to make a totally professional cabinet from pre veneered MDF and I have not looked back.

The veneer sticks to MDF much better than plywood by the way.

 

[highfigh]

They can both be an excellent material, but it depends on what the criteria for comparison are. If you want density and stiffness, MDF is better. If you want light and stiff, plywood is the better choice. Both are available in versions that have decreased off-gassing, so chemical sensitivity won't be as much of an issue. Both are dimensionally stable as long as all surfaces/edges are sealed to prevent moisture absorption. Avoiding inhalation of the dust is recommended for all wood products, especially if they have chemicals in them. It's best to use mechanical fasteners with both because when a speaker enclosure is being designed, it's the air vibrations that are creating the sound and anything that comes from the cabinet resonances will affect the end result. Ideally, you want the cabinet to be totally inert and one layer of either will miss on this issue. Internal bracing helps to place the resonance frequencies outside of the range of the driver's use. The more energy a driver imparts on the enclosure, the more mass and stiffness are required. IMO, extremely light and stiff isn't going to be the best because the cone's motion will try to move the assembly (that pesky Law of Physics about action applied resulting in an equal and opposite reaction). If the woofer cone assembly pushes in one direction, the rest of it has to push back in the opposite direction if it's going to remain motionless.

 

[Chopper Greg]

i don't know about the science aspect but I've built my own enclosures before with what I thought to be great success. The only material I use is MDF. I work with plywood daily (general contractor) and it just doesn't seem like the kinda stuff i want in speakers. But like I siad no science just my gut feelings.

I'm sort of the opposite.

I just don't feel confident about MDF, I feel the OSB is better than MDF, but it to has properties I don't like, while I also feel that ply is reasonable.

One of the things I dislike about MDF, is the fact that it seams to have wear issues ( unless extrema care is used, any time it's moved, a little more comes apart ). It also seams like the cheapest furniture made, uses MDF exclusively, and it falls apart in just a couple of years - and I just don't see that in ply construction.





Speaking of OSB, what about it's use as a speaker housing material?

 

[Chopper Greg]

If you use plywood, I would use cabinet grade plywood, so there are no voids.

I think in some ways plywood can be easier to work, as the edges don't break out and the dust is not so unpleasant.

However overall I prefer MDF. The edges are good and straight and the boards do not warp. You can make nice dado. MDT takes tight bond well.

I use pre veneered MDF. I use the type veneered both sides so it does not warp. I do extensive dado cuts. I do not use any fasteners, but clamp the enclosures together, after applying Tightbond.

Before the mid eighties, I wasted a lot of time and money on veneer. A professional cabinet maker showed me how to make a totally professional cabinet from pre veneered MDF and I have not looked back.

The veneer sticks to MDF much better than plywood by the way.

I was thinking of marine ply as it is required to have no voids, and uses a high quality adhesive.

I will most likely be using fasteners as I do not have access to the necessary clamps ( and it doesn't appear cost effective to by the clamps for just a few projects ).

Any idea how Liquid Nails would work for such a project?

I am currently inclined to use a sealed and painted surface rather than veneer.

 

[TLS Guy]

I'm sort of the opposite.

I just don't feel confident about MDF, I feel the OSB is better than MDF, but it to has properties I don't like, while I also feel that ply is reasonable.

One of the things I dislike about MDF, is the fact that it seams to have wear issues ( unless extrema care is used, any time it's moved, a little more comes apart ). It also seams like the cheapest furniture made, uses MDF exclusively, and it falls apart in just a couple of years - and I just don't see that in ply construction.





Speaking of OSB, what about it's use as a speaker housing material?

Using the methods, I have described above, I have had no issues with cabinets falling apart. I don't like fasteners, because the material from the holes pushes the seams apart. I have found since I stopped using fasteners cabinets are better and stronger. Do not use liquid mails. Cheap Tightbond is by far the best for speaker cabinets.

 

[highfigh]

I'm sort of the opposite.

I just don't feel confident about MDF, I feel the OSB is better than MDF, but it to has properties I don't like, while I also feel that ply is reasonable.

One of the things I dislike about MDF, is the fact that it seams to have wear issues ( unless extrema care is used, any time it's moved, a little more comes apart ). It also seams like the cheapest furniture made, uses MDF exclusively, and it falls apart in just a couple of years - and I just don't see that in ply construction.


Speaking of OSB, what about it's use as a speaker housing material?

The guy who sharpens tools for me called particle board "The hot dog of wood products". OSB is more like cat food. Chunks of something, but you really don't want to eat it. Plus, it smells bad.

OSB is made for resisting racking, not pressure into the sides. It's not a good material for this, at all. They used to call it 'flakeboard', for good reason. You think MDF is bad, cut a dado in OSB and see how well it holds up.

The cheapest furniture made uses lightweight particle board, not MDF. Go to Ikea and pick up one of their small tables with really thick sides- it weights a lot less than you would think. MDF is considered to be more of a paper product because of the particle size but the density makes it good for the use we're debating. New screws have a deeper thread and more coarse thread, which allows them to hold better in face-to-face and face-to-edge joining, as long as the holes are pre-drilled correctly.

 

[abjonesiii]

OSB? absolutely not a good choice. OSB has many fine applications but none of them have anything to do with speaker cabinets.

To echo an above statement most cheap furniture is particle board. If you look at a side by side cut away section of both materials you can actually see little pockets of void space in particle board were as MDF is solid and very tightly packed (density). One 3/4 4x8 sheet of MDF weighs around 100 pounds. A 3/4 4x8 sheet of particle board weighs around 50-60 pounds. If you find any furniture made of MDF it will require several men, exerting a lot of energy, to move.

 

[Chopper Greg]

Interesting - 1 inch homasote Roof Decking runs about 2.6 lbs / sq ft ( a little over 80 lb for a 4x8 sheet ), while the 3/4" 440 Sound Barrier runs about 1.8 lb / sq ft.

It's might be interesting to try a sheet of homasote to see how well it works - it's supposed to be able to hold fasteners better than either ply or MDF.

 

[highfigh]

Interesting - 1 inch homasote Roof Decking runs about 2.6 lbs / sq ft ( a little over 80 lb for a 4x8 sheet ), while the 3/4" 440 Sound Barrier runs about 1.8 lb / sq ft.

It's might be interesting to try a sheet of homasote to see how well it works - it's supposed to be able to hold fasteners better than either ply or MDF.

Roof decking, as in the substrate for shingles? That doesn't come close to the forces a sealed sub box exerts on the fasteners. The shingles are trying to come off as a unit, unless the asphalt adhesive has let go, and when that happens, the tabs usually tear. Plus, it specifies annular threaded nails (ring shank). Nobody is going to screw shingles down. The Homasote installation instructions indicates that fasteners need to be 3/4" from the ends. That tells me that it will either crumble or tear out when it expands and contracts (the sheets are to be spaced 1/8" apart, and they're only 24" wide).

You can try it but I seriously doubt it will be as strong or stiff as MDF or plywood. Plum Creek MDF was 105#/sheet when I was having it delivered.

 

[Chopper Greg]

It's just a thought - I know of folks that use the stuff in some unusual situations, includng some semi-supported conditions in 3-4 inch strips, and I havn't hear a word of tear out.

 

[basspig]

I use both MDF and 13-ply Baltic Birch to build enclosures.

MDF has the density and uniformity, plus mass, and plywood gives the strength to handle the bumps of transportation, if you move cabinets around a lot.

Pro audio gear road cabinets are almost always plywood because it is more durable for hauling. MDF is also heavier.

Building audio cabinets with both results in some very heavy cabinets!

 

[Chopper Greg]

I use both MDF and 13-ply Baltic Birch to build enclosures.

MDF has the density and uniformity, plus mass, and plywood gives the strength to handle the bumps of transportation, if you move cabinets around a lot.

Pro audio gear road cabinets are almost always plywood because it is more durable for hauling. MDF is also heavier.

Building audio cabinets with both results in some very heavy cabinets!

As I have a history of moving, I suspect that I will probably be opting for durability, if it comes down to having to make a choice.

Thanks.

 

[chris357]

Using the methods, I have described above, I have had no issues with cabinets falling apart. I don't like fasteners, because the material from the holes pushes the seams apart. I have found since I stopped using fasteners cabinets are better and stronger. Do not use liquid mails. Cheap Tightbond is by far the best for speaker cabinets.

so if I'm using cabinet grade ply and have enough clamps I can make the kappa subs with no screws? and it will be ok?

 

[Alex2507]

\ I don't like fasteners, because the material from the holes pushes the seams apart.

Even if you pre-drill?

 

[annunaki]

I was thinking of marine ply as it is required to have no voids, and uses a high quality adhesive.

I will most likely be using fasteners as I do not have access to the necessary clamps ( and it doesn't appear cost effective to by the clamps for just a few projects ).

Any idea how Liquid Nails would work for such a project?

I am currently inclined to use a sealed and painted surface rather than veneer.

Stick to the Original Titebond. Liquid nails works, but the tightbond seems to be stronger. The liquid nails will require at least 24 hours of cure time as well. Titebond will hold in just 30-45 minutes and solid permanent hold in about 6 hours.

 

[lsiberian]

I kind of like the lighter ply myself, but I move a lot. It really doesn't matter as long as you brace and dampen properly.

I would love to pick more brains on building method as I'm always looking for more options.