Can speakerboxes be made from plywood

[whamo]

Hey all I understand that speakers should be made from void free

plywood or mdf. But could one use 3/4 inch plywood and then line the

inside with masonite? That would prevent the cabinets from resonating

correct? I've been inspired by Chops to venture into building

something. My idea is to build a box for a k33 (to cornwall specs) I'd

like the box to be a little deeper. Then build a separate box to

accomodate some 511b's and a set of BEC tweeters. The crossover would

be in the rear of the horn box for easy access. I want the top box to

have those adjustable feet on them so you could change the angles to

get the desirable effects. Plus you could toe them in

effortlessly. Does this sound feasible? Or is it dumb?

Thanx, Mark

[PrestonTom]

The voids in the plywood may not be all that large.

MDF is fairly inexpensive and easy to work with. Although it does not hold screws all that well (esp if you take them in & out several times), you would be using glue also. It is the glue that really holds it together. Trying to line it with masonite, could be a good deal of work.

Really what you are looking for is a material that is dense and has mass. This can be (and should) augmented by bracing the structure itself. This is to reduce vibration & flex and keep the cabinet from weighing a ton.

The idea is not dumb. I am curious what you are up to. Incidentally, the size/volime of the box is not arbitrary. One of your comments left me confused about whether you were fully aware of this.

Good Luck,

-Tom

[whamo]

Yes, I understand. The size of the woofer box will be determined after

the top box is made. It'll have to be deeper and shorter as well. I

understand that it requires just the right dimensions to work right.

Right now I'm in the gathering phase of this project. Mark

[Jay481985]

box size is very important and the speaker should be obtained or known first then the box made after. Is this a speaker or subwoofer? subwoofer has more tolerance, full range have problems with wall reflection as one of the hertz will reflect and resonate....

also masonite or how about using two 1/4 inch plywood and making it hollow and filling it with cement? Cemenet happens to be one of the best acoustic material as its heavy and inert. I mean others used sand filled, aluminum, iron, anything that is heavy. MDF is really cheap though.

[Wrench722]

You can use plywood for speakers. They make Klipschorns out of it. Just make sure you use a very good grade and get the box size right.

[Jay481985]

You can use plywood for speakers. They make Klipschorns out of it. Just make sure you use a very good grade and get the box size right.

Used too.... Void Free Baltic Birch or Marine Grade or Furniture grade became too expensive and the Klipschorns are MDF too....

You want to use Marine or void free Baltic Birch, preferably not patched up voids or burrs but really void free which is expensive, expect to pay 80 dollars for a 5X5 sheet. MDF is 20 dollars a sheet of 49X97 both 3/4 inch. Also try not to use pine plywood or so because it is too light..... MDF does not have holes or grain hence great for speakers but they chip,tear, and break screws; absorb moisture, and dulls blades easier

[Xover]

The answer is yes of course speaker cabinets can be constructed of plywood. The considerations for you to ponder are cost, ease of construction, durability and rigidity.

Cost: Self explanatory, sometimes surplus plywood is available.

Ease of construction: I hate the itching from cutting MDF but it is a good compromise.

Durability: MDF does not do very well with moisture and if dampness is a possibility then plywood might be a better solution.

Rigidity: This is an area where science gets blurred by all the basement artists. You need rigidity to prevent the cabinet sides from acting as a diaphragm and to move the resonant frequency of those panels up as high as possible. While mass is commonly associated with rigidity mass itself is not desirable. Mass can store energy and cause a blurring of the sound. I have constructed panels out of a relatively light material then braced the inside with a "egg-crate" made of Masonite strips on edge and held with a rubber based glue that remains tough and never fully hardens (good quality construction adhesive). The resulting panel is very rigid without much mass and without robbing interior cabinet volume.

Now speaking of cabinet volume be sure you engineer your box to the T&S parameters of the driver. If you have trouble with this there are plenty of knowledgeable folks on this forum to help. Listen to experience, I measure the T&S parameters myself and find it common that the results of testing (either by added mass of known volume methods) will vary from the manufacturers advertised parameters by as much as 30% on quality drivers. The experience of others will help. You mention that you'd like to build the box a little deeper, changing the depth even a little will dramatically change box volume.

Good Luck and enjoy!

[Jay481985]

With MDF you should seal it well to prevent moisture. With the rigidity that is all true.

With the T&S parameters you also need to remember that this is not a subwoofer (I think) and the box will meet resonance with the shape of the box. Most subwoofers are crossed low as not to have box resonance. But If I remember right there is a method to building it is to build it as close to the golden ratio of speakers as possible.

[formica]

But could one use 3/4 inch plywood and then line the

inside with masonite?

Masonite? basically thin MDF?

I built my IB manifold

in a similar technique of MDF over plywood... which allowed a rigid

screwing surface, flush driver mounting, and I nice paintable

surface. Like Trey mentionned, the idea is to move the

enclosure's panel resonances out of the audible range... so bracing

goes a long way at achieving that.

OTOH, my box sub was built simply using braced baltic birch plywood and no MDF.

ROb

[whamo]

Nice. Thanx guys. Mark

[boom3]

Plywood by itself is a poor choice for speaker boxes. It has been shown to be almost acoustically transparent at some frequencies. MDF is a much better material, but as discussed, does not hold screws well in the edges.

I used a sandwich of void-free plywood over particle board (in 1983, MDF was difficult for home builders to obtain) and had a 1 1/2 inch wall, very solid box for two 12 inch woofers. Today I would use decorative plywood over MDF or just veneer over MDF for a direct-radiator box.

I have heard the remark that "if the K-horn is made of plywood, it must be OK to use it for non-horn boxes". Apples and oranges, folks. A folded horn requires compound miters which are difficult to reproduce cleanly, with any strength, in MDF. The horn structure of the K-horn is self-bracing , especially at the throat where pressures are highest. The later Cornwalls went to MDF with improved barcing and are less resonant than the earlier plywood versions.

[Guest " "]

Plywood by itself is a poor choice for speaker boxes. It has been shown to be almost acoustically transparent at some frequencies. MDF is a much better material, but as discussed, does not hold screws well in the edges.

I used a sandwich of void-free plywood over particle board (in 1983, MDF was difficult for home builders to obtain) and had a 1 1/2 inch wall,  very solid box for two 12 inch woofers. Today I would use decorative plywood over MDF or just veneer over MDF for a direct-radiator box.

I have heard the remark that "if the K-horn is made of plywood, it must be OK to use it for non-horn boxes". Apples and oranges, folks. A folded horn requires compound miters which are difficult to reproduce cleanly, with any strength, in MDF. The horn structure of the K-horn is self-bracing , especially at the throat where pressures are highest. The later Cornwalls went to MDF with improved barcing and are less resonant than the earlier plywood versions.

klipsch speakers (k-horn, hersey, lascala, etc) are made of a very high grade birchplywood (7 - 9 layers).

construction grade plywood is not the same as the furniture grade.....so if the question has to do with construction grade plywood....unless your going to seal, prime, paint, and use thick stock, the money you think you might save (construction grade 10 bucks, furniture grade birch 40 bucks) by using cheaper wood will be consumed by the extra prep (sealing, priming, painting, sanding, painting, sanding, painting, etc) snd cost of the extra prep items, labor another consideration.

[Guest " "]

Plywood by itself is a poor choice for speaker boxes. It has been shown to be almost acoustically transparent at some frequencies. MDF is a much better material, but as discussed, does not hold screws well in the edges.

I used a sandwich of void-free plywood over particle board (in 1983, MDF was difficult for home builders to obtain) and had a 1 1/2 inch wall,  very solid box for two 12 inch woofers. Today I would use decorative plywood over MDF or just veneer over MDF for a direct-radiator box.

I have heard the remark that "if the K-horn is made of plywood, it must be OK to use it for non-horn boxes". Apples and oranges, folks. A folded horn requires compound miters which are difficult to reproduce cleanly, with any strength, in MDF. The horn structure of the K-horn is self-bracing , especially at the throat where pressures are highest. The later Cornwalls went to MDF with improved barcing and are less resonant than the earlier plywood versions.

klipsch speakers (k-horn, hersey, lascala, etc) are made of a very high grade birchplywood (7 - 9 layers).

construction grade plywood is not the same as the furniture grade.....so if the question has to do with construction grade plywood....unless your going to seal, prime, paint, and use thick stock, the money you think you might save (construction grade 10 bucks, furniture grade birch 40 bucks) by using cheaper wood will be consumed by the extra prep (sealing, priming, painting, sanding, painting, sanding, painting, etc) snd cost of the extra prep items, labor another consideration.

[Guest " "]

Plywood by itself is a poor choice for speaker boxes. It has been shown to be almost acoustically transparent at some frequencies. MDF is a much better material, but as discussed, does not hold screws well in the edges.

I used a sandwich of void-free plywood over particle board (in 1983, MDF was difficult for home builders to obtain) and had a 1 1/2 inch wall,  very solid box for two 12 inch woofers. Today I would use decorative plywood over MDF or just veneer over MDF for a direct-radiator box.

I have heard the remark that "if the K-horn is made of plywood, it must be OK to use it for non-horn boxes". Apples and oranges, folks. A folded horn requires compound miters which are difficult to reproduce cleanly, with any strength, in MDF. The horn structure of the K-horn is self-bracing , especially at the throat where pressures are highest. The later Cornwalls went to MDF with improved barcing and are less resonant than the earlier plywood versions.

klipsch speakers (k-horn, hersey, lascala, etc) are made of a very high grade birchplywood (7 - 9 layers).

construction grade plywood is not the same as the furniture grade.....so if the question has to do with construction grade plywood....unless your going to seal, prime, paint, and use thick stock, the money you think you might save (construction grade 10 bucks, furniture grade birch 40 bucks) by using cheaper wood will be consumed by the extra prep (sealing, priming, painting, sanding, painting, sanding, painting, etc) snd cost of the extra prep items, labor another consideration.

[boom3]

klipsch speakers (k-horn, hersey, lascala, etc) are made of a very high grade birchplywood (7 - 9 layers). (snip).

Not any more. The LS and K-horn are made from a mixture of birch plywood and MDF. The Heresy and Cornwall are MDF.

[Wrench722]

[Wrench722]

Take Take a look at this. This has a better sound then the K Horn it self. (Plywood) Just make sure that it is a very good plywood.

[Xover]

Ooooo Sweeet sometimes just nekked plywood looks good.

[homemadeheresy]

It appears that your bifurcation is running the wrong way?

[DrWho]

Like Trey mentionned, the idea is to move the

enclosure's panel resonances out of the audible range... so bracing

goes a long way at achieving that.

To emphasize the point...structural integrity is not the issue with the

cabinet construction, but rather audible vibration - which will pretty

much only occur at resonance. The air pressure isn't enough to crush

your skull, so it's probably not going to crush the cabinet []

Anyways, this is where bracing comes into play. Everytime you cut the

vibrational area in half you effectively raise the resonance by one

octave and usually reduce the output by around 3dB (resulting in a

wider Q). And when you have a brace spanning across the interior of the

cabinet you are using the vibrational energy of both sides against each

other, which results in an even more inert cabinet.

The trick to good cabinet design isn't so much iron-fisting your way

(aka, mega thick layers of super dense wood), but rather highly

efficient approaches. Not only does it work better, but it usually weighs less too.