# What type of wood



## jwhite8086 (Feb 4, 2007)

I thimk most people use MDF, but are there advanteges/diadvanteges of using diferent types of wood?


----------



## Anthony (Oct 5, 2006)

MDF is flat, stable, and non-resonant (it does resonate a bit, but it's so heavy, it is very damped). It is also cheap and easy to paint or veneer.

Baltic Birch plywood is very similar to MDF in many ways, except it is lighter, more expensive, and some say less resonant. Its plywood edge is actually not that bad and can look like wood grain, making cabinet finishing easier.

Solid wood is not that stable, but is stronger and (for the most part) lighter than MDF. Cost can be very cheap (knotty pine) to car-payment expensive (Ebony). In most cases solid wood is unsuitable for boxes because of wood movement. Even when finished, wood will absorb moisture and expand. A box made of solid wood will eventually split if this is not taken into consideration. 

That being said, you can design a box that can take the stresses of the wood movement, but these are not always air-tight, so they wouldn't be suitable for a closed box speaker.

I am currently working on dipole open baffles, so wood movement isn't as much of an issue. I am planning on using solid bubinga and maple for the baffles.

Solid wood can be resonant, so you need to beware. It can and will color the sound if not braced properly. However solid wood can also look absolutely stunning.

I hope that is a good start for you. We have a lot of speaker builders here, so hopefully more of them will chime in.


----------



## tonyvdb (Sep 5, 2007)

MDF is the most economical and is very ridged its also easy to work with. It is best to use a wood or product that is solid and very dense as the less vibration that the cabinet has the better sounding the speaker will sound.. Oak is another wood of choice but because of the cost you wont find it in the budget line of speakers. Generally any hardwood will work well.


----------



## Guest (Dec 26, 2007)

Care must be taken to allow movenent for the wood. In high humidity wood expands, in dry air it contracts. If wood is glued onto MDF( speaker front ), it might be alright if the speaker is only 4 or 5" wide. It would be advisable to ask a cabinet manufacturer what they would recommend. 

I learned the hard way. I made a subwoofer with 2 x 12" high excursion woofers in a sealed bipolar design, with a 1600W peak digital amp. The box was approx 2' x 2' x 2', and I glued a nice piece of solid oak onto the top ( directly onto the MDF ).It wasn't long before there was a split down the middle. 

However, it sounds exceptional, deep and tight and at approx 150Lbs it is solid. I actually copied a Mirage BPS400 Desigg and got a reconditioned amp. One sub for the left channel, and one for the right. 

I am actually interested in LLT design for the LFE channel for some slam. A 15 or 18" vented sub would certainly move some air. Just make a storage cabinet for the back of the room and forget to put any doors on it!


----------



## imbeaujp (Oct 20, 2007)

Hello, I use 2 MDF sheet to get 1.5 inch thick. I use marine epoxy as glue and get good result.


----------



## drf (Oct 22, 2006)

If you are a real budget concious builder then you can use chipboard (sometimes called particle board)
for all intents and purposes it has very similar accoustical properties to MDF. The downside is that it is much harder to work with, won't last anywhere near as long and is a PITA if you want to paint it and get a flat finish.

If you are building somethine that will get transported alot, I.E p.a speakers, then use structural ply (at least 19mm) and extra bracing.

For everything else just use MDF, you can't go too far wrong with industry standard.

Cheers 
Dr F


----------



## Guest (Jan 12, 2008)

Wood is made of strands, and that is the concern of resonance when building a speaker. You also have to be concerned about shrinkage that is a normal part of wood movement based on humidity. When I was last at a menards I did see veneered MDF plywood that would work well for speakers. Veneering a MDF constructed cabinet allows all kinds of choices of wood finish, but be aware a good woodworker will veneer both sides so the forces are even, cheap on the botton or inside, nice on the outside. REally state of veneering is done with using a vacumn bag, bit this can be accomplished in a number of ways. I have used burl wood with sucess and it looks wonderful. I would stick with MDF for the issue of resonace, no speaker is made of solid wood that I am aware of.


----------



## Anthony (Oct 5, 2006)

I have seen small speakers (DIY not commercial) made of solid wood. I never heard a report as to shrinkage problems, but wood movement would not be as much of a problem for small speakers (think satellite size).

I did see plans for one subwoofer that was made of solid wood, but the guy did it right: dovetailed joinery for the sides, expansion slots for the front and back full of foam. He took movement into consideration and the result looked great. However that kind of planning and skill is above many people's patience and tools (myself included). I like to stick with plain ol' boxes 

Those are the exceptions, 99% of all other plans I've seen are MDF, plywood, or some combination of solid wood for the front baffle only.


----------



## Geoff St. Germain (Dec 18, 2006)

I have switched to using void free plywood instead of MDF. I used MDF for most of my first projects, but I find that it dulls tools much faster than solid wood or plywood. I also prefer the more coarse dust produced when cutting/shaping plywood compared with the very fine dust produced with MDF. As far as performance goes, I haven't really noticed much difference in the finished speakers. It's just a preference of working with plywood for me.


----------



## Mike P. (Apr 6, 2007)

Geoff St. Germain said:


> I have switched to using void free plywood instead of MDF. I used MDF for most of my first projects, but I find that it dulls tools much faster than solid wood or plywood. I also prefer the more coarse dust produced when cutting/shaping plywood compared with the very fine dust produced with MDF. As far as performance goes, I haven't really noticed much difference in the finished speakers. It's just a preference of working with plywood for me.


Geoff, I've never used void free plywood yet. How does it handle machining the edges? Let's say using a 3/4 inch round over bit. Does it finish smooth on the edges?


----------



## avaserfi (Jul 5, 2007)

Mike P. said:


> Geoff, I've never used void free plywood yet. How does it handle machining the edges? Let's say using a 3/4 inch round over bit. Does it finish smooth on the edges?


It does great check out my work .

http://www.hometheatershack.com/forums/70820-post16.html


----------



## Mike P. (Apr 6, 2007)

Thanks Andrew. It does look good.


----------



## Geoff St. Germain (Dec 18, 2006)

I haven't had any real issues with roundovers or chamfers on plywood. One thing to watch for is splintering near the corners if your bits are getting dull.


----------



## Warmon (Aug 25, 2007)

Another great product that nobody ever mentions is MDO or HDO - medium or high density overlay. This is mostly used in the sign making industry. It may or may not be cheaper than Baltic Birch.

M.D.O. (Guardian): Medium density paper overlay on top of exterior fir plywood for sign painting, or exterior construction, has a nice paintable surface. This two-step process includes the plywood substrate being sanded before M.D.O. overlay is applied to minimize wood grain and patch show-through. This is our standard grade of M.D.O. and grain telegraphing is more prevalent than in our Signal board.

M.D.O. (Signal): Premium grade Medium density paper overlay, the core is exterior fir plywood with an outer layer of exterior luan on front and back (under paper overlay) to prevent grain telegraphing. The signal grade uses premium face veneers and a solid core. Offers fewer (and tighter) core gaps giving the least amount of edge voids for better machineability and weatherability in cut shape applications. Mostly used for applications where smooth painted surface is essential. 

Hi-Way H.D.O.: High density overlay panel designed for applications of reflective film for hi-way signs; it is ideal for state, county and municipal signage. Every veneer layer is solid and care is taken to minimize core gaps. There is no preparation before applying film or paint. Excellent for vinyl graphic applications.


----------

