In theory the MDF might be more dense and offer better performance. But I don't know if it would make a noticeable difference in the real world. The Birch might last longer and resist humidity better. I don't have a problem working with either.

 

The biggest issue is moisture. Birch will stand up to humid climates MUCH better than MDF. As far as rigidity and the like, as long as you brace properly it will be negligible.

Birch=Humid Climates/Marine
MDF=Everything else

 

Oh, and as long as your saw is sharp and you take your time you don't have to worry about splinters with birch.

 

I just built mine with Birch from what I understand it is a bit lighter but the only thing I hate is the splintering. No matter what we were doing it peeled and splintered.

(Bit unnerving)

If I had to do it over again likely just 3/4 mdf (SQ build) but its working

I guess for me its going to be trial and error. Thanks for your replies so far. I'll try and look for good quality stuff ... which at the moment Marine bich seems to get a lot of mention.

 

The good thing about Birch is that it can be stained and clear coated for that pro look.
Nice for house speakers also.

 

Medite and Medex are superior to standard MDF for building sub boxes in every respect.

~JH

 

"medite" is just a brand name for MDF. that like saying that a skill saw is Superior to a circular saw.

 

I just built mine with Birch from what I understand it is a bit lighter but the only thing I hate is the splintering. No matter what we were doing it peeled and splintered.

(Bit unnerving)

If I had to do it over again likely just 3/4 mdf (SQ build) but its working

 

birch is lighter, stiffer, and holds up to abuse and moisture better. It also holds screws better.
Mdf is denser and cheaper.

 

Are you talking about solid birch or birch ply?

 

I've been told to go for 'Birch Ply'

 

I always used MDF for building installs and other audio-related projects, but now in Xenia's car, I'm using 18mm Meranti-ply, I think it's 9 ply's.

MDF is easier to saw and sand into shape without splintering, since it's basically grinded wood mixed with glue, there are no long fibres in it...

With the meranti-ply, every saw-cut is splintered at 1 side, even when using a very fine saw-blade and taking time, so if you want nice sharp 90° cuts, MDF is the way to go.
I chose meranti-ply-wood because of it's strength.
If you take a piece of 8mm MDF, you'll have to use a bit of force, but then it'll break quite easily. Do the same thing with the same thickness of meranti-play, it'll bend a little faster and the top layer will start to crackle, but it'll take longer and more energy to break it completely because of the long fibers that have a different direction in every layer...

The best stuff is the plywood they use to make molds for concrete walls/beams/... That's ordinary plywood with an epoxy-coating on it on both sides. Because of that coating, it's a lot stronger than regular plywood and it doesn't splinter when cutting it!
It is more expensive though...

 

As a beginner, I wonder if going to a timber merchant and getting them to cut it for me would be the best bet?

The comment given to me was to the effect of: use brich ply because it will show people tht you care about your products and that as a box builder (which i really want to get into) it also show you won't compromise your products and that you're not in it for the money etc, etc, (you get the picture).

 

If you have a timber merchant that is precise with measurements and cuts, I'd always recommend to let them do most of the cutting. These guys have professional machinery and lots of experience, but sometimes, you have to do something yourself.
For example, where I buy my sheets of wood, they have a great machine and experienced worker to cut rectangular shapes, but they can't do trapediums, triangles, circles... and they can't do a 45° cut, simply because their machine isn't made for this.
Sometimes, wood-shops have a CNC-router available and then they can do anything you want, including angled cuts, perfect round holes...

That comment is (crap of a male cow), a box made of MDF can sound just as good as a box made out of plywood, and it's easier to cut with hobby-equipment.
The only downside of MDF is the strength of it: you have to use at least 1" thick MDF to get the same solidness and toughness as with 3/4" ply, depending on the quality of the plywood and the MDF.

For subwoofer cabinets I always use 30mm (1 1/4") thick MDF, but now in the Saab I decided to use 3/4" meranti-ply to get the same strength out of thinner and lighter material (but it's harder to cut properly) because a Saab 900 classic is known for it's rather weak rear-suspension and I don't want to mess up it's great weight-balance too much.


For a planned home-audio project, I'm planning to use 30mm MDF for the bass-cabinet and 12-15mm plywood for the upper mid+tweeter cabinet to keep the gravity point low, which will increase the stability of the total speaker compared with all-MDF or all-ply.

 

I have issues with mdf here are my pros and cons.


Mdf cons : its dust is carcinogenic
is like a sponge if it gets wet its ruined
its hard on tools (saws routers)
It has no screw holding strength whatsoever and if you want to use a screw you need to predrill or it swells out making leaky joints or baffles
It doesn't paint consistantly on end grains and faces
It chips off corners when mistakes are made
Brads shoot wildly through it coming out the sides at very slight angles making finishing difficult
It truly has no strength unless its built into a box of some sort

Pros: it routers nice
Some people believe its more dense making a better non resonant enclosure
its usually cheaper than plywood variants

Ply/ birch Cons:
It splinters when cut sometimes
Its more expensive usually

Pros:
Its stronger
The dust is not nearly as unhealthy and doesn't stay floating for weeks in your shop
Tools last longer
It takes screws ( repeatedly without loosing strength or grip)
It takes brads and they go where they are told
Glues great
Paints the same on end grains usually
If you desire to build with screws they can be sunk under the surface and filled over with bonding making it invisible without predrillig

I'm sure there is more




Sent from my GT-P7510 using Tapatalk

 

you in buffalo new york rexxxlo?and those are all very interesting points.....in the process of making materials decisions for my box build as well id like to see some more comments.i think after reading this i very well may go to birch instead of the planned mdf.im exposed to enough carcinogens and i like strength altho for a single SWR-843D mdf would prob be plenty strong.it is going in a truck tho and may very well see some shockloads and whatnot.....

 

You can cut most plywood without splintering by scoring it with a utility knife just shy of the cut line. If it's poor quality or it's gotten wet it may splinter and peel no matter what.
IMO, If you're planning to paint it you should avoid exposing any end grain and miter your corners with either plywood or MDF. At the very least put a thin layer of filler on the end grain before you sand it.

 

I was in your shoes on Friday, but I went with MDF. I was looking for birch wood around my area and the only birch I was able to locate was 9 ply and I wanted 13 ply. Some people on here are using Arauco and have good results from what I have searched, might want to look into that aswell. Goodluck!

 

For HD applications, I have always used MDF, braced and doubled at the baffle. Someone said earlier that it's wood pieces and glue, not true (they may be thinking of particle or chip-board -- don't use those).

[WIKI=Medium-density fibreboard (MDF) is an engineered wood product formed by breaking down hardwood or softwood residuals into wood fibres, often in a defibrator, combining it with wax and a resin binder, and forming panels by applying high temperature and pressure.[1] MDF is denser than plywood. It is made up of separated fibres, but can be used as a building material similar in application to plywood. It is stronger and much more dense than normal particle board.]

Anyway, there are techniques you can use to make MDF solid as a rock. It paints perfectly. Smooth as hell. Easily routed, etc.

If you DO use plywood, here are a couple tricks.
-When you run plywood across the table saw, always run the "pretty" side up (bad side to table top).
-Run your saw blade all the way up! Contrary to the "one tooth rule", this will significantly reduce edge splintering.
-To further reduce edge splintering, put two layers of good quality masking tape where you about to cut, mark or position your piece, and then cut. When you remove the tape, it'll most likely be very clean.
-I have gone as far as to make a 1-3 diluted Elmer's white glue wash, and paint the edges of the plywood (then let dry for an hour) before sanding. (helps with edge splintering from the sander at hard edges)

This is my home entertainment center that I designed and built last year, it's primarily birch plywood. The large black squares you see on either side of the components are 12" subs...those are encased in MDF, THEN surrounded by the birch for aesthetics.

(Funny, the picture is over a year old, but the TV headline could be current from this morning, huh? lol Some things never change!)

--Radar

 

Thnaks for the tips. For the time being as I don't have a workshop, or garage to work from, i'm going to have to get a timber merchant to cut whatever wood I need. Tday I'm going to ask various merchants if they can cut at angles, mostly fror 45's but also for more complex, or tapered cuts.

the cost for me isn't an issue, I'll pay for quality, but when i do get my own tools, I'l practice on MDF then move onto Ply.

 

I use 13 ply birch plywood on my own sub boxes. My customers want MDF. I want to try Avantech flooring on my next box. Its dense,strong & has no formaldehyde in it. It should work good & its $27.00 a sheet

 

I spoke t a collegue at work today after finding out he's a trained carpenter. His view is what the view of all carpeters I've asked, including my bro-in-law, who has a £12,000 table saw (flooring biz).

They all say use Ply, that for my application, ply has better dampening than MDF, is stronger, and looks better. My friend Dave said, splintering shouldn't be a big issue to worry about. I'll talk to him more tomorrow.

 

Out of curitosity has anyone tried using HDF (High Density Fiberboard) for a project instead of the much more common MDF (Medium Density Fiberboard)? I know it exists and have read a little about it in some box design books.

 

it does exsist, but it is expsencive, heavy and actually pretty hard to find.

 

In my opinion the quality of MDF is waaay more degraded than what it used to be and the price ain't gettin no better. You add to it the fact that i live in AK where the birch is no more than 5 bucks more.......yeeeey Birch!!

 

5 bucks more ... sometimes ... jsut sometimes I wish I lived somewhere other than the UK. We pay thrught the nose for everything ...

 

You can get 13 ply in fir also. Its just as strong but it doesn't stain well. I use it inside my cabinets for the drawer units. I dovetail the joints & it works good. I hate MDF. I've grown allergic to it. If I use it much I get headaches & skin rash. Its the formaldehyde.It also is hard to control MDF dust. I can cut any other type of wood & the dust catchers get the dust. Cut MDF all day & your shop will have dust everywhere.

 

Here is a wonderful explanation of the resonance differences in Baltic Birch compared to MDF, solid oak, and Aircraft Aluminum Wilson Audio: Authentic Excellence: Materials

 

HDF is something I've only read about and my local specialty wood store that regularly stocks wood like purple heart, wenge, ebony, rosewood, zebrawood etc... responded with "We'd have to order that in."

Captainscarlett, in that second link of yours there were a number of HDF sheets available in 25mm or 30mm thicknesses. I'm pretty sure that'd be more than enough for even the largest of subwoofer enclosures - though one could always glue two sheets together if a 60mm baffle is needed.

 

I bought a sheet of avantech flooring for my next box. Its almost as heavy as MDF. Its dense very flat & only $25 a sheet. It should work good. No formaldehyde in it. It looks like OSB but its smooth & much denser than OSB. I'll post my opinion when I start using it.

 

Keep us posted.

 

First time I've heard of someone looking at using flooring for a box.



J

 

It isn't flooring per se, it is sub floor material- engineered plywood. Should work well. Looking at the Wilson site, MDF appears a poor choice for mid bass, but the graph in the 20-100 range where most of us ask our boxes to work looks like their secret stuff. I would think the subfloor being engineered should have the approximately same resonance as MDF. The only advantage over MDF is screw holding, but I doubt it is that much better, as a hobbiest woodworker I have experience with both. Screws are only used for the speakers, and most back up with T-nuts and the input connectors, what 8-12 screws? I would imagine that the waterproof coating on the flooring would dull router blades quicker, negating further the advantages. Just some food for thought.