I've been look around trying to get varying opinions on which is better from a sound standpoint. People seem to have a lot of varying opinions with little actual scientific data. I've been looking for a good FR graph that might demonstrate the differences between MDF and Birch Ply to give some measurable differences, but haven't found anything yet.
So far I've come up with Birch being about twice as stiff as MDF. Which in my mind would result in the greater ability of a driver to vibrate accurately. This is due to the fact that a less stiff material would vibrate more with the driver as it is being pushed and thus resulting in smaller difference between the vibration of the driver and it's holding box. I would think that would yield less SPL, but could be mistaken
Birch is also more durable. MDF can break, chip, and scratch more easily than birch.
MDF can also be harder to work with. I know that routing it results in dust cloud sometimes.
Any other thoughts would be appreciated. I would love to formulate a very accurate comparison maybe even a chart for future reference. Obviously I would share a chart with the community here.
Thanks in advance
Neither is particularly hard but you can make them harder by coating the box with polyester resin. In addition to hardening the surface, it also seals the joints. MDF is one of teh easiest materials to work with, IMO. It is dusty but if you have a shop vac with the larger hose, you can collect the dust easily using just about any power tool. Go to a woodworking supply store like Rockler or Woodcraft and look at the dust collection attachments. I bought my 2HP double bag collector at Harbor Freight and it works great. I looked at all of the others that are the same and there was no reason to spend more money and get the same thing. For routing, I use my shop vac.
I would estimate that literally millions of speakers have been made commercially, using MDF. Add the millions that have been made in large and small car stereo shops, garages and with minimal tools and you'd have to conclude that there's a reason it has been so widely used. If you go to a lot of new home jobsites when the trim is being installed, you'll see a lot of it there, too, because it paints so well.
Scientific data? Don't hold your breath. All you really want is a very inert cabinet, with bracing on long surfaces to break up resonances by stiffening the panel. Yellow carpenter's glue will work with either plywood or MDF and as long as any leaks are sealed, it will be fine. I did car audio for 20+ years and never had a glue joint let go on a box I built. I never bothered to use birch plywood for them because of the fragile edges, although I used it when I made the drawers for my kitchen.
With any woodworking that generates dust, regardless of whether a dust collector is used, a NIOSH approved dust mask should be worn, as well as safety glasses and hearing protection. I can't estimate how many people I have talked to who claimed to be "really into the sound of a great system" but you wouldn't catch them dead with ear plugs.
