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View Full Version : Any sound difference between MDF and Birch?



jmass03
07-24-2008, 02:50 AM
Getting a box made however the gentleman whos making it only has a 1.5" for the baffle. In the W7 manual I believe it says the baffle must be at least 1". Would a 3/4 13 ply birch be better, or just regular MDF?

What specs should I follow? JL's specs for the 12W7 at 15.5 H x 15.5 W x 15 D?

jmass03
07-24-2008, 02:56 AM
Nm, found the answer to the first question.

Can anyone answer the second one though? Didn't really get any useful replys in the subwoofer section.

helotaxi
07-24-2008, 05:38 AM
Either type wood will be fine. Just double up what is used for the baffle.

You can go with JL's spec or go a little bigger. The volume of air inside the box is what matters, not the dimensions. So if you want it wider or taller or whatever, take away from the other dimensions to get the internal air volume the same and you'll be good.

Ed Lester
07-24-2008, 11:00 AM
Either type wood will be fine. Just double up what is used for the baffle.

You can go with JL's spec or go a little bigger. The volume of air inside the box is what matters, not the dimensions. So if you want it wider or taller or whatever, take away from the other dimensions to get the internal air volume the same and you'll be good.

Not exactly true.
A deeper box will give you less impedance rise and sometimes a deeper response whereas a shallow box will have a higher box rise and more back pressure built up on the rear of the cone.

helotaxi
07-24-2008, 12:50 PM
If you say so. Yet to see that happen in practice but being not an SPL guy Ireally don't pay much attention to box rise.

iamamp3pimp
07-24-2008, 12:52 PM
ed lester, ive never heard of that, but it seems completely obviously true

Ed Lester
07-24-2008, 12:57 PM
If you say so. Yet to see that happen in practice but being not an SPL guy Ireally don't pay much attention to box rise.

It would be more of an SPL thing.
I have built hundreds if not thousands of boxes, mostly geared towards SPL, and can notice up to a 1.5 ohm difference when reducing depth by 2 inches and extending width.

But also for SQ, internal shape can be very important in ported boxes. angles can be adjusted to load the port properly. Also the shape can be adjusted to keep a standing wave from building behind the cone. A standing wave will limit the subs accuracy and make it sound sloppy.

helotaxi
07-25-2008, 10:02 AM
Sure. It makes sense for a ported enclosure. Sealed is a whole different ballgame and is the question at hand. In a SUB woofer setup you'd only have to worry about standing waves an the like and their effects on loading the cone in really big boxes that are allowed to play really high. For a smallish sealed setup, really only the volume of air behind the driver matters.

Ed Lester
07-25-2008, 12:14 PM
Yeah, ported boxes are more finicky. Shape can kame a difference in small ported, I have tested and heard differences but it is minute differences unless you run extremely high power.

PV Audio
07-25-2008, 01:53 PM
Short answer? Not that you'll notice.