Bracing with hardwood, need advise. *pics*

Apologies for posting in the loudspeaker forum, this place gets much more traffic than the subwoofer forum, and this question can apply to both.

I want to brace my MDF enclosure with Jatoba (Brazilian Cherry). After tons of searching the forums, the general consensus is to stay away from hardwood, because it changes shape based on moisture content, destroying an airtight enclosure. Opinions on mixing MDF with hardwood are mixed, so I'm posting this question.

First, a comparison with oak...

[IMGDEAD]http://www.michnicki.com/diy/Dayton12/WhiteOakJatoba.jpg[/IMGDEAD]

I will only be using two 2" x 1" x 24" pieces, which have been indoors for about a year. These will be positioned along the side of the enclosure, to transfer mechanical energy from the woofer and baffle to the enclosure as fast as possible. (I am assuming since Jatoba is stiffer than MDF, sound travels faster through it). The baffle will be 3/4" 13 ply baltic birch.

This is a pic of the unfinished enclosure, with the braces clamped where I want them to be.

[IMGDEAD]http://www.michnicki.com/diy/Dayton12/BracingTopBottom.jpg[/IMGDEAD]

The hole in this white foam is the size of the cutout.

[IMGDEAD]http://www.michnicki.com/diy/Dayton12/BracingCutout.jpg[/IMGDEAD]

I have more baltic birch which I will use to brace the enclosure against panel resonances. The purpose of the Jatoba side braces is only to couple the woofer to the enclosure. The brace will run all the length of the enclosure, because I will eventually add a second woofer on the other side for a push-pull config.

Is this OK, or will the Jatoba expand and rip off my front baffle? Has anyone here tried this?

Dan
 

Ron E

Member
2002-06-27 10:41 pm
USA, MN
Sound speed is related to stiffness/density. In that respect, Jatoba and oak are within 5% ;) Which costs more? ;)

Wood doesn't change dimension much along the length of the grain.

What you are trying to do doesn't really make much sense to me, honestly. The whole BS controversy about coupling is mostly nonsense. If you want to "couple" your woofer to the enclosure, a brace behind the magnet with a compliant substance captured between the magnet and brace will do admirably. You don't need some silly "exotic" wood to do it. Keep the Jatoba for decoration.
 
Thanks for the feedback, glad to hear this will work.

Jatoba is relatively cheap by "exotic" standards. These are just leftover scraps from a non-audio project. Crosscut hardwoods in Seattle sells it for $9.50 / bf, so this project is using $6 worth :) I have no other use for it, and I don't have enough plywood.

Dan
 
owdi said:
Thanks for the feedback, glad to hear this will work.

Jatoba is relatively cheap by "exotic" standards. These are just leftover scraps from a non-audio project. Crosscut hardwoods in Seattle sells it for $9.50 / bf, so this project is using $6 worth :) I have no other use for it, and I don't have enough plywood.

Dan


As the others have pointed out, the length won't change by much. I've used scraps many times including strips of leftover prefinished oak flooring. It's important to make sure the finished side faces the front baffle, so anyone looking inside will be impressed
;)

BTW: Nice work on those corner pieces.

Best Regards,
TerryO
 
TerryO said:



As the others have pointed out, the length won't change by much. I've used scraps many times including strips of leftover prefinished oak flooring. It's important to make sure the finished side faces the front baffle, so anyone looking inside will be impressed
;)

BTW: Nice work on those corner pieces.

Best Regards,
TerryO

I'll be sure to install a plexiglass baffle and neon lights so everybody can see it. :D

I can't take credit for the corner pieces, I bought them from rockler.com

Dan