best wood for speaker cabinets ? oak,cherry, balti

Matt - I don't quite understand analogy with guitar woods. Cedar and Spruce are two woods with the highest strength to weight ratio and often used for the guitar tops to make it vibrate well. You don't want vibration and the one of the best materials is high density MDF or stone (marble, granite etc). Some speakers (like Paradigm) have internal crate in form of crossing boards along and across that have holes (circles) cut outs resembling honeycomb. Some more expensive speakers have either irregular shapes or round sides getting narrower at the back, to prevent standing waves.

There might be different reasons why manufacturers use birch. One of them is perception of quality - hardwood vs. MDF. People often choose kitchen cabinets with plywood shelves not knowing that MDF works much better (less sagging). The other reason might be ease of working with (cutting, sanding, drilling) and finally weight. I have small bass cabinet made by Carvin built of light hardwood advertized as very light. Weight is important for people who play out and have to carry it. As for light bracing - I'm not an expert on speaker construction but it is definitely not a violin. Resonating walls add coloration to sound and 99% percent of manufacturers do anything possible to reduce it. Revel uses laser reflectometr to design for minimum vibration, Dali uses layers etc. Do you really believe that kit speaker was designed to have sound of it's own especially when before same box was called to be made of MDF?

Mapman - not every guitar is designed for long sustain. Flamenco guitar for instance isn't. Guitar has presence, projection, sustain, separation and tone. Some guitars have great presence but poor projection. Flamenco guitar has huge projection but poor presence and sustain, but good separation. If you design speaker cabinet to interact with guitar then how much of presence, projection, sustain, separation and tone it should have? Would it be the same if you listen to Flamenco?

I found this article that makes extensive comparison between birch plywood and MDF:

http://www.tnt-audio.com/clinica/cabinet_walls_e.html

To my surprise they found birch to be better. 11-ply Baltic Birch plywood might be good.