On Oct 8, 9:54*pm, fourrings wrote:
I've veneered over 3/4 birch ply with no problems. *The substrate
is stable and it doesn't seem to make any difference whether the
veneer is parallel or cross grain to the top layer of the ply. *The
edge is a different story as the internal layers can telegraph thru the
typical thin veneer. *Wrapping the edges with solid wood first solves
that. *I don't bother veneering both sides of 3/4 ply and have had no
issues with warping.

Alternatively you could use MDF for the substrate. *It's very flat and
usually less expensive than bitch ply. *If you already have the ply that's
a different matter.
Art

Perfect. *I'll have to keep an eye on the edges -- definitely not
something I would've thought about until too late. *I plan to do an
ebony stain on it, will that help or make it worse? *MDF would
definitely be perfect, but I hate working with it. *Last time I made a
subwoofer cab with it, every crevice in my garage was covered in fine
dust. *Plus something about using real wood makes me feel better about
quality, even if layered.

Ash veneer is usually thick enough not to have to worry about
telegraphing sanded end-grain. The stuff can be very crumbly though.
Making the torsion box out of 3/4" is overkill. imnsho. Maybe the
outer perimeter, but the cells and top itself would just as well be
made out of 1/2" (6x6 cells?).
If you're using wood glue on ash veneer anywhere, be careful. The
stuff bleeds through. Go for the paper-backed veneer, much safer and
usually better quality.
YMWV