Beech ply for Fostex BLH?

[kavermei]

Hi all,

Would beech ply be a suitable material for building the Fostex FE208ESigma recommended BLH enclosure (or any BLH for that matter), as compared to Baltic birch ply?

I'd be glad to hear any thoughts or experiences you may have.

Cheers,
Kenneth

[GM]

Greets!

The main thing about plywood is it needs to be void free (no missing knots or internal layers using scrap pieces as filler), which very few are and few places that sell to the public know whether it does or not, so usually you will have to ask either a major distributor or the manufacturer. FWIW, in my area it is strictly a furniture grade which is not void free.

GM

[musgofasa]

I have seen Beech that was good and I have seen it that was bad. For the record, I have seen more good than not. (Maple too). The best Beech or Maple I have seen around here was labled "cabinet grade". After cutting 4 sheets of this over the weekend, I can vouch for it being void free. The stuff I bought was 9 ply rather than 11 or 13 but it is really stiff and actually measures 3/4 inches.

I don't think it's the type of wood as much as the quality. Some has different filler layers and some are terrible where some are solid wood and no void. One good thing about living at the beach was being able to get "marine grade" ply. Man that stuff was heavy though, lol.

Take care,
Robert

[Scottmoose]

As GM said, void free is the critical factor. Look for 'closed core' which should mean there are no open defects anywhere in the core etc.

[kavermei]

Hi,

thanks for the info! I suspect the material I have access to is furniture grade also -- I know the face quality is B/B but I have no info on the interior quality. I've used it before and never saw voids in the saw cuts though.

I'll boil a scrap tonight, see if I can make the glue come apart and inspect the inner layers that way. I'll post back on how well that works

Cheers, Kenneth

[Scottmoose]

FWIW, remember there are voids & then there are voids. For most FR driver based apps., I doubt the odd small one (providing it's not a loose piece of material that buzzes) will make an audible difference at the listening position (a real PITA though if it happens to be at an edge. Still, that's what filler & veneer are for). When you get to larger ones of course, or are building a dedicated bass enclosure, that's a different story, and void free is pretty much a must.

[kavermei]

Well I put the beech ply to the test and the interior layers look pretty decent in most scraps I looked at -- not soft or anything. I can get some leftover panels cheaply from a friend, enough for a pair of BLHs, so I've decided to just go ahead and try my luck with it!

It's reassuring to know it won't a-priori take a backseat to birch ply for horns (as MDF reportedly does).

Robert, I read about the marine ply elsewhere on diyaudio -- sounds like it's the best plywood material out there, if cost is no objection... I remember somebody mentioned 150 UK Pounds for an 8' by 4' sheet

I'll be sure to post some building pics later!

Cheers, Kenneth