Wood options in 2023

[iansr]

I am going to be making some U frames for some AE Dipole 12 woofers. Birch ply would be my material of choice but it’s such a crazy price now and given that these will be open backed I’m thinking MDF will probably be adequate. One idea I’ve thought about previously is to apply a fibre glass layer or even carbon fibre layer to the inside faces with the aim of stiffening the MDF and hopefully making it less resonant. Anybody tried anything similar?

Any other options I should consider?

[vinylnvalves]

Send me your drawing dimensions and I can give you an idea on birch ply, as I still have a stash, and as nobody wants anymore horns, it’s sitting there. Otherwise I would be looking at OSB, the glue damps it a bit. Anything but MDF......

[simon]

Yes, anything but mdf. The baffles I built years ago were mdf as that's all I could get for the lash up. Sounded dreadful, played along with the music.

[simon]

To be more positive I imagine a solution could be engineered to make the mdf more damped and rigid, but it would perhaps end up costing more than the birch ply, take a lot longer, and probably be a lot heavier.

I've sometimes wondered how two skins if 6mm filled with expanding spray foam might perform, but never had enough time or interest to try.

[pre65]

but it would perhaps end up costing more than the birch ply, take a lot longer, and probably be a lot heavier.

Bite the bullet and use the "proper" stuff.

Shop around for best price.

[simon]

That's certainly the quickest and easiest way. But I have this nagging interest in whether a constrained layer type approach might be worth the effort. Briggs successfully used sand to damp baffles a long long time ago. Spray foam would be a lot lighter and potentially quite rigid.

[steve s]

Flooring grade chipboard is my choice, in my opinion it has less 'sound' than the best ply's.

[iansr]

Flooring grade chipboard is my choice, in my opinion it has less 'sound' than the best ply's.

That’s interesting Steve because I’ll soon be buying lots of it our for our house renovations - I assume you mean the stuff that’s used nowadays instead of floorboards?

[vinylnvalves]

Not sure whether it's true, but I read somewhere that the fire grade red one had the best sound.

[vinylnvalves]

When my old man was making speaker cabinets for AR in the 1960's they used to sand fill the bass cabinets. A particle damper as we would now know it, between two ply sheets.

[simon]

Flooring grade chipboard is my choice, in my opinion it has less 'sound' than the best ply's.

I think there's something in this Steve and wonder if the more random orientation of the chips encapsulated in glue provides a better 3D performance than ply which by its nature perhaps isn't so good in the third dimension? Only a musing.

[vinylnvalves]

Flooring grade chipboard is my choice, in my opinion it has less 'sound' than the best ply's.

I thought you were using furniture grade OSB for your cabinets 30 odd mm thick.

[pre65]

OSB vs Plywood.

OSB can be manufactured into larger panels than plywood.
OSB is generally less expensive than plywood.
OSB is more uniform, with fewer voids, soft spots, or gaps.
OSB is considered by many to be a more environmentally friendly product since it can be made from scrap and smaller trees, rather than old-growth trees.
OSB does not delaminate, as plywood can. Delamination is when plywood layers separate, largely due to humidity or extreme heat.
OSB weighs more than plywood.
OSB doesn’t hold screws, nails, and fasteners as firmly as plywood.
OSB swells more than plywood when it comes in contact with moisture, and it generally remains swollen to some degree.
While both OSB and plywood off-gases formaldehyde, OSB off-gasses more of the harmful gas than plywood.


I have no personal experience with OSB.

[steve s]

Flooring grade chipboard is my choice, in my opinion it has less 'sound' than the best ply's.

That’s interesting Steve because I’ll soon be buying lots of it our for our house renovations - I assume you mean the stuff that’s used nowadays instead of floorboards?

There a local offcuts type of wood yard near me, they have piles of speaker sized off cuts in ply chipboard and osb board,

You will have all have seen me touching up speakers at owston and occasionally at the wam show.

It always seems to me ply wants to join in with the music unless the bracing is exceptional of course.
And it's usually quite audible with a bit of volume.

Although my red speaker's do have mdf side panels, there's 25mm and 18mm chipboard dividers and alot of damping. The 18" drivers are in chipboard boxes again well damped

I've used standard and flooring grade,
wouldn't like to say which is best, but I always damp any internal surfaces

[iansr]

Send me your drawing dimensions and I can give you an idea on birch ply, as I still have a stash, and as nobody wants anymore horns, it’s sitting there. Otherwise I would be looking at OSB, the glue damps it a bit. Anything but MDF......

I’ll email you Steve.