[Peter J]

I’ll call it on topic.  While we’re at it, what thickness for all materials?  Thinner with more bracing ok? 
I have a small supply of 12mm BB to use up.

In general, thinner material would need to be braced more to get to same stiffness as thicker material. Stiffness and damping typically go hand in hand.

[Toecutter]

None of the PVC trim board or decking materials I've investigated are considered structural by their manufacturers. From my experience with they just move too much and would offer no sonic benefit either, not to mention their expense.

What would you imagine their advantage to be?

I dont know what advantages it would have , thats why I asked. I know that some speaker driver frames are plastic cause they won't resonate,  figured plastic would be a very uniform material. Maybe for an outdoor speaker it could be advantageous.
I'm very new to all this so I'm learning.

[jcsperson]

I’ll call it on topic.  While we’re at it, what thickness for all materials?  Thinner with more bracing ok? 
I have a small supply of 12mm BB to use up.

I've been known to be frugal. (OK, I'm cheap.) 

I built cabinets for a walk-in closet using odds and ends of 1/2" plywood that didn't really match in color or quality. I laminated a nice sheet of 1/4" oak plywood onto that and ended up with some attractive cabinet exteriors. If you get down on your knees, pull out a drawer, and look inside you'll see the cheap stuff, but that's not a factor in speakers.

[Hobbsmeerkat]

I dont know what advantages it would have , thats why I asked. I know that some speaker driver frames are plastic cause they won't resonate,  figured plastic would be a very uniform material. Maybe for an outdoor speaker it could be advantageous.
I'm very new to all this so I'm learning.

There are youtube channels dedicated to 3D printing speaker/subwoofer enclosures. So i imagine there's definitely a market for that out there in a way that could make plastic like PLA/ABS/PVC/PETG viable options for speaker enclosures, tho i am curious how different levels of infill change its tonal response. And if a sand/litter filled option would be better... 

Tho tbh there are definitely limitations on build volume that could be problematic for more traditional speaker builds

[planet10]

CommomSense site

A site where you need to look at anything they say with skeptism.

dave

[planet10]

I’ll call it on topic.  While we’re at it, what thickness for all materials?  Thinner with more bracing ok? 
I have a small supply of 12mm BB to use up.

More bracing is better than thicker material IMO.

12mm BB is hard to work with, we used 15mm in preference (with 18mm for some baffles and bigger boxes). We even built a pair of push-push subs with well-braced 15mm BB to prove a point (significant reduction in box load due to push-push operation)

Stiffness goes up with the cube of the thickness. Higher material density is not an asset unless it brings more stiffness. ie stranded bamboo ply.

dave

[emailtim]

... Stranded/fossilized bamboo plywood is even better but dearly priced (no need for veneer thou)

dave

You would think since Bamboo is fast growing grass, it would be cheap.  Same goes for "hemp wood".

This video does some resonance tests towards the end of the video including MDF, Plywood and Constrained Layer Dampening.  Also discusses different types/grades of plywood.

https://www.youtube.com/watch?v=EEh01PX-q9I

[planet10]

You would think since Bamboo is fast growing grass, it would be cheap.  Same goes for "hemp wood”.

At this point the high price of bamboo ply is because there is still a large amount of manual labour involved in its making. I am patiently waiting for similar based on hemp, could be even better.

And i’d like to see a plywood made of just the external veneers. 5 ply would be about 15mm thick and be incredibly stiff.

The guy in that video has dome many, and the ones i have seen place him in an intermediate stage of knowledge. Everything he says has to be examined, some is decidely off-base, some is solid.

dave

[MarvinTheMartian]

Bruynzeel  Super Hechthout  100% Sapele plywood
https://www.teakwoodsupply.com/bruynzeel-perfect-marine-plywood/

Price? I'm afraid to ask.
Shawn

[emailtim]

...
And i’d like to see a plywood made of just the external veneers. 5 ply would be about 15mm thick and be incredibly stiff.
...

They guy in the video identifies such plywood that uses veneer layers all the way through instead of a veneer/filler sandwich.  He discusses the various types before he does the resonance tests.

[mresseguie]

I found a layered product that appears very interesting, but I don't know how well it would work for speaker cabinets. Anyone familiar, or have experience with Richlite?

Links:

http://www.edensaw.com/MainSite/Store1/Store/CategoryHome/736

http://www.edensaw.com/MainSite/Store1/StoreProducts/ProductList/739

http://www.edensaw.com/MainSite/Store1/StoreProducts/ProductDetail/9347

Michael

[srb]

I've seen the solid Richlite countertops made of paper and phenolic resin, which are quite expensive and heavy, on par with quartz and granite.

This new countertop material Stratum, consisting of a Richlite and Plyboo sandwich, I haven't seen before, but it's also probably too expensive for large speaker cabinets.  I believe a 4' X 8' X 1" sheet retails for ~ $1300 and weighs 206lbs.

1" thick prototype samples are available directly from Richlite in 1' X 1' or 2' X 2' at $72/sq. ft.

Stratum is just one of Richlite's Cascade Series of layered products.

 

[mresseguie]

I've seen the solid Richlite countertops made of paper and phenolic resin, which are quite expensive and heavy, on par with quartz and granite.

This new countertop material Stratum, consisting of a Richlite and Plyboo sandwich, I haven't seen before, but it's also probably too expensive for large speaker cabinets.  I believe a 4' X 8' X 1" sheet retails for ~ $1300 and weighs 206lbs.

1" thick prototype samples are available directly from Richlite in 1' X 1' or 2' X 2' at $72/sq. ft.

Stratum is just one of Richlite's Cascade Series of layered products.

 

Ouch. That is expensive. I'd still be tempted to use it for the front baffle of a two-way monitor or stand-mounted three-way.

[planet10]

Bruynzeel  Super Hechthout  100% Sapele plywood

13 plies, looks pretty good and shouod have high construction standards.

dave

[planet10]

…Richlite...

I believe that is the material the fellow is using for the TAD 1601 monster miniOnkens i designed for him.



dave

[emailtim]

Here are some Magnepan panels made out of BauBuche Panel, 3mm laminated sheets of beech (higher strength engineered lumber). 

It seems more popular across the pond.

https://www.pollmeier.com/en_US/Products/baubuche-about

[emailtim]

Has anyone used EXTIRA (exterior water resistant) MDF and if so, is it a good speaker grade panel ?

https://miratecextira.com/extira-exterior-panels/

[Peter J]

Has anyone used EXTIRA (exterior water resistant) MDF and if so, is it a good speaker grade panel ?

https://miratecextira.com/extira-exterior-panels/

I would expect it to perform like MDF, since in essence that's what it is. While impregnated with resin to make it water resistant, it's less dense than Medex or Ranger Board. It's also nearly three times the price.

I used its cousin, MiraTEC, to trim exterior of my shop. Ten years in and it seems to be performing as advertised, but I question whether you'd see any effect building speaker boxes except a lighter wallet.

Richlite was mentioned earlier as well, my countertop fabricator gave me a piece to play with.  He cuts it with diamond tooling, I tried it with carbide, which I doubt I'd do again. It's incredibly hard and cutter life would be shortened significantly.