What Wood Type?

[lovinthehd]

Had never heard particularly about rubber content in trees (well outside of rubber trees). http://www.differencebetween.info/difference-between-teak-wood-and-rubber-wood

 

[Matthew J Poes]

Had never heard particularly about rubber content in trees (well outside of rubber trees). http://www.differencebetween.info/difference-between-teak-wood-and-rubber-wood

So we need rubberwood plywood and mdf sheets?

 

[Verdinut]

It would be good to have more rubber in trees. That would help prevent corner damage on furniture with the passage of time.

 

[Matthew J Poes]

While talking about unusual materials that make a good enclosure, these two are used in high end speakers and have some advantages.

https://www.curbellplastics.com/Shop-Materials/Specialty-Products/Prototyping-and-Tooling/High-Density-Urethane-(HDU)-Boards/High-Density-Urethane-(HDU)-Boards#?Shape=CRBL.SkuToolingBoard

You want the highest density stuff, the kind that is 20-30lbs/ft3, and 1” thick or so. It has very good self damping properties and takes a finish well.

Where greater rigidity is needed, this stuff is good:
https://www.curbellplastics.com/Shop-Materials/All-Materials/CE-Canvas-Phenolic/CE-Canvas-Phenolic-Sheet#?Shape=CRBL.SkuSheet

My own speakers where build with related materials. The front baffle is a sandwhich or MDF and HDU, but it was cast in HDU. The casting is mass loaded in mine with a lossy viscoelastic urethane layer.

It’s crazy expensive, and...a very famous high end speaker company uses variations of these as well.

 

[Verdinut]

So we need rubberwood plywood and mdf sheets?

Yeah! That would help make wood less resonant for better mid and high frequency performance in speaker enclosures.

 

[highfigh]

The article relating to rubber in teak:

https://home.howstuffworks.com/home-decor/decorating-styles-techniques/teak-wood-furniture1.htm

That's interesting- your link worked, but none of the ones at the bottom worked.

The writer called sapwood a type of Teak- it's not a type, just where it's located on the tree. Most people don't like a lot of sapwood in lumber because it doesn't look the same as the heartwood but it's no worse, generally, and in some cases (Black Walnut), steam can be used to darken the color. He wrote that trees grow from the inside, which seems to imply that the center is alive, but that's not true- it's the sapwood that's alive and where new growth occurs. It's the reason you don't need to drill halfway through a Maple tree to reach the sap.

 

[highfigh]

The last box I built doesn’t use any screws, but i did use those little grooved wood posts that you drill a hole for and put in place. I did it in a. Goofy way but I think it’s a good approach for strength. I used a special viscoelastic high-strength glue. I glued and clamped the box. Then drilled a hole the length of the dowel plus 1/2”. I filled the hole with glue and inserted the dowel. I wiped off excess and let dry. I finished with a finishing putty before paint. I did this instead of screws.

Why would ASTM have anything on this? Maybe. I didn’t find anything in the journals other than some Harman papers. Some old stuff from Bell labs.

They test all kinds of materials, including wood.

The cabinets for the speakers I'm using now are MDF and, because they were supposed to be a work in progress, I cut grooves and dados for the pieces to fit together, then used brad nails to hold the cabinets together while the wood glue dried. I use TiteBond II and it's one of the best for indoor use. The grooves and dados are very close, which adds rigidity, so any elasticity in the glue will be negligible. Since I hadn't decided that the crossovers were "done", I put terminal blocks on the rear for each band, so I wouldn't have to deal with threaded inserts, MDF failing from repeated screw removal and breaking any seals. About six months after I started using them, I heard a weird sound coming from one side, so I went to look at it. Being Winter, I found that the MDF had shrunk and it was then that I realized something- I had never glued the fronts onto the cabinet. I loaded the drivers when they were in my garage, carried them in and up the stairs of the house and never realized they could come off because they weren't simply inset or laid on the box. DOH!

I slapped the face into position and they still haven't been glued in.

The photos should show the dados and grooves- when they're this tight, it's sometimes called a 'piston fit'.

The screen shot is from where my head would be, at the listening position.

 

[highfigh]

While talking about unusual materials that make a good enclosure, these two are used in high end speakers and have some advantages.

https://www.curbellplastics.com/Shop-Materials/Specialty-Products/Prototyping-and-Tooling/High-Density-Urethane-(HDU)-Boards/High-Density-Urethane-(HDU)-Boards#?Shape=CRBL.SkuToolingBoard

You want the highest density stuff, the kind that is 20-30lbs/ft3, and 1” thick or so. It has very good self damping properties and takes a finish well.

Where greater rigidity is needed, this stuff is good:
https://www.curbellplastics.com/Shop-Materials/All-Materials/CE-Canvas-Phenolic/CE-Canvas-Phenolic-Sheet#?Shape=CRBL.SkuSheet

My own speakers where build with related materials. The front baffle is a sandwhich or MDF and HDU, but it was cast in HDU. The casting is mass loaded in mine with a lossy viscoelastic urethane layer.

It’s crazy expensive, and...a very famous high end speaker company uses variations of these as well.

Those are the kinds of materials ASTM probably has data- I didn't see actual numbers for stiffness.

Have you seen any info that showed test results from the relationship between adjacent materials with different properties when they were fastened to each other in some way? It wold be interesting to see what happens when the inner layer is more elastic and the outer is more rigid.

Sign me up!
CE Canvas Phenolic Sheet, Natural, Electrical Grade0.750 in48 in96 in$1,005.87/ea

 

[highfigh]

It would be good to have more rubber in trees. That would help prevent corner damage on furniture with the passage of time.

And less damage when heads hit it during a fall.

 

[Verdinut]

They test all kinds of materials, including wood.

The cabinets for the speakers I'm using now are MDF and, because they were supposed to be a work in progress, I cut grooves and dados for the pieces to fit together, then used brad nails to hold the cabinets together while the wood glue dried. I use TiteBond II and it's one of the best for indoor use. The grooves and dados are very close, which adds rigidity, so any elasticity in the glue will be negligible. Since I hadn't decided that the crossovers were "done", I put terminal blocks on the rear for each band, so I wouldn't have to deal with threaded inserts, MDF failing from repeated screw removal and breaking any seals. About six months after I started using them, I heard a weird sound coming from one side, so I went to look at it. Being Winter, I found that the MDF had shrunk and it was then that I realized something- I had never glued the fronts onto the cabinet. I loaded the drivers when they were in my garage, carried them in and up the stairs of the house and never realized they could come off because they weren't simply inset or laid on the box. DOH!

I slapped the face into position and they still haven't been glued in.

The photos should show the dados and grooves- when they're this tight, it's sometimes called a 'piston fit'.

The screen shot is from where my head would be, at the listening position.

Am I seeing the Peerless P830990 Glass Fiber Cone woofers which you were referring to a while ago in a previous post? I know that you like them and I also like the P830991 5¼ inch mid-woofers that I am using in my 3 front enclosures.

 

[highfigh]

Am I seeing the Peerless P830990 Glass Fiber Cone woofers which you were referring to a while ago in a previous post? I know that you like them and I also like the P830991 5¼ inch mid-woofers that I am using in my 3 front enclosures.

Nope- 830874 poly woofers- 6-1/2". I'm at my desk almost 30' from the speakers and when the bass thumps, it's definitely noticeable.

https://www.tymphany.com/transducers/hds-p830874/