A Study of DMLs as a Full Range Speaker

My ply was not coated.
Humans ,washing ,cooking ,gas fire's, all produce moisture in the air especially in winter .
Half the 2x3ft ply panel was unsupported ,maybe coating could have prevented this warping?
Steve.
All my panels are still in test stage.
I do thinking coat them on final. But worry which coat will not change the sound too much. Base on the EPS experience coating will change the sound A LOT.
I don't think PVA is a good coat for prevent humidity cause they will absorb mositure right?
Lacquer or epoxy seems too solid and heavy for a thin wood.

I will try coat some cheap ply to see how the sound change. My recent wood panels are not ply, and quite expensive. They are different types of wood I bought from a craftmanship material shop.
 
All my panels are still in test stage.
I do thinking coat them on final. But worry which coat will not change the sound too much. Base on the EPS experience coating will change the sound A LOT.
I don't think PVA is a good coat for prevent humidity cause they will absorb mositure right?
Lacquer or epoxy seems too solid and heavy for a thin wood.

I will try coat some cheap ply to see how the sound change. My recent wood panels are not ply, and quite expensive. They are different types of wood I bought from a craftmanship material shop.
Hi hkguy6
Yep.. Stay away from all water based products in your climate. Shellac doesn't like direct water contact but may still be worth a try

I have successfully used clear auto finish acrylic lacquer from a rattle can. Coatings can be light..I don't believe it is detrimental to the sound and it will stiffen the panel which is generally beneficial.

A few light coats to both sides and edges(!!). Sand lightly between coats. That's my recommendation

Regards
Eucy
 
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Hi hkguy6
Yep.. Stay away from all water based products in your climate. Shellac doesn't like direct water contact but may still be worth a try

I have successfully used clear auto finish acrylic lacquer from a rattle can. Coatings can be light..I don't believe it is detrimental to the sound and it will stiffen the panel which is generally beneficial.

A few light coats to both sides and edges(!!). Sand lightly between coats. That's my recommendation

Regards
Eucy
I read this thread mentioned Shellac few times but no idea what it is? Google translate it to Chinese as "bug gel". The pic looks like resin.

ps. OK I know what is it. We call it "polish base". Similar as Lacquer.
 
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Has anyone explored sandwiching dissimilar materials?
irishpatrick33,
I and others have tried lots of sandwich constructions. But the logic behind it is generally not to try and "combine" the frequency responses of the two individual materials, but rather to obtain a lightweight but relatively stiff panel, which results in good radiation efficiency. Such a panel is usually a combination of a lightweight core material (like balsa, nomex honeycomb, foam, etc) with thin stiff skins (like carbonfiber/epoxy, fiberglass/epoxy, wood veneer, etc,), on both sides.
Eric
 
I do thinking coat them on final. But worry which coat will not change the sound too much. Base on the EPS experience coating will change the sound A LOT.
I don't think PVA is a good coat for prevent humidity cause they will absorb mositure right?
Lacquer or epoxy seems too solid and heavy for a thin wood.
hkguy6,
I really like polyurethane finish for protecting wood from moisture, especially the Minwax Wipe-on product. You can apply very thin coats, and it looks great too.
Eric

https://www.minwax.com/en/products/protective-finishes/wipe-on-poly-oil-based-polyurethane-finish.
 
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Don't think so Steve - Its uni-directional ply (i.e. all layers running the same way) and you order it to bend either in the long or short direction

(It'd make a rather floppy crate) :giggle:

Eucy
This is my( floppy ) crate ply, I have mentioned before, that it bands more in one direction than the other.
Steve.
 

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Using the same sort of pressure in the other grain direction.
Steve.
Hi Steve what's the actual wood type of your "crate"?
We use EPS or Plastic box to replace crate long time ago. The only crate I found here is the Wine box. I think it may be a kind of Pine?
However the Wine box wood is quite light weight but stiff, cannot blend like what you did. And mostly are 1cm or thicker.

box.jpg
 
The ply is 3mm from this crate.
The second picture is of the end of the crate with a dust cover removed from a small cone driver, glued onto the exciter area.
The 4 thin sides I made into a single large panel by glueing them together with pva.
Steve.
 

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a quick recording of the floppy crate ply.
im tempted to order the 4x2ft panel just to see how it performs , but mainly to cut into two panels of 2x2ft panels to match the performance of the proplex,, which is also stiffer in one direction than the other, and compare .
steve.
 

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I visited Ikea today. I bought a set of smaller canvases. These will be turned into speakers with large 4mm poplar plywood panels and DAEX30HESF-4 exciters. A low volume bass unit is in its design phase for 2.1 operation. It is just a cheap and crazy idea, so I will share the bass module only if it will really work as intended.
 

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The exciter is the Dayton Audio EX32EP2-4 Thruster 32mm 2-Hole Exciter 40W 4 Ohm
Hey Burnt. I just had a look at this Dayton EX32EP2-4 exciter you are using. It is the first time this exciter is mentioned on this thread. Somehow I missed it, but I see Dayton now has a new range (EX) of 8 exciters that use an interchangeable mounting disc. That is brilliant. How do you find this new feature? And do you consider trying other exciters in this range for your application? I am interested in the 8 ohm one.
 
Hey Burnt. I just had a look at this Dayton EX32EP2-4 exciter you are using. It is the first time this exciter is mentioned on this thread. Somehow I missed it, but I see Dayton now has a new range (EX) of 8 exciters that use an interchangeable mounting disc. That is brilliant. How do you find this new feature? And do you consider trying other exciters in this range for your application? I am interested in the 8 ohm one.
Hi twocents,

I am in two minds about the interchangeable mounts. I had a severe buzz with one until I tightened to an extreme degree. The thread is to my mind too coarse and might be prone to releasing under vibration. Currently I am not a fan other than using it to test interchangeable exciters to test their effects. As this appears to be the way Dayton are going I will be using an adhesive to prevent the disc loosening during use.
 
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