"A sandwich panel is any structure made of three layers: a low-density core, and a thin skin-layer bonded to each side. Sandwich panels are used in applications where a combination of high structural rigidity and low weight is required.
The structural functionality of a sandwich panel is similar the classic I-beam, where two face sheets primarily resist the in-plane and lateral bending loads." There are lot of houses built with SIPs (Structural Insulated Panel) all over in the world.
Well, a couple of the thoughts were a dense elastomer as the glue between. Just thinkin' outside the "box".
Wonder what happens when you use a high density core, like rubber in between?
If I had a table saw I would've started with wood.
Today I had them cranked up pretty loud and noticed the foam core boxes weren't completely dead. I'm certain that wood properly braced and stuffed would tighten up the bass considerably. For the next phase of the project I'm thinking about designing an aperiodic box of the same volume.
I only need three things now. First; clear out some room in the garage. Second; find a great deal on a table saw. Third; convince my wife that I need one.
Rubber is elastic, while polystyrene is not. If the outer material is also elastic, one can make curved walls with such a composite. Usually, a composite material is much tougher than the used materials separately, for example SIPs.
If I do another build I am thinking foam core then covering with ¼" plywood (or wood).
They do have Ultrakote and it needs less heat than Monokote.
A few years back I covered a foam plane with tissue paper and water based polyurethane, once it dried I lightly sanded then coated with just the poly and it was hard and strong but very light and a much better surface to paint. You might need to seal the edges of the paper covered foam to prevent any lifting though.
A few years back I covered a foam plane with tissue paper and water based polyurethane, once it dried I lightly sanded then coated with just the poly and it was hard and strong but very light and a much better surface to paint. You might need to seal the edges of the paper covered foam to prevent any lifting though.
I’m going to have 4 unused CSS EL70 drivers soon and think I may try a build of microTowers or MTMs out of XPS or layered foamcore.
Here’s an old MTM crossover for EL70s:
Would this work?
I have some ApexJr $1 Audax poly dome tweeters.
$1 Apex Jr tweeter????
Could be an interesting experiment.
Here’s an old MTM crossover for EL70s:
Would this work?
I have some ApexJr $1 Audax poly dome tweeters.
$1 Apex Jr tweeter????
Could be an interesting experiment.
Yes, a simple XO with cap and resistor for tweeter and inductor for EL70 can work probably. Adason did a MTM with TC9 and 1in fabric dome tweeter.
MTM with TC9fd
MTM with TC9fd
I've been musing over a couple of designs recently, and then I discovered this thread showing off how the GRS 8" planar driver loads well into a horn.
After a brief chat with @xrk971 , I decided to go ahead and use @bwaslo 's spreadsheet to create a 250Hz horn, and then stretch the vertical dimension to accommodate for the rectangular shape of the driver.
I was told that the back chamber could be small, so I made it 6.5" wide, 10" tall and 1" deep.
I had some 1.75" machine bolts and nuts at hand, which allowed me to not only bolt the driver to the throat flange, but also bolt the rear chamber to the flange as well, which made life simpler - all I needed were 4 bolts and 8 nuts for each horn.
I've done a little bit of listening with them as a stereo pair, and they're very pleasant to listen to. Very accurate without sounding 'cold', and the transient response is fantastic. I did get the sensation of being enveloped in sound again, similar to that headphone effect, and the stereo separation was really accurate and created a very detailed image.
My crossover to my Bass speakers was a little high at 400Hz, so I'm not sure if I was missing any information, but I'm going to sort it out so that the crossover is at 250Hz.
All in all a quick build with a really good result. Highly recommended!
After a brief chat with @xrk971 , I decided to go ahead and use @bwaslo 's spreadsheet to create a 250Hz horn, and then stretch the vertical dimension to accommodate for the rectangular shape of the driver.
I was told that the back chamber could be small, so I made it 6.5" wide, 10" tall and 1" deep.
I had some 1.75" machine bolts and nuts at hand, which allowed me to not only bolt the driver to the throat flange, but also bolt the rear chamber to the flange as well, which made life simpler - all I needed were 4 bolts and 8 nuts for each horn.
I've done a little bit of listening with them as a stereo pair, and they're very pleasant to listen to. Very accurate without sounding 'cold', and the transient response is fantastic. I did get the sensation of being enveloped in sound again, similar to that headphone effect, and the stereo separation was really accurate and created a very detailed image.
My crossover to my Bass speakers was a little high at 400Hz, so I'm not sure if I was missing any information, but I'm going to sort it out so that the crossover is at 250Hz.
All in all a quick build with a really good result. Highly recommended!
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