Hey Dave. Sure it's nice to have only out of band resonances, but how to do that in a "unibody" full band speaker? It would be superbe engineering to somehow design for all your resonant energy to be centered in some narrow band where you could pit it against something that is either moving in anti-resonance or can't move at all for some reason.
In practice it turns out much simpler to try dragging immense interia into the picture, the closest thing you can get to an acoustic "ground" in a free standing structure. Mass. Light loudpeaker enclosures that sound good are no joke!
In practice it turns out much simpler to try dragging immense interia into the picture, the closest thing you can get to an acoustic "ground" in a free standing structure. Mass. Light loudpeaker enclosures that sound good are no joke!
I think you should head over to RC model plane forum, when I was heavily involved with that the most common wings where made from a piece of polystyrene foam cut to shape using a hotwire and then skinned with a very thin piece of balsa or ply and if you wanted to add a bit more strength you added a length wise brace just as you have, and trust me those things were incredibly strong and stiff basically impossible to twist unlike a conventional wing section made up of ribs and stringers that would tend to twist unless fully skinned.
Maybe you should look into using a solid piece of polystryene cut to shape with a hot wire and then skin it in your 1/4 hardboard, this would result in similar strength to your pored foam but the advantage is a greatly simplified build process. If you wanted to add even more strength just run a couple pieces of carbon fibre string lengthwise and diagonally. Trust me not only will it be light but incredibly strong and fairly resistant to resonance.
Maybe you should look into using a solid piece of polystryene cut to shape with a hot wire and then skin it in your 1/4 hardboard, this would result in similar strength to your pored foam but the advantage is a greatly simplified build process. If you wanted to add even more strength just run a couple pieces of carbon fibre string lengthwise and diagonally. Trust me not only will it be light but incredibly strong and fairly resistant to resonance.
I changed it to the flat back panel to (slightly) simplify construction. Having a flat edge (top, bottom) meet the curved panel at the back would make things needlessly complex. Flat front baffle gets braced to the flat rear panel creating a sort of I-beam which should be very strong structurally.
Mass works and is an established method but it is possible to build a low mass enclosure that has very low emissions.
Thanks for sharing your experiences.
I did consider using foam insulation board but thought the pour in foam will be more effective as it will bond to both skins as it expands in place and save time on shaping.
If every supplier here wasn't so keen on ripping off their customers, I'd probably have these panels finished already.
Ouch !
Thought it was a forum where someone discusses between electrical and mechanical model ,in electro acoustics .
I didn't tap on it, I swear!
On a bottle of single malt?
Unless the metal divider has added too much mass, I think you'll be impressed with your own work.
I am watching with interest as this is an unusual approach to panels. I'll be particularly interested in the accelerometer results.
I made some large speakers many years ago using foam sheets and laminex and thin ply to make a sandwich. Worked very well, and I have been contemplating something similar for the next builds after the current set, so your results are well worth seeing. My idea was for a fairly conventional sandwich as I used before.
My only concern is how it will look with the bowed external panels.
I made some large speakers many years ago using foam sheets and laminex and thin ply to make a sandwich. Worked very well, and I have been contemplating something similar for the next builds after the current set, so your results are well worth seeing. My idea was for a fairly conventional sandwich as I used before.
My only concern is how it will look with the bowed external panels.
Hi Brett,
It will look hot, of course!
I'll work on the Sketchup drawing in a bit.
Hi Chris,
I'm weighing all options. I'm not crazy about using a driver that is designed for coax use, from an aesthetics point of view. I have been looking at several other drivers and there are better possibilities.
Also I may just go with my original choice, even though it is not ideal.
Yes, I find some models with curved external bits very hot.Hi Brett,
It will look hot, of course!
Interesting panel construction and I have no doubt that those will be very effective indeed!
I was thinking about something similar but I was thinking of pre-shaped foam very much like surf boards are made, just laminated in hard board and ply (on the outside) rather than coated with epoxy.
Either way the result should be immensely strong.
I was thinking about something similar but I was thinking of pre-shaped foam very much like surf boards are made, just laminated in hard board and ply (on the outside) rather than coated with epoxy.
Either way the result should be immensely strong.
Thank you
Everyone who has seen these panels in person can't believe some of the things that are written here. It is simply amazing how STRONG and STIFF they are.
Come on folks! My support is falling and only a few days for this poll to run! Get in those YES votes!
I won't let you down.
You are correct, I didn't see that it is a coax. Next...
Possible candidates probably more lively or shouty sounding than Vifa or some monicor hi-fi midbass except for the last 8" delta pro
Dayton PK165-8 6" Professional Kevlar/Paper Cone Midrange
Eminence Alpha-6A or C 8 or 4 ohm
Eminence Alpha-8A
Eminence Delta Pro-8A
can you source Eminence in the great white north?
What ?? you want me to vote twice??
Perhaps it is because most people have never worked with foam-core panels before, just ask them to jump on a pair of slalom skis or one of the new short surf boards, you can use this construction to do almost anything you want, from ultra stiff and springy, really dead to flexible and lively
you want me to vote twice??Perhaps it is because most people have never worked with foam-core panels before, just ask them to jump on a pair of slalom skis or one of the new short surf boards, you can use this construction to do almost anything you want, from ultra stiff and springy, really dead to flexible and lively
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