Thanks, but my idea is much more primitive. I don’t have a voice coil, but a solenoid. I don’t have delicate suspension, I have a couple of magnets repelling.
Burntcoil.
Joppe is very open about what he does, and demonstrates how to do things, unlike some.
I intend to improve the ply and others stiff panels(I hope, if it works?) Next, year when I get time.
Or maybe panels in general, I will have to wait and see how it goes.
I have a few projects to test out and build a panel for a friend.
Hopefully it should be interesting.
Building a simple new type of exciter sounds fun, but how practical it will be , I'm not sure.
But it is worth a try.
Steve.
Joppe is very open about what he does, and demonstrates how to do things, unlike some.
I intend to improve the ply and others stiff panels(I hope, if it works?) Next, year when I get time.
Or maybe panels in general, I will have to wait and see how it goes.
I have a few projects to test out and build a panel for a friend.
Hopefully it should be interesting.
Building a simple new type of exciter sounds fun, but how practical it will be , I'm not sure.
But it is worth a try.
Steve.
The voice coil must've been printed from an alu foil. He'd been using an ink printer those days. Before this, he had been experimenting with Haddock's ideas, the rubanoide etc.
Its not only the thickness of the EPS that determines the so called tunnel (hollow/echo) effect but also the density of the EPS panel as there are various densities ranging from under 1lbs to 5lbs. Its the combination of thickness and density in the right ratio.
Pebble in the pond is just an analogy its not a liquid I agree. Speed of ripples in a pond moves way slower then the speed of sound vibrating through the panel. In fact the vibrations move so fast that most of the sound travels to the edges of the panel where its released at the edges. Damping of the edges using foam, rubber, cloth etc. will reduce it. Its the same with conventional cone drivers using some type of surround material at the edge of the cone diaphragm.
The rest I dont agree with it being better so I wont comment. lol
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For those interested
https://www.diyaudio.com/community/threads/dml-exciter-design.393544/#post-7209266
Burnt
It is the matter of how much air trapped in the EPS sheet. Density means how much pressure applied while producing the EPS block.
And, they don't return as in a liquid.
That pressure applied makes the panel dense and a denser material reduces the tunnel effect. Higher density less air trapped. Thats why a 5lbs density EPS has way less tunnel effect then a 1lbs density EPS.
Yes I agree they dont return as a liquid. What the foam, rubber, cloth etc does is reduce the vibrations from the edges just like a conventional cone drivers surround material.
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Sure they do. Waves are reflected from edges and form modal patterns. See Chladni plates demos on youtube. This knowledge, and the math that goes with it are the reason why we can predict the resonance frequencies of rectangular plates accurately, either with a direct formula for simple cases or with FEM for cases for which there is no closed-form solution.
But I think you've been advised of this before, no?
I was talking about the pressure applied to polystyrene beads when the EPS block was made. The panels are made by cutting the block with heated wire. EPS (and XPS) sheets are made primarily for construction purposes, usually used for thermal and sound insulation. EPS decays after a while.
That is the air dancing just above the plate, getting different frequencies. Ripples don't happen on solid surfaces, and if they happen they stay, deforming the surface. Ripples happen and die only on liquid surfaces.
The air dances because the plate dances. With enough force, even rock dances (ever heard of earthquake waves?). Solids absolutely do support waves - compression waves, bending waves, lamb waves, SAW waves. They deform and do not crease or permanently deform, unless the forces at play are beyond the elastic limit. It is very well established science, since hundreds of years it's been understood. Yet you keep repeating this. Read a book if you don't believe anyone here. Any good book on acoustics will cover this.
I thought we were talking about the tunnel effect? Yes I have a hot wire cutter it works great for cutting EPS......As long as EPS is not exposed to harsh elements it can last a very long time. My Bertagni speakers is around 40 something years old and the EPS diaphragm is still in good condition.
It only works if they start full.I tried this with 2 different bottles - one very heavy single malt bottle and one Jim Beam Black. I just held it to the neck ring. Failed to get excited about it and ditched the bottles (they were already empty)
Probably needed more patience..
Eucy
Ripples can happen on solid surface. There is water ripple and sound ripple. Water ripple is visible sound ripple is not. When I use 2 DAEX30HESF-4 exciters on a single panel with a sub amp you will literally see the panel bend starting from the middle and flapping wildly at the four corners.
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Tunnel effect happens because of the trapped air in the EPS sheet, and its thickness. The density of the EPS sheet depends on the pressure applied at the manufacturing state. EPS is manufactured primarily for construction matters. The same thickness of EPS75 sheet would give more tunnel effect than EPS300, which is more compact, that is, less trapped air.
Audiofrenzy,
Planning to share your designs? Sorry if you have and I missed the post. There are so many lately.
Eric
Just for fun I asked the GPTChat AI https://chat.openai.com/chat about holes and wavelength and got this answer.
"
... an array of small holes in a panel can potentially absorb sound waves that are propagating through the panel, even if the wavelength of the sound waves is greater than the small hole diameter.
One way that small holes in a panel can absorb sound waves propagating through the panel is by creating a scattering effect. When sound waves encounter the holes, they can be scattered in different directions, resulting in energy being dissipated and absorbed by the panel. This can be effective at absorbing low-frequency sound waves, as the scattering effect becomes more pronounced at lower frequencies.
Another way that small holes in a panel can absorb sound waves propagating through the panel is by creating a resonant effect. When sound waves encounter the holes, they can excite resonances within the panel, resulting in energy being dissipated and absorbed by the panel. This can be effective at absorbing higher-frequency sound waves, as the resonant effect becomes more pronounced at higher frequencies.
It's important to note that the effectiveness of small holes in a panel at absorbing sound waves will depend on a variety of factors, including the size, shape, and spacing of the holes, as well as the material of the panel and the characteristics of the incident sound waves."
Which I was amazed by. It quite a cool tool and free to use.
Burnt
"
... an array of small holes in a panel can potentially absorb sound waves that are propagating through the panel, even if the wavelength of the sound waves is greater than the small hole diameter.
One way that small holes in a panel can absorb sound waves propagating through the panel is by creating a scattering effect. When sound waves encounter the holes, they can be scattered in different directions, resulting in energy being dissipated and absorbed by the panel. This can be effective at absorbing low-frequency sound waves, as the scattering effect becomes more pronounced at lower frequencies.
Another way that small holes in a panel can absorb sound waves propagating through the panel is by creating a resonant effect. When sound waves encounter the holes, they can excite resonances within the panel, resulting in energy being dissipated and absorbed by the panel. This can be effective at absorbing higher-frequency sound waves, as the resonant effect becomes more pronounced at higher frequencies.
It's important to note that the effectiveness of small holes in a panel at absorbing sound waves will depend on a variety of factors, including the size, shape, and spacing of the holes, as well as the material of the panel and the characteristics of the incident sound waves."
Which I was amazed by. It quite a cool tool and free to use.
Burnt
Hi DMLBES.
I noticed it was you some time ago ,but you were being so nice I did not say anything.
But I can tell you are going to kick off again.
Should I not share my new ideas ?
Or shall I keep them to myself to the grave ?
Have you applied for patents yet so we can read all about them ?
Steve.