Goodbye ! No more speakers with cones !

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ondesx

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Most of these noises may be attenuated or for some almost removed...

The issue is the spining frequency in clockwise and cc at very high frequencies taking into account the inertial moment of the device, moreover with an excitation at one end only... The torque will probably have severe consequences on the "membrane" each time the actuator changes its spining direction!
 
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ondesx

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I'm not totally sure this thing will not produce good sound... I'll do some trials before any conclusion. The movement of the "membrane" could produce sound since it's a vibration. But the question now is how much "bending waves" of the material itself are "added" to the vibration of the device...

A very simple test is to change the material of the membrane...
 
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Remlab

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Joined 2011
ondesx said:
The specs of a material aren't the same for the purpose of the Planot and for bending waves.... In the present case, one looks for a material having a very high Critical Frequency Fc.
Click to expand...

I remember years ago, an article by one of the NXT guys saying that the best material they had ever found for NXT exciter panels were sheets of laminated Rohacell and carbon fiber(Helicopter blade material), because of its extreme rigidity, internal damping properties and light wieght. Correct me if I'm wrong, but doesn't extreme rigidity equal high Fc?

http://www.rohacell.com/product/rohacell/en/markets/aviation-aerospace/Pages/default.aspx

http://www.cstsales.com/carbon_sandwich_panel.html
 
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Remlab

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Joined 2011
sreten said:
Hi,

It simply doesn't work, it doesn't matter what you make it out
of, it still won't work, and having unobtanium available still won't
make any difference to the very simple physics being ignored.

rgds, sreten.
Click to expand...
Sreten
It does work. Just not in a conventional sense (A kind of BMR?). Julian Bunn told me via email that he was surprised as to how well it worked, but he couldn't surmise exactly as to how it worked. Before NXT technology became available(With big names backing it up) , people would have laughed and made fun of the concept. We all need to admit though, that BMR type technologies will never, ever come close to sounding as good or as accurate as conventional technologies. Resonances in a reproducer are, by definition, flaws. Even if you balance them perfectly..

Seth
 
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Remlab

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Joined 2011
I spent about two years being absolutely fascinated with NXT. I would go to home depot specifically looking for different things to attach them to, and would spend hours listening to the results. Every time my brother would visit, I would show him my latest creation. After I got burned out on the subject, I found the carbon fiber Rohacell panels website. If only I had found it sooner. That is why the Planot captured my attention. Even though it's ultimately flawed (obvious), it's Fascinating.That's why were all bickering over it..
 
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ondesx

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To Remlab :
In certain aspects the rigidity is connected to Fc since the Young's module E appears in the equation... For NXT/BMR the rigidity and weight are important parameters, but there are several other like the way thé membrane is excited, the position of the actuators, the spectral distribution of the modes, etc...

It seems you are confused with NXT/BMR and bending waves. Again, the Planot in not a DML/BMR device since, at least for a certain frequency range, it doesn't require to use the "modes" of the "diaphragm". The remaining unknow is the possible added effect of bending waves for the highs... I'm checking this point.
 
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Remlab

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Joined 2011
ondesx said:
To Remlab :
In certain aspects the rigidity is connected to Fc since the Young's module E appears in the equation... For NXT/BMR the rigidity and weight are important parameters, but there are several other like the way thé membrane is excited, the position of the actuators, the spectral distribution of the modes, etc...

It seems you are confused with NXT/BMR and bending waves. Again, the Planot in not a DML/BMR device since, at least for a certain frequency range, it doesn't require to use the "modes" of the "diaphragm". The remaining unknow is the possible added effect of bending waves for the highs... I'm checking this point.
Click to expand...
I do know the difference, but ultimately, they both take advantage of resonances to produce sound, while conventional diaphragms try to nullify them. That why I'm categorizing them together..
 
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ondesx

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Joined 2008
Remlab said:
I do know the difference, but ultimately, they both take advantage of resonances to produce sound, while conventional diaphragms try to nullify them. That why I'm categorizing them together..
Click to expand...

I'm afraid you are wrong. Bending waves aren't using resonance with the modes of the material the same way. The Walsh or the DDD are really different drivers. They avoid certain resonances instead and have different stiffnesses along their diaphragm. This isn't the case of the NXT/BMR membranes.

Other properties made these drivers different from each other, for example the way the sound radiates from the membrane or the way you use the actuator to stimulate the diaphragm.

But you have just to remember that the first group needs almost ALL the modes of the diaphragm, whereas the second group needs a Fc and avoid certain modes or frequencies of their diaphragm.

And to be complete, I think that you have to demonstrate and others too, that this device doesn't work!... In 1940 a guy derived on a blackboard that helicopters couldn't fly and 4 years after they were produced industrially...
 
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Remlab

Member
Joined 2011
ondesx said:
I'm afraid you are wrong. Bending waves aren't using resonance with the modes of the material the same way. The Walsh or the DDD are really different drivers. They avoid certain resonances instead and have different stiffnesses along their diaphragm. This isn't the case of the NXT/BMR membranes.

Other properties made these drivers different from each other, for example the way the sound radiates from the membrane or the way you use the actuator to stimulate the

But you have just to remember that the first group needs almost ALL the modes of the diaphragm, whereas the second group needs a Fc and avoid certain modes or frequencies of their diaphragm.

And to be complete, I think that you have to demonstrate and others too, that this device doesn't work!... In 1940 a guy derived on a blackboard that helicopters couldn't fly and 4 years after they were produced industrially...
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Are you saying that DDD and Walsh drivers don't take advantage of resonances to produce sound at some frequencies? If I'm mistaken, I stand corrected..
As far as the planot goes, I'm talking about my intuition. It does not, from a traditional physics perspective, make sense to my brain. I hope I am wrong, because that would be cool..
 
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ondesx

Member
Joined 2008
Remlab said:
From my perspective, any transducer that takes advantage of resonances to produce sound in any part of the frequency spectrum is inherently flawed..
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That's precisely what I would check with this device... The best thing you can do to better understand the bending waves transducers like the Walsh or the DDD is to read the Walsh patent available as a pdf on the Net. If you fail to find it, I can give you its reference.

It seems you're in California. Do you had listen to one of the MAD drivers ?
 
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