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Old 4th August 2012, 09:17 AM   #121
sreten is offline sreten  United Kingdom
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Quote:
Originally Posted by planot View Post
What do you mean when you say it doesn't work?
Hi,

Quite simply :

if the diaphragm is made of unobtainium that is infinitely stiff,
rotation of the diaphragm will produce no bass whatsoever.

The claimed subwoofer applications for the operating principle, e.g. :

Click the image to open in full size.

simply will not work. There is nothing to discuss about the basic
physics in the bass, it is not a voltage to pressure transducer.

There is nothing here that reduces the need for boxes for bass.

rgds, sreten.

(I never said it won't make some noise, it will, but I'm not
interested in something so fundamentally misrepresented.)
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Last edited by sreten; 4th August 2012 at 09:20 AM.
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Old 4th August 2012, 09:59 AM   #122
Remlab is offline Remlab  United States
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Quote:
Originally Posted by ondesx View Post
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 ?
Mad? As in Dragoslav Colich? He lives and works a couple of miles from my home but I have never heard his designs. He now owns a consulting business in Irvine.
If you have seen my speaker system on this website, you will see that I'm a big fan of BG Radia Planar Magnetic drive units. The Mad designs look cosmetically very similar.
As far as the DDD and Walsh drivers go, I understand that they operate in a pistonic manner up to a point, then will start to bend at a critical frequency. Correct? Jordan controflex cones are somewhat similar? There just seems to be an element of chaos involved that the best math can't overcome..

Last edited by Remlab; 4th August 2012 at 10:21 AM.
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Old 4th August 2012, 10:23 AM   #123
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The DDD does not work pistonic but produces 'bending waves' that ripple from the voice coil through the material to the surround where they are absorbed. The bending wave causes sound to radiate radially in a horizontal plane.
The DDD looks superfically like a cone pointing downwards, but it is not a piston. The flare and angle is more like a mildly flaring cone than a piston in shape.

jan didden
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Old 4th August 2012, 10:32 AM   #124
Remlab is offline Remlab  United States
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Quote:
Originally Posted by janneman View Post
The DDD does not work pistonic but produces 'bending waves' that ripple from the voice coil through the material to the surround where they are absorbed. The bending wave causes sound to radiate radially in a horizontal plane.
The DDD looks superfically like a cone pointing downwards, but it is not a piston. The flare and angle is more like a mildly flaring cone than a piston in shape.

jan didden
Read this..
German Physiks - High End Technology Loudspeaker Manufactur - DDD Driver - The DDD Driver
Jordan cones are sort of like a DDD cone, but used conventionally. At a certain critical frequency, they start to bend and produce the higher frequencies in a somewhat even manner, instead of a rigid cone that has one big resonant peak..

Last edited by Remlab; 4th August 2012 at 10:56 AM.
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Old 4th August 2012, 10:51 AM   #125
sreten is offline sreten  United Kingdom
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Hi,

The DDD driver inherently must have a pistonic region of operation at the low end.

rgds, sreten.

Click the image to open in full size.
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Old 4th August 2012, 11:29 AM   #126
ondesx is offline ondesx  France
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Quote:
Originally Posted by Remlab View Post
Mad? As in Dragoslav Colich? He lives and works a couple of miles from my home but I have never heard his designs. He now owns a consulting business in Irvine.
If you have seen my speaker system on this website, you will see that I'm a big fan of BG Radia Planar Magnetic drive units. The Mad designs look cosmetically very similar.
As far as the DDD and Walsh drivers go, I understand that they operate in a pistonic manner up to a point, then will start to bend at a critical frequency. Correct? Jordan controflex cones are somewhat similar? There just seems to be an element of chaos involved that the best math can't overcome..
Yes, this is the driver I mentioned... Unfortunately, this guy never answers my request for a couple of this planar driver... The radia BG are unfortunatey poorly manufactured and you can easily spin the driver on his axis, this gives you an idea of its rigidity. If you have the opportunity to listen or try the MAD please let me know your feelings...

It's correct that the Walsh and the DDD have both a pistonic "range"... Then this is another difference with NXT/BMR drivers !...

Last edited by ondesx; 4th August 2012 at 11:47 AM.
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Old 4th August 2012, 12:46 PM   #127
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Quote:
Originally Posted by ondesx View Post
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!
Maybe a nice subwoofer, if it's huge enough.

(damn, i already have a set of pivoting transducers and didn't know, only requires to raise the frequency setting Quantum Stabilizers- Lambert Dinnissen explains rotary yacht stabilizers - YouTube )
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Old 4th August 2012, 01:13 PM   #128
ondesx is offline ondesx  France
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Quote:
Originally Posted by jacco vermeulen View Post
Maybe a nice subwoofer, if it's huge enough.

(damn, i already have a set of pivoting transducers and didn't know, only requires to raise the frequency setting Quantum Stabilizers- Lambert Dinnissen explains rotary yacht stabilizers - YouTube )


Since a simple and thin chord is able to deliver a sound like on a violin or a guitar, why a thin and light diaphragm wouldn't have a similar action ?... The unknow remains the high frequency cut-off of the system : if the actuator isn't correctly dimensioned, the diaphragm will stop its spining at a given frequency, then the system behaves like a low-pass filter !
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Old 4th August 2012, 01:53 PM   #129
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Quote:
Originally Posted by ondesx View Post


Since a simple and thin chord is able to deliver a sound like on a violin or a guitar, why a thin and light diaphragm wouldn't have a similar action ?...
Yes that may be the case here - that it delivers a specific tone, with some overtones, but not a full spectrum.

jan
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Old 4th August 2012, 02:08 PM   #130
ondesx is offline ondesx  France
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Quote:
Originally Posted by janneman View Post
Yes that may be the case here - that it delivers a specific tone, with some overtones, but not a full spectrum.

jan
Are you sure of this statement ?... I definitely will give a try before any conclusion...
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