Are AMTs dipoles?

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el`Ol

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Are AMTs dipoles?
« on: 27 Jun 2007, 11:15 am »
Hello all!

I often heard and read about dipoles in combination with enclosure-less AMTs, even on manufacturers sites. Is that true? When the folded diaphragm contracts, the air is pressed out both to front and rear. So far my understanding of the concept. Then it would be a monopole. Am I right?

Oliver

JohninCR

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Re: Are AMTs dipoles?
« Reply #1 on: 27 Jun 2007, 03:10 pm »
Hello all!

I often heard and read about dipoles in combination with enclosure-less AMTs, even on manufacturers sites. Is that true? When the folded diaphragm contracts, the air is pressed out both to front and rear. So far my understanding of the concept. Then it would be a monopole. Am I right?

Oliver

Oliver,
If that's the way they work, with the same phase signal exiting front and rear, they would be Bipole, not dipole or monopole.

morayjames

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Re: Are AMTs dipoles?
« Reply #2 on: 29 Jun 2007, 02:29 am »
Oliver: AMT's are in fact true dipoles. The diaphragm is folded into a series of pleats while the voice coil is printed upon the pleated diaphragm. The action of the diaphragm is such that on one side of the diaphragm as the pleats are squeezed closed the back side of the pleats are opened apart. So air is squeezed out of the front side of the diaphragm pleats while at the same time it is drawn into the opening pleats on the other side. This process repeats so the wavefront is dipole as in an ESL.

el`Ol

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Re: Are AMTs dipoles?
« Reply #3 on: 29 Jun 2007, 06:36 am »
Thanks, MJ.

Does it work in that way:

The diaphragm moves back an forth, and the air moves effectively in the opposite direction because of the expansion / contraction of the pleats?