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Author Topic: New "crossover" schematic and diagram  (Read 58239 times)
Ed Schilling
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« Reply #135 on: October 08, 2013, 02:23:29 PM »

Tre', in your opinion is The Great Heil a Bipole or Dipole?
Ed
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Steve F
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« Reply #136 on: October 08, 2013, 03:21:53 PM »

Ed, I concede that it is a dipole. Not a pretty one though.

Steve

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Pit Hinder
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« Reply #137 on: October 08, 2013, 04:17:36 PM »

Making it into a bipole just costs twice as much, so no problem.
But new living room furnture and a divorce...you gotta be rich.
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Tre
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« Reply #138 on: October 08, 2013, 05:58:31 PM »

Tre', in your opinion is The Great Heil a Bipole or Dipole?
Ed

IMO it's a bipole. There's no way to make the front pleats squeeze together while at the same make the back pleats spread apart.

However the pleats are being squeezed, they are all being squeezed at the same time.


S       N

For the pleats to move, each half towards and then away from the center, the poles of one magnet would have to be reversed from the other.

Tre'
« Last Edit: October 08, 2013, 09:36:29 PM by Tre » Logged
Tre
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« Reply #139 on: October 08, 2013, 06:13:43 PM »

Ed, I concede that it is a dipole. Not a pretty one though.

Steve



Steve, what made you change your mind?

Tre'
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Ed Schilling
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« Reply #140 on: October 08, 2013, 06:48:37 PM »

Tre' I have always thought they were a bipole even though I think everyone else including ESS calls them a dipole! Nice to see someone else sees it like I do.
Ed
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Pit Hinder
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« Reply #141 on: October 08, 2013, 08:28:25 PM »

Hmm. When a Heil squeezes you get a pressure wave front AND back - a cone driver sucks behind when it blows in front (no sexual phantasies please). 180° phase shift?

Pit
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Tre
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« Reply #142 on: October 08, 2013, 09:32:39 PM »

Hmm. When a Heil squeezes you get a pressure wave front AND back - a cone driver sucks behind when it blows in front (no sexual phantasies please). 180° phase shift?

Pit

Yes, with all piston like drivers the back wave is out of phase WRT the front wave. If not placed in a box the back wave will cancel the front wave. Because of the wave length, much more so at the low frequencies than the high frequencies.

I should add that you can place a cone driver in a back loaded horn enclosure and that will act like an acoustic phase inverter and then the back wave will be in phase with the front wave.

A tuned ported box does the same thing but only for the low frequencies and there would be no acoustic amplification like with a horn.

Tre'
« Last Edit: October 08, 2013, 10:15:16 PM by Tre » Logged
Ed Schilling
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« Reply #143 on: October 08, 2013, 09:41:18 PM »

With the Heil there should be no cancellation, at least if I understand the way it is claimed to work.

Tre', please fix your diagram to show the back wave Smiley
Ed
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Tre
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« Reply #144 on: October 08, 2013, 10:08:42 PM »

Sorry, I was answering just the second half of Pit's question. I should have answered both parts.

"When a Heil squeezes you get a pressure wave front AND back"

Yes and when the pleats are pulled apart you get a refraction wave, front and back.


"..a cone driver sucks behind when it blows in front (no sexual phantasies please). 180° phase shift?"

Yes, that is true with all piston type drivers.

I can't fix the gif, it's not mine but yes, the back wave would be exactly the same as the front wave and in phase with the front. When air is squeezed out the front, air is squeezed out the back at the same time. And when the pleats pull apart air is drawn back in toward the driver, front and back at the same time.

Tre'
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Steve F
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« Reply #145 on: October 09, 2013, 10:04:05 AM »

Ed & Tre,

Here is why I changed my mind on the Heils.  First, I cut an old diaphragm in half. It was one of the old mylar ones that tended to seperate the aluminum voice coils from the mylar backing. Might be an age & heat related problem. The new ones are made with different diaphragms and adhesives.  The principle and basic design remain the same as before.  The channels of the diaphragm aren't pleated. They are U shaped. One U is up, the next is down, and so on. The curved parts of the U's act as surrounds. The edges of the diaphragm are attached to a plastic frame, and do not move. Therefore, when every other U shape closes with current applied, the ones opposite open with opposite current applied. The whole diaphragm is a combination of alternate expansions and contractions along the width of the diaphragm. It is a slick system. The diaphragm really doesnt act as one when driven. I wish I could draw this out on the computer, but Im an old notebook guy with minimal computer skills.

The Gif image is wrong. If the diaphragm moved that way it would be a bipole.

Steve
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Tre
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« Reply #146 on: October 09, 2013, 11:56:20 AM »

"They are U shaped. One U is up, the next is down, and so on. "

Do you mean just like the patent shows. Like a sine wave?




"Therefore, when every other U shape closes with current applied, the ones opposite open with opposite current applied. The whole diaphragm is a combination of alternate expansions and contractions along the width of the diaphragm. It is a slick system. The diaphragm really doesn't act as one when driven."

Steve, where is the opposite current coming from. If you mean the second half of the input wave form... I still don't understand how every other pleat can act different from the one beside it.

The current through the diaphragm, at any moment, is the same all the way across the diaphragm.

And the permanent magnet field is flipped , right side vs. left side.

Hey, I have a theory. I think you think that the metal moves one direction with a positive charge moving up and the opposite direction with a positive charge moving down. Same wire same charge, up one side of a pleat and down the other side of that pleat? Am I right? Is that what you think?

That isn't going to happen. It's the direction of the magnetic field created by the current through the entire "voice coil" vs. the permanent magnet field that determines the direction of movement not the direction of the wire.

 Current through the "voice coil" wire will cause a magnetic field (across the whole diaphragm) of one polarity and movement in one direction for one half of the diaphragm but movement of the opposite direction for the other half.

When the current turns around and flows the other direction through the wire, the magnetic field of the "voice coil" will invert and that will cause a movement in the other direction (for each half of the diaphragm) regardless of the direction (up or down) of the wire as it hangs within the permanent magnetic fields (that do not change, they are one polarity for one half of the diaphragm and the other polarity for the other half of the diaphragm).

It's the polarity (direction) of the magnetic fields (left half and right half) created by the two, separate permanent magnet structures vs. the direction of the magnetic field created by driving a current through the flat, up and down "voice coil"  that determines the direction of movement not the direction (up vs. down) of the wire and the direction of the magnetic field of the "voice coil" is the same, at any moment in time, all the way across the whole diaphragm but the direction of the permanent magnet structures (left half and right half) are not.

Both left and right halves of the diaphragm move toward the center, squeezing the pleats (this is the positive half of the input wave form) then both left and right halves of the diaphragm move away from the center stretching the pleats (this is the negative half of the input wave form).

All other explanations do not account for the second half of the input wave form. The rarefaction half. The other explanations I have read only account for the compression. If this tweeter was just compressing and then compressing over and over again it wouldn't sound very good.

Tre'
« Last Edit: October 11, 2013, 05:24:22 PM by Tre » Logged
Steve F
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« Reply #147 on: October 09, 2013, 01:23:21 PM »

Tre,

I just knew I wasn't going to be clear enough. If I still had the cutaway product materials, I'd mail them to you. I do agree I should have used the words "polarity and charge." I'm sorry that my explanation isn't sufficient. Perhaps Ed can get Rico at ESS to comment.

Steve
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Tre
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« Reply #148 on: October 09, 2013, 01:58:20 PM »

Steve, can you post a picture of the diaphragm you cut?

Thanks

Tre'
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Steve F
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« Reply #149 on: October 09, 2013, 02:28:23 PM »

Sorry Tre, it is long gone. At the time I didn't have the foresight  to take a picture, and the diaphragms were pretty much toasted. I wish I did because I'm sure I still don't have it quite right and I would like to take a really good look. But I do believe it to be a dipole. And I switched camps on that one because I originally thought the diaphragm was folded. We should just call it a weird driver that sounds really good.

Perhaps, and I'm just throwing this out there, how it responds may have some frequency dependent relationships. I'll read the patent over the next couple of days.  I wonder if anybody has the old Speaker Builder issue in which a guy built and then horn loaded an amt. He might have made the diaphragms too. Take care.

Steve
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