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how do Heil drivers work [message #78070] Thu, 10 October 2013 02:07 Go to next message
steve f is currently offline  steve f
Messages: 236
Registered: May 2009
Master
Here is the question.. Are they dipoles or bipoles. I believe they are dipoles, but I haven't been able to find a polar response chart of an open back Heil driver. Please help solve a friendly argument. Thanks.

Steve
Re: how do Heil drivers work [message #78116 is a reply to message #78070] Wed, 16 October 2013 13:03 Go to previous messageGo to next message
Wayne Parham is currently offline  Wayne Parham
Messages: 18669
Registered: January 2001
Illuminati (33rd Degree)

I haven't looked at one closely. But if it has one diaphragm and the front and back are exposed, then it is a dipole.

If it has two diaphragms, or any other mechanism that can pressurize the front and rear surfaces in phase, then it is a bipole.

Re: how do Heil drivers work [message #78129 is a reply to message #78070] Thu, 17 October 2013 13:30 Go to previous messageGo to next message
steve f is currently offline  steve f
Messages: 236
Registered: May 2009
Master
The controversy is basically about how the diaphragm works due to its shape. Some feel that it operates like an accordian and then both sides of the diaphragm would have the same action. The patents show a series of 'S' shaped pleats that expand and contract with the curved areas acting as surrounds. It looks like an AMT operates like a group of tweeters side by side. Therefore a dipole. I don't see how the diaphragm can work any other way.
As always, thank you for your help.

Steve
Re: how do Heil drivers work [message #78132 is a reply to message #78129] Thu, 17 October 2013 16:48 Go to previous messageGo to next message
Wayne Parham is currently offline  Wayne Parham
Messages: 18669
Registered: January 2001
Illuminati (33rd Degree)

I think I see what you mean. If it moves up and down as an accordian, one might theorize that it is creating positive pressure on both sides equally when compressed, and negative pressure when expanded.

There is still a very easy answer, and that is to measure the device. You can easily see its behavior in measurements. If the acoustic pressure on both sides are phased the same, it's a bipole. If it's opposite on each side, it's a dipole. Then I suppose there's also the possibility it's something else. Look at the polars, and see its radiation pattern. Dipoles, bipole and monopoles all create different polar patterns.

Where both sides are driven, the only real difference between bipole and dipole is phase. They're 180° apart. But you can have any oter kind of phase relationship too, and then it is something else. So do some measurements. They'll tell you what it is.

Re: how do Heil drivers work [message #78371 is a reply to message #78129] Fri, 15 November 2013 23:16 Go to previous message
Bill Wassilak is currently offline  Bill Wassilak
Messages: 402
Registered: May 2009
Illuminati (1st Degree)
From my experience Heil is know for AMT's. I'm not sure how they work, that's all I'm saying (I know nothing Smile ). But the one's I've known of, compare to the ribbon tweeter principle now day's. But the Heil AMT's I've heard we're omni-directional's(360deg), and you could never blow them as long as they we're x-over at the recommend freq... This made room acoustics come into play as far the placement speaker's that are using the Heil AMT's. But it's been years since I've heard about them.
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