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Old 04-22-2011, 11:05 AM
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njDan njDan is offline
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Infinite Baffle vs. Dipole

I am a car audio enthusiast making the way to home audio. I know car audio has it's limitations. I mention car audio only as reference to my question. We use the term "infinite baffle" for a woofer mounted in a car door. I believe "quasi-infinite baffle is a better term.

A proper infinite baffle is a different thing altogether. What is "dipole" and how is it different than infinite baffle? Without getting too technical, what makes a driver good for a dipole configuration?
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Old 04-22-2011, 11:23 AM
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JoeESP9 JoeESP9 is offline
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First, dipole and bipole are not the same thing. Both radiate sound to the front and rear. With a bipolar such as a lot of Definitive Technology speakers the rear wave is in phase with the front. That is when the front pushes the rear also pushes. This requires one speaker facing forward and one facing the rear.

With dipole's (ribbons, electrostatics, planar magnetics) the rear wave is out of phase with the front. There is only one diaphragm that radiates front and rear. When the diaphragm moves foward so does the rear of the diaphragm. Consequently the rear wave is out of phase with the front.

Dipolar = When the front pushes the rear pulls.
Bipolar = When the front pushes the rear pushes.

AFAIK: The are no dipolar speakers that use conventional cone and voice coil technology except for open baffle. They are in essence a speaker mounted on a tall wide board. The board is placed where any other dipolar speaker would be placed.

Open baffle is not the same as infinite baffle. In home gear infinite baffle usually refers to a sub woofer where the rear wave is vented to a very large area. Some mount them in the floor and let the basement serve as the infinite baffle. You could just mount them through your wall and let the rear wave vent to the outside. Your neighbors probably wouldn't like that.
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Old 04-22-2011, 03:10 PM
donberry donberry is offline
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once you go dipole you never go back
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Old 04-22-2011, 05:50 PM
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Tom Brennan Tom Brennan is offline
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Quote:
Originally Posted by donberry View Post
once you go dipole you never go back

Maybe you don't; I've gone back and forth (pun intended) a couple of times.
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Old 04-22-2011, 05:54 PM
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njDan njDan is offline
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I was taking for granted that dipole and open baffle are the same. Are they?

I have a pair of Audax PR170MO 6.5". I am looking for a diy design for them. I have read that they are great open baffle. Can it be that simple that you slap it on a open baffle and you're golden?
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Old 04-22-2011, 09:16 PM
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TerryO TerryO is offline
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Quote:
Originally Posted by njDan View Post
I was taking for granted that dipole and open baffle are the same. Are they?

I have a pair of Audax PR170MO 6.5". I am looking for a diy design for them. I have read that they are great open baffle. Can it be that simple that you slap it on a open baffle and you're golden?
Most of the OB speakers I've seen are dipole. I'm sure that now I've said that, someone will come up with something entirely different.

It's a simple concept, but like anything else it's the implentation that decides if you have a winning setup. Crossovers, associated drivers, baffle width, EQ (or not), etc., all have a role in the final outcome.

Best Regards,
TerryO
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Old 04-22-2011, 10:29 PM
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JoeESP9 JoeESP9 is offline
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With any voice coil driven speaker the rear wave is 180 Deg. out of phase with the front. If it's not trapped in an enclosure but allowed to radiate into free air it's functioning as a dipole.
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