Terminology: BiPole/DiPole - Clarification?

[BlueWizard]

Yes, this subject has certainly been discussed before, but this time, I'm not interested in the Merits and Demerits of bipole vs dipole vs hibrid vs standard speakers.

I simply want a clarification of the terminology. What is a Bipole in terms of mechanical phase and electrical phase, and what is a Dipole in the same sense?

At one point I was given this pneumonic -

Be In Doubt

Meaning, relative to mechanical phase, or so I interpreted -

B = Bi-pole = In phase

D = Di-pole = Out of phase

B=In
D=Out

I even created a graphic -



- which based on further discussion, seems exactly the opposite of what it should be.

It seems that rather than -

Mechanically, Be in Doubt

it should be -

Electrically, Be in Doubt.

In the said same discussion, some one posted this explanation, which somewhat ignore electrical phase -

"If the cones move Out together (your top diagram) they are bi-pole. If one moves Out while the other moves In (your bottom diagram), they are di-pole.

This is regardless of the orientation of the drivers within the cabinet. I.e. they could be at 180 degrees to each other or at 90 degrees or any other angle."

Since this group is the most thoroughly knowledgeable group of people I know, I will ask you to clear this up for me, and will take your word as the definitive statement on the matter.

I though this was cleared up once and for all with the "Be in Doubt" pneumonic, but then remember Open Back Speakers being referred to as Dipole. So, then I was thoroughly confused again.

So -

Clarification? Bipole? Dipole?

Steve/bluewizard

[jwmbro]

I see your bipole has some 1930s German ideologies going on :P

But I've also never been able to remember which is which, hope someone can clear it up for me too.

What are speakers that don't beam at 180deg angles to one another? Like this Klipsch? Is that even a BiPole or a DiPole? Or neither?

[Andrew Eckhardt]

The one you have drawn as a bipole is a dipole, and vice versa. Your "definitive" clarification is at dictionary.com

[Rudolf]

Originally Posted by BlueWizard

I even created a graphic -



- which based on further discussion, seems exactly the opposite of what it should be.

Yes, the opposite of what is shown in the diagram is right.

In the said same discussion, some one posted this explanation, which somewhat ignore electrical phase -

"If the cones move Out together (your top diagram) they are bi-pole. If one moves Out while the other moves In (your bottom diagram), they are di-pole.

This is regardless of the orientation of the drivers within the cabinet. I.e. they could be at 180 degrees to each other"

That is the correct explanation. Don´t look for the electrical phase or whether the baskets are face-to-face", magnet-to-magnet" or "in-line".

I would NOT subscribe to "... at 90 degrees or any other angle." I have to add, that having two drivers in a box as a dipole is not the usual way to design a dipole speaker.

Rudolf

[BlueWizard]

I'm partly looking for confirmation of what is what, but I'm also looking for a pneumonic that will help me remember this forever.

I thought I had this in "Be In Doubt" modified to "Mechanically, Be In Doubt", but now that seems blown.

So, while not perfect, perhaps "Electrically, Be In Doubt" might substitute.

Though I think the longer explanation of whether one speaker goes in while the other goes out, or they both go in and out together is probably more accurate, I would need a pneumonic to remember it.

I have resolved this on previous occasions by looking it up, but can never remember.

What I need is sufficient confirmation of the terminology to get an unquestionable consensus. Then I can correct my drawing, remember the pneumonic, and happily move on from there.

Thanks for the response so far.

Steve/bluewizard

[planet10]

If you have a driver on the back and a driver on the front, a bipole is in phase, both push the same way into the box.

In a dipole the drivers would be out of phase, and they push opposite ways into a box.

There is no practical reason for making a dipole in a box (at one time dipole surrounds were made, they have been shown, with the current surround tech, to be BAD). it will not make any bass. A dipole will not have a box.

So to make it easy, a bipole will be 2 drivers in a box (facing different directions). A dipole will be a driver on an open baffle (or an electrostat or electrodynamic planar).

So Box = Bipole, Open Baffle No Box = Dipole

dave

[dcathro]

Originally Posted by planet10

If you have a driver on the back and a driver on the front, a bipole is in phase, both push the same way into the box.

In a dipole the drivers would be out of phase, and they push opposite ways into a box.

There is no practical reason for making a dipole in a box (at one time dipole surrounds were made, they have been shown, with the current surround tech, to be BAD). it will not make any bass. A dipole will not have a box.

So to make it easy, a bipole will be 2 drivers in a box (facing different directions). A dipole will be a driver on an open baffle (or an electrostat or electrodynamic planar).

So Box = Bipole, Open Baffle No Box = Dipole

dave

Nice explanation!

[BlueWizard]

Well, Planet10... sort of.

True an open baffle or open back speaker would be a Dipole, which is what lead me to realize my error.

But some "FX" surround speakers can be switched so the forward facing and the rear facing speakers are either in-phase or out. So, in a sense, they are switchable between Bipole and Dipole modes.

Though few of these FX speakers are true bipole or dipoles since they have drivers facing forward and to both sides.

However, now that it has dawned on me, if I just remember that open baffle or open back speakers are Dipole, I'll have it nailed.

Thanks for the help.

Steve/bluewizard

[planet10]

Originally Posted by BlueWizard

But some "FX" surround speakers can be switched so the forward facing and the rear facing speakers are either in-phase or out. So, in a sense, they are switchable between Bipole and Dipole modes.

Any speaker with that capability that should have the switch ripped out and just be wired as bi-poles.

The dipole function is a left over, not all that effective band-aid from the very 1st (and very bad) surround scheme. They should NEVER be used as dipoles -- hence my discounting of their existance. (ref Toole)

dave

[David_Web]

Be-pole is an entity having two poles of same polarity.
Di-pole is an entity having two poles of opposite polarity.

Nothing regarding alignment or anything else is attached to the term.

Although if people refer to something as di-pole they usually means open-baffle that due to it's construction have two poles of opposite polarity.