bi/di pole

[Vancouver]

Can someone tell me how what is the difference between di pole, bi pole and mono pole. It is not a usual spec i see when reading about speakers. I hear a lot more talk abotu it when talking about picking sournd speakers

[Bryce_H]

Bi-pole - 2 speakers typically on opposite sides of an encloseure moving in-phase (i.e. both moving in or both moving out the produce sound)

Di-pole - 2 speakers typically on opposite sides of an encloseure moving out-of-phase (i.e. one side is moving in while the other side is moving out)

Mono-pole - your typical enclosure with all the speakers facing the same direction and firing in-phase

[Spiffyfast]

Really good for side surround sound speakers

[Takeereasy]

Really crappy at producing accurate multi channel music IMO though. Great for HT.

[rschleicher]

In order of precise imaging and localization of sound source (greatest to least):

1. direct-radiating (monopole)
2. bipole
3. dipole

Conversely, in order of perceived size of sound-stage (largest to smallest)

1. dipole
2. bipole
3. direct-radiator

Because dipoles have the two sets of speakers out-of-phase, you actually get a null on both sides of the speakers. This is why they were the preferred type of surround speaker in the old Pro-Logic (version I) days, where there was just a single surround channel, and the objective was to have that channel appear to be both around and behind you, with as little localization of sound as possible. Dipoles also have limited bass output, due to cancellation of the out-of-phase responses of the woofers or mid-bass speakers. Again, this wasn't a problem with pro-Logic set-ups, since the surround channel was band-limited anyway.

With 5.1 (and greater) systems, with 2 or more separate, potentially full-range surround channels, it is more important to have at least some level of bass response, and (arguably) better imaging and sound-localization. Bipoles therefore represent a good option for the surround speakers in 5.1 (plus) systems.

If you are using a sub for all of the bass content (below your receiver's crossover freq.) anyway, then a lot of the distinctions between dipoles and bipoles diminish.

As to bipoles versus direct radiators - depends on your personal preferences. A fair number of people (most) like bipoles (or dipoles) for surrounds, but not for L/C/R speakers. But there are also a fair number of fans for bipoles at all speaker positions.

[cam]

I don't know about all manufacturers di-pole design but my Paradigm ADP 370's are di-poles but with a little twist, 150 hz and up is out of phase and below 150 is in phase. I don't know how they designed it to work. The letters ADP actually stand for what I am talking about but I can't remember right now.

[korgoth]

should check out the axiom qs8 quadpoles too..

dont know exactly what the difference in sound would be though.

[MDS]

I don't know about all manufacturers di-pole design but my Paradigm ADP 370's are di-poles but with a little twist, 150 hz and up is out of phase and below 150 is in phase. I don't know how they designed it to work. The letters ADP actually stand for what I am talking about but I can't remember right now.

Adaptive Di-Pole.

[soniceuphoria]

I think that a quadrapole speaker is more for sound projection to fill a room. A dipole such as a ribbon or a planar emits both waves from one driver instead of two there is less chance for distortion. The sound from the line source dipole has a very tall and accurate soundstage if they are propperly set up.

[cam]

Adaptive Di-Pole.
Thats it, thanks dude.

[Jaycan]

Does anyone know which type is most common in movie theaters (bi/di/direct) for sorround channels?

[supervij]

I think they use direct for the surround channels. But they use a whole bunch of speakers on either side of the seating area that it sounds diffuse.

When it comes to trying to recreate the theatre experience at home, we find that there isn't enough room in most living rooms to put two, three, or four or more sets of side surrounds. There's only room for one set usually. And that's where it becomes handy to use the diffuse speakers (either bi or di).

cheers,
supervij