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Bi-polar speaker: Drivers on opposing faces of the speaker are connected "in phase", electrically speaking, and move into or out of the speaker cabinet in tandem, which means they emit sound most like real sound sources.


Benefit is sound in all directions, and a firm sound-source location, which is, in my opinion, better now that we have discrete multi-channel sound. I want to know where the sounds are coming from.


Di-polar speakers have the drivers on opposing faces connected "out-of-phase", electrically speaking, which means that one driver (or group) move into the cabinet while the driver(s) on the other face move out of the cabinet.


Benefit is that it's harder to discern the sound's point of origin, which was important in the old days of non-discrete surround sound, when the surround channel was mono.


One major problem with speakers driven out of phase with any others is that it is harder to create a "phantom image" of sound from the space between any two speakers, just like trying to hear a mono center image when the stereo speakers are mis-wired.


Speakers in phase reinforce each other, strengthening the overall sound levels, while speakers not in phase partially cancel one another, which weakens the overall sound. For me, it's a no-brainer. (No comments, please! : - ))
 

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Larry's description is excellent.


There's also an "adaptive" di-pole. This is something some manufacturers do to attempt to overcome the negatives associated with either bi-pole and/or di-pole. In this way, the high frequencies are wired out of phase to create the difuse sound that di-polars are known for. The lower frequencies are wired in phase to reinforce the bass and result in somewhat better pinpoint imaging (like bi-poles). Interesting philosophy that in my mind works pretty well. Paradigm's "ADP" series of speakers are this type. Many others use this or some variation of this as well.
 

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But, again, which way to you mount the surrounds; so the in-phase or out-of-phase tweeter point forward, and how do you know whcih tweeter is which?
 

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A book could be written on this subject but I just want to point out that main speakers can also be dipole or bipole and that could bring up an entirely different discussion. An electrostatic speaker is a dipole speaker for example. So are some of Audio Artistry's designs.
 

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Quote:
But, again, which way to you mount the surrounds; so the in-phase or out-of-phase tweeter point forward, and how do you know whcih tweeter is which?
Paradigm labels the speakers "left" and "right". I'm currently auditioning some ADP-370's at the moment and find the sound better than my directs for rear surround duty. Sounds are still localizable to me and the sound field is much wider. Though I will give the nod to the directs for multi-channel music, just a more focused, stronger signal with them. But since I found myself watching much more movies than listening to multi-channel music, I figured I'd try them. I also guess I still prefer 2-channel audio listening. It looks like I'm converting to the di-poles.
 

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Quote:
Originally posted by Larry Fine
But, again, which way to you mount the surrounds; so the in-phase or out-of-phase tweeter point forward?
Out of phase side faces the back wall, the in-phase side faces the front.


The speakers should have a label on the back to identifty which is which.
 

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Quote:
Originally posted by Larry Fine


One major problem with speakers driven out of phase with any others is that it is harder to create a "phantom image" of sound from the space between any two speakers, just like trying to hear a mono center image when the stereo speakers are mis-wired.
Larry,


I would have to disagree with the above. Some of the best imaging speakers are di-poles.


[Besides - you are never trying to create a phantom image between the pair of

out of phase drivers in a di-pole speaker. The phantom image is between the

front driver of one di-pole of a pair and the front driver of its companion di-pole.

Those drivers are "in-phase" with respect to the common mode of their respective

channels.]


It is true that bi-poles emit sounds more like what is found in nature - an "isotropic"

radiation pattern. Our ears / brains evolved to localize isotropic sources.


However, the ability to be better localized is NOT a characteristic you want in a speaker.

The speaker has a different job - it has to "fool" your senses that the sonic image is

somewhere else.


A speaker with an isotropic radiation pattern is easier for the ears / brain to localize the

speaker as the source of the sound - not what you want.


Properly setup di-poles will sonically "disappear" - because it is more difficult for the

algorithms our ears / brains use for localization to localize the speaker itself, because,

they don't work as well on a dipolar radiation source. Hence our ears / brains don't

localize the speaker as the source of sound.
 

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I understand that, alright. It's just that I still disagree with intentionally introducing an artificial characteristic to sound that doesn't occur in real life. (The electronic reproduction of audio (and video) has enough anomolies already.) Variations, sure; our ears depend on phase shift, caused by the pinnae, to localize sounds. However, 180 deg. is beyong nature.


As for the need to "de-localize" sound sources (speakers), I feel (my opinion via experience and study) that bi-polars, as surrounds, have the dispersion of multiple side speakers without the likelihood of comb effect, more like a point source, but they certainly don't call attention to themselves. When I hear a surround effect, I look up and around, never "there" and "there".


To me, nothing makes the room "disappear" like my all-bi-pole (except center) system. Granted, I haven't heard a good di-pole speaker here, but I've heard them. I still think "out-of-phase speakers" when I hear them, rather than "the source of the sound is in my environment" like I do here. I think the goal is to make the system disappear.
 

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Hi

I have the Axiom QS4'swhich have 4 drivers, the sides and top and bottom.

as far as I can tell they fire 2 ways X 2.


That's how they seem to fire so call them what you like.


Peter m.
 

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Quote:
Originally posted by Larry Fine
I understand that, alright. It's just that I still disagree with intentionally introducing an artificial characteristic to sound that doesn't occur in real life. (The electronic reproduction of audio (and video) has enough anomolies already.) Variations, sure; our ears depend on phase shift, caused by the pinnae, to localize sounds. However, 180 deg. is beyong nature.
Larry,


The whole idea of trying to convey a whole soundstage from 2 sources [ in the case of

stereo ] is also artificial.


In reality - the sound sources are spread out across the soundstage - with varying distances

from the listener. Because of the differential in path lengths - you DO get 180 degree

phase shifts in nature!! That second sound source that is 1/2 wavelength farther from you

than the first sound source IS 180 degrees out of phase with respect to the first.


What one wants to accomplish ultimately is a recreation of a 3-D soundfield using a

limited number of sonic sources [ speakers ]. If the sources are "artificial" with respect

to Nature's sound sources, but give a good approximation to the desired 3-D soundfield -

then so be it.


The "artificial" nature of di-poles is no more "artificial" than trying to recreate the

soundfield of an entire orchestra - using just a few sound sources. The whole audio

process is inherently "artificial".
 

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I certainly agree with the last statement. I often ask people how they (dare) listen to music, or even watch movies, through an electronic system, and then worry about a more expensive cable or switching video through an AV receiver.


If sound in nature already has a 180 deg. phase shift in it, because that's the "nature" of the sound being recorded, along with the location of the microphone(s), that's fine. I want to hear those phase shifts in phase, not futz with them further.


What I'm saying is that any phase "anomolies" inherent in the sound as recorded are acceptable to me, but I chose to keep those characteristics as close as possible to the original, and reproduce them accurately, with no intentional changes.


As I said, the purpose of a good sound system is to reproduce the sound with as little change as possible. Remember an ideal amplifier's definition as "a straight wire with gain"? No mention of phase reversal. Well, I wish to carry that to the extreme.


There are people who believe that absolute phase (from microphone to speaker) is as important as relative phase (channel to channel). Why on earth flip phase from one speaker when the same results can be obtained without doing that?


Back to my original reasoning, I believe that we now have enough discrete channels, and speaker positions within the sound room, that single-speaker decorrelation is no longer a priority. Any sounds meant to come from all over behind the listener are in the 'mix'.


If a surround effect is meant to come from one side or the other, the directionality is desirable. Since we don't face the surround speakers, and especially with rear speakers that blend the side surrounds, pinpointing the source is not a problem.


Maybe my room is larger than your's (16' wide x 25.5' deep), and therefor, I'm not much closer to any one speaker than the others. My speaker setup is fairly close to circular; the sides are on the side walls, but the front and rear pairs are floor standing.
 

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I'll just note that bipolar speakers also add qualities to the sound that are not present in nature or in the recorded signal... some of which dipoles circumvent. In the end, both dipolar and bipolar speakers are imperfect transducers, and each has their own problems and benefits. Dipoles don't introduce any more "abnormalities" into the sound than bipoles do... they just introduce different abnormalities.


Pick your poison, they are both imperfect, and your personal preference should be the deciding factor.
 

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Quote:
Originally posted by Larry Fine


If sound in nature already has a 180 deg. phase shift in it, because that's the "nature" of the sound being recorded, along with the location of the microphone(s), that's fine. I want to hear those phase shifts in phase, not futz with them further.
Larry,


You are already "futzing" with the phase shifts.


The recording process has only a limited number of microphones - a limited number of

samples of the soundfield - so you don't have enough degrees of freedom in the

recording process to preserve all the phase shifts found in the recording session.


Then Lord knows how the limited number of recorded channels are mixed down to the

two stereo channels. Channels from microphones that are in different locations are

blended together - which does not preserve the phase shifts.


Then the two stereo channels are played back using only two sources [ speakers ].


As Bigus points out, bi-poles are also introducing their own errors.


If you had a microphone right at the position of a sound source in the recording session,

that sound source will radiate isotropically both forward and backward. A bi-polar

speaker given the signal that the microphone picked up would correctly radiate the

sound pattern.


However, the microphones are seldom AT the location of all sound sources.


If the microphone is located some distance away from the sound source - then when

the bi-pole given that signal emits sound isotropically at the analogous location of the

microphone - NOT the analogous location of the sound source. So the bi-pole is making

as big an error as the dipole does.


I think Bigus puts it best - bipoles and dipoles BOTH are imperfect and make errors -

they just make different errors. You can't say di-poles are "wrong" and bi-poles

are "right". They are both "wrong" in different ways - and you decide which you

prefer based on your preferences.
 

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Quote:
Originally posted by Morbius
I think Bigus puts it best - bipoles and dipoles BOTH are imperfect and make errors -

they just make different errors. You can't say di-poles are "wrong" and bi-poles

are "right". They are both "wrong" in different ways - and you decide which you

prefer based on your preferences.
I 100% agree with both of you.
 

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Quote:
Originally posted by Mikeyb
Regarding the question about Axiom's Quadpolar speakers: They are bi-poles.....all drivers/signals are in phase.


Thank you




Stew (ducking away quietly)
 
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