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Triad’s OnWall Silver surround is a dipole speaker with two 4-inch drivers that fire “out of phase.”
Bipole, dipole, North Pole: What’s the difference and why do you need them?
Ho, ho, ho: Mr. Technology is here to explain. Bipole and dipole speakers are primarily used for the surround channels in a home theater. Both types contain two sets of speaker drivers that direct sound to both the front and back of the room, thereby dispersing the sound.
This is what surround speakers should do, after all. They are intended to reproduce ambient effects like crickets chirping in the night or the hum of a spaceship so they sound like they’re coming from everywhere in the room—not just where your speakers are located. That’s why bipole and dipole speakers have two sets of speaker drivers pointing in opposite directions. And that’s why they are often triangular in shape, with baffles sticking out slightly from an in-wall or in-ceiling installation. That, at least, is the extent of a bipole speaker.
A dipole goes one step further, making the sound from the two sets of drivers “out of phase.” What happens is this: As a speaker driver on one side or baffle moves outward to fire sound, its companion on the opposite side moves inward. Any opposing bass waves cancel themselves out at the sides of the speaker (similar to what happens in noise-cancellation headphones), and the higher and midrange sounds are dispersed throughout the room, creating an even more ambient quality. Dipole speakers are often used in higher-end home theaters, so consult with a professional if you’re thinking of using them.
Arguments will vary from person to person, based upon the preference of the individual or theory that they themselves practice. By THX specs, the dipole is the rear speaker of choice, placed at or above ear level, to the sides of the listening area in 5.1 systems. When doing 7.x, the additional pair is placed behind the listener, again at or above ear level. These are said to provide the most room filling ambient effect, but sacrifice a little bass as the drivers are wired out of phase. That is where the bipole makes a difference, as the drivers are wired in phase, thus provide a bit more bass; on the down side, they don’t have quite the soundfield of the dipole (not as open sounding). However, some would argue that the use of a monopole, or “direct radiating” speaker as the rear would provide a more direct sound, which can be of some benefit in listening to multi-channel music. In most cases, the room you are using will have a direct correlation to the choice of loudspeaker, as a speakers placement is just as important as its makeup or construction. Sorry this took so long, but I tend to be a bit long winded. Best of luck!
So how does this impact a surround system setup? Which type should be used for 7.2 surround? Or a simple 5.1 system? Rear or side speakers? How does the ambiance differ by speaker type? Need info beyond just a technical description.
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Di-Pole’s were used with the original THX systems of the early 90’s as a band-aid cure for antiquated Pro-Logic systems (mono rear channel)