When my partners, Don Givogue and Ed Blais, and I started Definitive in 1990, our first product, the BP10 loudspeaker, was also a narrow tower with basically two complete full-range driver arrays. One faced forward and the other rearward. This is the basic concept of a bipolar speaker. The two driver arrays radiate sound (in phase with one another) in what is basically an omnidirec- tional pattern, exactly as sound is radiated in real life from an original sonic event. This technology provides a lifelike balance of early-arrival sound information, which provides focus, clarity, and location data. This combines with properly delayed com- plex and somewhat random late-arrival ambient information (just like the ambience of an instrument in a concert hall), which conveys the lush, natural three-dimensional soundstage of a live musical performance or cinematically portrayed event. These effects very much help to make the walls of the listening room disappear and expand the apparent size of the listening room into something that more closely approximates the sound-space in which the live event took place. Listeners I've spoken with consis- tently find that the difference bipolar technology makes is dramatic, involving, and quite captivating.
There is another benefit of bipolar tech- nology, which is not as important to me as a critical listener but has been praised by many reviewers and listeners. Because a bipolar loudspeaker closely approximates an omnidirectional sound source, it does a bet- ter job of delivering superior sound throughout the room for all listeners in that room. In effect, the "sweet spot" is greatly expanded—a real-world benefit for listeners who tend to move around the room or who
share their music listening or movie experiences with friends and family. Now let me talk a little about built-in powered subwoofers. Definitive
was the first company to introduce the concept of built-in powered subwoofers to the marketplace—technology that first appeared in the BP2000 loudspeaker we released several years ago. Interestingly, our concept grew out of our search
for better-quality audiophile/music reproduction—not out of a search for a place to "hide" the subwoofer in a home theater system. Our belief was (and still is) that there are sig- nificant advantages (especially for the subtleties of music reproduc- tion) in having dual stereo sub- woofers that have been specifically
engineered to blend ideally with the rest of the speaker system. In addi- tion, two subwoofers are really a lot more powerful than one. By locating the subwoofer(s) at the same position as the rest of the speaker system(s), you also eliminate the inconsistencies related to variable placement of the subwoofer(s) in the room. We also believe that there are sonic advantages to stereo subwoofers beyond the obvious ones of better coupling to the room and more linear response (itself owing to better spreading out of the excitation of the room's eigenmodes). For exam-
ple, you can engineer the subwoofer as an inte- gral part of a true full-range system, as we do in
the Definitive "SuperTowers," rather than designing a general-purpose subwoofer that has to be adaptable for use with a vari- ety of other systems. We design our speak- ers to take full advantage of the fact that they incorporate built-in subwoofers by fur- ther optimizing the performance of the rest of the system (which no longer has to han- dle the mid- and low-bass frequencies cov- ered by the subwoofers) and by properly integrating the subwoofers into the system. This level of integration is very difficult to achieve with a single stand-alone sub- woofer (since it is tricky to get one sub- woofer to blend equally well with multiple satellite speakers that are placed several feet apart). In practice, the subwoofer-with- in-main-speaker idea has really caught on with the public, though I think some cus- tomers probably value the idea as much because it eliminates an extra subwoofer box or two as for the better sound quality it affords. But I really do want to stress that, when properly utilized, building a powered subwoofer into the speaker allows you to optimize many other aspects of the speak- er's design, and the resulting performance (at least in the case of Definitive) is clearly superior for both music and home theater. Not surprisingly, when the Dolby folks intro- duced Dolby Digital, they demonstrated the then-new system with a separate subwoofer for every channel and still recommend this approach for top performance.
Interestingly, you can also make, as Definitive does, bookshelf speakers and center channels with built-in powered sub- woofers. The concept of a built-in powered subwoofer in the center channel is often misunderstood. It goes way beyond just putting more bass energy into the room:
the intent is really to make the center channel a true full-range loud- speaker (i.e., one with extended bass capabilities) in order to give it total harmonic integrity, which is important for both music and home theater. Remember that in many movie mixes (and some multichannel audio mixes —Ed.), the center channel is really the main channel. Because of the
logistics of setting up a home the- ater, the center channel normally has size limitations. Building in a powered subwoofer in effect allows the center channel to achieve the performance of a large full-range floor-standing tower. It can have much the same effect in bookshelf speakers. Building a subwoofer into smaller speakers
allows the designer to put some of the performance of a large tower into moderately sized models.
Definitive Technology SuperTowers are designed on the concept that bipolar driver arrays and built-in powered subwoofer technologies com- bine to bring more realistic and satisfying musical reproduction into all home-listening environments. Importantly, these design approaches yield products that offer many of the advantages of large, exotic, and expen-
sive high-end loudspeakers, but that take up less space, and that can be built (and bought)
for a fraction of the price.
