Klipsch KS-525-THX
I encounter a variety of side surround speakers in homes in the course of my work. The designs that I find to generally be most effective in a home theater are ones that have the speakers at about a 90 degree angle to each other like that shown in the Klipsch KS-525-THX above.
Side surround speakers that use this type of speaker orientation provide good coverage of a relatively large listening area assuming that they are placed at least 2 feet above the listener ear level and slightly behind or to the side. Some speakers will have a dipole/bipole switch or possibly crossover gain adjustments for treble and boundary compensation. These switches can be useful, but I would place much more importance on the positioning of the drivers in the cabinet and the sound output capabilities of the speaker for the intended application.
Deciding between bipole and dipole will depend on the location of the speaker to the listener. If the speaker is less than three feet from a listening position a dipole configuration may be preferred. Using a dipole will create a dead zone of sound in front of the speaker from phase cancellation. This can be very helpful for balancing surround levels at various listening positions if one seat is too close to the speaker. The best design for most home theaters is to use a bipole for the side surround and position it relatively high in the room away from any seating. In a large home theater with three or more rows of seating it makes sense to consider two or more side surround speakers on each side using a standard direct firing speaker design to get better coverage. Doing this will require additional amplifiers and electronics to properly set the phase and level of these additional side surround speakers. Using back/rear channel speakers for this purpose is not appropriate.
Paradigm Signature ADP3
A popular orientation that I find to be very poor is one like the Paradigm Signature ADP3. This design sends a high percentage of the sound in front of the listener reducing the surround effect. The opposing mid-range and tweeter drivers facing to the rear will also require a rear wall perpendicular to the speakers to reflect the sound back to the listener. Requiring a specific wall configuration makes this design relatively poor and highly dependent on the configuration of the walls in the theater.
Klipsch KL-7800
Another option is to use a standard direct firing speaker design like the one shown above for the side surround speaker. The viability of this choice will depend on the location of the seats in the theater. When you have a single row to cover or a few seats this can work well assuming you place the speakers at least 2 feet above the listening position and directly to the side of the seating position. The benefit of the bipole design recommended above is that it will cover a larger area more evenly with less sensitivity to placement.
One of the best indicators of bipole side surround speaker design quality is THX Ultra certification. Products that carry this certification are available from Atlantic Technology, Klipsch and Teufel. Having the proper design and position of the side surround speakers is much more important than matching the manufacturer of the surround speakers to that used for the mains and center channel. Without the proper dispersion of sound the surround effect will be greatly reduced.
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