Home Theater Hacks

Hack #38. Select the Perfect Rear and Side Speakers

The primary decision in choosing a rear or side speaker is selecting a monopole, bipole, or dipole unit. Learn the difference, and when each is appropriate.

Although the side and rear speakers generally are used only for effects, and then only a small portion of the time, they make a tremendous difference in the overall feel of a theater's soundscape. There's nothing as impressive as hearing a shuttle fly overhead, as well as seeing it move across the screen. The type of speaker—monopole, dipole, or bipole—determines much of the quality of these effects.

Monopole Speakers

A speaker that fires sound in a single direction is called a monopole speaker. The most conservative (and arguably the best choice) for rear and side speakers are monopoles. Rear- and side-channel effects are usually simple, direct, and best served by being fired straight out.

Dipole Speakers

Another speaker that fires sound in a single direction is called a dipole speaker. In the days of stereo videotape, the engineers at Dolby Labs figured out how to take sounds and direct some to the front speakers, while sending others to rear speakers. This eventually evolved into Dolby ProLogic decoding. Although this was a tremendous leap forward, there were some serious drawbacks:

• Sound came out of both rear speakers, instead of being directed to just one rear or the other.

• Sound couldn't play below 150 Hz.

• Rear sounds were limited to ambient noise, as engineers could not ...