Dispersion

Being directed by the waveguide, sound is radiated into the environment with a 120° horizontal angle of dispersion from approximately 1,000 to 10,000Hz. This means that as the frequency varies, the area that is "illuminated" by the driver remains the same over a 120° arc, symmetrically and directly in front of the waveguide. Without some form of wave "directing" device this simply is not possible.

Drivers mounted on a flat baffle produce a coverage pattern that often varies considerably. Many times they will be found to be very broad at the lower end of their operating range then begin to narrow as the frequency is increased, only to widen and then narrow again at the highest frequencies. This unpredictable behavior makes placement difficult and the optimal listening area quite narrow. The problem is highly multiplied when multi-way (3+) driver arrays are employed.

The advantage that controlled dispersion offers is quickly realized when one is faced with "not so perfect" room placement options. In more ideal settings, the reduction of reflected sound from nearby walls permits the natural ambiance in a given recording to be heard clearly with less of the masking effect caused by early room reflections. A 120° dispersion angle is ideal for achieving this while still providing a very wide listening area.

Professional recording engineers will most certainly appreciate such controlled dispersion characteristics. The ability to monitor recording sessions with near-field accuracy and mid-field freedom of movement is a combination seldom experienced and highly sought after.

In addition, with the recent advent of home theater, designers have sought to find ways to control the vertical dispersion of their designs in order to comply with the THX™ specification. A common technique is to employ two or more drivers operating over the same frequency range that are spaced some fixed distance apart. This method causes destructive interference at angles off-axis vertically from a pre-determined listening position. While this does effectively limit vertical dispersion to some degree, it most frequently does so in a rather erratic manner. Upon close analysis it can be found to produce a vertical pattern that varies with frequency. A stable, controlled pattern at all frequencies is much more preferred and is a natural by product of waveguide technology. Hence, you will find that SP Technology Loudspeakers products are inherently more "home theater ready" than many products advertised as such and without their inherent musical limitations.

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