Find a central place in the audience where the center cluster is 6 to 8 dB louder than the direct
sound from the performer. Delay them so that their sound arrives 5 to 8 milliseconds after the
direct sound from the performer. Experiment by bypassing the POWER-Q in and out to hear how
the source of the sound seems to move from the loudspeakers to the performer and back. Now
your ears have the same directional information as your eyes, so the performance will sound more
natural and exciting. The best seats in the house just got better.
What about the front fills? Their purpose is to add intelligibility and listening comfort to the first few
rows nearest the stage by filling in the areas missed by the center clusters. Add about 8 msec. to
the front fills to take advantage of the Precedence Effect.
The 8 msec. setting presumes the performer is standing on the front few feet of the stage. But
some stages are well over 30 feet deep. What if there is a second performer standing 25 feet
behind the first? The direct sound from his or her voice will reach the first few rows about 25
msec. after the first performer's. The audience will perceive the first performer directly and the
second performer through the loudspeakers.
We can add the advantage of the Precedence Effect to the second performer by placing the
POWER-Q in the mixer's channel insert point and adding a 25 msec. delay.
Certainly taking advantage of the Precedence Effect is not as obvious to the audience as eliminat-
ing feedback, but it is nice to know you did all that is possible to make the performance enjoyable.
Application III: Synchronizing the signals of a far-throw and short-throw loudspeaker.
In order to reach the proper coverage in larger venues, we often stack two full range speakers - a
short-throw center cluster for the audience below and a far-throw speaker for the back of the
auditorium. It is almost impossible to perfectly align the stacked speakers mechanically, so comb
filter distortion becomes a problem in the area where the levels from both speakers are equal.
The same thing happens with speakers mounted on the right and left sides.
It is impossible to remove comb filters with equalization, but the POWER-Q eliminates them in
short order without affecting the spectral balance for the rest of the audience. Find the axis where
the levels from the two speakers are equal. This is where the comb filters are most severe.
Carefully adjust the POWER-Q so that the signal from both speakers arrives at precisely the same
time. The POWER-Q provides 20 microsecond resolution for this purpose.
Use the same procedure to align speakers within a cluster when necessary.
Section 8: Digital Delay
19
Fig. 14: Aligning far- and
short-throw speakers. (The
level from both speakers is
equal.)
