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 an
SDA-102 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
eliminating feedback, but it is nice to know you did all that is possible to make the perfor-
mance 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 SDA-102 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 SDA-102 so that the signal from both speakers arrives at
precisely the same time. The SDA provides 20 microsecond resolution for this purpose.
Use the same procedure to align speakers within a cluster when necessary.
8
Fig. 7:
Aligning far- and
short-throw
speakers. (The
level from both
speakers is equal.)
