Orban OPTIMOD-FM 8700, Operating Manual

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OPTIMOD-FM DIGITAL OPERATION
3-105
that requires suppression. By using sophisticated signal processing, the MX limiter
not only avoids this problem but improves transient punch compared to the older
technology.
The center (under the small orange triangle) of Figure 3-12 on page 3-104 shows a
snare drum hit from Simple Minds, “Alive and Kicking.” The original CD dates from
the days before “hypercompression” in mastering ruined the sound of most CDs; the
snare drum has plenty of peak level. The new limiter preserves the transient (center
of the screen) about 3 dB more effectively than does the old technology (bottom).
Conclusions
The marketing of broadcast audio processors has often suffered from objectively
unverifiable hyperbole. Meanwhile, traditional measurements using static test sig-
nals like single-tone harmonic distortion and multi-tone IM distortion cannot rigor-
ously predict the subjective listening qualities of broadcast processors because these
processors are purposely very nonlinear, so that the assumptions implicit in test-tone
measurements (that the systems being measured are ideally linear and that their
nonlinearities are weak) do not hold.
This white paper has shown that with today’s sophisticated digital measurement
techniques, it is possible to verify some subjective claims objectively by making
measurements that use real-world program material as the excitation. These meas-
Figure 3-13
Stanford Research Systems Model SR785 Dynamic Signal Analyzer