Orban OPTIMOD-FM 8600S, Operating Manual

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OPTIMOD-FM DIGITAL OPERATION
3-103
the combination of improved HF response (about 2 dB) and midrange IM suppres-
sion is plainly visible and very audible in the 8600.
Transient Punch : Decreasing distortion often comes at the expense of decreased
transient punch because in competitively processed FM, transients must be clipped
and may therefore appear incorrectly to the distortion controller as “distortion”
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 3-8 on page 3-102 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
Figure 3-9
Stanford Research Systems Model SR785 Dynamic Signal Analyzer