Orban OPTIMOD-FM 8600, Operating Manual

Page: 226 / 397

3-46
OPERATION ORBAN MODEL 8600
The square waves produced by this clipper are filtered through a 6
dB/octave lowpass filter that is down 3 dB at 400 Hz. This greatly reduces
the audibility of the higher clipper-generated harmonics. Nevertheless,
the downside is that material with sustained bass (including speech) will
sound substantially less clean than it will with the Medium or Soft set-
tings.
Note that the
H
ARD
C
LIP
S
HAPE
control determines how squared-off the
clipped bass waveforms become. (See Hard Clip Shape on page 3-49.)
•
LLH
ARD
differs in two ways from the normal
H
ARD
mode of the bass clipper:
•
LLH
ARD
automatically defeats the compressor lookahead. This action
is functionally equivalent to setting the
L
OOKAHEAD
control to
O
UT
,
except that it reduces input/output delay by 5 ms).
•
LLH
ARD
prevents the bass clipper from switching to
M
EDIUM
mode
whenever speech is detected. By constraining the system in these
ways, it ensures that the delay is always 13 ms.
To minimize speech distortion, the speech/music detector automatically
switches the bass clipper to
M
EDIUM
when speech is detected, provided
that the Five-Band structure is active,
L
ATENCY
is
H
IGH
, and the
B
ASS
C
LIP
M
ODE
is set to
H
ARD
. (See “Lookahead” on page 3-70 for more about the
speech/music detector.) If the bass clipper is set to
LLH
ARD
, the
speech/music detector will reset the clipper threshold to the setting speci-
fied by the
S
PEECH
BCT
HR
control. The default setting is “0 dB,” which re-
sults in very little bass clipper action during speech. This prevents audible
speech distortion that this clipper might otherwise introduce.
Switching the
B
ASS
C
LIP
M
ODE
to
LLH
ARD
(from any other mode) removes
five milliseconds of delay from the signal path. Switching can cause audi-
ble clicks, pops, or thumps (due to waveform discontinuity) if it occurs
during program material. If you have some presets with
LLH
ARD
bass
clipper mode and some without, switching between these presets is likely
to cause clicks unless you do it during silence. However, these clicks will
never cause modulation to exceed 100%.
One of the essential differences between the
H
ARD
and
LLH
ARD
bass clip-
per modes is that switching between Hard and Med does not change de-
lay and is therefore less likely to cause audible clicks.
8500-Style Peak limiter Controls
Intermediate Name Advanced Name Range
— OSComp Dr –2.0 … +2.0
Bass Clip Thresh BassClpThre –6.0 … 0.00
— SpeechBCTh –6.0 … 0.00
Bass Clip Mode BassClpMode Soft, Medium, Hard, LLHard
— Hard Clip Shap 0 … 10
HF Clip Thr HF Clipping 0 ... 6.0 dB
Table 3-6: 8500-Style Peak Limiter Controls