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INPUT
,
NPU T L E VE L SELECT
9
) SERVO
S AUNCUO
N EDAORA
LPL) T
(.)
S TAGE
V GA Or
' TH RESHOLD'
S IL E NCE GAT
DETECTOR
... SG L ED ( TELL OSTI
•fflocEss
B A LANCE
A EAP C
DETECT OR
LAST L ED ( RED )
J RC
C.OLPR E I IMO R
SI DE C s 'AM
' OUTPUT'
' LEVEL NG TE
Me Leo IL et Mum.
.q•ner Air ems unes
L EVEU M3
LOE OMNI
t
ait
' CANE*
SE F F I C I
)
BALANCED
Ou T A LTT
S T AGE
(
OUTPUT
LED ( RED .
GREEN . OUT)
I N men dews
NAMES ENCLOSED IN QUOTES ARE OPERATOR CONTROLS
AUDIO SIGNAL PATH
—00 - CONTROL SIGNAL PATH
- AUDIO GROUND
B A R GRUNT I SETER AND MUTER SELECT
›
.
GAI N REM/ M ir
>INP UT'
Fig. 2-2. Block diagram of COMPELLOR Model 301 circuits.
To illustrate the co-functioning of the three systems, imagine a sudden 20 dB
increase in signal level above 0 VU. The limiter will catch the peak and hold
it, if necessary, until the compressor reduces the level. If the increase is
maintained, the leveler will then further reduce gain, freeing the compressor.
Even with the best and most modern of conventional gain control devices,
one can only imagine the quantity of controls necessary to handle severe and
complex dynamic changes while avoiding sonic degradation. If a proper
setting could be be found, it would be optimized for only one audio texture
and level, necessitating constant control changes to maintain audio quality.
The COMPELLOR's control circuits have the intelligence to analyze the
incoming audio and make all the control changes automatically on a real-time
basis, resulting in inaudible, continually-optimized dynamic range control.
2.1 Control Circuits
The COMPELLOR's compression level detector is influenced not only by the
RMS level of the audio, but also by program dynamics and wave complexity,
so audio quality is greatly enhanced over simple RMS or average responding
processors. Transient sounds are preserved, pumping and breathing elimi-
nated, etc.
The level detector has a "soft knee" compression characteristic, with the ratio
varying from 1.1 to 1 at onset of compression and gently increasing to 8 to 1
at 20 dB of pure compression. The attack and release times are automatically
varied from 5 to 50 ms for attack and 200 to 1000 ms for release.
2-2 Operational Characteristics
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