Rane C4 Operator's Manual - page 9
Manual-9
Figure 5. The Hard Knee compression characteristic has a 0 dB span.
The Soft Knee compression characteristic has a 0 dB span.
SIDE-CHAIN Mode and Listen
*OQVUE#V
0
V
U
Q
V
U
E
#
V
5ISFTIPME
)BSE
4PGU
E#TQBO
SIDE-CHAIN Parametric EQ
Comp
selects Compressor mode for the channel.
Dynamic EQ
selects this mode for the channel.
Tip: A small t pointer next to a control indicates a typical set-
ting for De-essing.
Listen
routes the side-chain signal to the channel output, allow-
ing you to hear exactly what the detector “hears,” and is especial-
ly useful when making precise PEQ adjustments for frequency
sensitive compression or de-essing. The yellow indicator flashes
when Listen is engaged, as a friendly reminder to toggle back to
Comp or Dynamic EQ mode before show time.
The Listen source depends on the selected mode (Comp or
Dynamic EQ), so the switch operates as follows: when switch-
ing from Comp to Listen, the Comp indicator remains lit and
the Listen indicator flashes, which signifies you are listening
to the Compressor side-chain PEQ response. When the switch
is moved to Dynamic EQ, the Listen and Comp indicators
are turned off and the Dynamic EQ indicator is lit. When the
switch is then moved from Dynamic EQ to Listen, the Dynamic
EQ indicator remains lit and the Listen indicator flashes, which
signifies you are listening to the Dynamic EQ response.
Remember: once the show begins the audience never hears
the filtered side-chain signal – unless you accidentally leave
Listen mode engaged, of course. If something sounds a bit odd
during the gig, look over at the C4 and see if any of the yellow
Listen lights are flashing. If so, casually saunter over to the rack
and toggle the side-chain out of Listen mode…as if you meant
to have it engaged for the first six songs.
The Side-chain PEQ filter operates in one of two ways, depend-
ing on whether the channel is operating in Compressor mode or
Dynamic EQ mode.
PEQ in Compressor Mode
In Compressor mode, the PEQ section operates as a normal,
2
nd
-order, parametric filter with independent BANDWIDTH,
FREQUENCY and GAIN controls. The GAIN control has a
center detent position indicating 0 dB, or unity gain. Use the
PEQ to adjust the sensitivity of the rms detector to specific
frequencies. Boosting a particular frequency makes the detector
more sensitive to this frequency, while cutting makes it less sensi-
tive. Broadband compression still takes place; the filter does not
directly affect the frequency response of the main signal, as is
done with the Dynamic EQ used in de-essing.
Example: reducing detector sensitivity to low frequencies
helps avoid the pumping and breathing often associated with
compressing an overall mix of instruments. Start by engaging
Listen mode and set the PEQ Gain to –12 dB with a bandwidth
of 1 to 2 octaves. Adjust the frequency and bandwidth controls
until most of the low frequency sound disappears (125 Hz is a
good start). Oh…and don’t forget to dis-engage Listen mode
when you’re done.
PEQ in Dynamic EQ Mode
In Dynamic EQ mode, the PEQ controls define a bandpass filter
in the side-chain and a Dynamic EQ in the main signal path.
The difference in the rms level of the broadband signal and that
of the bandpassed side-chain signal is compared to the threshold,
and the Dynamic EQ’s gain is automatically adjusted to main-
tain the proper ratio of sibilant to non-sibilant content.
See the examples in the Dynamci EQ Applications section on
page Manual-4.
0
dB
Hz
oct
10
2
1
5
0.5
20k
640
125
3.15k
20
+12
-12
GAIN
FREQUENCY
BANDWIDTH
PEQ
SIDE-CHAIN
Listen Dynamic
EQ
Comp