Rolls RP252 - Manual (Page 4)

DESCRIPTION
FRONT PANEL
NOTE: Descriptions are identical for both Channels One and Two
STEREO
PWR
COMPRESSOR/LIMITER
GATE
RP252 -40 +10
-30
-24
-12 -6
2:1 :1
9:1
7:1 4:1
10 1 5 .5
2.5
-10 +20 -30
+4
slow off fast THRESHOLD RATIO ATTACK RELEASE LEVEL GATE THRESH GATE REL
GATE ACTIVE GAIN REDUCTION
1 2 4 6 8 10 12 18 24 38
GATE ACTIVE GAIN REDUCTION
1 2 4 6 8 10 12 18 24 38
-18
0
mS dB dB dB
0 0
Sec -40 +10
-30
-24
-12 -6
2:1 :1
9:1 7:1 4:1
10 1 5 .5
2.5
-10 +20 -30 slow off fast THRESHOLD
RATIO
ATTACK RELEASE LEVEL GATE THRESH GATE REL
-18
0
mS dB dB dB
0 0
Sec
+10 +10
+4
THRESHOLD: Sets the level at which the RP252 becomes active. When the
signal level is below the threshold point, the signal is unprocessed. When the
signal level is above the threshold point, there may be compression/limiting.
RATIO: This sets the ratio of input signal to signal compression. Called ‘signal-to-
compression ratio, at 1:1 the signal is left unprocessed and at infinity:1, no matter
how much the input increases, the output will not be above the threshold - this is
called limiting.
ATTACK: Adjusts how fast the control circuits respond to the dynamics of the
input. If this is set longer, it will take more time for gain reduction to occur, so
rapidly rising inputs will go through for a short period of time.
RELEASE: Adjusts how long before the control circuits return to a steady state. A
short release time can make sound be choppy and gated. A long release time can
make music seem to rise and fall as a wave. It is recommended to start with a
long Release time, then shorten it if necessary.
OUTPUT LEVEL: Sets the output level to help compensate for compression
losses. If the Threshold is set low, more output level may be needed because gain
reduction starts at a low level.
GATE THRESHOLD: Included in the RP252 is a noise gate circuit which is
accessed with the two gate controls. The Gate Threshold sets the point at which
the gate “opens” to let the sound through. Below this level, the entire signal is shut
off. When the GATE LED is off there is enough level to operate the gate.
GATE RELEASE: As before, this adjusts how long until the gate closes or stops
sound after the signal has fallen below the threshold.
ACTIVE SWITCH: Pressing this switch inward activates the compressor.
STEREO SWITCH: This switch joins the control circuits of the two channels so
they operate together. When processing a stereo signal, this helps maintain a
more natural sound because both sides are processed exactly the same.
GAIN REDUCTION LEDs: These 10 LEDs display, in dB, how much the signal is
being compressed (i.e., how much gain reduction).
GATE LED: When this is lit, no signal passes through the processing circuits and
the sound is muted.
DESCRIPTION CONT.
REAR PANEL
NOTE: Descriptions are identical for both Channels One and Two
120 VAC
50/60 Hz 15 VA
MADE IN U.S.A.
MODEL RP252
SERIAL NUMBER
252-
OUTPUT
CHANNEL 2
SIDE CHAIN INPUT
INPUT OUTPUT
RISQUE DE CHOC - NE PAS ENLEVER
OUTPUT
CHANNEL 1
SIDE CHAIN INPUT
INST
LINE
INST
LINE
INPUT OUTPUT
C US
WARNING: To reduce the risk of electric shock or fire,
do not expose this device to
rain or moisture. :
CAUTION: To reduce the risk of electric shock do not remove
lid. No user serviceable parts
inside. Refer servicing to
qualified service personnel.
INPUT: Use mono (or TRS) 1/4" phone connectors or balanced XLR inputs from
your line-level audio source.
OUTPUT: Use mono (or TRS) 1/4" phone connectors or balanced XLR to connect
to the line inputs on the next device (i.e., mixer, recording device, amplifier, etc.)
SIDE CHAIN: The side chain ins/outs are 1/4" unbalanced jacks used for control-
ling the gain reduction circuits with an external signal. This is for special effects
such as “ducking”.
INST/LINE SWITCH: This switch changes the RP252 dynamic range by 20 dB. In
for instrument level, out for line level signals.
OPERATION
Smoothing Out Electric Bass
Bass lines often are inconsistent in level and lack the sustain needed to give a
solid bottom end. Set the Threshold so that peaks cause 10 dB to 12 dB of
compression. Use more for increased sustain and for more percussive attacks on
the trainsients.
Fattening Kick Drums and Compressing Other Drum Sounds
Weak, flabby kick drums often have too much boom and not enough slap. Tighen
them up by increasing the Attack time and setting the threshold for 15 dB of
compression on the peak of the kick. Because the RP252 takes time to react, this
will emphasize the slap at the beginning of the note and reduce the boominess of
its body. The RP252 also works well for tightening snare drums and tom toms and
can be used with drum machines to effectively alter the character of any elec-
tronic drum sound.
Variations in Mic Levels
In musical applications, paging systems, churches, speaking events, etc., as the
distance between the microphone and the speaker or the vocalist changes, signal
levels change. To keep the level near constant, set the threshold and ratio so an
average of 6 - 8 dB of compression is established.
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