Rane MC 22 User Manual

OPERATORS MANUAL

STEREO COMPRESSOR

MC 22

QUICK START

Shredded, this document makes excellent packing material. In its present form, it makes interesting and useful reading.
If you run out of patience quickly, at least read this part to make sure you don’t exterminate everything within a two mile
radius by doing something wrong.

Attach one or two channels of inputs and outputs to the respective connectors on the rear. This device uses low imped-

ance balanced line drivers. Do not connect the XLR “+” or “–” output pins to ground, as this may cause the power supply
to shut down. For unbalanced use, leave the unused output pin (“+” or “–”) unterminated.

With the RATIO turned all the way down at 1:1, THRESHOLD turned all the way up to 20 dBu, and the LEVEL
controls in their center at 0 dB, you have an expensive patch cord.

While sending a signal to the MC 22, adjust the INPUT LEVEL so the +4 dBu LED lights occasionally, but the OL
LED does not light. Now increase the RATIO to something useful, like 2:1 (with the control set at 2, the Ratio is 2:1; at 5,
it is 5:1.) Adjust the THRESHOLD to the point you want the Compressor to kick in. The GAIN REDUCTION meter
reads the amount of signal compression.

Both Compressors will activate by the source material applied to either Channel if the LINK switch is ON. This is the
preferred setting for stereo program material.

WEAR PARTS: This product contains no wear parts.

Manual-1

COMPRESSOR
ACTIVE/BYPASS switch

GAIN REDUCTION LEDs

THRESHOLD control

This switch compares compressed and non­compressed signal. There is one for each
Channel. The INPUT LEVEL remains active
regardless of switch position.

INPUT LEVEL control

This controls the overall level. Unity gain is
reached at “0”. With signal applied, set this

These LEDs show the amount of average
signal reduction in dB. This aids in setting
the THRESHOLD and RATIO controls by
showing how much compression is occuring.

adx

LED

This illuminates whenever noise reduction is
active. This automatic downward expander

This control sets the point at which the Input
signal level causes the Compressor to
become active. See Figure 1 on page
Manual-4.

RATIO control

Once the threshold is exceeded, the ratio of

input change to output change is determined
control so the +4 dBu LED lights occasion­ally. If the OL (overload) LED flashes, turn
the INPUT LEVEL control down.

circuit acts like a gate to keep the system
quiet when no signal is present. When the
input level drops below -55 dBu, downward
expansion occurs at a ratio of 2:1. See
Figure 3 on page Manual-5.

CHANNEL 2 OUTPUT

Same as Channel 1 Output.

by this control. The compressor has no

effect when set at 1:1. But at 10:1, it takes

a 10 dB input signal increase above the

Threshold to produce a 1 dB increase in

Output Gain. See Figure 2 on page

Manual-4.

CHANNEL 2 INPUT

Same as Channel 1 Input.

Manual-2

LINK switch

Switch this to ON when using stereo
material. This activates both Compressors
when either Channel’s signal exceeds the set

CHANNEL 2 controls

Threshold, preserving stereo imaging.

These duplicate the controls in Channel 1.

Power ON switch and LED

Your basic, straightforward power switch.
When the switch is depressed and the
yellow LED is lit, the MC 22 is ready to go.

Cable Wiring

In agreement with IEC and AES/ANSI
standards, XLR wiring convention is pin 2
Positive (hot), pin 3 Negative (cold), and
pin 1 chassis grounded and signal grounded
(to allow unbalanced operation). The XLR
case is chassis grounded.

CHANNEL 1 OUTPUT

Use either the balanced XLR or the unbal­anced ¼" TS jack. Using both types of
Outputs are permissible to drive two devices,
such as an amplifier and a recorder.

device uses low impedance balanced line
drivers.

Do not

connect the XLR “+” or “–”
output pins to ground, as this may cause the
power supply to shut down. For unbalanced
use, leave the unused output pin (“+” or
“–”) unterminated.

This

CHANNEL 1 INPUT

Choose between the balanced XLR or the
balanced/unbalanced ¼" TRS jacks, but
only use one. Inserting a ¼" TS jack will
work—however—use balanced lines,
especially when connecting cables over 10
feet in length. Consult SOUND SYSTEM
INTERCONNECTION on page Manual-10.

Manual-3

OPERATING INSTRUCTIONS

1:1

2:1

4:1

10:1

A PRIMER

Let’s start with what a compressor actually does. No
matter how you cut it, this is an automatic volume control. It
is a hand on a knob, turning the volume down and turning it
up again. The hand is really quick and really accurate, but it’s
just turning a volume control.

When the input signal reaches a level set by the THRESH­OLD control, the compressor begins turning down the signal
by an amount determined by the RATIO control. The MC 22,
like most compressors, operates by making the loud signals
quieter, but does not make the quiet parts louder. However,
by keeping the loud signals under control, the entire system
may be turned up when necessary to make the quiet parts
louder.

PRE-FLIGHT CHECKLIST

Before proceeding, it’s a good idea to turn the control
knobs to the following positions:

1. LEVEL control ....................... 0 dB

2. THRESHOLD control .......... fully clockwise

3. RATIO control ....................... fully counterclockwise

4. COMPRESSOR switches .. ACTIVE (out)

This renders the MC 22 with no compression, but allows
signal through at unity gain. No change occurs either in the
ACTIVE or BYPASS position of the COMPRESSOR switch.

LEVEL

Before making any Threshold adjustments, set the LEVEL
control so the +4 dBu LED lights occasionally, and the OL
LED does not light. Be aware that changes to the Input Level
will affect the Threshold level.

THRESHOLD

The threshold is the point at which gain adjustment
begins. When the input signal is below the threshold, the MC

22 acts like a straight wire. When the signal is loud enough to
cross the Threshold, the compressor is active and turns the
volume down. Various Threshold points are illustrated in
Figure 1 below. How much it gets turned down is determined
by the RATIO control (shown at 2:1).

RATIO

Once the threshold is exceeded, the increase in output
compared to the input signal increase depends on the RATIO
setting. An ordinary preamp set for unity gain or a straight
wire has a ratio of 1:1, that is, the output level tracks the input
level perfectly. A 2 dB change at the input produces a 2 dB
change at the output.

For a 10:1 ratio, a 10 dB blast at the input would rise only
1 dB at the output – heavy compression. Kinder, gentler ratios
are in the 2:1 to 3:1 range. Figure 2 illustrates various Ratios.

FIgure 2. Threshold at -20 dBu. Ratios of 1:1, 2:1, 4:1, and 10:1.

Vertical axis = output level, horizontal axis = input level.

Referring to Figure 2, note that the Ratio indicated is the
average over 40 dB of compression. The ratio is initially
lower. This action provides a “soft” response which is less
audible than hard limiting. For example, the 10:1 ratio
response shows an initial ratio of about 6:1 and ends with a
ratio of ∞:1.

ATTACK TIME

Attack is the time which passes between the moment the
input signal exceeds the threshold, and the moment that the
gain is actually reduced. This can be a difficult control to set,
so Rane made it easier by pre-setting an attack time of 30 ms/
10 dB step, an optimal setting for a wide variety of material.

Figure 1. Set to 2:1 Ratio. Thresholds at -40 dBu, -20 dBu, and 0 dBu.

Vertical axis = output level, horizontal axis = input level.

Manual-4

0 dBu

-20 dBu

-40 dBu

RELEASE TIME

Release time is the time which passes between the
moment the input signal drops below the threshold and the
moment that the gain is restored. Another difficult control for
the average user to adjust, Rane presets the release rate at

0.3 dB/ms.

LIMITING

A limiter is a special form of compressor set up especially
to reduce peaks for overload protection. In other words, it is
a compressor with a maximum ratio. A compressor is usually
set up to change the dynamics for purposes of aesthetics,
intelligibility, or recording or broadcast limitations. Once the
threshold of a limiter is reached, no more signal increase is
allowed. The MC 22 acts as a limiter when set at a very high
ratio of 10:1.