McIntosh C32 Owner's Manual page 11

EXPANDER
The EXPANDER affects both channels of the LISTEN
program line only. The circuit enables you to correct for
the compression that is imposed on most of the program
material available—records, tapes and FM. Compression
is used for many practical reasons but limits the dynamic
range—and, therefore, the realism—of the music. Programs
vary in their need for expansion. Live recordings may not
need any at all. Rotation of the EXPANDER causes the
loudness of the program to be affected logarithmically.
The point at which operation of the expander starts is
selected by the rotary LEVEL MATCH control on the top
panel. The attack speed of the expander is set with the
SPEED switch on the top panel. Settings of FAST, NORM
and SLOW change the attack time of the expander.
As the EXPANDER control is rotated clockwise the circuit
acts in two ways:
1. Loudness is reduced for signals below a predetermined
set level. The farther below set level the program is, the
more the loudness is reduced.
2. Loudness is increased for signals above set level. The
greater the program is above set level, the more the
loudness is increased.
The amount of loudness expansion imposed on incoming
signals is determined by the position of the EXPANDER
control. Clockwise rotation increases the effect. As the
EXPANDER knob is rotated clockwise, undesirable noises
such as hum, scratch and hiss are reduced. The charts
show the action of the EXPANDER CIRCUIT. When rotated
fully counterclockwise, the front panel EXPANDER knob
activates a switch which completely by-passes all EX-
PANDER circuitry.
The LEVEL MATCH control on the top panel of the C 32
adjusts the set level. This is the point above and below
which expansion is introduced when the EXPANDER knob
is turned clockwise. Set the LEVEL MATCH controls for each
channel while listening to a program. Switch the EXPANDER
in and out. The average sound level of the system should be
the same with the EXPANDER knob in the desired position
of EXPANSION as it is in the bypass (OFF) position.
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