McIntosh C33 Owner's Manual page 10

Two stereo power amplifiers or two delay units
may be connected in the same fashion to the OUT-
PUT 1 and OUTPUT 2 jacks. Audio output signal is
supplied to these jacks only when the front panel
pushbutton SPEAKER/OUTPUT 1 and/or 2 pushbut-
tons are pushed. This arrangement is useful for
large systems where separate amplifiers and
loudspeakers are used at distant locations.
SPEAKER CONTROL RELAY (an optional accessory)
The SPEAKER CONTROL RELAY, or SCR, is de-
signed to provide both speaker control switching
and high power switched AC outlets. To control
loudspeakers, SPEAKERS 1 and 2 pushbuttons on
the front panel must be used. When this is done,
OUTPUT jacks 1 and 2 are normally not used. The op-
eration of output jacks and speaker control will
otherwise interfere with each other.
Plug the cable from the SCR into the C 33 back
panel SPEAKER CONTROL RELAY receptacle. Con-
nect the power amplifier output to the FROM
POWER AMPLIFIER terminals on the SCR. Observe
correct channel identification as well as correct
polarity. The MAIN speakers (controlled by SPEAK-
ER 1 pushbutton) are connected at the TO MAIN
SPEAKER terminals. The REMOTE speakers (con-
trolled by SPEAKER 2 pushbutton) are connected at
the TO REMOTE SPEAKERS terminals. Again
observe correct channel identification and polarity.
The SCR also has two AC power outlets that pro-
vide additional capacity of 2400 watts switched by
the C 33. Use these outlets to supply AC power to
amplifiers or other components whenever the total
load to be switched by the C 33 exceeds the rating of
1200 watts. For proper operation, the cable from the
SCR must remain connected to the SCR receptacle
at the back of the C 33. Plug the SCR heavy line cord
directly into a wall outlet. Do not plug it into the C 33.
When the C 33 is turned on, power from the C 33 will
energize a relay in the SCR which connects the two
SCR AC outlets directly to the wall outlet.
MONITOR AMPLIFIER
Although its primary purpose is to drive head-
phones, the monitor amplifier can also be used to
drive speakers. This eliminates the need for a separ-
ate stereo monitor amplifier. The monitor amplifier
will furnish 20 watts per channel into 8 ohms or 12.6
volts RMS into a 600 ohm line. For operation see
MONITOR AMPLIFIER page 17. The speakers can be
connected to the red and black output terminals at
the rear of the C 33. Connect the left speaker minus
lead to the black OUTPUT COM terminal closest to
the center of the C 33. Connect the left plus speaker
lead to the red OUTPUT L terminal. Connect the right
speaker minus lead to the black OUTPUT COM ter-
minal closest to the C 33 ground terminal. Connect
the right plus lead to the red OUTPUT R terminal.
Resistance of the speaker hookup wire should be
kept less than 0.5 ohms to avoid losses and
response changes.
The monitor OUTPUT jacks can be connected to
drive a low impedance
The INPUT jacks are used when an external source
is fed to the monitor amplifier.
CONNNECTING AC POWER
The preamplifier AC power cord is to be plugged
into a 120 volt 60 Hz wall outlet.
Two types of AC power outlets are on the back
panel of the C 33. Four are black and two are green.
The black outlets are switched on and off when
the C 33 is turned on and off. These are intended for
power amplifiers, equalizers, and others accessor-
ies totaling up to 1200 watts capacity.
The green AC power outlets are on at all times and
are for use only with turntables. Do not use them for
any other purpose. The turntable can be used as a
power switch as described in the following section.
USING THE TURNTABLE AS A POWER SWITCH
If a turntable is used with the C 33, it can often be
used to turn your entire system on and off. The turn-
table must be plugged into one of the green AC out-
lets at the rear of the C 33. The AUTO/MANUAL
switch also at the rear must be in the AUTO position.
When you switch on the power to the turntable, a
special sensor circuit will detect the current drain of
the turntable and will turn on the C 33 the same way
the red POWER pushbutton does. The red pushbut-
ton must be in the OFF or out position to do this.
Read the section on AUTO-ON SENSIVITY on page
17 before using this feature.
CONNECTING PROGRAM SOURCE GROUNDS
A GROUND post is provided to connect the grounds
from record changers, tape decks, etc. To prevent
hum pick-up, the left and right program cables and
the ground wire from that source should be wound
or twisted together. Make sure the ground wire does
not make any connection to the shields of the left
and right program cables as they run between the
source and the input of the preamplifier.
FUSE
A 1.0 AMP fast acting fuse protects the C 33 turn-
table current sensing circuits and the green AC turn-
table outlets. The fuse does not protect equipment
connected to the black AC outlets. This fuse must
be replaced with the same type and rating. Do not
use SLO BLO fuses.
-8-
unbalanced line.