Output Connections; Ground Connections (Program Sources) - McIntosh C20 Owner's Manual

Figure 7. Turntables Feeding Low Level Input.

OUTPUT CONNECTIONS

Two sets of outputs, located in the upper left-hand
corner of the back panel, are provided. (See Figure 8.)
The MAIN output connects to power amplifiers
(Figure 9) and the TAPE output to feed a tape recorder.
Figure 8. Output Connections
LEFT AMPLIFIER
Figure 9. MAIN Output Connected to Power Amplifiers
The MAIN and TAPE output jacks are fed from
cathode followers. The input impedance of devices
connected to these outputs should be 50,000 ohms or
greater, and the capacitive reactance of audio cables
connecting these devices should not be less than 8,000
ohms at 20,000 cycles. This is the reactance of a
capacity of 1,000 mmf. Audio cable having a capacity
of 25 mmf per foot may be 40 feet long; 13.5 mmf per
foot cable may be 75 feet long.
The TAPE OUTPUT is unaffected by any adjust-
ments made with the following controls: MODE SELEC-
TOR, BALANCE, PHASE, LOUDNESS, BASS, TREBLE,
RUMBLE FILTER and VOLUME. Any adjustments made
in the INPUT SELECTOR, RECORD COMPENSATOR,
and the HF CUTOFF FILTER will affect the signal at
the TAPE OUTPUT jacks if the signal originates in the
phono or tape heads inputs.
C20 Preamplifiers, Serial No. 6L700 and later,
have an additional left plus right output jack. A mono-
phonic signal can be distributed to other rooms by con-
necting this jack to a power amplifier to drive the
monophonic loudspeakers. The cable connecting to
this output should not have a capacity of more than
30mmf. The input impedance of the power amplifier
connecting to this output should not be less than
150,000 ohms (150K). The generator impedance at
this output is approximately 23,000 ohms (23K).
G R O U N D CONNECTION (PROGRAM SOURCES)
A single ground post
ground from turntable, record changers (motors used
with each), tape decks, etc.,
post. Do not duplicate this ground
sirable hum is likely to be heard in the system if dupli-
cate ground returns are used.
The left and right program cables from each
source should be twisted together and the ground wire
from each source can be wound or twisted in with these
cables. To avoid hum. make sure the ground wire does
not make any connections to shields of the left and
right channel cables except for the connection pro-
vided with the C20 ground post.
RIGHT AMPLIFIER
is provided. The chassis
should be returned to this
circuit. Unde-
9