MR-66
MULTIPLEX
GENERAL DESCRIPTION
Use the Mclntosh MA6 Multiplex Adapter to
hear FM stereo from the MR66 FM Tuner.
Careful, thorough engineering and superior designing eliminate the need for critical adjustment in the field.
In multiplex broadcasting, both left and
right channels of a stereo program are transmitted over one FM station. The simple broadcasting of left channel and right channel
needed one basic improvement. Those who did
not have multiplex equipment would only
receive half a program. A new broadcast technique called matrixing was developed to overcome this problem. In the new technique the
left and right programs (L + R) are added elec-
tronically. The L + R signal is centered on a
portion of the station's assigned spectrum
called the main carrier. At the same time the
left and right programs are subtracted (L- R).
ADAPTER
MA6
The L— R signal is centered on another portion
of the station's assigned spectrum called the
sub-carrier. (The FCC also permits the stations, if they choose, to use another part of the
assigned spectrum for non stereo music trans-
mission. This additional program is called SCA,
sub-carrier authorization. The multiplex unit
electronically protects your stereo listening by
preventing SCA from interfering.)
In a FM tuner receiving multiplex, the sig-
nals are again matrixed. The matrixing in the
tuner separates the two channels so that we
hear the broadcast as stereo. The process
written algebraically is: (L + R) + (L-R) = 2L;
(L + R) - (L-R) = 2R. In a FM tuner not
equipped with a multiplex decoder, the broadcast is heard as L + R, a complete monophonic
program.
TECHNICAL DESCRIPTION
The MA6 Multiplex Adapter uses a special
Mclntosh developed detecting circuit. One of
the advantages of this circuit is the elimination of the critical adjustments necessary with
commonly used matrixing methods.
A temperature stabilized 19KC amplifier
locks-in a highly stable push-pull synchronous
oscillator. Apart from other advantages this
SPECIFICATIONS
Weight: 1 Ib. 2 oz.
Shipping Weight: 1 Ib. 10 oz.
Dimensions: 21/8 inches wide; 3¾ inches high
83/16 inches long.
Hum Level: Better than 60db below 100%
stereo modulation.
Distortion: Less than 0.3% (Multiplex Unit
only).
Suppression of pilot (19KC) and Carrier
(38KC): Greater than 40db below 100%
modulation.
method provides greatest noise immunity.
Balanced detectors cancel 19KC and 38KC
components in the output and assure low noise
and distortion.
A three-section sharp cut-off filter rejects
SCA interference and reduces susceptibility
to spurious signals.
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