McIntosh MA6 Installation And Connections

Use the Mclntosh MA6 Multiplex Adapter to
hear FM stereo from the MR66 FM Tuner.
Careful, thorough engineering and superior de-
signing eliminate the need for critical adjust-
ment in the field.
In multiplex broadcasting, both left and
right channels of a stereo program are trans-
mitted over one FM station. The simple broad-
casting 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 tech-
nique called matrixing was developed to over-
come 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).
The MA6 Multiplex Adapter uses a special
Mclntosh developed detecting circuit. One of
the advantages of this circuit is the elimina-
tion 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

GENERAL DESCRIPTION

TECHNICAL DESCRIPTION

SPECIFICATIONS

Weight: 1 Ib. 2 oz.
Shipping Weight: 1 Ib. 10 oz.
1
Dimensions: 2 / inches wide; 3¾ inches high
8
3
8 / inches long.
16
Hum Level: Better than 60db below 100%
stereo modulation.
Distortion: Less than 0.3% (Multiplex Unit
only).
Suppression of pilot (19KC)
(38KC): Greater than 40db below 100%
modulation.
MULTIPLEX
ADAPTER
The L— R signal is centered on another portion
of the station's assigned spectrum called the
sub-carrier. (The FCC also permits the sta-
tions, 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 broad-
cast is heard as L + R, a complete monophonic
program.
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.
and Carrier
MA6