Marantz 4270 - Marantz 4270 Dolby Unit

In the VARI-MATRIX position, 2-channel stereo input signals are converted into quadra-
phonic signals through the vari-matrix circuit; the input right and teft channel signals are fed
directly to the LF and RF channels, while the signals to the LR and RR channels are synthesized
from the 2-channel input signals under the control of the DIMENSION control. The LR and
RR channel signal components are controlled by the DIMENSION control as shown below.
DIMENSION Control Setting
Minimum {FCCW)
Center
Maximum (FCW)
When the DIMENSION control is set to the minimum position the LR and RR channel
signals become monophonic, to the center are stereophonic, and to the maximum are out of
phase, thus providing vanished sound image positioning.
In the SQ DECODER position, signal sources encoded by the CBS SO system are ideally
decoded into 4-channel signals. Required for this operation is incorporation of the SQ Adaptor,
Model SQA-1, into the Model 4270. :
4.2 Balance Control
Signals from the buffer amplifiers are fed into the balance control circuit, in which the
signals are controlled by three balancers: FRONT L-R, REAR L-R, and FRONT-REAR. By
setting the FRONT-REAR balancer to the “FRONT” side and the FRONT L-R balancer to the
“LY” side,.for example, only the front left channel is drived.
The
balance
control
circuit
is
provided
with
the
REMOTE
control
switch
which
makes
the
Model RC-4
Remote
Control!
Box
operative
when
set
to
the “REMOTE”
position.
In
the
“REMOTE”
position
the BALANCE
and VOLUME
controls
on the
Model 4270
become
ineffective
since
signals
are
led
to
the Model
RC-4.
The
balance and
volume
level
can
be
adjusted
by
the
Model
RC-4. Balanced
and
volume
controlled
signals
are
led
to
the
tone
control
amplifier.
5. DOLBY UNIT
The
Dolby
unit
built
in
Model
4270,
which
is
a
switchable
processor,
is
inserted
in
each
of
both FRONT
R
and
L
channels.
The
attached
‘‘DOLBY
PROCESSING
CHART”
will
facilitate
you
to
well
understand
the operation
of the
Dolby
circuit.
An input signal coming to J601 is amplified by H601, and its output signal is led to the filter
which cuts off the tape bias. The signal passed through the filter is further amplified and comes
to the mixing circuit of resistors R623 and R625 and to the phase inverting circuit of H607 and
H609. The output signal is fed out from J607.
In the recording mode of operation, the signal is fed out from J605 preceding the mixing
circuit and applied at J611. The signal is then discriminated in the frequency and level by the
dynamic filter consisting of H611, H613, H615 and H617, and is fed back to the mixing circuit.
in the playback mode of operation, a part of the output signal (at J607) is fed to J611 and
discriminated in the frequency and level by the dynamic filter consisting of H611, H613, H615
and H617 and fed back to the mixing circuit.
6. 400Hz TONE
The
400Hz
tone
signal
which
is
a
580mV,
400Hz
sine
wave
is
available
at
the
FRONT
and
REAR
TAPE
MONITOR
OUT
terminals
at
any
position of
the
DOLBY
switch (with
the
exception
of
the
RECORD
II position)
and
the
SELECTOR
switch.
The
output
signal
of
the
400Hz
oscillator
consisting
of
HLO1
and
HLO2
is
fed
to
JLO2
and
JLO3
through
the emitter
follower
HLO3. The output
levels
at JLO2
and
JLO3
are adjusted
to
580mV
and
approximately
50mV, respectively.