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. High-Selectivity and Low-Distortion 1F Amplifier Using ICs, and 3 Ceramic Filters
A 4-stage differential amplifier is employed. The extensive use of |Cs, together with 3 cermic filter elements
having good phase characteristics in the FM-IF amplitier greatly improves the limiter and selectivity character-
istics.
. Quadrature Detection
Quadrature detection with the extensive use of ICs yields a wide band coverage and low distortion.
. Phase-Locked Loop IC for FM/MPX Circuit
A PLL-IC, which was developed by HITACHI, is used for the FM/MPX
circuit to produce a high separation
and low distortion, Also, high reliability is achieved with respect to temperature and aging.
. Ceramic Filter, iCs tn AM Tuner
A ceramic filter is employed in the AM tuner to obtain high selectivity and AGC characteristics. The extensive
_use of ICs enables stable reception to be achieved.
. Two Large Easy-to-read meters and a Large-sized Fiy-wheel Tuning Knob
Two easy-to-read
meters are used for signal tuning. The dial mechanism employs a large-sized flywheel with
a high moment of inertia for easy operation.
Audio Section
1.
Newly Developed High-Efficiency High Power Audio Amplifier (Dynaharmony Amplifier)
This amplifier delivers a higher dynamic power output (150 watts per channel, 8 ohms) without distortion
than conventional Class B amplifiers.
|
The relative low power consumption of Dynaharmony operation minimizes the heat sink of power transistors,
and slims down the weight and size of the whole amplifier. This amplifier has 2 pairs of DC power supplies.
Under this method, Dynaharmony operation can deliver dynamic power which is more than twice the value of
the maximum rated power output or more.
. Electronic Protection Circuits
HITACHI's
original, highly reliable electronic protection circuits protect the speakers and power transistors.
When a fault occurs, the circuit is switched off and this is then displayed on the front panel by the light-
emitting diode.
. Separate Power Meters (L and R channels)
To see the actual power output while you are listening, two new attractive power meters are provided.
. Tape Dubbing
Tape dubbing can be done either from TAPE-1 to TAPE-2 or vice versa. |n addition, a source monitor circuit,
with which tape dubbing is possible while listening to an FM broadcast or a record, is provided.
. Midrange Tone Control
This amplifier has not only BASS and TREBLE tone controls but also a MIDRANGE
tone control.
By setting these three controls, you
can
choose
the preferred frequency characteristics of the amplifier.
The controls all have 11 click stops. This feature offers good feel which makes for easier setting and resetting.
. Low Filter and High Filter
The {ow filter cuts out the low frequency noise such as the turntable rumble and the high filter cuts out high
frequency noise such as the scratch noise of records while listening to FM broadcasts.
. Two Speaker Systems
Two different types of speaker systems can be connected to the unit and they can be selected simply by
flipping a switch.
CONNECTING
1.
It
CONNECTION
OF SPEAKERS
is possible to connect two pairs of speaker systems to the SR-904, You can use the two pairs of speakers simul-
taneously and enjoy music in different rooms using the SPEAKERS switches @.
NOTES:
pedance of the speakers is only 2 ohms and so
(1) As illustrated in the figure, on the cover page,
the PROTECTION indicator @ will come on.
the right side terminals are for the left chan-
Avoid
using
this arrangement.
Be sure
to
nel, and left side channel are for right channel.
connect speakers of more than 8 ohms when
The red terminals. are positive
(+), and the
two
sets
of
speakers
are
to
be operated
black terminals
are negative
(-). Make
sure
simultaneously.
the polarities of the terminals in this receiver
(3) Turn
the SPEAKERS
switches
@) off when
correspond to those of the speakers terminals
only headphones are being used.
85).
(2) When 4-ohm
speakers are connected to both
A and B, and the SPEAKERS
switches A and
B @ are both depressed, the combined im-
of the speakers
Is only 2 ohms
and so the
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