|75,000yen(around the 1978 time)
It is the stereo power amplifier aiming at a miniaturization, maintaining
In order to improve a low-pass phase distortion and TIM, direct-current-ization which excluded entirely the capacitor used as the damping time constant of a circuit is adopted. This has realized the characteristic [ flat / to a direct-current region ].
In order to improve the elongation
of a high region, RET (ring emitter transistor) is adopted as a power
transistor. furthermore, the gain before applying a negative return -- each of
each stage -- the negative return which is aiming at improvement in the
nakedness characteristic by distributing the optimal, and was stabilized to high
frequency is made easy to apply.
The amount of negative returns in low
frequency was reduced, increased the amount of negative returns in that much
high frequency, and, specifically, has proposed distortion.
characteristic is well equal to the first rank, and also gm (mutual inductance)
is large, and the noise of itself has adopted extremely little original low
noise dual FET. This has improved the S/N ratio.
Two filter condensers
of 55V/20,000micro F and the power transformer of 250VA which efficiency carried
out the cut core which can do a miniaturization highly, and it had are adopted
as a power-source part. This power-source part is the magnitude which occupies
about 40% of the capacity inside amplifier, and has structure with a power
source powerful with small size.
The peak level indicator by the LED display of 12 single-sided channels
In order to attain a
miniaturization, power supply circuits other than a power transformer and a heat
sink are summarized on the printed circuit board of one sheet.
[ and others ] cautions are in combination of the magnetic flux produced by a
large power-source part, and in order to lose the magnetic flux combination
during input and output, consideration fine also about part arrangement of an
input circuit and an output circuit and leading about of a Copper-foil pattern
is carried out.
Furthermore, by miniaturizing a printed circuit board, a
Copper-foil pattern becomes narrow, about the problem which affects the
impedance of a pattern, in proportion to the magnitude of current, a Copper-foil
pattern is made large, and influence of pattern impedance is lessened.
The heat sink was exposed on the right-and-left side, and also air was
taken in from the front panel lower part, the convection current was caused also
inside the set, and the heat stability which also bears the Oide power is
The protection circuit respectively independent of the speaker
and amplifier side is carried.
||Stereo power amplifier
||Three steps of differential amplification
Current mirror drive Darlington single PP (direct-current amplifier)
||70W+70W (8 ohms, 15Hz - 20kHz, THD0.01%)
||0.004% (8 ohms, a rated-3dB output, 20Hz - 20kHz)
0.006% (8 ohms, 1W output, 20Hz - 20kHz)
|Cross modulation distortion
|0.008% (8 ohms, Output power)
ohms, 1W output)
||10Hz - 60kHz (8 ohms, THD 0.05%)
||80 microvolts or less
|Phono Output voltage
||Width 270x height 140x depth of 243mm