|220,000yen(December, 1980 release)
The stereo control center which adopted the Duo beta
Superfluous NFB of physical characteristic priority was eliminated and
the Duo beta circuitry is adopted as a technology controlled by balance
with a tone quality. This circuitry makes an amplifier circuitry to the
extent that it is used also from a nakedness property as it is, and adds
a proper quantity of NFB and DC servoes as finish of a tone quality.
carrying out like this, by NFB, musicality is oppressed, the transitional
distorted occurrence of TIM etc. by · and superfluous NFB is suppressed, and
musicality is raised.
The Duo beta plusX which introduced the thought of
the suitable control also into the feedback circuit of the power-source part is
The general stabilizing supply was given training in gap of an outgoing
end, applied the feedback powerfully, and has lowered the impedance. On
the other hand, although the impedance characteristic of the unstable power
source itself rises on low-pass and a tone quality improves, there are
problems low-pass dumping does not become sweet or the stability in a
direct-current region is not acquired.
The low-impedance power source without the necessity
of depending on a superfluous feedback was made from plusX, and the control of
the control in which this nakedness property was harnessed corresponding to the amplifier circuitry in low-pass is set up in the mid-high range.
equalizer circuitry, the cascode bootstrap input by low-noise dual FET of high
Gm was adopted as the first rank by the current mirror load intensity, and the
low distortion and the high SN ratio have been obtained.
In the second step, the cascode constant current load-intensity amplifying
circuit with the high fT-PNP transistor which allotted the dynamic-resistance
circuitry is constituted. An electric current is sent through an output
stage as a Class-A push pull stream composition with the transistor of
high fT, and the margin is also given to the load intensity of the NFB
element while impedance low -izing sending.
The same circuitry as
an equalizer is fundamentally used for flat amplifier, and it has secured
especially DC stability which carried the operational amplifier by an FET input
in DC servo circuitry, and was excellent.
By this, the output capacitor was
removed and coloring of sound is eliminated.
MC head amplifier of DC
stream composition by a right-and-left independent source uses the first rank as
the direct couple type of an FET parallel input, makes the output unit a Class-A
pure complimentary push pull, arranges a voltage stabilizer for exclusive use to
an adjacency, and is reducing a noise and source impedance.
power-source part serves as right-and-left full independence from the coil of
the transformer, is included to a rectifier circuit and a voltage stabilizer, and constitutes the twin monophonic power source.
This is suppressing the interference between right-and-left channels. Moreover,
the tone-quality modification is aimed at by arranging the orientation
of a coil the primary side of a transformer, and by the side of secondary.
A large size and
mass thing is adopted as the transformer and capacitor of this power source, and
low-impedance-ization is attained.
A good film capacitor is adopted as
the coupling capacitor of each stage, or the capacitor of a power source, and
parallel connection of the small capacity styrene capacitor is carried out to
All these film capacitors and most styrene capacitors arrange a
polarity, and they are carrying out the tone-quality mandatory.
the succession good transformation precision type Detent volume containing an
aluminum die-casting case, the oxygen-free-high-conductivity-copper 500 core
shielded cable, etc. are adopted.
Required sufficient functionality is
carried, a product-line path is arranged according to the fluence of a signal, and the simplification is attained.
The turnover shift type tone control
from which the balance of the purpose is obtained by simple operation is
In order that a turnover frequency may carry out a succession
migration according to a variation, two conventional operations are simplified.
The polarity of domestic AC plug socket is detected and the line phase
sensor which can unify the polarity of an equipment is carried.
T type subsonic-speed circuitry constituted only from a passive element is
Furthermore, in order to improve a tone quality, various
measures are taken everywhere.
Making it a chassis design by which the
magnetic substance does not approach a substrate opposite side etc. has put into
practice and eliminated a magnetic distortion.
Moreover, gilding is adopted
as an input/output terminal, it is made the secondary fuse of a transformer with
a pewter between fuse holders, and contact resistance is reduced.
Furthermore, the Tape system adopted the remote switch and has simplified
the product line.
The native wood cabinet was adopted, aluminum foil was
stuck on the rear view, and the shielding effect has been acquired.
||Duo beta plusX stereo control center
||Pre Out: -- standard -- a maximum of [ 1V
and ] -- 20V
Rec Out: Standard 140mV, a maximum of 20v
|Output load impedance
||Pre Out: 47ohms
Rec Out: 100ohms
|THD (20Hz - 20kHz)
||Phono man month/MC: Less than 0.005% (Rec
Tuner, AUX: 0.005% or less (Pre Out:1V)
or less (Rec Out:1V)
|Cross modulation distortion (60Hz:7kHz=4:1)
||Phono man month/MC: Less than 0.002% (Rec
Tuner, AUX: 0.002% or less (Pre Out:1V)
or less (Pre Out:1V)
0.5Hz - -140kHz 0.5dB
Monitor1, -2:0.5 Hz - 140kHz 0.5dB
|Input sensitivity (Pre Out:1V)
Tuner, AUX: 140mV
||Phono MC:high 100 ohm, Low 50ohm
man month:man month 50kohm, MC 100ohm
|SN ratio (an IHF-A correction, input
||Phono MC: -148 dB/V (input conversion noise)
Tuner, AUX: 100dB
||Turnover-frequency shift expression (the
object for high regions, for low-pass)
||7Hz (twin T type)
||MC impedance switching (high, low)
month/MCdirect impedance switching
Tone it1 switchpoint
Two tapes monitors (1, 2)
Tapes dubbing (1->2, 2->1)
Line phase sensor
||25W (Electrical Appliance and Material
||Switched: Two lines, total450W
Unswitched: One line, 500W
||Width 478x height 163x depth of 384mm