|315,000yen(around the 1975 time)
Stereo power amplifier
which challenged the threshold of the likelihood based on the true nature of an
audio in order to make true quality articles, finished by handmade carefully
from the assembly of component partses to the last coordination, and was
completed at the high number of dimensions.
Using a differential
amplification as two steps and a balanced amplification, the input circuit drove
the driver stage with the pre driver of the Class-A push-pull circuit, and also
has adopted the circuit system led to the power stage of the good triple push
pull of a linearity also at the time of a large current.
All the circuitries
have improved the property which adjusts a gain the optimal and to which NFB is
not applied by local current feedback, and have stopped the quantity of NFB to
Moreover, the Class-A PP circuitry of the pre-driver
stage has balanced completely in direct current, it starts with
low-distortion-ization, and the improvement in a property has an effect.
The peek power meter which can carry out the Direct reading of the
musical peaking capacity level in the value of power is carried, and the tick
mark can carry out a Direct reading without a sensitivity change by adopting a
logarithmic comression circuitry to 0.01W-200W (-40dB - +3dB).
adopts the 磁 type meter outside large-sized with a quick and sufficient dumping
as meter, and a pointer sways in a legible location also at the time of a small
The glass epoxy group board with high intensity and
robustness is adopted as the printed circuit board.
and reliable component partses are selected carefully and used for the volume
for level controls of a speaker until it results a sealing type communicated
type in each of the resistors from a transistor further.
A power-source part
has little leakage magnetic flux, and the large-sized cut-core power transformer
excellent in the regulation and the power source capacitor of 33,000 micro Fx2
Three speaker terminations are carried and each system
carries the level control.
The protection network has adopted the scheme
which divided the functionality into two.
One protects a speaker, when
direct current voltage occurs in an output, and it serves also as the
power-source muting. Another prevents a corruption of amplifier from the
overcurrent by a load-intensity short-circuit etc., and the method of detecting
a trouble and restricting an input is taken.
Both detected the operation
quickly in the detection circuitry, and circuit component part and a speaker
system are protected certainly.
In order to prevent the surge current at
the time of a power-switch injection, the current limiting was performed using
the relay at the time of a switchpoint injection, and the surge current
preventing circuitry which will be in normal operating state in several seconds
By the circuit changing switch of the front panel, a
selection of 1V and 2V is possible for Input sensitivity according to a
Moreover, the Subsonic Filter builds in CR type and
on/off of it is possible if needed.
The actual measurement measured for
every set is attached as it is.
||Stereo power amplifier
||2 steps of differentials PP drive
Three-step Darlington triple PP
Pure complimentary OCL scheme
||150W+150W (8 ohm, 20Hz - 20kHz, B.C.D)
||0.1% or less (at the time of an Output
||5Hz - 35kHz
||10Hz-80kHz+0 -1 dB
||35 (8ohm) or more
||Input1, 2:1V, 2V
||8Hz, 6dB / oct
|Speaker level control
||A, B, and C are :0--20dB.
|Peek meter indicating range
||0.01W-200W (-40dB - +3dB)
|The semiconductor used
||Transistor: 84 pieces
IC: Six pieces
Diode: 82 pieces
||Width 468x height 206x depth of 370mm