Audio Database


A compact stereo power amplifier that maintains high performance.

In order to improve low-frequency phase distortion and transient cross-modulation distortion, we have adopted DC without any capacitor, which is the time constant of the circuit, thereby realizing flat characteristics up to the DC range.

A RET (Ring Emitter Transistor) is used for the power transistor in order to improve the elongation of the high-frequency range. In addition, the gain before applying negative feedback is optimally distributed to each stage to improve the bare characteristics, making it easier to apply stable negative feedback to high frequencies.
Specifically, we propose distortion by reducing the negative feedback at low frequencies and increasing the negative feedback at high frequencies.

In the first stage, a unique low-noise dual FET with uniform characteristics, high gm (mutual inductance) and extremely low noise is adopted, which improves the S/N ratio.

The power supply consists of two 55V/20,000 μ F filter capacitors and a 250 va power transformer with a highly efficient and compact cut core. This power supply occupies approximately 40% of the volume inside the amplifier and is small but has a strong power supply.

It is equipped with peak level indicator by 12 LED display of one channel.

In order to reduce the size, the power supply circuits other than the power transformer and heat sink are integrated on a single printed circuit board.
In addition, attention is paid to the coupling of magnetic flux generated by the large power supply. In order to eliminate the coupling of magnetic flux between input and output, detailed consideration is also given to the arrangement of parts of input and output circuits and the routing of copper foil patterns.
In addition, with regard to the problem that the copper foil pattern becomes narrow by reducing the size of the printed circuit board and affects the impedance of the pattern, we have widened the copper foil pattern in proportion to the magnitude of the current to reduce the effect of the pattern impedance.

The heat sink is exposed on the right and left sides, and air is taken in from the lower part of the front panel, and convection is generated inside the set to ensure thermal stability that can withstand large output.

Independent protection circuits are mounted on the speaker side and amplifier side respectively.

Model Rating
Type Stereo power amplifier
Circuit system Differential amplifier 3-stage
Current Mirror Drive Darlington Single PP (DC Amplifier)
Rated output 70W + 70W (8 Ω, 15 hz to 20 khz, THD0.01%)
Harmonic distortion factor 0.004% (8 ohm, rated -3dB output, 20 hz to 20 khz)
0.006% (8 Ω, 1W output, 20 hz to 20 khz)
Cross modulation distortion factor
0.008% (8 Ω, Rated Output)
0.005% (8 Ω, 1W output)
Output bandwidth 10 Hz ~ 60 kHz (8 Ω, THD 0.05%)
Frequency characteristic DC ~ 200 khz + 0 -1dB
Input Sensitivity / Impedance 1V/50k Ω
Damping factor 100
Residual noise 80 μ V or less
S/N 123dB
Phono output level 0.1mW/W
Pwer 100 VAC, 50Hz/60Hz
Power consumption 160W
External dimensions Width 270x Height 140x Depth 243 mm
Weight 10kg
Attachment PIN-PIN code