Audio Database

SC-55
Commentary

A thin-design stereo power amplifier with affordable output and high quality playback sound.

A 2-stage 3-stage Darlington direct-coupled pure complimentary service OCL circuit with cascode connection at the first stage is adopted.
In addition to making the phase correction capacitor as small as possible, by adopting a differential driver circuit that changes from common-emitter to common-base in the high frequency range, the naked gain at the high frequency range is improved.

The power supply section has an independent power transformer for the left and right channels to improve the separation.
The power supply unit is equipped with two low-magnification 10,000 μ F capacitors for each channel. This capacitor increases the current density by widening the current path and keeps the impedance low. In addition, a metalized polyester film capacitor is used in parallel for the electrolytic capacitor to improve the high-frequency characteristics.
Each stage up to the driver stage is supplied with power by a constant voltage circuit to improve the stability of operation.

Copper foil with a thickness of 70 μ m is used for the PC board, and the SN ratio and separation are improved by reducing the impedance of the signal system.

A metal-coated high-precision attenuator is used for level control.

It is equipped with a gain selector switch that can increase the input sensitivity by 6 dB. This switch adopts a method of changing the amount of NF in the first stage.

It is equipped with protective circuit which combines electronic circuit and relay, and protects amplifier and speaker.
This circuit has a structure that uses both midpoint voltage detection and abnormal voltage detection, and at the same time prevents click noise during power ON/OFF.

2-series speaker switching is possible.

The meter detection terminal is installed in parallel with the speaker terminal, and the output level can be checked by connecting to the peak meter unit (PM-55, sold separately).

A CADIS data sheet is attached.

There was a carrying handle for mounting on a standard 480 mm wide rack sold separately.

Model Rating
Type Stereo power amplifier
Circuit system First Stage Cascord Connection / Differential 2-Stage
Pure complimentary service OCL circuit directly connected to all stages
Continuous Output (20 Hz to 20 kHz, Both Channels Driven, 0.05% Distortion) 60W + 60W (8 Ω)
85W + 85W (4 Ω)
Harmonic distortion factor
20 Hz to 20 kHz :


1kHz:
50kHz:
0.05% (Continuous Output)
0.02% (at 30W output)
0.05% (at 1W output)
0.005% (at 30W output)
0.03% (at 30W output)
Intermodulation distortion factor (50 hz : 7 khz = 4 : 1) 0.08% (at continuous output)
0.05% (at 1W output)
Output Bandwidth (IHF) 5 Hz ~ 80 kHz (0.1% Distortion)
Frequency characteristic 5 Hz ~ 100 kHz + 0 -3dB at 1W Output
Input Sensitivity / Impedance 1.0V/50k Ω
* Sensitivity can be increased by 6 db by switching the switch.
Damping factor 50 (8 Ω)
Signal-to-noise ratio (IHF-A network) 105dB
Channel separation 80dB(1kHz)
65dB(10kHz)
Residual noise 0.3mV
Semiconductor used Transistor : 38
Diode : 16 pcs
Pwer 100 VAC, 50Hz/60Hz
Power consumption 165W
External dimensions Width 450x Height 93x Depth 375 mm
Weight 14kg
Sold Separately Carrying Handle TO-1 (Left / Right 1 Set, ¥ 3,000)