Audio Database

Commentary

Stereo pre-main amplifier with all stages directly connected + pure complimentary service circuit.

The power amplifier consists of an all-stage direct-coupled circuit from the first stage to the last stage without the interstage coupling capacitor, a pure complimentary service circuit using the Darlington method of PNP-NPN for the output stage, and a ± 2 power supply system using the first stage differential-type.
As a result, various characteristics in the low frequency range have been thoroughly improved, and stable output has been obtained over the entire audible frequency range.

A limiter protection circuit is used to protect the transistors, and a relay is used to protect the speakers and prevent shock noise when the power is turned ON/OFF.
When the output terminal is short-circuited, the limiter level is lowered within 100m ・ sec to protect the transistor.

The equalizer uses a 3-stage direct-coupled first stage differential circuit.

The tone control circuit uses a DLOA (dual low-noise operational amplifier).
The DLOA consists of a first stage differential amplifier, a buffer, a 3-stage class A drive, and a pure complimentary service. This realizes a high dynamic range, high input impedance, high power utilization factor, low impedance, and low distortion factor. Shock noise is also suppressed because the DC current at the output terminal is 0 v.
In addition, a tone control defeat switch is provided.

The low filter uses a subsonic filter and a rumble filter.
Also, a scratch filter is used for the high filter.

Equipped with audio muting and mode selector.

Equipped with 4 ch input / output terminal.

Equipped with a microphone terminal.

Since around 1975, carrying handles have been sold as a separately sold option.

Model Rating
Type Solid-state stereo premain amplifier
Power Amplifier Unit
Effective power
20 Hz to 20 kHz, both channel operation : 50W + 50W (8 Ω)
1 kHz Single channel operation : 90W/90W (4 Ω)
65W/65W (8 Ω)
Both channel operation : 70W + 70W (4 Ω)
55W + 55W (8 Ω)
Music Power (IHF) 250W (4 Ω)
160W (8 Ω)
Total harmonic distortion factor (8 Ω) 0.3% (at rated output)
0.05% (Rated Output -3dB)
Cross modulation distortion factor 0.3% (at rated output)
0.05% (Rated Output -3dB)
Output Bandwidth (IHF) 6 Hz to 45 kHz
Residual noise (8 Ω) 0.5mV
Damping factor (8 Ω) 30
Optimum load impedance 4 Ω ~ 16 Ω
Preamplifier Section
Input Sensitivity / Impedance Phono1, 2 : 2.5mV/50k Ω
Tuner, Aux, Tape playA, B : 150mV/50k Ω
Mic : 2.5mV/50k Ω
4 ch input : 150mV/50k Ω
Signal-to-noise ratio (IHF-A network) Phono1, 2 : 84 dB (input 5 mV)
Tuner, Aux, Tape PlayA, B : 95 dB
4ch input:95dB
Output Level / Impedance Tape rec Pin : 150mV/50 Ω
Tape rec Din : 40mV/70k Ω
4 ch out : 150mV/50 Ω
Maximum Allowable Input (1 kHz, RMS) Phono:250mV
Frequency characteristic Tuner, Aux, Tape play : 10 hz to 20 khz + 0 to 0.5 db
Phono : RIAA deviation ± 0.5 dB
Tone control Bass : ± 10 dB (100 Hz)
Treble : ± 10 dB (10 kHz)
Filter Low : 20, 40 Hz, 12dB/oct.
High : 7 kHz, 6dB/oct.
Loudness control (Volume-30dB) +8dB(100Hz)
+3dB(10kHz)
<General>
AC outlet Power switch interlock : 2 systems
Power switch not linked : 1 system
Power supply voltage 100 VAC, 50Hz/60Hz
Rated power consumption (Electrical Appliance and Material Control Law) 140W
External dimensions Width 435x Height 157x Depth 300 mm
Weight 11.8kg
Sold Separately Carrying Handle D-9 (1 pair, ¥ 5,000)