Audio Database


A newly designed stereo pre-main amplifier with performance and functions similar to the AU 999.

The main amplifier section is fully connected with a 2-stage differential-amplifier circuit and two positive and negative power supplies without capacitor, and adopts complimentary service Darlington circuit system.
As a result, uniform NFB is applied from the DC range to the entire audio range, the damping factor and output characteristics are constant up to the ultra-low range, and the speaker's blur in the ultra-low range is reduced, reducing intermodulation distortion.

The preamp section uses a PNP silicon transistor which has less noise than the NPN silicon transistor to reduce noise.

We use direct-coupled circuits as much as possible, minimize capacitors, increase circuit impedance where necessary, and use a Mylar type to reduce electric field capacitors as much as possible.
In addition, Mylar type capacitors are used in parallel for areas where electric field capacitors are absolutely necessary to improve high-frequency characteristics.

A dedicated transistor is used for temperature compensation, a differential amplifier stabilization circuit is used for the 2-stage differential amplifier to further stabilize the differential amplifier, and a protective circuit is used with 6 quick disconnect fuses.
When the power transistor is damaged, an abnormal voltage is generated and DC current does not flow to the speaker. A speaker protection circuit using SCR is installed to protect the speaker even in an emergency.

Includes Bass, Midrange and Treble T. T. C (Triple Tone Control).
This allows for more accurate program and room acoustic compensation.

The preamp and main amplifier can be used independently at the position of the speaker switching C system so that a multi-amplifier system can be constructed while taking advantage of the performance of the preamp and main amplifier sections.

Mid-range correction is more accurate with a tone selector that allows you to switch between two frequencies of up and down defeat.

The + and - power supplies of the main amplifier and the power supply of the preamplifier are equipped with independent ripple filter circuits to cut off ham components and stabilize the power supply.

It is equipped with functions such as low filter, high filter, loudness, headphone jack and muting switch.

Model Rating
Type Stereo pre-main amplifier
Main Amplifier Section
Rated output
Music Power (IHF) : 140W (4 Ω)
100W (8 Ω)
Effective power : 50/50W (4 Ω)
45/45W (8 Ω)
Total harmonic distortion factor 0.4% or Less (Rated Output)
Intermodulation Distortion Factor (SMPTE, 60 hz : 7 khz = 4 : 1) 0.4% or Less (Rated Output)
Power Band With (IHF) 10 Hz ~ 40,000 Hz (8 Ω)
Frequency characteristic 10 Hz to 70,000 Hz, ± 1 dB
Channel separation 50 dB or More (1 kHz, Rated Output)
Hum and noise (IHF) 100 dB or more
Input Sensitivity / Impedance (Rated Output, 1 kHz) 1V/50k Ω
Damping factor 20 (8 Ω Load)
Load impedance 4 Ω ~ 16 Ω
Preamplifier Section
Output voltage Maximum output voltage : 4 V
Rated output voltage : 1 V
Total harmonic distortion factor 0.1% (Rated Output Voltage)
Frequency characteristic 15 Hz to 50,000 Hz, + 0.5 -1.5 dB
Channel separation Phono:50dB
Hum and noise (IHF) Phono1, 2 : 80 dB or more
MIC : 80 dB or more
Tuner, AUX : 85 dB or higher
Input Sensitivity / Impedance
(Rated Output Voltage, 1 kHz)
Phono1 : 2mV/50k Ω
Phono2 : 2mV/30k Ω, 50k Ω, 100k Ω
MIC : 2mV/50k Ω
Tuner : 180mV/100k Ω
AUX : 180mV/100k Ω
Tape Mon (Pin) : 180mV/100k Ω
Tape Recorder (Din) : 180mV/50k Ω
Recorded output Tape Rec(Pin):180mV
Tape Recorder(Din):30mV
Tone control Bass : 20 Hz + 12 -8dB (2 dB step)
Midrange : 1,000 Hz, 2,000 Hz ± 5 dB (in 1 dB steps)
Treble : 20,000 Hz + 12 -8dB in 2 dB steps
Tone selector Midrange : Defeat, 1,000 Hz, 2,000 Hz
Loudness : + 8 dB (50 Hz), + 3 dB (10,000 Hz)
SWITCH High Filter : 10,000 Hz, -8dB (12dB/oct, NF Type)
Low Filter : 50 Hz, -8dB (12dB/oct, NF Type)
Muting : -20dB
Power supply voltage 100 V, 50Hz/60Hz
Power consumption 400W at maximum input
External dimensions Width 460x Height 140x Depth 305 mm
Weight 12.6kg