Commentary

This pre-main amplifier was developed for the new audio era by making use of the development technology and materials of the separate amplifier cultivated over many years.

A full-scale 3-amp configuration consisting of an equalizer amplifier for analog disks, a high-gain pre-amplifier and a power amplifier has been adopted to enhance the perfection of each.

The output stage of the power amplifier is 3 parallel push-pull with 6 transistors, and Pc (collector loss) is 130W per element, making up a powerful output stage with a total of 780W.
This realizes "low load drive" that can deliver sufficient power even for low load impedance.
MOS FET is used in the front stage of driving the output stage.
In addition, the input stage is a cascode system, and together with a constant current load, wide bandwidth and high linearity are realized.
The second stage differential amplifier circuit consists of a single-chip dual transistor as a complimentary service circuit, resulting in low noise and excellent stability.

All the unit amplifiers of each stage are connected directly from the analog disk input.
The problem of DC drift caused by direct connection is solved by stabilizing each unit amplifier with DC servo.

In order to suppress interference between unit amplifiers due to the power supply, electrostatic and electromagnetic induction, the transformer windings of the preamplifier and power amplifier are separated to prevent interference around the power supply, and a dedicated power supply is configured.
In addition, the preamp section is stabilized by a full-scale constant voltage circuit, and has been improved to the same level as an independent case amplifier.
In addition, it is carefully arranged and shielded against electrostatic and electromagnetic induction.

The equalizer amplifier section switches between the MC type and MM type according to the required gain.
A low-noise, high-gm FET is connected to a 3-parallel cascode and bootstrap differential circuit to achieve a stable circuit with excellent S/N. Especially for the MC cartridge with Oire force signal, 3-parallel reduces residual noise.

To prevent signal degradation caused by switching or routing of the signal path, the input section uses a method in which relays are installed where switching is necessary and controlled electronically by a logic circuit.
This relay uses a sealed type with cross-bar twin silver-palladium gold-plated contacts.

It has 8 input terminals and 2 balance terminals.
In addition, the built-in recording selector is independent of the input selector, so you can record FM broadcasts while listening to CDs.
It is also equipped with a copy switch that allows independent dubbing between sound recorders.

It is equipped with separate input / output terminals that can be used as an independent amplifier by electrically separating the preamplifier and the power amplifier.

For tone control, we have developed an additive active filter method which is also used in graphic equalizers.
In this method, the original flat signal passes straight through, another characteristic is created as necessary, and the signal is adjusted from the flat signal.

Equipped with a peak power meter of logarithmic compression peak indication type.

It includes a speaker selector that switches between two pairs of speakers, a mode switch that mixes the left and right sounds, a subsonic filter that cuts out the harmful ultra-low noise of analog disks, and a compensator that enhances the low-sound feel when the volume is low.

The front panel features a gold-style scratch hairline design with natural Persimmon sideboards on both sides.

Model Rating

Type	Integrated Stereo Pre-Main Amplifier
continuous average output (both channel operation, 20 Hz ~ 20 kHz, Distortion Factor 0.02%)	4 ohm load : 180W/ch 8 ohm load : 130W/ch
Total Harmonic Distortion Factor	0.02% (4-16 Ω load, dual-channel operation, 0.25W to continuous output, 20 hz to 20 khz)
IM Distortion Factor	0.01%
Frequency Response	Main Amp Input: 20 Hz ~ 20000 Hz + 0 -0.2 dB at rated output 0.5 Hz ~ 150000 Hz + 0 -3.0 dB at 1W Output High Level Input: 20 Hz to 20000 Hz + 0 -0.2 dB at rated output Low Level Input: 20 Hz to 20000 Hz + 0.2 -0.5 dB at rated output
Damping factor	100 (8 ohm load, 50 Hz)
Rated Input / Impedance	Input Sensitivity Impedance At rated output EIA at 1W output AD Input(MC): 0.128mV 0.01mV 100 ω AD Input(MM): 4.3mV 0.38mV 47k Ω High Level Input: 125mV 11.8mV 20k Ω Balanced Input: 125mV 11.8mV 40k Ω Main Amp Input: 1.28V 121mV 20k Ω
Disk Max Input (1 kHz, 0.005% distortion)	MM Input : 300 mVrms (Rec Out) MC input : 8.0 mVrms (Rec Out)
Rated Output / Impedance	Pre Output : 1.28V/200 Ω Tape Rec Output : 125mV/200 Ω (from AD) Headphones : 0.4 v, Applicable Impedance 4 ~ 100 Ω
Gain	Main Input → Output : 28 dB High Level Input → Pre Output : 20 dB AD Input (MM) → Tape Rec Output : 29 db AD Input (MC) → Tape Rec Output : 60 dB
S/N, input conversion noise	Input Short A-Compensation EIA S/N S/N at rated input Input Conversion Noise Main Amp Input: 123dB -121dBV 102dB High Level Input: 108dB -126dBV 82dB Balanced Input: 90dB -108dBV 82dB AD Input(MM): 86dB -137dBV 80dB AD Input(MC): 66dB -147dBV 75dB
Tone Controls	Bass : turnover frequency 300 Hz, ± 10 dB (50 Hz) Treble : Turnover frequency 3 kHz, ± 10 dB (20 kHz)
Loudness Compensator	+ 6 dB (100 Hz, Volume -30dB)
Subsonic Filter	17 Hz, -12dB/oct
Attenuator	-20dB
Power Meter	Logarithmic Compression Peak Level Display Direct reading of output at dB scale and 8 Ω load
Load Impedance	2 to 16 ohms
Semiconductors used	Transistors : 77 FET : 34 IC : 20 pcs Diode : 78
Power Supply	100V/117V/220V/240V, 50Hz/60Hz
Power Consumption	No input : 60W Electrical Appliance and Material Control Law : 310W 8 Ω load at rated output : 490W
External Dimensions	Width 475x Height 170 (including legs) x Depth 375 mm
Weight	20.5kg