Audio Database


Pre-main amplifier with UHC single push-pull configuration.

A UHC single push-pull circuit using a high current amplifier UHC-MOS is adopted.
The UHC-MOS has an improved current supply capability equal to or higher than that of a bipolar transistor, and also has the sound quality advantage of a MOS-FET. Therefore, the UHC-MOS solves the conflicting problem of expressive power and speaker drive power.

The power transformer uses a large magnetic circuit with a low magnetic flux density to improve its ability to follow music signals with a wide dynamic range in the magnetic saturation region. The power transformer also uses an LC mount system to significantly reduce leakage flux, which is a source of noise in the amplifier.
In addition, the windings of the power supply for the voltage amplifier stage and phono equalizer are independent, and the transformer of the power supply for the control circuit that controls the signal relay is also independent, so that mutual interference between each circuit is suppressed.

In order to suppress the deterioration of sound quality due to interference between circuits and inflow of noise, we have adopted a twin monaural configuration in which power amplifier blocks are independent on the left and right, and a 6-block structure in which circuits with different signal levels are separated and shielded.
In addition, in order to reduce noise caused by vibration, the chassis is made of 1.6 mm thick steel plate with black paint of the same grade as the separate amplifier.
In addition, the power transformer mounting part adopts a laminated structure combining different materials with excellent vibration damping characteristics, ensuring high rigidity and vibration resistance to suppress vibration generated by the power transformer.

The insulator uses a sintered alloy that converts vibration into heat and suppresses propagation to the chassis. In addition, a new material with high vibration absorption is attached to the insulator to suppress propagation of vibration.

The speaker terminal is gold-plated on brass machined parts to reduce transmission loss.
In addition, the hole diameter of the clamp section has been enlarged to φ 6 mm to accommodate very thick speaker cables.

The rectifier circuit in the power supply section employs a high-current fast recovery diode connected in parallel, which has excellent high-current supply capability and greatly improved operating speed and voltage loss.
In addition, a combination of a high-capacity high-sound electrolytic capacitor using a low-impedance electrode foil and a film capacitor with different frequency characteristics is used to improve the characteristics.
In addition, extremely thick OFC wiring material is used for the wiring from the output of the power transformer to the output stage of the power amplifier to minimize energy loss.

The phono equalizer uses a discrete first stage circuit that uses a low-noise FET.
In addition, the sound quality is improved by installing a stabilizing power supply for the phono equalizer.

It uses parts adopted in the S1 series such as 40-inch 4-channel volume, large machined gold-plated pin jack, OFC internal wiring material, inert gas-filled relay, high sound quality condenser, detachable AC cord, etc.

Model Rating
Type Pre-main amplifier
Power Amplifier Unit
Rated output
(Both channel drive, CD → SP out)
100W + 100W (8 Ω, 20 Hz to 20 kHz, THD 0.07%)
200W + 200W (4 ω, 1 khz, 0.7% THD)
Total harmonic distortion factor 0.01% (8 Ω at -3dB rated output, 1 kHz)
Output terminal Speaker AORb : 4 Ω ~ 16 Ω
Speaker A + B : 8 Ω ~ 16 Ω
Biwiring : 4 Ω ~ 16 Ω
Preamplifier Section
Input Sensitivity / Impedance Line : 150mV/47k Ω (source direct off)
150mV/15k Ω (Source Direct On)
Phono MM : 2.5mV/47k Ω
Phono MC : 0.2mV/100 Ω
Equalizer amplifier output 150mV
RIAA deviation Phono MM : 20 Hz to 20 kHz ± 0.3 dB
Phono MC : 30 Hz to 20 kHz ± 0.5 dB
Signal-to-noise ratio (A network
Input terminal short-circuited)
Phono MM : 91 dB (at 5 mV input)
Phono MC : 78 dB (at 0.5 mV input)
Tone control Bass : ± 8 dB (100 Hz)
Treble : ± 8 dB (10 kHz)
Power outlet Switched : 2 systems, total 120W
Unswitched : 1 line, 240W
Power supply voltage 100 VAC, 50Hz/60Hz
Power consumption 300W
External dimensions Width 434x Height 181x Depth 485 mm
(including legs, knobs and terminals)
Weight 30.0kg