Audio Database

SU-A808
Commentary

Integrated amplifier with VGCA for low noise.

The amplifier circuit uses a unique low-noise amplifier VGCA (Variable Gain Control Amplifier).
In this circuit, the conventional amplifier configuration that narrows down the signal using the input volume and then amplifies the signal is eliminated. By changing the gain of the amplifier section itself, the amplifier is provided with a gain as much as necessary for amplification, and operates as a buffer amplifier with a gain lower than that. Volume control is performed by the volume linked after the amplifier, so that clearer sound can be played back at the normally used volume position.

It is equipped with MOS ClassAA circuit which adopts MOS FET as amplifying device based on ClassAA circuit.
The ClassAA circuit uses separate amplifiers for voltage amplification and current supply to achieve high power and complete class A voltage control.
The SU-A808 has a MOS ClassAA circuit equipped with a MOS FET amplifier with extremely high input impedance and excellent linearity at the final stage of controlling the outputs of a pure class A voltage control amplifier. In addition, the final stage of the current supply amplifier employs a bipolar transistor, which has a reputation for low-loss and high-power operation. The class AA Bridge effect maximizes the advantages of each amplifier, enabling compatibility with digital formats such as DVD audio.

The power supply section is equipped with a virtual battery operation circuit, which reduces noise from other circuits to achieve the same operating capability as a battery-driven power supply and provides a stable power supply.
In addition, the power transformer employs an R-core power transformer with a circular core cross-sectional shape. Since the magnetic flux is uniform and there is no junction in the core, leakage magnetic flux is extremely small, and noise generation due to magnetic field is suppressed.

TAKEII electrolytic capacitors are used as electrolytic capacitors.
This is a new version of an electrolytic capacitor using a bamboo mixing separator. Mechanical and electrical characteristics have been greatly improved. In addition, a spiral coil is attached to the exterior of the aluminum case, and it is fixed with a polyolefin sleep to prevent vibration. This reduces the generation of unwanted incidental sounds.

Speaker terminals compatible with gold plated RCA terminals and banana plugs are used.

System remote control is included.

Model Rating
Type Integrated amplifier
Rated output 70W + 70W (6 ohm, 20 hz to 20 khz, 0.03%)
60W + 60W (8 ω, 20 Hz-20 kHz, 0.03%)
Total harmonic distortion factor 0.03% (20 Hz to 20 kHz, rated output -3dB, 8 Ω, sum up to 10th harmonic)
Damping factor 60 (8 Ω)
Load impedance A or B : 4 Ω ~ 16 Ω
A + B : 8 Ω ~ 16 Ω
Frequency characteristic Tuner, CD, DVD, Aux, Tape1, Tape2/MD : 3 Hz to 100 kHz + 0 -3dB
20 Hz ~ 20 kHz + 0 -0.3 dB
Input Sensitivity / Impedance Tuner, CD, DVD, Aux, Tape1, Tape2/MD : 150mV/22k Ω
Phono MM : 2.5mV/47k Ω
Signal-to-noise ratio 98 dB (JEITA) for Tuner, CDs, DVDs, Aux, Tape1, Tape2 / MDs
114 dB (S = 2 V rated output IHF'A)
Phono MM:80dB(JEITA)
76dB(IHF'66)
Rated output voltage Tape1, Tape2/MD Rec out : 150 mv
Pwer 100 VAC, 50Hz/60Hz
Power consumption 160W
External dimensions Width 430x Height 136x Depth 368 mm
Weight 8.3kg
Attachment System remote control