Audio Database

AU - α 777 dg
Commentary

A pre-main amplifier with a Mash D/A converter.

The New L. D. C. S (linear & direct D/A conversion system) based on the Mash method is installed in the D to A converter section.
The Mash method is a D/A conversion method that uses the frequencies of a crystal oscillator as the conversion standard. It uses high-order oversampling and third order noise-shaping to instantaneously convert digital signals into high-precision analog signals, and has the feature that 0 cross distortion and nonlinear distortion do not occur in principle.
In order to take advantage of the high accuracy of the Mash system, the AU-alpha 777 dg has an accuracy close to that of a crystal oscillator and uses a lithium tantalate device with a wide lock range, making it a unique linear & direct D/A conversion system (L. D. C. S).
The New L. D. C. S further improves the S / N ratio by upgrading all peripheral circuits.

The power supply section is completely separated from the power supply section by installing dedicated transformers for both digital and analog circuits.
This prevents electromagnetic pulses peculiar to digital from mixing into the analog part.

The amplifier section uses an α -X balanced circuit with unique know-how, and the circuit itself cancels noise and distortion by balance operation.

A twin monaural construction with the power supply in the center and the power units symmetrically arranged ensures that the digital section to be shielded outside the left channel unit and the analog input section to be shielded outside the right channel unit so that the digital and analog sections are clearly separated.

In order to achieve both sound quality and convenience, it comes with a remote controller that uses a direct access rotary switch. It is possible to increase or decrease the volume by 6 connected volumes and switch the source.

It is equipped with functions such as source direct operation, REC selector and direct access rotary switch.

Uses gold-plated input terminal, very thick power cord with polarity display, and AC outlet.

There was a side wood sold separately.

Model Rating
Type Α -X Balanced Integrated Amplifier
Digital Part
Frequency characteristic 4 Hz to 20 kHz ± 0.5 dB
Signal-to-noise ratio 108 dB or more (EIAJ)
High frequency distortion factor Not more than 0.003%
Digital input level 0.5Vp-p/75 Ω
Optical input 660 nm (emission wavelength)
Power Amplifier Unit
Effective output (10 Hz to 20 kHz
Both channel operation)
105W + 105W (6 Ω)
90W + 90W (8 Ω)
Dynamic Power 230W (2 Ω)
220W (4 Ω)
155W (6 Ω)
Total harmonic distortion factor (at effective output) 0.003% or Less (8 Ω)
Cross modulation distortion factor 0.003% or Less (8 Ω)
Damping factor 150 (8 Ω)
Frequency Response (1W) DC ~ 200 khz + 0 -3dB
TIM (SAWTOOTH) Measurement limit value or less
Slew rate 180 V / μ sec
Rise time 0.6 μ sec
Preamplifier Section
Input Sensitivity / Impedance
(1kHz)
Phono MM : 2.5mV/47k Ω
Phono MC : 300 μ V/100 Ω
CD, Tuner, Line, Tape/DAT1, 2, 3 : 150mV/20k Ω
Phono maximum allowable input MM(THD 0.01%):210mV
MC(THD 0.1%):21mV
Frequency characteristic Phono MM : 20 Hz to 20 kHz ± 0.2 dB
CD, Tuner, Line, Tape/DAT1, 2, 3 : DC ~ 200 khz + 0 -3dB
Signal-to-noise ratio (A network) Phono MM : 88 dB or more
Phono MC : 70 dB or more
CD, Tuner, Line, Tape/DAT1, 2, 3 : 110 dB or more
Tone control Bass : ± 6 dB (50 Hz)
Treble : ± 6 dB (15 kHz)
Subsonic filter 16 Hz (-3dB), 6dB/oct.
Loudness + 6 dB (50 Hz), + 4 dB (10 kHz)
<General>
Rated power consumption 250W
External dimensions Width 430x Height 163x Depth 450 mm
Weight 18.2kg
Attachment Wireless Remote Control RS 1130
Sold Separately Real Side Wood SW-AU1 (¥ 10,000)