SANSUI AU - α 707 nra

Commentary

Pre-main amplifier with Ultimate α -X balance circuit.

The Ultimate α -X balance circuit achieves an excellent operating environment in the transmission and amplification process from the input to the output of the initial stage, driver stage and final stage by raising the current margin of the driver stage to twice that of the conventional one and operating it in A-class operation.

The driver stage employs a NEW diamond differential circuit that can take out + - output without phase inversion. This has excellent current supply capability even for instantaneous input signals and suppresses TIM distortion, which is harmful to the sense of hearing.

A total of four dedicated amplifiers are arranged on the + and - sides of L and R of the output stage, and a NM-LAPT single push-pull system is adopted in which the speakers are dynamically driven from both + and - sides under the same conditions.

The mechanical floating system that floats the power transformer from the chassis prevents the vibration of the power system from being transmitted to the chassis.
In addition, by adopting a new shape radiator, the generation of vibration is minimized.
In addition, by floating the side wood with a pure copper plate embedded in the 3-part bonnet, the structure is resistant to vibration.
An elliptical insulator is used to disperse vibration effectively.

An α -X balanced power supply is used for the power supply.
The output stage is a balanced closed type, the first stage is an upper symmetric balanced constant current type power supply, and the secondary side of the transformer is a separate winding. The closed loop configuration is completely independent from the ground.

The master volume is mounted on a pure copper plate by means of an opposed mechanical feedback and uses a 6-strand master volume with controlled vibration.

The source connected to the direct input of the Route 3 can be directly connected to the power amplifier section.

Equipped with a balanced input.

Uses a power cord with polarity display.

Model Rating

Type	Integrated amplifier
Power Amplifier Unit
Effective output (10 Hz to 20 kHz Simultaneous operation of both channels)	160W + 160W (6 Ω) 130W + 130W (8 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 ~ 300 khz + 0 -3dB
Input Sensitivity / Impedance	1V/10k Ω (1 kHz)
Signal-to-noise ratio (A network)	120 dB or more
Dynamic Power	405W (2 Ω) 320W (4 Ω) 210W (6 Ω)
TIM (SAWTOOTH)	Measurement limit value or less
Slew rate	200 V / μ sec
Rise time	0.5 μ sec
Preamplifier Section
Input Sensitivity / Impedance (1kHz)	Phono MM : 2.5mV/47k Ω Phono MC : 300 μ V/100 Ω CD, Tuner, Line, MD/Tape1, Tape2 : 150mV/20k Ω
Phono maximum allowable input	MM(THD 0.01%):210mV MC(THD 0.1%):21mV
Frequency Response (1W)	Phono MM : 20 Hz to 20 kHz ± 0.2 dB CD, Tuner, Line, MD/Tape-1, Tape-2 : DC ~ 300 khz + 0 -3dB
Signal-to-noise ratio (A network)	Phono MM : 88 dB or more Phono MC : 70 dB or more CD, Tuner, Line, MD/Tape-1, Tape2 : 110 dB or more
Tone control	Maximum variation of Bass : ± 6 dB (50 Hz) Maximum variation of Treble : ± 6 dB (15 kHz)
Subsonic filter	16 Hz (-3dB), 6dB/oct.
Loudness	+6dB(50Hz) +4dB(10kHz)
<General>
Rated power consumption	330W
External dimensions	Width 462x Height 165x Depth 446 mm
Weight	23.6kg