SANSUI AU - α 707 kx

Commentary

707 series pre-main amplifier with advanced α -X balance circuit.
The technology introduced is almost the same as that of AU - α 907 kx, and newly developed insulator is adopted.

The advanced α -X balanced circuit has a balanced configuration in which signals are transmitted and amplified simultaneously. The amplifier circuit and the ground circuit of the amplifier are completely separated. Therefore, the circuit itself blocks the in-phase distortion caused by counter electromotive current and external noise generated at the speaker side.
In addition, a push-pull system in which a total of four dedicated amplifiers on the + side and - side of the output drive the speakers under the same conditions from both + and - sides realizes a low distortion factor, and dynamic frequency characteristics are greatly improved by lowering the circuit impedance.

The power stage is equipped with the NM-LAPT developed exclusively for audio. The bonding wires are completely made of pure copper and non-magnetic. Excellent high-frequency characteristics and current limit values are obtained.

All stages from input to output are configured as a wide-range DC amplifier, and NFB is minimized by expanding frequency characteristics in bare characteristics, improving phase characteristics, and reducing distortion factor.

The power stage uses the NEW diamond differential circuit that can take out the - side output without phase inversion, and the generation of TIM distortion is suppressed by the quick response to the instantaneous input signal.
In addition, by cascading the first stage FET, the circuit is made wide range and high speed.

NEW α -X balanced power supply is used for the power supply part.
As a closed loop isolated from ground, the unbalanced power supply, which causes sound quality degradation, is minimized.

The power supply unit is placed in the center of the amplifier, and the power units are symmetrically arranged on the left and right sides of the power supply unit using twin monaural construction to achieve the optimum weight balance as a structure.

In order to control the vibration and resonance of the amplifier, an integrated mechanical feedback is introduced.
Vibration control isolation parts made of pure copper are used in the vibration transmission path between the master volume and the chassis and between the power transistor and the radiator.
In addition, a Teflon sheet with high internal loss and excellent vibration absorption capacity is placed between the insulator and the bottom plate, and a Teflon tape is placed between the radiator, bonnet and chassis to isolate vibration.

Newly developed special structure insulator is fixed with copper plated screws to suppress sound quality degradation due to vibration.

This product is selected carefully from the high-quality parts obtained from the development of the Vintage series of SANSUI.
In particular, gold-plated lead resistors are used for important parts of the circuit where signals directly pass through and affect sound quality. Gold plated leads are also used for the film capacitor of the power supply part in order to pursue pure sound.
In addition, copper-plated screws are used for front panel mounting screws.

Equipped with source power direct, all line inputs can be connected directly to the power amplifier section.

It uses a REC selector, all-gold plated input terminal 11 systems, 6-row detent volume, real side wood, power cord with polarity display, etc.

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/5k 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
<Pre-part>
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 Response (1W)	Phono MM : 20 Hz to 20 kHz ± 0.2 dB CD, Tuner, Line, Tape/DAT-1 / 2 / 3 : DC ~ 200 Hz, + 0 -3dB
Signal-to-noise ratio (A network)	Phono MM : 88 dB or more Phono MC : 70 dB or more CD, Tuner, Line, Tape/DAT-1 / 2 / 3 : 110 dB or more
Tone control	Maximum variation of BASS : + / - 6 dB at 50 Hz Maximum change of TREBLE : ± 6 dB (15 kHz)
Subsonic filter	16 Hz (-3dB), 6dB/oct.
Loudness	50Hz:+6dB 10kHz:+4dB
<General>
Rated power consumption	330W
External dimensions	Width 460x Height 161x Depth 446 mm
Weight	22.5kg