SANSUI AU - α 707
¥ 129,000 (released in 1986)
Commentary
Integrated amplifier with α -X balanced circuit.
The power amplifier section uses SANSUI's unique α -X balanced circuit.
In the α -X balanced circuit, the signal circuit, the power supply circuit, and the NFB circuit completely separate the signal from the earth, eliminating the IHM distortion. Furthermore, the balance amplifier in the pre-part enables the α -X balanced transmission of not only the α -X balanced input but also the normal input.
In this circuit, the + and - sides of the speakers are each driven by a dedicated amplifier, so the speaker movement can be controlled by the amplifier.
The power supply section uses an α - X balanced power supply that supplies energy independently of the ground. This eliminates noise from the AC line and prevents unbalanced and ripple currents from flowing into the speakers. In addition, the power supply system separates the power stage from the voltage amplification stage to eliminate mutual interference.
The power transformer is an ultra-heavyweight transformer, and the condenser is a pure focus condenser or a gold supply condenser.
Power Amp Direct is installed and the input signal can be directly connected to the power amp.
Two systems are provided for the direct terminal : a normal terminal and a balanced input.
A specially developed 6-string master volume is used for the volume.
This volume consists of a total of six tracks, two for the pre-main amplifier and four for the low-impedance direct position, enabling transmission and amplification without loss of sound quality.
The master volume knob shows the scale for the power amp direct, and the panel shows the scale for the pre-main amp.
A newly developed solid chassis has been adopted for the chassis structure, and a high rigidity separator is installed inside the external panel to increase the rigidity of the whole amplifier and cut electromagnetic noise.
CF5 (Chassis Fixed 5-point Support) insulator is used for the leg part. By placing a fifth compliant insulator near the power supply part where the weight is concentrated, load balance is taken and mechanical earth is realized.
It uses a CF12 (chassis fixed, 12-point) bonnet.
In the CF12 bonnet, the U-shaped rigid bonnet determined from the results of vibration analysis is fixed to a solid chassis using 12 screws, which are much larger than conventional ones, to suppress resonance and vibration.
The MM/MC phono equalizer uses an FET input.
Equipped with a source direct function, all sources can be directly connected to the α -X balance circuit without passing through an accessory circuit, and the tone control can also be used for source direct.
Equipped with a tone control with defeat.
This tone control allows you to change the turnover frequency.
Gold plated terminals are used for the Phono, CD, Tape/DAT-1 and Power amp direct (Normal) terminals.
Uses a power cord with polarity display.
Equipped with a REC selector with OFF position.
The front panel is a glossy & hairline finish made of aluminum material.
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Model Rating
| Type | Integrated DC amplifier |
| Power Amplifier Unit | |
| Effective output (10 Hz to 20 kHz, both channels driven) | 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 | 100 (6 Ω) |
| Frequency Response (1W) | DC ~ 300 khz + 0 -3dB |
| Input Sensitivity / Impedance (1 kHz) | Normal : 1V/5k Ω Balance : 1V/5k Ω |
| Signal-to-noise ratio (A network) | 120 dB or more |
| TIM (SAWTOOTH) | Below the measurement limit |
| Slew rate | ± 200 V / μ sec |
| Rise time | 0.5 μ sec |
| Equalizer Section | |
| Input Sensitivity / Impedance (1 kHz) | Phono MM : 2.5mV/47k Ω Phono MC : 300 μ V/100 Ω CD, Tuner, Line, Processor : 150mV/47k Ω Tape play/DAT-1, 2, 3 : 150mV/47k Ω |
| Phono maximum allowable input (New IHF, THD 0.01%) |
MM:210mV MC:21mV |
| Frequency Response (at 1W) | Phono MM : 20 Hz to 20 kHz ± 0.2 dB CD, Line, Tape play/DAT-1, 2, 3 : 1 hz ~ 300 khz + 0 -3dB |
| SN ratio (at 1W) | Phono MM : 88 dB or more Phono MC : 70 dB or more Tuner, Line, CD : 110 dB or higher Tape play/DAT-1, 2, 3 : 110 dB or more |
| Tone control | Bass : + / - 5 dB (50 Hz) Treble : ± 5 dB (15 kHz) |
| Turnover frequency | 75 hz, 150 hz, 7 khz |
| Subsonic filter | 16 Hz (-3dB, 6dB/oct.) |
| Loudness | + 8 dB at 50 Hz, + 6 dB at 10 kHz |
| <General> | |
| Rated power consumption (Electrical Appliance and Material Control Law) | 320W |
| External dimensions | Width 448x Height 160x Depth 441 mm |
| Weight | 20.3kg |