SANSUI AU-D707XCD DECADE
¥ 145,000 (around 1986)
Commentary
A pre-main amplifier developed with the aim of purer playback of digital sources such as CDs.
The CD Direct Position is installed to reproduce the sound quality of the CD as completely as possible.
When the CD Direct switch is pressed, the signal from the CD player goes directly to the Twin Diamond X Balance section via the dedicated volume without passing through any switches or circuits.
The volume section uses a special 4-row detent volume in which a CD-only volume and a master volume are co-located, and is also a low-impedance type that advantageous in sound quality.
The volume level display in the CD Direct Position is separate from that in the normal position. The CD Direct Position Indicator lights up to indicate the volume knob.
Twin Diamond X balance system is adopted for the power amplifier section.
In this circuit system, balanced input, transmission, and amplification are performed on the plus side and the minus side equally, and hum and noise are canceled. Moreover, since it is completely separated from ground, it is not affected by ground.
Also, in a normal amplifier, the back electromotive force from the speaker flows into the ground line which is also used for the negative side, causing interference with the ripple current of the power supply and causing IHM distortion. However, in an X balanced amplifier, the current supply to the speaker is under the same condition for both the positive side and the negative side. In addition, a twin diamond differential circuit is used to drive the power in a two group configuration to increase the speaker drive capability.
The power supply section uses a heavyweight power transformer and a pure focus capacitor.
Large heat sink is adopted.
Equipped with a subsonic filter with a cutoff frequency of 6 Hz.
Equipped with tone control with turnover frequency switching.
Equipped with a 4-position speaker selector.
Equipped with a REC selector with OFF position.
The input jacks include CD, Tuner, Line1/2, Tape1/2/3, and Adaptor for connecting graphic equalizers, etc. The input jacks for CD, Tuner, and Line are gold-plated.
Power cord with polarity display is used.
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Model Rating
| Type | Integrated 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 rate (10 Hz to 20 kHz) | 0.003% or Less (8 Ω, Effective Output) 0.005% or Less (6 Ω, 1/2 Effective Output) |
| Intermodulation Distortion Factor (60 Hz : 7 kHz = 4 : 1, SMPTE) | 0.003% or Less (8 Ω) |
| Damping factor (new IHF, 20 Hz to 20 kHz) | 100 (6 Ω) |
| Frequency Response (1W) | DC ~ 300 khz + 0 -3dB |
| Input Sensitivity / Impedance (1 kHz) | CDDirect : 0.5V/5k Ω |
| Slew rate | ± 200 v / μ sec (8 Ω) |
| Rise time | 0.5 μ sec |
| Headphone out | 500 mW (33 Ω) |
| Load impedance | 4 Ω ~ 16 Ω |
| Preamplifier Section | |
| Input Sensitivity / Impedance (1 kHz) | Tuner, CD : 150mV/47k Ω Line 1, 2 : 150mV/47k Ω Tape play1, 2, 3 : 150mV/47k Ω Adaptor : 150mV/47k Ω |
| Signal-to-noise ratio (A network) | CD, Tuner, Line : 110 dB or higher |
| Tone Control Maximum Change | Bass : ± 10 dB (20 Hz) Treble : ± 10 dB (20 kHz) |
| Turnover frequency | Bass : 100 Hz, 200 Hz Treble : 4 kHz, 8 kHz |
| Subsonic filter | 6 Hz (-3dB), 6dB/oct. |
| Audio Muting | -20dB |
| <General> | |
| Rated power consumption (Electrical Appliance and Material Control Law) | 320W |
| External dimensions | Width 466x Height 161x Depth 431 mm |
| Weight | 20.6kg |