SANSUI AU-D707X
¥ 129,000 (released in 1984)
Commentary
Integrated amplifier with X-balanced amplifier.
The basic configuration of the amplifier is an X-balanced amplifier.
The X-balanced amplifier consists of balanced input, balanced output, balanced power supply, twin diamond balanced differential circuit, and balanced feedback technology. It has a balanced configuration from input to output and drives the speakers from both the + and - sides.
As a result, the IHM distortion caused by the power supply ripple current and the interaction between external noise and the back electromotive force, which was caused by using the - side of the speaker for the common ground in the conventional amplifier, is suppressed. In addition, the distortion and characteristics in the actual operation of the amplifier are greatly improved by the configuration in which the balance feedback is applied to the plus and minus two output stages.
The power supply section uses a toroidal transformer and a pure focus capacitor with excellent transient charge-discharge characteristics. Furthermore, the pre-section, pre-drive section, and power section L/R are composed of four independent power supplies to prevent interference between circuits.
In addition, it is combined with a balanced power supply system without ground to prevent noise from the power supply.
Equipped with MC transformer to support MC cartridge.
This MC transformer uses permalloy with high purity and low magnetostriction as a core with excellent characteristics, and the transformer unit is fixed with filler to prevent vibration and strain.
In addition, the load impedance of the MM cartridge and MC cartridge is independent to provide an optimum load, enabling optimum matching and ideal amplification that were impossible with conventional MC transformer mounting methods or external transformers.
The equalizer has a discrete configuration that avoids the need for an IC, which tends to degrade sound quality. The DC amplifier configuration and Hi-Precision equalizer cover the wide range from 20 hz to 300 khz with ± 0.2 db accuracy.
It is equipped with a large aluminum block heat sink with high heat radiation effect to prevent generation of vibration and modulation distortion of the power transistor.
Uses high-quality parts such as copper foil Styrofoam capacitors, non-resonant RM resistors, non-magnetic elements, etc.
A copper-plated rear panel is used to eliminate magnetic modulation of signals caused by magnetic fields.
Input terminals for CD and PCM are mounted.
In addition, gold plated terminals are used without Phono and CDt.
The phono input terminal has four positions : MM, High-MC, and MC transformer (High and Low).
Equipped with a tone control that can switch the turnover frequency between two stages.
Uses AC power cord with polarity display.
Equipped with a subsonic filter.
Equipped with mirror finish side wood.
There are 2 color variations of black and silver.
.jpg)
.jpg)
.jpg)
.jpg)
Model Rating
| Type | Integrated DC amplifier |
| <Power Amplifier Section (Twin Diamond Balanced Drive Amp system)> | |
| Effective output (both channel drive) | 150W + 150W (6 Ω, 10 Hz to 20 kHz) 130W + 130W (8 Ω, 10 Hz to 20 kHz) 200W + 200W (4 ω, 1 kHz) 170W + 170W (6 ohm, 1 khz) 150W + 150W (8 ω, 1 kHz) |
| Total harmonic distortion factor | 0.003% (8 Ω, 10 Hz to 20 kHz, Effective Output) 0.005% (6 Ω, 10 Hz to 20 kHz, 1/2 Effective Output) |
| Intermodulation distortion factor (60 hz : 7 khz = 4 : 1) | 0.003% (8 Ω, Effective Output) |
| Output Bandwidth (IHF, both channel operation, THD0.03%) | 5 Hz to 80 kHz |
| Damping factor (new IHF, 20 Hz to 20 kHz) | 100 (6 Ω) |
| Frequency Response (1W) | DC ~ 300 khz + 0 -3dB |
| Envelope distortion | Below the measurement limit |
| TIM Strain (Sawtooth method) | Below the measurement limit |
| Slew rate | ± 200 v / μ sec (6 Ω) |
| Rise time | 0.5 μ sec |
| <Equalizer amplifier section (Hi-precision equalizer)> | |
| Input Sensitivity / Input Impedance (1 kHz) | Phono MM : 2.5mV/47k Ω Phono High MC : 2.5mV/100 Ω Phono MC Low : 100 μ V/5.3 Ω (Uses MC transformer) Phono MC High : 300 μ V/40 Ω (Uses MC transformer) CD, Tuner, Tape1, 2 : 150mV/47k Ω |
| Phono maximum allowable input (1 kHz, THD 0.01%) | MM:300mV High MC:300mV MC High : 25 mV (Transformer Type) |
| Output Level / Impedance | Tape rec : 150mV/600 Ω |
| RIAA Deviation (MM, Rec out) | 20 Hz to 300 kHz ± 0.2 dB |
| Signal-to-noise ratio (A network, short circuit) | Phono MM:90dB Phono MC : 80 dB or more (70 μ V) CD, Tuner, Tape : 110 dB |
| Tone control | Bass : ± 10 dB (20 Hz) Treble : ± 10 dB (20 kHz) |
| Tone selector | Bass : 100 Hz, 200 Hz Treble : 4 kHz, 8 kHz |
| Subsonic filter | 16 Hz (-3dB, 6dB/oct.) |
| Loudness (Volume-30dB) | + 8 dB at 50 Hz, + 6 dB at 10 kHz |
| Audio Muting | -20dB |
| <General> | |
| Rated power consumption (Electrical Appliance and Material Control Law) | 320W |
| External dimensions | Width 466x Height 161x Depth 431 mm |
| Weight | 17.5kg |