SANSUI AU-D7
¥ 59,800 (released in 1980)
Commentary
A pre-main amplifier using a diamond differential circuit and newly developed linear A circuit.
Equipped with the diamond differential circuit adopted in the AU-D series.
This circuit is an ideal circuit that can instantaneously supply a large amount of drive current to the power stage for any input. The TIM (Transient Intermodulation Distortion), which is the most harmful dynamic distortion for music playback, is as close to 0 as possible. As a result, the AU-D7 achieves a slew rate of ± 120 V / μ sec (inside slew rate ± 220 V / μ sec), which is twice as fast as conventional same class amplifiers.
The power amplifier section is composed of a DC amplifier, and the newly developed linear A circuit is used for the amplification method to achieve both A-class sound quality and B-class efficiency.
In this method, the bias of the output stage is controlled in real time so that it does not cut off in response to the input signal. In principle, there is no switching distortion or crossover distortion, and at the same time, high efficiency comparable to that of B-class is obtained.
A non-magnetic (NM) power transistor is used as the power transistor element.
The circuit is composed of two amplifiers without a flat amplifier, and the MC output is also directly input to the equalizer, making it simple and straight.
The equalizer amplifier section consists of 10 transistors with cascode connection of FET differential input. By changing the gain, the optimum amplification degree is obtained for both MM cartridge and MC cartridge.
The tone control section uses four cross-band tone control that two common high and low tones, plus medium and ultra low tones.
The direct access input selector allows one touch switching of the input source.
In addition, it uses a REC selector and can connect two tape decks.
Equipped with a full mode selector, you can choose between stereo, monaural, reverse, L and R.
A speaker selector using a large relay is adopted.
Equipped with an LED digital peak power display.
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Model Rating
| Type | Pre-main amplifier |
| Power Amplifier Unit | |
| Effective output (20 Hz to 20 kHz, THD 0.009%) | 65W + 65W (8 Ω) |
| Total harmonic distortion rate (20 Hz to 20 kHz) | 0.008% or Less (at 1/2 Effective Output) |
| Output Bandwidth (IHF, THD 0.02%) | 10 Hz ~ 70 kHz (8 Ω) |
| Damping factor (new IHF, 1 kHz) | 200 (8 Ω) |
| Frequency Response (1W) | DC ~ 100 kHz + 0 -0.5 dB |
| Envelope distortion | Unmeasurable |
| TIM Strain (Sawtooth method) | Unmeasurable |
| Slew rate | ± 120 v / μ sec (8 Ω) Inside ± 220 v / μ sec |
| Rise time | 0.6 μ sec (at 2Vp-p output) |
| Preamplifier Section | |
| Input Sensitivity / Impedance (1 kHz) | Phono MM : 2.5mV/47k Ω Phono MC : 200 μ V/100 Ω Tuner, Aux, Tape Play : 200mV/47k Ω |
| Phono maximum allowable input (1 kHz) | Phono MM:200mV(THD 0.01%) Phono MC:15mV(THD 0.1%) |
| Output Voltage / Impedance | Tape rec : 200 mv (47k Ω, 1 khz) / 600 Ω |
| Total harmonic distortion factor (at 6 v output) | Not more than 0.003% |
| RIAA Deviation at 0.5 v output | 20 Hz to 20 kHz ± 0.5 dB |
| Signal-to-noise ratio (A network, short circuit) | Phono MM : 86 dB or more Phono MC : 67 dB or more Tuner, Aux, Tape play : 110 dB or higher |
| Input conversion noise (A network, short circuit | Phono MM:-138dBV Phono MC:-141dBV |
| Channel Separation (1 kHz) | Phono MM : 55 dB or more Tuner, Aux, Tape play : 60 dB or more (10k Ω termination) |
| Tone control | Super Bass : ± 6 dB (10 Hz) Bass : ± 6 dB (100 Hz, Vol-30dB) Presence : ± 6 dB (1.2 kHz) Treble : ± 6 dB (10 kHz, Vol-30dB) |
| Loudness (Vol-30dB) | + 6 dB (50 Hz), 10 kHz (+ 5 dB) |
| <General> | |
| Rated power consumption | 135W (Electrical Appliance and Material Control Law) |
| External dimensions | Width 430x Height 148x Depth 327 mm |
| Weight | 10.2kg |
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