ONKYO Integra A-817D
¥ 69,800 (around 1981)
Commentary
A stereo pre-main amplifier that adopts the W super servo system.
The W Super Servo System is a system in which only the extra noise and distortion components in the signal other than the music signal are fed back from the + and - poles of the output terminal of the amplifier through the servo operational circuit respectively, and the feedback is canceled.
On the positive side, ultra-low frequency components due to fluctuations in the power supply generated inside the amplifier and temperature changes in the semiconductor are suppressed. On the negative side, electromotive force induced by the impedance of the power supply is suppressed.
In addition, the resolution of the reproduced sound is improved without affecting the sound quality because it is suppressed without depending on the element which influences the sound quality such as the condenser.
Linear switching method is adopted for the operation of the final transistor.
The point of amplifying with two transistors is the same as the efficient class B. In this case, the linearity of the joint of the operation curve is corrected by a special bias circuit to obtain linear operation characteristics.
And High fTBy using a power transistor, we have succeeded in suppressing switching distortion to a negligible range.
To take advantage of the MC cartridge, it is equipped with an MC straight equalizer amplifier.
This amplifier has a high-gain design with the MC as the main part, and it can be directly connected to the equalizer without putting any unnecessary things in between.
The quality of MM cartridges has also been improved.
It is possible to switch between MC and High MC depending on the output voltage.
As the gain of the power amplifier increases, the direct tone is composed of only passive elements that do not affect the sound quality because the tone amplifier is omitted and the tone is changed by the loudness circuit associated with the volume control.
As a result, the change in sound quality caused by using tone is no longer a problem.
It uses an auto tracking bias system that detects the temperature difference in the final stage and always supplies a stable bias.
Non-magnetic material is used to suppress the generation of higher harmonic waves.
Large power supply unit and direct power supply system are adopted.
Model Rating
| Type | W super servo type pre-main amplifier | ||||
| Rated Output (Aux → SP out) | 75W + 75W (20 Hz ~ 20 kHz, 8 Ω, both channel drive) | ||||
| Total harmonic distortion rate (20 Hz to 20 kHz) | 0.015% / 0.012% (AUX → SP Out, at rated output / at 1/2 output) 0.003% (Phono MM → Rec Out, 3 V) 0.015% (Phono MC → Rec Out, 3 v) |
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| Intermodulation distortion factor (Aux → SP out) | 0.008% | ||||
| Powerbandwidth | 5 Hz ~ 100 kHz (Aux → SP out) | ||||
| Damping factor (1 kHz, 8 Ω) | 100 | ||||
| Frequency characteristic |
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| Input Sensitivity / Impedance | Phono MM : 2.9mV/47k Ω Phono High MC : 2.9mV/100 Ω Phono MC : 280 μ V/330 Ω Tuner, AUX, Tape Play1, 2 : 150mV/47k Ω |
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| Phono maximum allowable input (1kHz/10kHz, 0.05%) |
Phono MM:250mV/1200mV Phono High MC:250mV/1200mV Phono MC:23mV/110mV |
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| Output Voltage / Impedance | Tape Rec1, 2 : 150mV/2.2k Ω | ||||
| S/N ratio (IHF A-short) | Phono MM:87dB Phono MC:72dB Tuner, AUX, Tape Play1, 2 : 100 dB |
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| Tone Control (Vol-16dB) | Bass : ± 8 dB (70 Hz) Treble : ± 8 dB (20 kHz) |
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| Loudness | +6dB(100Hz) | ||||
| Subsonic filter | 15Hz/20Hz, 6dB/oct. | ||||
| Muting | -20dB | ||||
| Pwer | 100 V, 50/60Hz | ||||
| Power consumption | 120W (Electrical Appliance and Material Control Law Standard) | ||||
| AC outlet | Unswitched-1 (200W) Switched : 2 (total 200W) |
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| External dimensions | Width 435x Height 142x Depth 385 mm | ||||
| Weight | 11kg |