ONKYO Integra A-817
¥ 69,800 (around 1980)
Commentary
Pre-main amplifier with dual direct amplifier configuration using W / Super Servo system.
The W / Super Servo system is incorporated into the power amplifier and equalizer amplifier.
This system feeds back only the extra noise and distortion components contained in the signal other than the music signal from both positive and negative poles of the amplifier output terminal via a servo operational circuit, and cancels the feedback. On the positive side, ultra-low frequency components due to fluctuations in the power supply generated inside the amplifier and temperature changes in semiconductors are mainly suppressed. On the negative side, the electromotive force induced by the impedance of the power supply is suppressed.
Moreover, we have dramatically improved the resolution of reproduced sound by suppressing it without relying on capacitors and other devices that are problematic in terms of sound quality.
Linear switching method is adopted for the transistor operation of the final stage.
This method is the same as Class B in that it is amplified by two transistors, but the linearity of the joint of the operation curve, which is a problem in this case, is corrected by a special bias circuit to obtain linear operation characteristics.
And High fTBy using a power transistor, the switching distortion can be suppressed to a completely negligible range.
To support MC cartridge, MC straight equalizer amplifier is mounted.
It has a high gain design with MC as the main role, and it can be directly connected to the equalizer without putting any extra things in between.
It is also possible to switch between MC and High MC depending on the output voltage.
Uses a direct tone system.
In this method, as the gain of the power amplifier increases, the tone amplifier is omitted, and the tone is changed by the loudness circuit related to the volume control. Therefore, it is composed only of passive elements with no problem in sound quality, so that the change in sound quality caused by the use of tone hardly becomes a problem.
Uses an auto tracking bias system that detects temperature differences in the final stage and always supplies a stable bias.
Non-magnetic material is used to suppress the generation of higher harmonic waves.
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Model Rating
| Type | W super servo type pre-main amplifier |
| Rated Output (20 Hz ~ 20 kHz) | 70W + 70W (8 Ω, AUX → SP out, both channels driven) |
| Total harmonic distortion rate (20 Hz to 20 kHz) | 0.015% (AUX → SP out, rated) 0.008% (AUX → SP out, 1/2 rated) 0.003% (PH ・ MM → Rec out, 3 v) 0.015% (PH ・ MC → Rec out, 3 v) |
| Cross modulation distortion factor | 0.008% (AUX → SP out) |
| Powerbandwidth | 5 Hz to 100 kHz (IHF-3dB, THD0.2%) |
| Damping factor | 100 (1 kHz, 8 Ω) |
| Frequency characteristic | 20 Hz to 20 kHz ± 0.2 dB (PH → Rec out, RIAA deviation) 2 Hz ~ 100 kHz + 0 dB -2dB (AUX → SP out, RIAA deviation) |
| 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 |
| Phono maximum allowable input (1kHz/10kHz 0.05%) |
Phono MM:250mV/1200mV Phono High MC:250mV/1200mV Phono MC:23mV/110mV |
| Output Voltage / Impedance | Tape Rec1, 2 : 150mV/2.2k Ω |
| S/N ratio (IHF A, input short) | Phono MM:87dB Phono MC:72dB Tuner, AUX, Tape Play1, 2 : 100 dB |
| Tone Control (Vol-16dB) | Bass (70 Hz) : ± 8 dB Treble (20 kHz) : ± 8 dB |
| Loudness | + 6 dB, 100 Hz |
| Subsonic filter | 15 Hz, 20 Hz 6dB/oct. |
| Muting | -20dB |
| Pwer | 100 V, 50/60Hz |
| Power consumption (Electrical Appliance and Material Control Law standard) | 110W |
| AC outlet | Unswitched-1 (200W) Switched : 2 (total 200W) |
| External dimensions | Width 435x Height 142x Depth 385 mm |
| Weight | 11.0kg |