ONKYO Integra A-766mkII/50
¥ 59,800 (released in October 1974)
Commentary
This pre-main amplifier uses the same circuit configuration as the high-end model of the MKII series except for some power and functions.
In tone amplifiers, various elements, including the NF circuit that controls tone characteristics, change the rise and fall characteristics of middle and low frequencies, which adversely affect sound quality. This part of the MKII series that had been overlooked in the past has been thoroughly clarified by computer simulation and various problems have been solved.
In the tone amplifier, a variable β circuit is inserted in the NF circuit to give tone characteristics, and it has four time constants in the ultra-low frequency range. If this time constant is not carefully selected, a flat amplifier with excellent feedback stability cannot be realized. In the MKII series, a circuit that is advantageous to ensure feedback stability in a sufficiently low frequency range is selected and adopted, and a stable circuit with a large phase margin is realized.
In addition, in order to keep the high-pass cutoff high with a simple circuit while taking into consideration the balance between the high-pass and low-pass, and to ensure sufficient dynamic range even with a simple configuration, we have adopted a unique 2-stage circuit with a differential 1-stage emitter grounding.
In order to improve the signal-to-noise ratio, we have selected a PNP type transistor for the tone amplifier section, which has less 1/f noise due to its structure, and set the impedance level at the best point of the noise characteristic of the transistor.
In order to eliminate adverse effects of power supply voltage fluctuations, a differential circuit is used for the tone circuit, which is less affected by voltage fluctuations. In addition, the voltage is supplied through a ± 2 power supply type low voltage circuit with a voltage fluctuation rate of 1.7%, which prevents intermodulation due to voltage fluctuations in the power amplifier section.
Pure complimentary service with improved transient response characteristics in all stages Technologies developed in the conventional Integra series, such as power amplifiers with all stages connected directly, and operational amplifier type equalizer circuits, have also been introduced.
The wood case was sold separately as an option.
Model Rating
Type | Pre-main amplifier | ||||
Power Amplifier Unit | |||||
Rated Output (1 kHz) | 8 Ω : 25W + 25W 4 Ω : 27W + 27W |
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Dynamic Power (IFF8 Ω) | 75W | ||||
Total Harmonic Distortion Factor (T. H. D., 1 kHz) | 0.1% or Less (at Rated Output) 0.04% or Less (at 10W Output) 0.04% or Less (at 0.5W Output) |
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Intermodulation Distortion Factor (S. M. P. T. E, 70 hz : 7 khz = 4 : 1) | 0.05% or Less (at Rated Output) | ||||
Power Band With (IHF-3dB, THD 0.3%) | 10 Hz to 60 kHz | ||||
Signal-to-noise ratio (IHF A network, input shunt) | 110 dB or more | ||||
Damping factor (DC ~ 20 kHz) | 8 Ω : 60 4 Ω : 30 |
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Load impedance | 4 Ω ~ 16 Ω | ||||
Gain | 23.5dB | ||||
Output terminal | Speaker : A, B, A + B switching Headphone jack |
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Preamplifier Section | |||||
Input Sensitivity / Impedance | Phono1, 2 : 1.2 mV, 2.4 mV, 4.8mV/50k Ω Tuner, AUX1, 2, Play : 100mV/50k Ω |
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Total Harmonic Distortion Factor (1 v, 1 khz) | Not more than 0.03% | ||||
Intermodulation Distortion Factor (S. M. P. T. E, 70 hz : 7 khz = 4 : 1) | 0.05% or Less (1 V) | ||||
RIAA deviation (Phono1, 2) | 20 Hz to 20 kHz ± 0.5 dB | ||||
Phono maximum allowable input (1kHz/10kHz, THD 0.1% (R. M.S.)) |
Input sensitivity 4.8 mv : 400mV/1850mV Input sensitivity 2.4 mv : 200mV/970mV Input sensitivity : 1.2 mv : 100mV/480mV |
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S/N (IHF A network, input shunt) | Phono1, 2 : 75 dB or more Tuner, AUX1, 2, Play : 90 dB or higher |
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Output Voltage / Impedance |
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Tone Control (2 db Step Type) | Treble : ± 10 dB (10 kHz) Bass : ± 10 dB (100 Hz) |
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Turnover frequency | Treble:2kHz Bass:400Hz |
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Loudness (at volume -30dB) | +5dB/70Hz | ||||
Filter | High-Filter : 5 kHz, 6dB/oct. Low-Filter : 30 Hz, 6dB/oct. |
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Muting | -20dB | ||||
<General> | |||||
Semiconductor used | Transistor : 33 Diode : 20 pcs |
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Pwer | 100 VAC, 50Hz/60Hz | ||||
AC Output | Switched : 1 system, 200 VA Unswitched : 1 line, 200 VA |
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Power consumption | Electrical Appliance and Material Control Law Standard : 75W Maximum power consumption : 160W |
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External dimensions | Width 440x Height 150x Depth 386 mm | ||||
Weight | 9.3kg | ||||
Sold Separately | Wood Case CW-5 (¥ 3,000) |