TRIO KA-8300
¥ 78,000 (released in 1978)
Commentary
High-speed DC integrated amplifier with MC head amplifier of DC configuration.
The MC head amplifier consists of all stages complimentary service push-pull DC-configuration using newly developed ultra-low noise transistor in the first stage.
A newly developed FET is used in the first stage of the equalizer amplifier section, and a high signal-to-noise ratio is obtained by lowering the impedance of the whole circuit. The circuit configuration consists of the first stage cascode-connected FET input, cascode-connected A-class amplification, and Darlington connection complimentary service push-pull output. The A-class amplification stage is cascode-connected and constant-current load, and transistors are used in the operation range with good linearity to achieve low distortion factor.
From the Tuner (Aux) jack to the SP jack, all signal systems, including those in the NF loop, are straight DC amplifiers without a capacitor for low-pass cutting. When playing analog discs, only the equalizer amplifier and straight DC amplifier are used.
The tone control amplifier uses a unique NF-CR type that uses an operational amplifier.
This circuit is superior in that it does not have gain or phase inversion as a whole, and can be inserted anywhere regardless of the impedance before or after it.
The power amplifier section is a high-gain type that absorbs the gain of approximately 20 dB that conventional flat amplifiers had. The circuit configuration consists of a cascode-connected FET differential amplifier at the first stage, and all three differential stages are direct-coupled ICL, OCL and DC power amplifiers.
In the final stage, a transistor with excellent high-frequency characteristics and a wide safe operating range is used. The drift amount of this transistor is as small as 100 mv (P-P) at maximum under all conditions from -10 ℃ low temperature to + 60 ℃ high temperature, demonstrating excellent stability.
The power supply section consists of a large power transformer with windings separated left and right from the secondary side and four 10,000 μ F high-capacity electrolytic capacitors. The left and right channels are separated.
Equipped with a 3-stage switching type loudness control circuit.
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Model Rating
| Type | Integrated amplifier | ||
| Rated output (phono → sp terminal, both channel operation) |
80W + 80W (8 Ω, 20 Hz to 20 kHz) 110W + 110W (4 ω, 1 kHz) 85W + 85W (8 ohm, 1 khz) |
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| Total harmonic distortion factor (8 Ω) |
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| Cross modulation distortion factor | Tuner, Aux, Tape → SP terminal : 0.003% (at rated output, 8 Ω, 60 hz : 7 khz = 4 : 1) | ||
| Frequency characteristic | Tuner, Aux, Tape → SP jacks (straight DC on) : DC ~ 400 khz -3dB Tuner, Aux, Tape to SP jacks (straight DC off) : 18 Hz to 400 kHz -3dB |
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| Output Bandwidth (IHF) | Tuner, Aux, Tape → SP terminal : 5 Hz to 65 kHz (8 Ω at 0.03% distortion rate) | ||
| Damping factor | 100 (Tuner, Aux, Tape to SP terminal, DC to 20 kHz, 8 Ω) | ||
| Input Sensitivity / Impedance | Phono MM → SP Terminal : 2.5mV/50k Ω Phono MC → SP Terminal : 0.1mV/100 Ω Tuner, Aux, Tape → SP terminal : 200mV/50k Ω |
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| Signal-to-noise ratio (IHF-A) | Phono → SP Terminal : 89 dB (2.5 mV input) Phono MC → SP terminal : 68 dB (0.1 mV input) Tuner, Aux, Tape → SP terminal : 110 db |
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| Tone control (Tuner, Aux, Tape → SP connector) |
Bass : ± 7.5 dB (100 Hz, 50 Hz) Treble : ± 7.5 dB (10 kHz, 20 kHz) |
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| Loudness control | + 3 db, + 6 db, + 9 db (Tuner, Aux, Tape → SP terminal) | ||
| Transient response | Rise time : 0.9 μ s (Tuner, Aux, Tape → SP terminal) Slew rate : ± 120 V / μ s (Tuner, Aux, Tape → SP terminal) |
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| Phono maximum allowable input (Rec out, 1 kHz) |
MM : 220 mV (distortion rate 0.01%) MC : 8 mv (Distortion rate 0.01%) |
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| Phono RIAA deviation | 20 Hz to 20 kHz ± 0.2 mV | ||
| Output Level / Impedance | Tapre rec pin : 200mV/120 Ω | ||
| Power outlet | Power switch interlock : 2 systems Power switch not linked : 1 system |
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| Power supply voltage | 100 VAC, 50Hz/60Hz | ||
| Rated power consumption | 200W (Electrical Appliance and Material Control Law) | ||
| External dimensions | Width 440x Height 153 (146) x Depth 403 mm | ||
| Weight | 13.5kg |