TRIO KA-1000
¥ 145,000 (around 1980)
Commentary
Pre-main amplifier with Σ drive.
In the Σ drive system, the conventional concept of NFB, which was completed in the case of the amplifier, is extended to the input terminal of the speaker. The speaker cable is also considered as one of the internal wiring of the amplifier, and the performance at the input terminal of the speaker is guaranteed.
First of all, we have installed a unique Σ cable that connects the + side of the speaker and the feedback point of the power amplifier to control various types of distortion at the input terminal of the speaker, including reverse distortion caused by the magnetic circuit of the speaker.
In addition, by separating the ground point and the power loop on the - side cable, the potential difference between the input terminal of the speaker and the ground point is completely eliminated from the concept of one point grounding.
A non-magnetic structure is adopted in order to further reduce harmful auditory distortion caused by magnetic distortion.
The bottom plate is made of resin to eliminate interference with the most sensitive power amplifier, and the side plate is also made of resin to minimize interference with the equalizer.
The power transformer, which is a mass of magnetic material, is completely separated from the audio signal.
It uses a dynamic power supply that separates the transformer from the audio signal and is housed in a separate case, which was adopted in the L-01A.
A large-capacity transformer is used for each L/Rch, making it possible to drive stably even when a speaker with a strong impedance change is connected. Four large-capacity transformers of 10,000 μ F are used for the Chemicon for power amplification. In addition to two independent power sources on the left and right left and right sides, the class A amplifier is also equipped with a rectifier circuit with separate windings. This is a three power supply system.
The equalizer amplifier is equipped with a new IC with superior basic performance, which simplifies the circuit and eliminates extra wiring and improves performance and sound quality.
The MC adopts one NF loop system by gain switching, and the signal path can be simplified because the head amplifier system is not adopted.
In the power amplifier section, we have developed a new high-speed amplifier that eliminates TIM distortion and switching distortion by applying uniform NFB to all audible frequency bands based on Trio's high-speed theory.
From the Tuner (AUX) terminal to the sp terminal, it is a straight DC amplifier configuration without a condenser for low-pass cutting, and a heat pipe with high thermal conductivity is used for the radiator.
It uses a fader that can be called an auto volume with one touch, and is effective for switching records and switching sources.
Equipped with a recout selector, the signal to the recout can be freely selected regardless of the input selector.
Both Bass and Treble are equipped with a tone control that can be switched between two levels.
The main tone circuit is equipped with a tone defeat circuit that can cancel the tone circuit.
Equipped with a subsonic filter and balance jump circuit.
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Model Rating
| Type | Σ drive amplifier | ||||
| Rated Output (20 Hz to 20 kHz, Both Channel Operation) | 100W + 100W (8 Ω, Phono → sp out) | ||||
| Total Harmonic Distortion Factor (20 Hz to 20 kHz, 8 Ω) |
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| Intermodulation distortion factor (60 hz : 7 khz = 4 : 1) | Tuner, AUX, Tape → sp out : 0.005% (8 Ω at rated output) | ||||
| Frequency characteristic | DC ~ 400 khz -3dB (Tuner, AUX, Tape → sp out) | ||||
| Damping factor (100 Hz) | Amplifier unit : 600 Σ Cable termination : 600 |
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| Input Sensitivity / Impedance | Phono MM → sp out : 2.5mV/47k Ω Phono MC → sp out : 0.2mV/100 Ω Tuner, AUX, Tape → sp out : 150mV/47k Ω |
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| Signal-to-noise ratio (IHF-A) | Phono MM → sp out : 87 dB Phono MC → sp out : 67 dB Tuner, AUX, Tape → sp out : 105 dB |
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| Tone control |
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| Loudness control | + 10 dB (100 Hz, Volume -30dB) | ||||
| Subsonic filter (-3dB) | 18 Hz, 6dB/oct. | ||||
| Rise time | 0.9 μ s (Tuner, AUX, Tape → sp out) | ||||
| Slew rate | ± 120 V / μ s (Tuner, AUX, Tape → sp out) | ||||
| Phono maximum allowable input (Phono → Tape rec, 1 kHz, 0.003% distortion factor) | MM:270mV MC:15mV |
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| PhonoRIAA deviation | 20 Hz to 20 kHz ± 0.2 dB | ||||
| Output Level / Impedance | Tape rec (PIN) : 150mV/330 Ω | ||||
| Power supply voltage | 100 VAC, 50Hz/60Hz | ||||
| Rated power consumption (Electrical Appliance and Material Control Law) | 320W | ||||
| Power outlet | Power switch interlock : 2 systems Power switch not linked : 2 systems |
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| External dimensions | Body : Width 440x Height 123x Depth 375 mm Power Supply : W 140x H 123x D 358 mm |
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| Weight | 14.4 kg (Body + Power Supply) |