TRIO KA-4000
¥ 49,800 (around 1968)
Commentary
A pre-main amplifier developed based on Trio's excellent amplifier results.
High-quality silicon transistors are used from the preamp to the main amplifier, and both frequency and output band characteristics have improved high-frequency characteristics.
The preamplifier section is directly connected 3-stage amplification, and a large amount of NF is applied to improve the dynamic range.
The tone control for both Bass and Treble uses an 11-contact rotary switch that can change the tone in increments of 2 dB per step.
It also has a muting circuit so that the volume can be reduced by -20dB with a single switch.
The preamp and main amp can be used independently.
To protect the power transistor in case of emergency, it is equipped with an automatic return type pure electronic protection circuit.
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Model Rating
| Type | Pre-main amplifier |
| Power Amplifier Unit | |
| Rated output | 40W/40W (8 Ω, 0.5% strain) |
| Music power | 120W (4 Ω, 0.8% strain) 100W (8 Ω, Strain 0.8%) |
| Frequency characteristic | 15 Hz to 60,000 Hz ± 0.5 dB |
| Output band characteristics (distortion 0.5%) | 10 Hz to 60,000 Hz -3dB |
| Distortion Factor (1 kHz, 8 Ω Load) | 0.1%(35W/35W) 0.05%(20W/20W) 0.1%(300mW/300mW) |
| Intermodulation distortion factor (60 Hz : 70 kHz, 8 Ω load) | 0.2%(35W/35W) 0.08%(10W/10W) |
| Residual noise | 0.5mV |
| Damping factor | 30 (8 Ω) 60 (16 Ω) |
| Preamplifier Section | |
| Input Sensitivity / Impedance | Phono1, 2 : 2mV/100k Ω Tape HD : 2mV/100k Ω MIC : 2mV/100k Ω AUX, Tuner, Tape Play : 200mV/100k Ω |
| Tone control | Bass : 100 Hz ± 10 dB Treble : 10 kHz ± 10 dB |
| Loudness control | + 6 dB (100 Hz), + 2 dB (10 kHz) |
| Filter | Low Filter : 80 Hz, -12dB/oct. Hihg Filter : 8 kHz, -12dB/oct. |
| Equalizer | Within ± 0.2 dB of the RIAA NAB standard curve |
| Signal-to-noise ratio | Phono1, 2 : 70 dB Tape HD, MIC : 70 dB Tuner, AUX, Tape Play : 80 dB |
| <General> | |
| Accessory circuit | Audio muting switch Pre-Main jumper circuit DIN standard recording and re-connector Tape monitor switch 2-speaker selector switch Mono output 12dB/oct Cut Low / High Filter |
| Semiconductor used | Transistor : 30 Diode : 6 pcs |
| Power supply voltage | 100 VAC / 117 V, 50Hz/60Hz |
| Power consumption | No signal : 13W Maximum output : 180W |
| External dimensions | Width 408x Height 134x Depth 280 mm |
| Weight | 8kg |