NIKKO TRM-50A
Price unknown (around 1960 s?)
Commentary
Pre-main amplifier with FM circuit breaker.
It employs a direct coupling circuit that eliminates the audio transformer that causes distortion, and realizes excellent frequency characteristics and distortion factor by using a high-frequency power transistor.
Generally used alloy-type power transistors have an f α (cutoff frequency) of 250 Hz to 350 kHz, so output drops and distortion increase at around 5 kHz. Therefore, they cannot be used in high-fidelity amplifiers. The TRM-50A uses a diffused base alloy emitter high-frequency power transistor with an f α of 5 MHz, enabling excellent frequency characteristics and low distortion factor.
Using a special temperature compensator, the output does not decrease even when the ambient temperature is 50 ℃.
To protect the power transistor from problems such as short-circuiting the speaker terminals or excessive input, an FM-type circuit breaker is mounted. This FM-type circuit breaker conforms to the BTS standard used by broadcasting stations for communications, and is highly reliable.
Equipped with left and right independent tone control.
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Model Rating
| Type | Pre-main amplifier |
| Music power (when one channel is output) | 22.5W (8 Ω) 16W (16 Ω) |
| Undistorted output (sine wave, 1% distortion rate) | 17W (8 Ω) 12W (16 Ω) |
| Frequency characteristic | 15 Hz to 60 kHz ± 1 dB |
| Distortion factor | 0.2% or Less (1 kHz) |
| Input sensitivity | Tape head:2mV Phono MAG:4mV Phono CER:250mV Tuner, Aux : 500 mv |
| Tone control | Bass : ± 15 dB (50 Hz) Treble : ± 15 dB (10 kHz) |
| Accessory circuit | Mode Loudness Scratch Rumble |
| Semiconductor used | Transistor : 18 Silicon Diode : 2 pcs Temperature Compensator : 4 Pieces |
| Circuit protection | FM MM-type circuit breaker |
| Pwer | 100 VAC, 50Hz/60Hz |
| Power consumption | 15 VA (No Signal) 80 VA (at maximum output) |
| External dimensions | Width 295x Height 85x Depth 240 mm |
| Weight | 4.2kg |