YAMAHA TX-900
¥ 49,800 (released in 1987)
Commentary
FM/AM digital tuner that adopts CSL tuning system.
It uses Yamaha's original CSL (Computer Servo Locked) tuning system for digital tuning and analog reception.
Once the CSL selects the digital channel, it automatically tracks the tuning point with good sound quality by the FM servo, so that high S/N reception is possible in all reception bands.
Combined with the use of LDC display, which generates very little noise, high S/N is achieved.
Also, an IF direct distortion correction circuit is mounted together with this CSL.
In order to find the tuning point of the best sound without being affected by jamming stations, a 10-double precision fine tuning system is adopted, which is superior to ordinary synth tuners.
This method drives the tuning point in 0.01 MHz steps. When a interfering station is adjacent to the desired station, the tuning point is slightly detuned in 0.01 MHz steps to avoid interfering waves and achieve the best sound quality.
In the case of AM reception as well, fine tuning of 1 kHz step is possible from the usual 9 kHz step tuning, and the reception listening ability is expanded by minimizing interference.
In order to mode automatic IF band switching circuit of WIDE/NARROW/SUPER NARROW is installed in the IF stage in order to secure accurate tuning point and to obtain complete eliminating capability of interfering signals.
When there is no interfering signal, WIDE has a wide band selectivity ; when there is an interfering signal, NARROW has a narrow band selectivity ; and when there is a strong interfering signal, SUPER NARROW extracts the desired signal with a sharp selectivity. These switches automatically according to the reception conditions, and clear reception is obtained without interference from noise and beats.
The RF stage and MIX stage are equipped with a high-sensitivity MOS FET front-end with excellent interference rejection characteristics, and the performance equivalent to FM4-series is demonstrated.
In addition, the newly developed MPX IC is used in the stereo demodulation circuit. When a signal with a flat modulation frequency from low to high frequency is input, there is no beat-down due to a 38 kHz subcarrier signal, the phase characteristic is kept flat, and low distortion factor and high separation are obtained.
It is equipped with a newly developed multi-color LCD by metal mask system.
The transmission efficiency of the light-emitting element is improved by realizing 0 light leakage to the non-illuminated part and infinite high contrast with the illuminated part, and the viewing angle is also expanded beyond conventional LCDs.
The display functions include a signal quality meter with station frequency, preset channel, and 24-segment bar display, an IF mode graphic display with initial selectivity characteristics, and various operation status displays.
Preset memories range from general station frequency only memories to more practical 3-way multi-state memories including reception conditions.
Three reception modes (stereo mode, high blend mode and IF mode) can be stored together with the station frequency. Once stored, the desired station can be called up at any time with comfortable sound quality.
Equipped with FM/AM20-station random access preset.
You can call up the desired FM or AM station with one touch operation without changing the band. Moreover, the preset keys are 1-key / 2-state, and you can preset up to two stations for one key, so you can preset up to a total of 20 FM/AM stations with 10 keys.
Equipped with manually selectable IF band selector switch, AUTO/MANUAL tuning mode selector switch, AUTO STEREO/MONO mode selector switch and high blend switch.
Equipped with 75 Ω dedicated FM antenna terminal (with antenna plug for both 75 Ω / 30 Ω)
Equipped with AM loop antenna.
Model Rating
| Type | FM/AM digital tuner |
| <FM Part> | |
| Practical sensitivity | Mono : 0.9 μ V (10.3 dBf) / 75 Ω |
| S/N ratio 50 dB sensitivity | Mono : 1.55 μ V (15.1 dBf) / 75 Ω Stereo : 20 μ V (37.2 dBf) / 75 Ω |
| Capture ratio | 1.2dB(WIDE) |
| Image interference ratio | 90dB |
| IF interference ratio | 110dB |
| Spurious interference ratio | 110dB |
| AM suppression ratio | 70dB |
| Effective selectivity | 90dB |
| Signal-to-noise ratio | mono:100dB stereo:91dB |
| Total harmonic distortion factor | Stereo : 0.015% (WIDE, 1 kHz) Mono : 0.0095% (WIDE, 1 kHz) |
| Stereo separation | 65dB(1kHz) |
| Frequency characteristic | 20 Hz to 15000 Hz, ± 0.5 dB |
| <AM Department> | |
| Effective selectivity | 250 μ V/m |
| Image interference ratio | 40dB |
| Spurious interference ratio | 50dB |
| Signal-to-noise ratio | 52dB |
| Total harmonic distortion factor | 0.3% |
| <General> | |
| Pwer | AC100V 50/60Hz |
| Power consumption | 10W |
| External dimensions | Width 435x Height 94x Depth 282.5 mm |
| Weight | 3.3kg |