YAMAHA CDX-900D
¥ 89,800 (released in 1987)
Commentary
A CD player with a high-bit digital filter and an independent left-right glitch less high-speed twin D/A converter.
Equipped with 4 x oversampling high-bit digital filter.
By high-precision digital operation with 225 + 41 operation degree and coefficient word length up to 32 bits, noise and ripple are suppressed to 16 bit resolution level or less as a characteristic of the filter itself. Out-of-band noise is less than -100dB, and in-band ripple is within ± 0.0001 dB.
The D/A converter is equipped with a glitch less high-speed D/A converter that eliminates the generation of harmful glitch noise through high-speed serial processing. This eliminates the need for a switching circuit that switches the audio signal to the left and right channels and allows the output of the D/A converter to be directly connected to a low-pass filter.
Design Rule It is equipped with Yamaha's original newly developed signal processing CD LSI using a small flat package of 2 μ m in size. By integrating signal processing and servo circuit control into one chip, peripheral parts are greatly reduced. This not only simplifies the circuit, but also realizes low power consumption and low noise.
Equipped with 75 Ω coaxial type digital output terminal.
An on / off switch is also provided at the digital out terminal on the rear panel.
A high-speed photo coupler (optical coupling element) is used to prevent digital noise from entering the audio section. The optical transmission method that transmits signals while maintaining electrical insulation between the digital section and audio section prevents sound quality degradation.
The use of separate sheets with separate circuit boards for the digital and audio sections reduces the effect of electrical and mechanical vibration on sound quality.
In order to suppress mutual interference via the power supply, it is equipped with a 2-transformer power supply that feeds the digital servo and audio sections independently.
In addition, a shunt regulator system is adopted for each power supply circuit, and A-class operation is performed by continuously supplying a current larger than the fluctuation range of the load current to the power supply control transistor.
The analog circuit section employs a 5th-order new active low-pass filter combining a Bessel type with excellent phase characteristics and a Butterworth type with excellent amplitude characteristics for high-frequency use, and a DC amplifier with all stages connected directly for low-frequency use.
In particular, the DC amplifier section is fully DC-connected without any low-frequency time-constant elements such as DC servo to enhance the low-frequency reproduction capability.
High-quality electrolytic capacitors for audio are used in the power and audio sections.
A carefully selected Mylar capacitor for audio is used for the low-pass filter that affects the high-frequency characteristics.
Equipped with an 8-digit FL display with calendar function.
It is equipped with a 24 song random program function that can pick up up to 24 songs from the disc, rearrange them in the order of preference and play them.
It is equipped with a delete program function that can cut and play back songs you don't want to listen to.
It has a random play function.
Equipped with a repeat function that allows you to select one song, all songs, program songs, or between A and B.
Equipped with an index search.
It is equipped with a space insert function that can set a space between songs of approximately 4 seconds.
2-speed monitor search is adopted, and fast forward and fast backward are performed at low speed at first, and then fast forward and fast backward are performed by switching to high speed.
Equipped with a headphone port with volume.
Equipped with a timer play function that can be combined with an external timer for playback.
Wireless remote control with 24 keys is included.
This remote control is of the full mode specification perform almost all operations such as program operation and opening and closing of tray.
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Model Rating
| Type | CD Player |
| Frequency characteristic | DC ~ 20 khz ± 0.3 db |
| Harmonic distortion factor | 0.003% (1 kHz, EIAJ) |
| Signal-to-noise ratio | 110dB(EIAJ) |
| Dynamic range | 100dB(EIAJ) |
| Wow flutter | Below the measurement limit |
| Output voltage | 2 Vrms (fixed) |
| Power supply voltage | 100 VAC, 50Hz/60Hz |
| Power consumption | 18W |
| External dimensions | Width 435x Height 107x Depth 347 mm |
| Weight | 6.6kg |
| Attachment | Wireless Remote Control RS-CD9 |