YAMAHA CDX-10000

Commentary

A CD player developed by Yamaha to commemorate the 100th anniversary of its founding.
We have introduced high-bit digital technology in pursuit of precision that can be called digital resolution.

The High-Bit Digital Filter is a digital filter with 225 degree + 41 degree operation and a maximum coefficient word length of 32 bits. It is a four times oversampled digital filter of two stage continuation type that performs double oversampling at the first 225 degree operation and double oversampling at the second 41 degree operation and double oversampling at the second 41 degree operation.
As a result, the sampling noise that adversely affects the audio signal is pushed up to 176.4 kHz ± 20 kHz, and the analog low-pass filter in the latter stage has only a gradual cut-off characteristic up to the lower limit of the sampling noise of 156.4 kHz. At the same time, the high-frequency phase shift of the audio signal caused by the analog low-pass filter with steep cut-off characteristic can be eliminated.
In terms of digital data interpolation, the sampling frequency of 176.4 kHz allows sample values to be obtained at a time interval of approximately 5.7 μ s. The D/A output is closer to the original analog signal, reducing the load on the low-pass filter and realizing more faithful analog reproduction.

The High-bit D/A conversion system consists of an LR-independent twin-configuration glitch less D/A converter, a high-bit processor DVC with a digital volume controller in the front stage, and a floating high-bit sample-and-hold IC FSH in the rear stage of the D/A converter.
The high-bit digital filter can perform 4-times O-field sampling, i.e., interpolation on the time axis, with 225 + 41 operation orders. At the same time, it has a high resolution that can perform an 18-bit output, i.e., interpolation on the amplitude axis, with a coefficient word length of up to 32 bits. The high-bit D/A conversion system receives the 18-bit output of the high-bit digital filter, detects its level by DVC, shifts up all digital signals by 2 bits at most signal levels where the high-order 1 bit is not used, outputs the signals to the D/A converter, and lowers the gain to 1/4 with the FSH at the later stage to realize D/A conversion of 18-bit operation.
As a result, the S/N ratio is over 115 dB.

It is equipped with digital volume of digital control method, which is essentially free from changes in frequency characteristics when narrowing down and gang errors for each LR channel, which cannot be avoided with conventional analog volume.
The digital volume is embedded in a high-bit D/A conversion system to perform 20-bit operations and has a dynamic range of 120 dB to prevent S/N degradation when directly connected to a power amplifier for playback.
The volume resolution is 240 points in 0.4 dB steps and can be controlled between -∞～ and 0 dB with logarithmic change along the auditory sense.

We have developed and installed a linear tracking Shinme or unit that employs a linear motor for the optical head feed in order to take advantage of the unique functions of CDs such as track search and index search.
Linear motor and linear tracking enable the optical head to be sent from the innermost circumference of the disc to the outermost circumference at right angles to the pit row in the shortest stroke. In the new mechanism unit, when a song is selected, an 8-bit microcomputer stores the head position of each song by replacing it with the position of potentiometers, and the linear motor sends the optical head to the target position by using these potentiometers. Finally, the cue is corrected using the time information of the disc, and high-speed access is realized in which you can quickly call up your favorite song and favorite measure.
For the disk drive, we have adopted an FG servo coreless motor, a precision and extremely thick spindle with a diameter of 4.5 mm as specified for broadcasting stations, and high magnetic flux samarium-cobalt is used for the motor magnet. We have achieved high torque and high durability, enhanced stability of disk holding, and increased reliability.

Equipped with a tray mechanism that employs a high-torque DC motor for the tray drive and a DC motor for the disk stabilizer.
The tray drive motor uses a timing belt drive system instead of a gear drive to prevent unwanted vibration from being transmitted to the tray. A rubber idler is used as the guide roller to ensure quiet and smooth tray opening and closing.
A magnetic chucking system has been adopted for the stabilizers that are lifted by a disk stabilizer motor. When the disk rotates, the stabilizers come into close contact with the turntable, eliminating unnecessary vibration to the disk and improving rotational stability.
In addition, aluminum extruded material is used abundantly for the tray material, and the disk pad is structured to receive the disk at the outermost circumference of the disk to avoid the risk of damage to the disk signal surface.

Based on the concept that good sound comes from good structure, a highly rigid chassis / cabinet is adopted.
The front panel is 9 mm thick, the top and bottom plates are 5 mm thick, and the rear panel is 3 mm thick. Inside the external chassis, it is a highly rigid 2-box double chassis with another internal chassis.
The internal chassis is divided into two parts, a digital servo mechanical part and an audio part, and constitutes an independent box. The rigid structure design suppresses external vibration and shields electrical noise generated from the digital servo part. This separative integrated CD player is completed.
In addition, in order to cope with internal vibration of optical head mechanism and tray mechanism, etc., floating structures are introduced at important points such as floating of optical head chassis by rubber damper, floating of tray chassis by rubber bush, and floating of main body by large insulator made of sintered alloy to suppress internal and external vibration.

The power supply unit is separated from not only the power supply circuit but also from the transformer to provide independent power to the digital servo unit and audio unit. In addition, a shunt regulator power supply is used for the audio unit.
The shunt regulator power supply can be said to be ideal for the crisis of relatively low power consumption. It stabilizes the power supply by always supplying the control transistor with a current larger than the load fluctuation width required by the circuit and making it operate in class A operation.

In order to prevent noise from entering the audio part from the digital servo part in the signal path, an optical transmission method using a photocoupler is adopted so that all electric circuits operate independently.
Using seven high-speed photocouplers with a transmission speed of 10 Mbit / s, all signals are separated, the signal paths are connected by light, the digital servo part and audio part are isolated, and the electrical loop is cut off by photo isolation to prevent sound quality degradation.

In order to eliminate interference caused by electrical and mechanical vibration between circuits, the digital circuit, audio circuit and power supply circuit from the digital servo section to the audio section are composed of independent boards, and a separate sheet configuration is adopted in which each is separated.
The audio circuit board epoxy is used for the audio circuit board to suppress unwanted vibrations in the circuit board and circuit board and to prevent modulation noise.

The low-pass filter at the end of the high-bit D/A conversion system employs a fifth order new active type with a gentle cut-off characteristic, and the output buffer employs a full DC amplifier, in order to eliminate high-pass and low-pass group delay distortion and realize flat phase and amplitude characteristics over the entire audio band.
The low-pass filter does not require a high-bit digital filter. Since the high-frequency noise is sufficiently reduced, the cut-off frequency is set at a position higher than 20 kHz. In the low-frequency range, elements with a low-frequency time constant such as a DC servo are excluded. As a fully connected DC amplifier, high fidelity waveform transmission from DC to 20 kHz is promised.
Even when the severest square wave is input, waveform disturbance such as ringing hardly occurs, and excellent transient response characteristics are obtained.

It comes with a wireless remote control so that you can enjoy the CD player by remote control.
The 44-key, full-mode specification allows you to open and close the tray, play and pause / stop, as well as track search, index search, 24-track random programs, repeat playback (1 song, all songs, program songs, A ⇔ B section) and output level control.

In addition to with not only analog output terminal but also digital out terminal of 75 Ω coaxial pin jack specification based on digital audio interface format.
Digital output has on / off switch.

The audio section and power supply circuit are equipped with Chemi-Con 3300 μ Fx2 for audio with low magnification foil and high sound quality. In addition, Chemi-Con for audio with low noise characteristics is installed at important points on the circuit board, and high-grade parts such as Mylar capacitors are installed in low-pass filters.
In order to reduce the impedance of the circuit, we have embedded pure copper bus bars and other sound quality measures on the audio circuit board.

Gold plated brass machined pin jack with excellent corrosion resistance and contact properties is used for analog and digital output terminals.

The AC power cord uses a 10 mm diameter cable made of OFC wire and has polarity indication on the power plug.

Model Rating

Type	CD Player
Laser pickup	3-beam laser / optical pickup head Linear motor and linear tracking mechanism
Digital filter	18-bit 4 x oversampling High-bit digital filter
D/A converter	18-bit operation / high-bit D/A conversion system (LR Independent Twin D/A Converter Configuration)
Analog filter	Fifth order new active low-pass filter
Frequency characteristic	DC ~ 20000 Hz ± 0.3 dB
Harmonic distortion factor + noise	0.002% (1 kHz, EIAJ)
Signal-to-noise ratio	115dB(EIAJ)
Dynamic range	100dB(EIAJ)
Wow flutter	Below the measurement limit
Maximum output voltage	2Vrms
Output Voltage / Impedance	Digital : 0.5Vp-p/75 Ω
Pwer	AC100V 50/60Hz
Power consumption	25W
External dimensions	Width 475x Height 157x Depth 406 mm
Weight	25.5kg
Attachment	Wireless Remote Control