YAMAHA CX-2000

Commentary

A stereo control amplifier developed as a reference for the multimedia era.

The digital part is equipped with a wide-capture range jitterless PLL circuit to cope with the fluctuation (jitter) in the time axis direction that occurs in the received waveform due to the difference in the ON / OFF speed of the LED for optical / electric conversion. This minimizes the contamination of harmful jitter.
A new fully second order integration filter circuit is incorporated into the data demodulation circuit to attenuate the high-frequency gain of the loop filter when the PLL draws in the normal data and to reduce the high-frequency jitter component. Thus, a data lock signal with minimal fluctuation is sent to the D/A converter.
In addition, in the data demodulation circuit, by connecting this perfect second order integration filter circuit to the VCO and forming a multiple feedback loop from the VCO to the PD, the pull-in capability of the PLL for the input signal is improved, and by expanding the capture range to infinity, highly stable digital data reception is realized.
In addition, in order to prevent malfunction due to external noise entering the data demodulation circuit, DC servo is applied to the input signal using a differential integration circuit to make the DC component 0, thereby realizing reproduction with less distortion.

The D/A converter features a high-bit system consisting of an 8fsx 18-bit digital filter and an 18-bit operating twin D/A converter.
This high-bit system increases the resolution of digital signals to a total resolution of 32 times, 8 times the time axis and 4 times the amplitude width, enabling smooth analog signal output immediately after D/A conversion.
This enables pure DAC direct playback in which the D/A converted signal is sent as it is without the need for an analog low-pass filter in the latter stage, which has a significant effect on sound quality.
In the high-bit system of the CX 2000, the built-in I/V conversion operational amplifier in the D/A converter LSI itself is not used. Instead, an original I/V conversion operational amplifier is used to extract the signal from the D/A converter while keeping the current output, and the gain is improved by 10 dB compared to the conventional one. The gain is lowered by 10 dB by FSH (Floating Sample and Hold) in the latter stage, thereby reducing D/A conversion noise.

In order to send the analog signal to the power amplifier in high purity, the high-level amplifier is composed of 2 stages of 20 db flat amplifier and 0 db buffer amplifier, and 4 connected volume which can be adjusted by remote control is adopted, and the volume is narrowed in 2 places before and after input / output, so that the S/N ratio in actual use is improved.
In the case of source direct, tone control, mode switching and balance are bypassed, and a simple and straight signal path is achieved.

It is equipped with a phono EQ with a built-in MC head amplifier for record playback.
Equipped with 6-position impedance switching function, various types of cartridges can be used under optimum conditions.

In order to prevent degradation of characteristics due to the routing of internal wiring, a semiconductor selector switch is adopted and designed to be switched close to the input / output terminal.
In addition, the logic control of the microcomputer enables you to enjoy A/V independent selective playback such as listening to CD while watching video.

In order to eliminate the mutual interference through the power supply line, it is equipped with 3 independent power transformers in which the digital video part, analog part and microcomputer part are separated from each transformer.
In addition, the transformer for digital video is separated into three windings and the transformer for analog is separated into two windings. A multi-regulator system is adopted in which a constant voltage circuit is provided for each board such as a phono equalizer amplifier board, tone amplifier board, digital board and microcomputer system control board. This improves sound quality by supplying low-noise, low-impedance power.
The power supply for the video section can be turned on and off independently, and the digital section stops the IC operation of the data demodulation circuit when the analog source is selected (including when the analog input of the digital source is selected), enabling pure use for each source selection.

In order to eliminate signal interference, the board is separated into separate sheets for each section, and a 6-box chassis has been adopted in which each section is separated and stored in separate boxes.
The 6 box consists of a digital part, a microcomputer part, a phono equalizer part, a power supply part, a tone amplifier part and a flat amplifier part. The interior of the cabinet is divided vertically and horizontally by a non-magnetic copper-plated frame. Moreover, the digital & microcomputer part and the line amplifier part are divided into two parts, one above the other, and the whole cabinet is assembled on top of that. This structure greatly improves durability and prevents the occurrence of modulation due to mechanical vibration.
In addition, in consideration of the pulse noise peculiar to digital, a non-magnetic, copper-plated top cover is separately prepared for the digital section to cover the entire digital section and prevent propagation of digital noise.

Equipped with optical / coaxial digital accessory input / output jacks, 12-position digital & AV Rec Out Selector, 3-band tone control with source direct, balance control, stereo / mono mode switching, subsonic filter, headphone jacks, gold-plated jack jacks, extra-thick OFC power cord with polarity display, etc.

Uses a remote control unit that can switch inputs and adjust volume.
This remote control is compatible with RS system, and products with RS mark can also be operated by remote control.

Model Rating

Type	Control amplifier
Input Sensitivity / Impedance	Phono MC : 100 μ V/10 Ω, 100 Ω, 1k Ω Phono MM : 2.5mV/47k Ω · 330 pF, 47k Ω · 220 pF, 1k Ω Line : 150mV/47k Ω
Maximum power output	12V
Signal-to-noise ratio	Phono MC : 85 dB (250 μ V input short) Phono MM : 90 dB (2.5 mV input short) Line : 106 dB (150 mV input short)
Total harmonic distortion factor (20 Hz to 20 kHz)	Phono MC:0.002% Phono MM:0.001% Line:0.001%
Frequency characteristic	20 Hz ~ 20 kHz + 0 -0.2 dB
RIAA deviation	± 0.2 dB (20 Hz to 20 kHz)
Channel separation	Phono MC : 80 dB (input short) Phono MM : 85 dB (input short) Line : 90 dB (5.1k Ω)
Residual noise	1.5 μ V or less
Tone control characteristics	Bass : 20 Hz, ± 10 dB (turnover Frequency : 350 Hz) Mid : 1 kHz, ± 10 dB Treble : 20 kHz, ± 10 dB (turnover : 3.5 kHz)
Subsonic filter	15 Hz, 12dB/oct.
Power supply voltage	100 VAC, 50Hz/60Hz
Power consumption	35W
External dimensions	Width 473x Height 130x Depth 400 mm
Weight	12.2kg
Attachment	Remote Controller RS-CX2000