YAMAHA CDX-640

Commentary

A CD player equipped with an I-PDM D/A converter, similar to the high-end CDX 1050.

The newly developed I-PDM (Independent Pulse Density Modulation) system is used in the D/A converter.
In this method, the output pulse is made independent so that even if the output waveform is not ideal, it can be accurately converted into an analog waveform as long as the independent pulses have the same area, so that no distortion occurs in the analog waveform in principle.

The noise shaping method employs a second order noise shaping method that can theoretically ensure an S/N ratio of 140 dB or higher within the audio band and reduce noise from 100 kHz to 500 kHz. This eliminates the need for an analog filter with a steep low-pass filter, which is disadvantageous in terms of sound quality. Thus, superior sound quality is achieved.

A low-pass filter with a gentle curve is used in the analog audio section, and the characteristics of the low-pass filter itself are also taken into consideration and the material and shape of the filter are carefully examined.

Audio parts such as capacitors and resistors are used for audio parts.

In order to prevent distortion and noise caused by interference between the digital and audio signals, the DAC is housed in a shield case and is separated from the audio signal. In addition, in consideration of interference via the power supply line, an independent power supply system is adopted in which the digital / mechanical / display system and the audio system are separated.

The servo circuit is equipped with an intelligent digital servo that quickly reads out the reflectivity and modulation of the disc and controls it digitally. This makes it possible to automatically adjust the response characteristics of each disc so that all operations can be reproduced stably in the optimum condition for each disc.

The chassis base plate uses a double-structured double bottom to increase rigidity and eliminate vibration.
The top panel is equipped with a damper attached with a rubber damper, which is highly effective in suppressing chassis squeal and vibration control.

A large giant leg is used to prevent external vibration from being transmitted to the inside of the player.

It is equipped with a tape edit function. In this function, first enter the recording time of the tape, then enter the number of songs you want to edit and the remaining time will be displayed.
The auto-program function selects songs to be recorded in random order and automatically allocates them to the A side and B side.

It is equipped with functions such as index search, 4-mode repeat play between 1 song / all songs / program songs / A and B, random play, 25-song program play, delete program play, etc.

Equipped with an autospace function, it can automatically create unrecorded sections between songs to make it easier to start and program when dubbing to tape.

You can switch the display contents between Total, Single, and Remain.

The alarm clock can be played back by combining with an external timer.

Equipped with a headphone port with output volume.

10-key direct access is available.

Remote Controller Includes a wireless remote controller with volume.

There are 2 color variations of titanium and black.

Model Rating

Type	CD Player
Frequency characteristic	2 Hz ~ 20 kHz + 0.5 -1.0 dB
Harmonic distortion factor	0.0028%(EIAJ)
Signal-to-noise ratio	106dB(EIAJ)
Dynamic range	100dB(EIAJ)
Output impedance	1k Ω
Headphone out	306mV
Power supply voltage	100 VAC, 50Hz/60Hz
Power consumption	10W
External dimensions	Width 435x Height 92.5x Depth 271 mm
Weight	4.7kg
Attachment	Wireless Remote Control