Audio Database

CD - α 717D LTD
Commentary

This is a limited model CD player with improvements based on CD - α 717D Extra.

The D/A converter is equipped with a third generation Mash based on crystal oscillation.
The Mash converts the digital signal read from the disk into a 1-bit PWM signal and outputs the analog signal directly through a low-pass filter. In principle, the 0 cross distortion and non-linear distortion that were generated by the conventional multi-bit conversion method do not occur, so the reproduction capability of the minute level signal is improved.
In addition, since the PWM output of the D/A converter is configured as a 4 dac twin balance system, an excellent SN ratio is obtained by eliminating the common mode noise which is a feature of the balance.

Since the balance operation is performed by digital processing in the DAC, there is no need for an inverting amplifier, and the balance output is less susceptible to noise from the ground.

In the power supply section, one transformer is equipped with an electrostatic shield for both digital and analog systems. Both systems are completely separated from each other. In addition, the power supply section is composed of nine independent power sources to eliminate mutual interference between each system.
We have also newly developed an electrolytic capacitor using low-magnification aluminum foil and installed it in the analog section and the high-speed power supply of the Mash DAC.

In order to eliminate the adverse effect of the servo system on sound quality, we have adopted a balance servo system developed in-house.
The servo circuit is balanced to improve the ability to deal with disc scratches and dirt and to prevent leakage current from flowing into the audio circuit through the ground.
It also uses a discrete balanced low-pass filter that balances the output of the D/A converter by preventing high-frequency components that degrade sound quality from entering the ground.
In addition, the NEW Dynamic Servo System, which cancels the crossover distortion of the servo drive amplifier, improves data reading accuracy.

In the mechanism section, a linear motor with superior quietness and high-speed access performance is adopted in order to reduce microvibration generated when the disk is rotated. In addition, a spindle motor and independent 2 motors for tray loading and mechanical chassis up are also installed, and a 4-motor mechanism is adopted.
In addition, the vibration isolation effect is improved by adopting a triple chassis structure in which the play chassis floats in four places from the mechanical chassis and sub-chassis by spring and oil dump.
In addition, various measures have been taken to prevent distortion of sound caused by vibration during motor rotation, such as a 2-axis sliding type pickup and a rail holder of a die cast base.

The disc tray is made of a rigid and elastic liquid crystal polymer, which has a low coefficient of expansion and excellent vibration absorption properties. As a result, the disc tray achieves high dimensional accuracy and vibration damping.
As for the body structure, we have adopted a double chassis structure with an outer chassis based on a 1.6 mm bottom plate and an inner chassis installed in the CD to improve rigidity and vibration isolation, and to block and eliminate adverse effects on sound quality caused by external vibration and microvibration generated by the mechanism.

In order to ensure the sound quality as a limited model, the performance of each part is thoroughly examined and adopted.
First of all, the power supply section employs a newly developed special electrolytic capacitor with low signal loss and a wide passband. In addition, high-quality parts such as transformers with separate windings for servo and analog systems and fast recovery diodes are used.
We have also adopted a copper-plated rear panel that suppresses magnetostriction and unwanted vibration, and a special insulator made of stainless containing powder that protects the pickup section from external vibration.

Equipped with digital output of 2 optical and coaxial systems with on/off switch.

A display with on/off function capable of text display and twin time display is adopted.

It is equipped with functions such as Compuedit function to realize effective tape dubbing, variable scan convenient for program setting, and follow-up memory.

Wireless remote control is included.

Model Rating
Type Α -X Balanced CD Player
Reading system Non-contact optical system
Pick-up form 3-beam laser pickup
Number of revolutions 200 rpm ~ 500 rpm
Number of channels 2 Channel
D/A converter 18-bit resolution Mash DAC
Frequency characteristic DC ~ 20 khz ± 0.3 db
Harmonic distortion factor (1 kHz) Not more than 0.0025%
Dynamic range 98 dB or More (EIAJ)
Wow and flutter Measurement limit value or less
Signal-to-noise ratio 105 dB or more (EIAJ)
Output voltage 2V
Output impedance Normal : 5k Ω or more
Balance : 600 Ω or more
Rated power consumption 27W
External dimensions Width 466x Height 127.5x Depth 397.5 mm
Weight 11.0kg
Attachment Wireless Remote Control
Sold Separately Canon Cable for Balance Connection PS-01 (¥ 10,000)