Audio Database

Image of the PD-T07A
Commentary

A CD turntable type CD player equipped with a high-speed pulse flow D/A converter.

The mechanism uses a CD turntable system that moves the pickup and spindle motor from the bottom of the disk to the top of the disk to hold the disk from the bottom to the entire surface.
Compared with the conventional tray system, the moment of inertia is improved by about three times, and unwanted vibrations caused by external vibration, sound pressure, sagging of the disk, and surface blurring are also suppressed.

The D/A converter is equipped with an originally developed high-speed pulse flow D/A converter.
In this D/A converter, the noise shaper operates at a high oversampling frequency of 384 fs, enabling fine sampling and greatly reducing the noise floor due to requantization. As a result, the noise shaper order can also be used at second and lower orders, reducing the impact of out-of-band noise and analog low-pass filters that cancel it.
Furthermore, since the effect of jitter becomes more pronounced as the master clock frequency becomes higher, the effect of jitter is reduced by operating the master clock at a lower clock frequency of 16.93 MHz.
In addition, the duty ratio, which is the on/off timing ratio of 1-bit output, has been improved from 50% to 100%. This doubles the output level and provides audio output with a high SN ratio and low distortion.

It uses direct construction to guide the picked up music signal to the output terminal in the shortest distance. It separates the center tray design, digital & servo and audio board to prevent mutual interference.
In addition, a sealed PCB (double-sided printed circuit board) is used for both digital and analog circuits to provide an effective shield against noise from the digital circuit to the analog circuit. In addition, the analog circuit board uses OFC (oxygen-free copper) for the copper foil and is connected at the same time with the shortest distance to form a symmetrical structure.

A clean laser pickup developed in-house is used in the pickup section.
By reducing the number of optical components, such as collimator lenses, and by reducing aberrations in the optical path, laser efficiency is improved and signals with less distortion can be read.
A built-in I/V head amplifier photodetector is used to amplify the signal to the order of approximately 200 mV. In combination with the Accu-Focus system, it enables signal transmission with less signal reading error and jitter due to disturbance.
In addition, a high-precision engineering plastic body is adopted for the pickup body, and together with the high-precision shape, high rigidity and high internal loss are realized.

Class A FET buffer amplifier is used for the audio circuit.
By lowering the output impedance, the influence of the load of the connected amplifier is suppressed. Moreover, by making the operation class A, fluctuation of power consumption during operation can be reduced, and low distortion factor is realized.

The spindle motor is equipped with a large brushless Hall motor with a starting torque of 65g ・ cm. Combined with a φ 4.5 mm thick shaft, it is resistant to load fluctuations and achieves stable rotational characteristics.
In addition, a silent linear motor servo mechanism with excellent response is adopted for the pickup drive to realize quiet and quick access.

In the PD-T07A, the vibration resistance of the turntable system has been further improved, and by covering the mechanism part with a silent chassis, the vibration resistance of the whole mechanism has been improved.
In addition, the mechanical base is a lamisert mechanical base made of two layers of different metals and molded with special resin. The vibration damping characteristics are improved and the generation of magnetic strain is suppressed by copper plating. This mechanical base is mounted on the mechanical chassis via a coaxial suspension made of special rubber and springs, and the turntable base is also mounted via a coaxial suspension. Each of them has a float structure to block external vibration from the chassis.

The newly developed multi-layered honeycomb chassis is used for the chassis.
Based on a honeycomb chassis made of BMC (Bulk Molding Compound) with high internal loss and high rigidity, steel plates with excellent electromagnetic shielding and cushioning materials are layered on top of each other. The excellent vibration control reduces unnecessary vibration and suppresses sound reflection from the floor.
In addition to the large-size honeycomb insulator that absorbs external vibration, the fifth insulator is adopted to provide vibration resistance and weight balance, thereby reliably maintaining the center mechanism.

The power supply section is equipped with a twin power transformer with digital / analog separation. The power supply circuit uses a 5-part 14 regulator. The 5 parts of servo / digital, servo drive, D/A converter and audio + and - are independently rectified to eliminate mutual interference.
The audio circuit uses a discrete push-pull power supply, while the D/A converter uses a dedicated winding and power supply circuit to eliminate the influence of other power supplies.
The transformer for the audio circuit uses bifilar winding to improve the balance of output impedance, etc., and the + side and - side power supply are supplied under the same condition to improve the sound quality.

Uses an extra-thick 4-core cord with separate core wires for servo / analog only from the power plug.
It is made of OFC (high-purity oxygen-free copper) and has a separate structure that eliminates the influence of the AC power supply itself on other circuits.

Equipped with a balanced output that is not easily affected by external noise.

Uses an aluminum extruded top bonnet with excellent vibration control properties.
In addition, we have adopted an aluminum panel stabilizer that increases rigidity and prevents the occurrence of slight vibration of the front panel.


Equipped with a display off switch to prevent scanning noise. Also equipped with a clean microcomputer to cancel scanning noise. (Backup supported)

Equipped with digital / anlogout change-over switch (supports backup).

Model Rating
Type CD Player
Pick-up Three beam semiconductor laser system
Frequency characteristic 2 Hz to 20 kHz
Signal-to-noise ratio (EIAJ) 115 dB or more
Dynamic Range (EIAJ) 99 dB or more
Channel Separation (EIAJ) 110 dB or more
Wow & flutter (EIAJ) Measurement limit (± 0.001% W. PEAK) or less
Harmonic distortion factor (EIAJ) Not more than 0.0015%
Output voltage 2.0Vrms
Number of channels 2 channels (stereo)
Digital output Coaxial Output : 0.5Vp-p/75 Ω
Optical output : -15dBm ~ -20dBm (wavelength 660 nm)
Pwer 100 VAC, 50Hz/60Hz
Power consumption 18W
External dimensions Width 440x Height 140x Depth 365 mm
Weight 12kg
Attachment Wireless Remote Control