Accuphase DP-70V
¥ 480,000 (Released in November 1990)
Commentary
A CD player developed by introducing the technology cultivated in the DP-80L/DC-81L.
The DP-70V is equipped with a digital control center function and can demodulate digital signals from multiple DAT and BS tuners via digital input / output jacks.
In order to realize the function as a digital control center, three sampling frequencies are built in, and the source frequency is automatically selected.
A 20-bit discrete D/A converter is used for the D/A converter.
Each bit has a precision of 1/220=9.54x10-7With 16 times the accuracy of 16 bits, achieving excellent performance and greatly reducing quantization noise.
The DP-70V consists of a current addition type with an advantage in linearity. It is composed of a discrete method with carefully selected elements in order to realize the performance of the 20-bit theoretical limit value. The DP-70V consists of a current switch element and an ultra-precision resistor. Each unit is strictly adjusted for complete operation. This realizes ideal linearity in the whole output level range from minute level to large level, and eliminates 0 cross distortion and distortion at small output.
The digital filter uses an independent 20-bit 8 x oversampling digital filter on the left and right sides.
The DP-70V filter uses advanced digital calculation techniques to successfully suppress the frequency range between 24.1 and 328.7 kHz to an excellent value of -110dB, while limiting the passband ripple, which causes sound quality degradation, to within ± 0.00005 dB.
The audio low-pass filter uses a GIC third order Butterworth active filter with carefully selected elements.
This output is directly output through a buffer amplifier with a gain of 0 dB.
The digital signal section and analog circuits after the D/A converter are electrically separated by an opto-coupler to prevent deterioration of sound quality caused by digital signals. The opto-coupler is a high-speed type with a transmission capacity of 40Mbit/sec. The DP-70V uses four opto-couplers per channel for electrical insulation and faithful optical signal transmission.
In addition, in order to prevent adverse effects through the power supply, the digital and analog power transformers are each separated into two transformer configuration, and the winding of the analog transformer is left and right independent to prevent interference between the left and right channels.
Each circuit is completely shielded by a thick metal plate to prevent high-frequency noise components from interfering both electrostatically and electromagnetically through space.
A lithium tantalate single crystal oscillator is used for the VCO that produces the sampling frequency.
The lithium tantalate has a feature that the side spectrum (impurity component) can be controlled to the level of the crystal oscillator while the sampling frequency lock range can be set wide.
The digital input terminal is equipped with four systems, two optical systems and two coaxial systems.
The output terminal is equipped with one optical and one coaxial system.
Equipped with a noise shaper, the noise within the audible band is reduced by reducing noise by feeding back the rounding error generated by the digital filter to the next data.
A digital de-emphasis circuit is incorporated to support CDs with emphasis, which raises the high frequency range during recording and lowers it accordingly during playback.
Normally, the CR element is used to change the frequency characteristics of the audio circuit, but the DP-70V achieves excellent characteristics by changing the characteristics according to the state of the digital signal through digital de-emphasis.
Equipped with digital level control, it can be adjusted up to -40dB in 1 dB steps. The DP-70V has a 4-bit margin for ideal level control with little degradation in sound quality even when the volume is reduced.
It can be adjusted from the listening position by the remote commander.
Analog outputs include XLR-type balanced outputs and RCA phono jacks.
The mechanism is mounted on an aluminum die-cast frame to prevent resonance, and floating from the chassis to cut off vibration transmission. The disk table is also floating to minimize external vibration to the mechanism body.
In addition, by analyzing the vibration mode of the structure and supporting the mechanism body with a thick metal chassis, we have thoroughly strengthened the mechanism against secondary resonance.
In conventional CD players, the output of the photo detector, which reads the signal attached to the laser pickup, is directly led outside the unit and amplified by an RF amplifier. In the DP-70V, a very small and lightweight RF amplifier is attached in contact with the detector to obtain a large signal output, thereby suppressing interference caused by noise.
The timing of all operations is controlled by a single master clock, which prevents beats that can occur when two types of signals are used, one for digital signal processing and the other for microprocessors.
It uses a linear motor mechanism to track the laser pickup and is controlled by a specially developed 8-bit microprocessor to enable speedy and smooth music selection.
Equipped with a frame playback function, it can start and play back in units of one frame (1/75 second).
Wireless remote control is included.
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Model Rating
| Type | CD Player |
| <Player Part> | |
| Formatting | CD standard format Error correction method : CIRC Number of channels : 2 channels Rotation speed : 500 ~ 200 rpm (CLV) Performance speed : constant 1.2 ~ 1.4m/s |
| Reading system | Non-contact optical reading (using semiconductor laser) |
| Laser | GaAlAs (double hetero diode) |
| Digital Output Format Level (equivalent to EIA) | Formatting : Digital Audio Interface Optical : Optical power : -21 to -15dBm (EIAJ) Emission wavelength : 660 nm Coaxial : 0.5Vp-p/75 Ω |
| Digital Processor Division | |
| Formatting | EIA standard format |
| Quantization number | 16-bit straight line |
| Sampling frequency | (Timing Accuracy : Level II) 32.0 kHz ± 0.1% 44.1 kHz ± 0.1% 48.0 kHz ± 0.1% |
| Frequency characteristic | 4.0 Hz to 20 kHz ± 0.3 dB |
| D/A converter | Discrete 20-bit |
| Digital filter | 20-bit 8 x oversampling Noise shaper function Digital de-emphasis function Deviation ± 0.001 dB |
| Total harmonic distortion factor + noise | 0.0016%(1kHz) 0.002% (20 Hz to 20 kHz) |
| S/N | 119dB |
| Dynamic range | 98dB |
| Channel separation | 109dB |
| Rated Output / Impedance | Balanced : 2.5V/50 Ω (25 Ω / 25 Ω), balanced XLR type Unbalanced : 2.5V/50 ohm, RCA phono jack |
| Output level control | 0 ~ -40dB, 1 dB step (digital type) |
| Digital Input Format Level (equivalent to EIA) | Formatting : Digital Audio Interface Optical : Received power : -15dBm to -27dBm Coaxial : 0.5Vp-p/75 Ω |
| <Others> | |
| Semiconductor used | Transistor : 32 IC : 74 Diode : 66 units |
| Pwer | 100V/117V/220V/240V, 50Hz/60Hz |
| Power consumption | 23W |
| External dimensions | Width 475x Height 135x Depth 389 mm |
| Weight | 24.3kg |
| Attachment : Remote Commander RC-7 | |
| Remote control system | Infrared pulse system |
| Pwer | DC 3V |
| Dry battery | SUM-3 (IEC Designation, R6), 2 units |
| Maximum external dimensions | 64 mm wide x 176 mm high x 18 mm deep |
| Weight | 180g (including dry batteries) |
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