Accuphase DP-11
¥ 270,000 (released in December 1989)
Commentary
This CD player was developed using the technology cultivated in the top-of-the-line separate-type CD player.
18-bit D/A converters are carefully selected and used as D/A converters.
In order to maximize the performance of this converter, the bit accuracy can be adjusted. Taking full advantage of this advantage, all products on the production line can be adjusted to achieve the maximum performance.
The sampling frequency is increased by an integer multiple, and the cut-off characteristic of the audio filter, which removes unwanted noise components, is relaxed to remove the noise interference factor.
The DP-11 uses an 8 x oversampling digital filter to suppress the amount of reduction between 24.1 kHz and 328.7 kHz to -110dB.
In addition, the passband ripple, which causes sound quality degradation, was within ± 0.00005 dB, making it the highest level filter available at that time.
The audio low-pal filter uses a carefully selected discrete GIC third order Butterworth active filter, and it cuts unnecessary components with a gentle characteristic of 18dB/oct.
An optocoupler electrically separates the digital signal portion from the analog circuit.
The opto-coupler is an ultra-high-speed 40Mbit/sec. Four opto-couplers are used per channel for complete electrical separation and faithful optical signal transmission.
In addition, in order to prevent entry through the power supply even if it is cut off in the signal path, the power transformer of digital and analog circuit is made into a 2-transformer configuration separately. In order to improve audio characteristics, the winding of the analog transformer is made into the left and right independently.
In addition, each circuit is completely shielded by a thick metal plate to prevent high-frequency noise components that interfere electrostatically through space.
The laser pickup uses a linear motor mechanism for tracking and is controlled by a specially developed 8-bit microprocessor, enabling quick music selection in about one second.
The mechanism is mounted on an aluminum die-cast frame to prevent resonance. Furthermore, the mechanism is floating from the chassis to prevent transmission of vibration. This allows the mechanism to float together with the disk table to minimize external vibration to the mechanism.
In addition, the mechanism body is supported by a thick metal chassis and is thoroughly strengthened against vibration, and the structure is strong against resonance and vibration by making the whole frame structure robust.
A noise shaper is installed to further reduce quantization noise.
This method reduces noise within the audible band by reducing noise by returning the rounding error generated by the digital filter to the next data.
In order to support CDs with emphasis, which raises the high-frequency range during recording and lowers the high-frequency range during playback, digital deemphasis, which changes characteristics according to the state of the digital signal, is incorporated.
As a result, the characteristics of deviation ± 0.001 dB and phase difference within 1.5 degrees with respect to the specified characteristics are realized.
In the audio stage, the output of the converter is set so that there is no need for amplification, and the amplifier is a DC servo directly connected type with only buffer, thus improving S/N and distortion characteristics.
For volume control, it is equipped with digital volume control taking advantage of 18-bit.
Thanks to the 2-bit margin, there is little degradation in the sound quality even when the volume is reduced, allowing for excellent level control.
The variable range is 0 ~ -24dB and can be adjusted with a remote commander.
Two RCA phono jacks and one XLR-type balanced output are installed as output terminals.
It is equipped with an optical fiber and 75 Ω coaxial output based on the digital audio interface proposed by AccuPhase and established in the EIAJ standard.
Equipped with a power-on play function that automatically starts playing when the power is turned on in conjunction with a timer.
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Model Rating
| Type | CD-dedicated digital signal reproducer |
| Formatting | CD standard format Quantization : 16 bits Sampling frequency : 44.1 kHz 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) |
| Frequency characteristic | 4.0 Hz to 20000 Hz ± 0.3 dB |
| D/A Converter - | Ladder Resistance Type 18 Bit |
| Digital filter | 8 x Oversampling Noise shaver function Digital de-emphasis function Deviation ± 0.001 dB |
| Total harmonic distortion factor + noise | 0.002% (between 20 Hz and 20000 Hz) |
| S/N | 114dB |
| Dynamic range | 98dB |
| Channel separation | 106dB |
| Rated output / output impedance | Balanced : 2.5V/50 Ω (25 Ω / 25 Ω), balanced XLR type Unbalanced : 2.5V/50 ohm, RCA phono jack Digital Level Control : 0 to -24dB in 1 dB steps |
| Digital output format level | Formatting : Digital Audio Interface Optical : Optical output : -21 to -15dBm (EIAJ), emission wavelength : 660 nm Coaxial : 0.5Vp-p/75 Ω |
| Semiconductor used | Transistor : 15 IC : 46 Diode : 26 Units |
| Pwer | AC100V/117V/220V/240V, 50Hz/60Hz |
| Power consumption | 20W |
| External dimensions | Width 445x Height 95 (Including Legs) x Depth 325 mm |
| Weight | 13.7kg |
| Attachment : Remote Commander RC-4 | |
| 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) |