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The combination of the Accuphase DP-80 digital transport and the Accuphase DC-81 digital-to-analogue converter represented one of the most refined expressions of Japanese design philosophy applied to digital reproduction in the second half of the 1980s. These were two separate units, designed according to a modular approach that physically separated the playback mechanism from the digital-to-analogue conversion, a solution that reflected the pursuit of maximum signal purity and stood at the pinnacle of audio engineering at the time.
The DP-80 was the first Compact Disc player produced by Accuphase and was released in 1986, at the height of the golden age of Japanese hi-fi equipment. The unit was designed as a pure transport, i.e. a CD player dedicated exclusively to reading the digital signal, with output available in both coaxial and optical fibre formats. This modular approach allowed for the separation of functions and enabled the digital-to-analogue converter to be used with other digital sources as well, a feature particularly appreciated by the most demanding audiophiles keen to experiment with D/A conversion. Despite this design versatility, the system had been specifically developed to operate in conjunction with the Accuphase DC-81 converter, included in this package.
The DP-80’s playback section employed a sophisticated linear motor mechanism that ensured rapid operation and exceptionally smooth performance. At the heart of the system was the renowned Sony BU-1C mechanism, a laser pickup destined to become one of the historic benchmarks in the field of Compact Disc playback. Control of operations was entrusted to a specially developed 8-bit microprocessor, capable of selecting tracks in less than a second – a particularly remarkable achievement for the digital technology of that era.
The mechanical assembly was mounted on a base made from a special high-rigidity ceramic-reinforced resin, a design choice intended to reduce resonance and improve structural stability. The entire mechanism was also floating relative to the main chassis, a solution intended to limit the transmission of vibrations and allow the disc and the turntable to operate under conditions of greater mechanical isolation. The timing of all operations was governed by a single master clock, a solution that eliminated the jitter problems typical of systems equipped with separate clocks for digital processing and microprocessor control.
The digital outputs included a 75-ohm coaxial connection compliant with the standards of the time and an optical fibre terminal developed specifically for interfacing with the DC-81 converter. The optical transmitter had a transmission capacity of 7 Mbit/sec and allowed high-quality digital signals to be transferred to the processor. The power supply also incorporated a comprehensive mains filter designed to reduce unwanted interference from the mains supply. As was the case with many Accuphase units of the period, the DP-80 also boasted a particularly refined aesthetic, characterised by luxurious construction and a strong attention to detail.
The Accuphase DC-81 digital-to-analogue converter, also released in 1986, was specifically designed to operate in conjunction with the DP-80 transport. This converter employed a current-summing structure capable of reaching the theoretical limit of 16 bits via a discrete configuration, a solution that reflected the aim of achieving extremely accurate conversion performance.
In the DC-81, the signal from the digital filter was transmitted optically via 34 opto-isolators with a bandwidth of 7 Mbit/sec. Each bit of the signal was then converted back into electrical form and sent to the D/A converter, a process that ensured complete electrical isolation and helped eliminate noise interference that might otherwise have propagated through the conductors. Inside the unit, the opto-isolator output passed through a printed circuit board located outside the chassis shielding and was then fed into an analogue converter that was both physically and electrically shielded.
The digital filter was of the independent double oversampling type for the left and right channels and consisted of 121 high-order elements. This architecture made it possible to maintain the passband ripple within ±0.001 dB and to achieve an attenuation of –90 dB at 24.7 kHz, values that helped define the system’s theoretical performance. The low-pass filter, on the other hand, employed a ninth-order active Butterworth configuration of the discrete GIC type, with components selected with particular care.
The output stage consisted of a buffer amplifier with gain set to 0 dB, a solution that allowed the converter’s output to be adapted without introducing further amplification stages. The circuit employed a directly coupled DC push-pull servo system, designed to ensure particularly low distortion characteristics. The optical receiver also had a bandwidth of 7 Mbit/sec, identical to that of the transmitter, and helped to eliminate high-frequency noise radiation.
The converter was also equipped with an emphasis circuit featuring a passive filter dedicated to Compact Discs with applied emphasis, flanked by an additional buffer stage. The digital and analogue circuits were shielded by separate metal structures, and the power supply was provided by a dedicated, fully isolated transformer. The internal layout also reflected a rigorous approach to signal separation, as the left and right channel audio circuits were placed on independent printed circuit boards to minimise mutual interference.
To further limit unwanted radiation, the digital circuits utilised low-emission high-speed CMOS integrated circuits, supplemented by a line filter designed to prevent noise leakage through the power supply. The rear panel featured two RCA outputs, one fixed-level and one variable, as well as a balanced XLR output.
This combination of transport and converter thus represented one of the most sophisticated interpretations of digital technology of the period, a testament to an era in which the Japanese hi-fi industry was experimenting with advanced design solutions to set new standards for music reproduction on Compact Discs.
Refurbished collector’s items. The CD player also plays burned discs.
The cosmetic condition is also excellent.
