Accuphase DP 57 Brochure

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A player dedicated to CD playback Fully independent transport and digital processor sections. MDS ++ type D/A converter for even better performance. Optical and coaxial digital inputs and transport outputs provide added flexibility. Fully digital control of CD mechanism achieves optimization of servo parameters in real time. The DP-57 was created by further refining the Accuphase model DP-55V using the very latest in digital technology. The end product is a player solely dedicated to reproducing Compact Disc sources with impeccable quality. Although the number of discs released in SACD format is increasing, the CD which boasts a history of over 20 years is still the main source format for music lovers the world over. The capability to reproduce existing CDs with even higher sound quality was a wish often voiced by audiophiles, and Accuphase has responded by further strengthening its lineup of dedicated CD players. As a result of intensive and innovative research, Accuphase helps listeners rediscover the immense musical potential of the CD, by making discs sound as lively and detailed as never before. Spindle Motor & Driver Sled Motor & Driver Driver RF Signal Processor EFM Decoder & Error Corrector Digital Audio Data Encoder Optical Receiver Pulse Amp Spindle Servo Controller Focus & Tracking Servo Controller Clock Generator Key MatrixInfrared Receiver From Remote Commander Master Control Computer Display Driver Balanced Buffer 3-Pole Linear Phase Low-Pass FilterBalanced Buffer Digital Audio Interface DecoderOptical Coaxial Unbalanced Balanced Unbalanced Balanced Left Analog Outputs Digital Inputs Right Analog Outputs MDS ++ D/A Conversion System × 2 MDS ++ D/A Conversion System × 2 Optical Head Focus Coil & Tracking Coil Tray Motor & Driver Disc Clamp Motor & Driver Optical Transmitter Coaxial Transmitter Optical Coaxial Transport Outputs MS dB Display CD 3-Pole Linear Phase Low-Pass Filter DIGITAL SECTION ANALOG SECTION The DP-57 fea- tures totally separate CD transpor t and processor sec- tions, allowing individual use of each. The pro- cessor employs an ultra-precise 24-bit D/A converter using a newly developed MDS ++ converter. This takes the MDS (Mul- tiple Delta Sigma) principle pioneered by Accuphase to new heights. All electrical char- acteristics have been fur ther improved, as exemplified by minimal distortion, extremely low noise, and superb linearity. The outstanding sound quality and high performance of the processor section can be accessed also by external digital components, via the optical and coaxial digital inputs. The high conversion accuracy of the D/A converter ensures that any digital signal will be reproduced with optimum fidelity. The transport section is also equipped with two outputs (optical and coaxial). This allows connection of a digital recorder for formats such as CD-R, DAT, or MD, to record the signal from the CD transport of the DP-57 in the digital domain. n nn n nFully digital control of CD mechanism Control of the mechanism section is fully digital, allowing the use of adaptive circuits to optimize servo performance for each individual disc. This results in a drastically reduced error rate and enhanced operation stability, even when the ambient temperature fluctuates. n nn n nLaser pickup with integrated RF amplifier The pickup used in the DP-57 employs a miniature RF amplifier which is so compact that it can be directly mounted in the photodetector pickup assembly. This provides a high-level output signal free from noise interference, which in turn reduces the error rate. n nn n nBalanced drive circuitry for servo motors The motors and actuators which move the disc tray, spindle, sled, and the focussing and tracking assembly are driven by two amplifiers arranged in a balanced configuration. Because there is no circuit flowing in the ground line, the operation of other circuits in the player remains entirely unaffected. CD Transport Section Features and Functions Driver Driver Driver Drive signal Load Drive current Drive currentLoad Drive signal Conventional circuit (current flows in ground line)Balanced drive circuit (no current flows in ground line) n nn n nTray lock prevents resonances If the disc tray which is used to slide the disc into the unit resonates due to vibrations generated in the rotating assembly while the disc is playing, signal quality can be degraded. In the DP-57, the tray is firmly secured during playback, to eliminate any possibility of harmful resonances. n nn n nPower-on play and frame display Power-on play means that the DP-57 can start playback when power is turned on, allowing automatic playback in conjunction with an audio timer. For precise location of any spot on a disc, the player can display frame information (1 frame = 1/75 second), and functions such as repeat can be carried out in steps of individual frames. CD actuator drive circuit DP-57 Block Diagram Display example for optical input Display example for coaxial input

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S0 (Signal) e0(Conversion error) Digital inputSignal Conversion error MDS output Note the ratio between signal and conversion error. In the MDS output, the error is very small in relation to the signal. (Normal phase output) (Normal phase output) (Reverse phase output) (Reverse phase output) I (current) /V (voltage) converter Voltage summing SubtractionDAC output Analog output Digital input MDS ++ D/A converter moves another step ahead MDS (Multiple Delta Sigma) is a revolutionary design which employs several delta sigma type converters in a parallel configuration. In the combined output of these multiple converters, conversion errors cancel each other out, resulting in a drastic improvement in all relevant aspects of conver ter performance including accuracy, S/N ratio, dynamic range, linearity, and THD. In the DP-57, two delta sigma type PCM1796 converters (made by Texas Instruments) are driven in parallel. Compared to a single converter, this results in an overall performance improvement by a factor of 1.4 (= -ˆš2). As shown in the diagram, the MDS ++ used in the DP-57 features an enhanced current-to-voltage (I/V) converter for processing the D/A converter output current. In combination with voltage summing, this design results in even better stability and top-notch performance. The music emerges from a totally silent background, with breathtaking detail resolution and accurate spatial information. n nn n n MDS type D/A converter principle n n n n n Block diagram of MDS ++ converter in DP-57 n nn n nAssembly with CD transport control cir- cuitry, digital inputs, transport outputs, MDS ++ D/A converter, 3-pole analog filter, balanced/unbalanced analog output circuitry, power supply, etc. n nn n nSupplied remote commander RC-18 Offers a host of functions such as input switching, direct play, program play, repeat, etc. Linearity (digital input vs. analog output)