Accuphase DP 67 Brochure
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Witness the ultimate high-end integrated type CD player -- MDS++ type D/A converter makes a good thing even better. Fully independent transport and processor sections and EXT DSP connectors allow use of DG-38 for sound field compensation. Optical and coaxial digital inputs and outputs provide added flexibility. Fully digital control of CD mechanism achieves optimization of servo parameters in real time. The DP-67 is an integrated player dedicated to Compact Disc playback with superb sound quality. It has inherited many technological features originally developed for reproduction of new-generation formats such as SACD. The DP-67 has been refined through extensive listening tests and can also serve as a stand-alone digital processor. It lets you discover untold riches of musical detail even in CDs with which you are thoroughly familiar. The processor section features an ultra-precise 24-bit D/A converter using a newly developed MDS++ converter. This takes the MDS (Multiple Delta Sigma) principle pioneered by Accuphase to new heights. It features minimal distortion, excellent S/N ratio, superb linearity at low signal levels, and outstanding performance in all other aspects. Since the DP- 67 provides access to this converter via a set of two digital inputs (optical and coaxial), its sound quality and performance can be utilized also by external components capable of supplying a digital signal. The benefits of super-accurate D/A conversion will let any digital signal sound its very best. A set of digital outputs (optical and coaxial) is also provided, allowing connection of a digital recorder for formats such as CD-R, DAT, or MD. This lets you record either the signal from the internal CD transport or from an external source. In addition, the EXT DSP connectors are convenient when wishing to use the Digital Voicing Equalizer DG-28/DG-38 for sound field compensation in the digital domain. Spindle Motor & Driver Sled Motor & Driver Driver RF Signal Processor EFM Decoder & Error Corrector Digital Audio Data Encoder Optical Receiver Pulse Amp 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 Filter Balanced Buffer 3-Pole Linear Phase Low-pass Filter Digital Audio Interface DecoderOptical Coaxial Output Input Unbalanced Output Balanced Output Unbalanced Output Balanced Output EXT DSP Left Digital Inputs Right ×4 MDS++ D/A Conversion System ×4 MDS++ D/A Conversion System Optical Head Focus Coil & Tracking Coil Tray Motor & Driver Disc Clamp Motor & Driver Optical Transmitter Coaxial Transmitter Optical Coaxial Digital Outputs MS dB Display CD ANALOG SECTIONDIGITAL SECTION Driver Coaxial Transmitter Optical input display example Coaxial input display example DriverDriver Driver Balanced drive circuit (no current flows in ground line) Fully 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 assures enhanced operation stability and a drastic reduction in error rate. Long-term reliability and performance uniformity are also improved, since fluctuations in ambient temperature can have no adverse influence. Laser pickup with integrated RF amplifier Since the output level of a laser pickup is very low, it is highly vulnerable to externally induced noise. To prevent such problems, the pickup used in the DP-67 employs an RF amplifier which is so compact that it can be directly integrated in the pickup assembly. This assures that the high-level output signal remains free from noise interference, which in turn reduces the error rate. Balanced drive circuitry for servo motors The motors and actuators which drive the disc tray, spindle, sled, and the focussing and tracking assembly require a rapidly fluctuating drive current, which can affect other circuit areas and cause sound quality degradation. In the DP-67, the drive current for each actuator is provided 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. Tray 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-67, the tray is firmly secured during playback, to eliminate any possibility of harmful resonances. Power-on play and frame display Power-on play means that the DP-67 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 Transport Section Features and Functions Digital Processor Section Features and Functions MDS++ type D/A converter achieves stunning performance and sound quality Jitter-free high-performance digital demodulator 3-pole linear phase analog filter with outstanding phase characteristics Digital level control with adjustment range 0 dB to –40 dB Balanced and unbalanced analog outputs Delta Sigma D/A converter Digital demodulator IC DP-67 Block DiagramCD actuator drive circuit Drive signal Load Load current Conventional circuit (current flows in ground line) Drive signal Load current Load
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I/V I/V – + DAC 1 DAC 2 DAC 3 DAC 4 I/V I/V DAC #1 #2 S 1 e1 S2 e2 Sn-1 en-1 Sn en #n-1 #n Digital inputSignal Conversion error S0 (Signal) e0(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) (Reverse phase output) I (current)/V (voltage) converter Current summing Voltage summingSubtractionDAC output 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 converter performance: accuracy, S/N ratio, dynamic range, linearity, THD, etc. In the DP-67, four delta sigma type AD1955 converters made by Analog Devices are driven in parallel. This results in an overall performance improvement by a factor of 2 (= √4). As shown in the diagram, the MDS++ features an enhanced current-to-voltage (I/V) converter for processing the D/A converter output current. A combination of current summing and voltage summing is used, resulting in even better stability and top-notch performance. When listening to a CD with this system, the music emerges from a totally silent background. Breathtaking detail resolution and a highly accurate sound stage are immediately apparent characteristics. MDS++ D/A converter moves another step ahead MDS type D/A converter principle MDS++ converter block diagram Assembly with CD transport control circuitry and digital input/output circuitry etc.Assembly with MDS++ D/A converter and analog output circuitry etc. Supplied remote commander RC-18 Offers a host of functions such as input switching, direct play, program play, repeat, etc.