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Achieves 18% lower output noise voltage compared to the former DP-720 model.
Utilizes 8 parallel DACs per channel with MDS++ architecture for enhanced digital-to-analog conversion.
Explains how MDS++ paralleling of DACs sums signals and cancels conversion errors for improved performance.
Details how MDS++ processing improves overall performance by a factor of 2.8.
Highlights the advantage of sending music signal and master clock separately to eliminate jitter.
The Accuphase MDS SA-CD Player DP-750 is a superlative integrated SACD/CD player, representing a significant advancement from its predecessor, the DP-720, launched in 2013. This device is engineered to deliver the best possible performance and sound quality, incorporating advanced technologies derived from Accuphase's high-end DP-950/DC-950 combo.
At its core, the DP-750 functions as a high-fidelity SACD/CD player, capable of reproducing both Super Audio CDs and standard audio CDs with exceptional clarity. Beyond disc playback, it also serves as a versatile digital-to-analog converter (DAC) with multiple digital inputs, allowing it to process external digital audio signals from various sources.
The D/A converter section of the DP-750 features ESS Technology's 32-bit Hyperstream II DAC ES9028PRO. This advanced DAC chip, which contains eight internal DACs, is utilized in a parallel configuration per channel. Accuphase's unique MDS++ conversion system is employed for PCM signals, while the MDSD architecture is used for DSD signals. The MDS++ technique involves supplying the same digital signal to each of the parallel converters and summing their outputs. This process effectively adds the audio signal values while canceling out conversion errors and noise, thereby improving the signal-to-conversion error ratio and overall converter performance. The improvement factor is proportional to the square root of the number of DACs, resulting in a 2.8-fold performance enhancement in the DP-750.
For DSD signals, the MDSD architecture functions as a low-pass filter in the high-frequency range to remove inherent DSD noise, and as an MDS++ principle in the low-frequency range to improve characteristics. The key to MDSD lies in its delay elements, where DSD signals are D/A converted with half-delayed clocks and then combined at the output. This results in an analog output with half-clock time resolution, effectively operating at double speed. This configuration acts as a moving-average filter, providing a linear phase low-pass filter that efficiently removes high-frequency noise from the DSD signal.
The DP-750 offers a comprehensive array of digital inputs and outputs. It includes HS-LINK, Coaxial, Optical, and USB-B inputs. The USB input is particularly robust, accepting up to 384kHz/32bit PCM and 11.2896MHz DSD data. DSD data can be received via both DoP (DSD over PCM) and ASIO2.1 (for 11.2896MHz DSD, ASIO only). The HS-LINK has been upgraded to Version 2, supporting higher data rates of 384kHz/32bit PCM and 5.6448MHz DSD, in addition to the Version 1 capabilities of 192kHz/24bit PCM and 2.8224MHz DSD. The DP-750 automatically recognizes either Version 1 or Version 2 transmissions.
A notable feature of HS-LINK Version 2 is its ability to transmit the master clock separately from the audio data. In contrast to Version 1, which merges the master clock with the music signal, requiring a PLL circuit for clock recovery at the receiver, Version 2 eliminates the need for such a circuit. This direct transmission of the master clock removes jitter that would otherwise be introduced by the PLL circuit, leading to a cleaner and more accurate signal. For backward compatibility, the DP-750 still provides a HS-LINK Version 1 output.
Furthermore, the newly developed SA-CD drive in the DP-750 can play "DATA Discs" created on a PC. This allows users to record music files onto blank DVDs (DVD-R, DVD-RW, DVD+R, DVD+RW) and play them back on the DP-750. Supported formats include 192kHz 24-bit WAV, FLAC, AIFF, and 5.6MHz 1-bit DSD data, offering broad compatibility for various digital audio files.
The DP-750 is designed for ease of use, featuring a clear and informative front display. This display provides essential information such as the sampling frequency and the number of effective bits for all input signals. The quantization bits are accurately counted directly from raw data using a high-speed Field Programmable Gate Array (FPGA), ensuring precise representation of the incoming signal characteristics.
The device's internal layout is systematically organized to ensure the shortest possible signal paths, minimizing interference and preserving signal integrity. The digital circuit, including the DAC chip, is located on the right side, while the analog circuit, built on a glass cloth fluorocarbon resin PC board, is positioned on the left side at the back panel. The logic control board is on the right side of the SA-CD drive mechanism, and a reinforced power supply is situated on the left side. This meticulous separation of circuit blocks contributes to the DP-750's exceptional performance.
From an electrical performance standpoint, the DP-750 boasts ultra-low noise characteristics. It achieves an 18% lower output noise voltage compared to its predecessor, the DP-720, which itself was known for excellent noise performance. This reduction in noise allows the DP-750 to dynamically express the sonic purity and emotional depth of music with greater clarity.
The DP-750 also exhibits superb low distortion and noise performance, exceeding that of the former model. It maintains an almost flat response across the entire frequency range, from low to high frequencies, achieving less than 0.0002% THD+Noise in all frequency bands. This characteristic is crucial for delivering high-quality sound.
While the manual does not explicitly detail user-level maintenance features, the design principles of the DP-750 suggest a focus on long-term reliability and performance stability. The robust construction and careful component selection contribute to its durability.
The newly developed SACD/CD drive mechanism incorporates effective vibration control measures. Vibrations are completely isolated from the power transformer to the optical pick-up, and operating motion noise is dramatically reduced. This is achieved through a larger and longer bridge cover for the SA-CD drive mechanism, which is bigger than that of the former model. An outer rotor brushless DC motor is installed at the spindle to drive the discs, effectively reducing motion noise from the motor drive and air flow caused by disc rotation.
Furthermore, the laser pick-up module is mounted with high-performance vibration absorbers made of a special silicon, carefully selected for this mechanism. This design prevents external vibrations, reducing them by 4dB at the resonance peak. These materials are mounted directly on an aluminum base plate, which further contributes to reducing motion noise by half compared to the DP-720. These design choices suggest a device built for stable, long-term operation with minimal degradation due to mechanical factors.
The dimensions of the DP-750 are identical to those of the DP-720 (W: 477 mm, H: 156 mm, D: 394 mm), ensuring compatibility with existing setups. However, the DP-750 is slightly heavier (28.2 kg compared to 28.0 kg for the DP-720), a difference attributed to the inclusion of a long and heavy bridge dedicated to the new SA-CD drive mechanism, designed for quietness and enhanced performance. This indicates a commitment to robust mechanical design for improved reliability and sound quality.
General| Type | CD Player |
|---|---|
| Disc formats | CD, CD-R, CD-RW |
| Digital Outputs | Coaxial, Optical |
| Digital to Analog Converter | 32-bit/384kHz |
| Analog Outputs | Balanced, Unbalanced |
| Total Harmonic Distortion | 0.0005% (1kHz) |
| Channel Separation | 110 dB |
| Dimensions | 477mm x 156mm x 394mm (W x H x D) |
