Accuphase DP-55V

A CD player that refined the DP-55 and introduced the latest digital technology.

The D/A converter is equipped with a newly developed MDS D/A converter.
The MDS (Multiple Delta Sigma) system is designed to improve the performance significantly by connecting multiple delta-sigma D/A converters in parallel. The delta-sigma D/A converter uses oversampling and noise shaping (digital feedback) to expand the amplitude information of the input digital signal in the time axis direction to obtain conversion accuracy. Multiple delta-sigma D/A converters are prepared, the same digital signal is input to each converter, and the output of each converter is added to obtain the overall output.
The DP--55V has two delta-sigma D/A converters operating in parallel, the overall performance is 1.4 (= 2) times higher than that of the converter 1 circuit. In addition, since the MDS method can improve performance at all frequencies and all signal levels regardless of signal frequency or signal level, it is possible to reduce micro-level noise that is stuck in the output signal, which is difficult to resolve with conventional delta-sigma D/A converters.

It has 2 digital input terminals, coaxial and optical, and can play back other digital devices.
These digital inputs are processed internally to accept 24-bit audio data.Soundproofing solutions

It is equipped with two digital output terminals, coaxial and optical.

For demodulation of the input digital signal, a demodulation IC : CS8412 (manufactured by Crystal Semiconductor) is used, which generates very little jitter and sufficiently attenuates the jitter component contained in the input signal.
The CS8412 can demodulate up to 24 up to 24 bits and exhibits the capability of the MDS system for various inputs.

The digital filter uses a 24bit8 x oversampling digital filter.
This digital filter achieves almost the limits of a digital filter in terms of group delay distortion, passband ripple, and stopband attenuation, while the de-emphasis section uses an IIR filter to achieve accurate gain and phase characteristics.

The analog filter uses a third order linear phase filter with excellent phase characteristics.
This filter circuit optimizes the cut-off frequency to minimize phase rotation in the passband and, together with carefully selected elements, enables excellent music playback.

The analog output consists of a fully balanced circuit floating from ground.
There are two types of output connectors : a balanced XLR-type connector and an unbalanced RCA-type connector.

The level control is digital and can be adjusted up to -40dB.
The DP-55V has an 8-bit margin for 16-bit signals such as CDs due to the 24 bitMDS D/A converter, which prevents noise generation and enables volume adjustment with less sound quality degradation.

A digital system is used to control the mechanism.
Digital control allows the use of an active filter, allowing optimal servo circuit settings for each disc, ensuring stable control and greatly reducing errors.

The laser detector has a built-in RF amplifier.
Since the output of the laser pickup is very small, it is subject to interference by ambient noise. To solve this problem, the DP-55V's pickup section is equipped with an ultra-small and lightweight RF amplifier attached to the photo detector to cope with the interference by noise by sending out an amplified s-large signal.
As a result, digital signals with few errors can be extracted.

The tray unit has a locking mechanism that securely locks the tray during playback to minimize resonance.

The drive circuit for the current flowing through each actuator of spindle, thread, focus, r, and tray employs a balance drive circuit driven by two amplifiers.
This balance drive circuit is isolated from other circuits because no current flows to ground, preventing mutual interference.

Equipped with a power-on play function that automatically starts playback when the power is turned on, and can be linked with a timer.
You can also display a frame (1 frame = 1/75 sec), start or repeat a frame unit.

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