YAMAHA DX-U1

Commentary

A D/A converter equipped with a high-bit digital filter and high-bit D/A conversion system.

Equipped with 4 x oversampling high-bit digital filter.
By high-precision digital operation with operation degree 225 + 41 and coefficient word length up to 32 bits, the filter itself has realized out-of-band noise of -100dB or less and out-of-band ripple of ± 0.0001 dB, and noise and ripple are suppressed to 16 bit resolution level or less.

The D/A conversion system is equipped with Yamaha's original High-bit D/A conversion system that performs D/A conversion in 18-bit operation. In this system, a high-bit digital filter is output in 18-bit operation to obtain a digital signal with higher resolution. Then, the D/A converter is operated in floating operation to shift up the digital signal by 2 bits at most levels where the upper bits are not used. Thus, D/A conversion with 18-bit accuracy is achieved.
This reduces the signal waveform immediately after D/A conversion and the step distortion which is the original error component to 1/4 of reduced to 1/4 of the conventional one, improving reproducibility at a minute level.

The D/A converter used in the high-bit D/A conversion system employs a glitch less D/A converter that performs high-speed serial processing of digital signals. It eliminates the harmful glitch noise that occurs when switching digital signals. Moreover, the left and right sides of the D/A converter are made into independent twin configurations to improve separation.

Digital input terminals of 75 Ω coaxial type are installed Route 3.
Equipped with an original Yamaha digital I/O receiver that automatically follows the sampling frequency of 32k/44.1k/48kHz, it is compatible with digital output of CD and DAT.

The digital and audio sections are separated and separated by a high-speed photocoupler (optical coupling element) in order to prevent digital noise from entering the audio section and high-frequency digital signals from jumping into the audio section. The optical transmission method that transmits signals while maintaining electrical insulation prevents sound quality degradation.
In consideration of the effect of electrical and mechanical vibration on sound quality, we have adopted a separate sheet in which the digital and audio sections are composed of independent circuit boards.
In addition, a two transformer shunt regulator power supply, which feeds the digital and audio sections independently, is a fully digital-separated design.

The output terminal has a variable output in addition to a fixed output.
The output level of the variable output terminal can be adjusted from the front panel.

It uses a Mylar capacitor for audio and is equipped with a fifth order new active filter with excellent group delay characteristics.

The output stage is a full DC amplifier with no low-frequency time constant.

Equipped with a digital indicator that turns on when a digital signal is received.

Equipped with a headphone port with volume.

Model Rating

Type	Digital processor
Frequency characteristic	DC ~ 20 khz ± 0.3 db
Harmonic distortion factor + noise	0.002% (EIAJ, 1 kHz)
Signal-to-noise ratio (EIAJ)	115dB
Dynamic Range (EIAJ)	100dB
Digital input	0.5Vp-p/75 Ω
Output voltage	Fixed : 2 Vrms (0 dB) Variable : Pre-out level (-∞～+ 20 dB)
Power supply voltage	AC100V 50Hz/60Hz
Power consumption	12W
External dimensions	Width 435x Height 90x Depth 361 mm
Weight	6.2kg