SONY DAS-R1a
¥ 400,000 (around 1989)
Commentary
R series D/A converter equipped with high density linear converter system composed mainly of pulse D/A converter.
A pulse D/A converter uses one current source and one electronic switch and has only two output values, high (current flow) and low (no current flow). And all the intermediate values of audio waveforms are obtained by the time average of the pulse output, which is the spread of the binary output in the time axis direction. Therefore, in principle, the differential non-linear distortion caused by the error of the current source, the glitch and 0 cross distortion caused by the difference in the operation timing of the electronic switch, which are unavoidable in the conventional D/A converter, do not occur.
The Pulse D/A converter achieves a maximum operating frequency of 50 MHz for the master clock and 50 million pulses per second. The Sony Extended Noise Shaping calculation method is used to calculate the pulses, and a high dynamic range is achieved by generating a high-density pulse train.
The DAS-R1a uses two pulse D/A converters in complimentary service mode to cancel harmonic distortion with auxiliary positive - and negative-phase outputs and to increase the S / N ratio by doubling the output current.
The CDP-R1a and DAS-R1a use the Twin Link S method, which enables one master clock, in order to realize a more complete separate type.
Apart from the data tradition from the player side to the converter, it is equipped with an interface that sends a clock signal from the converter side to the player. This is structured so that both units are connected by two optical cables in a round trip, and data read from the disk can be sent out in synchronization with the movement of the D/A converter.
The master clock is placed so close to the pulse D/A converter that it can be said that it is directly attached, and a direct digital sync circuit for rearranging the data on the chip of the pulse D/A converter is mounted. This realizes a clean D/A conversion without jitter.
We have also developed a logical synchronous circuit based on a high-purity twin PLL interface purity twin PLL interface with less leakage of digital noise, and developed an interface IC with this built-in circuit.
The characteristics are improved by installing a low-jitter optical input unit.
FB chassis is adopted for the chassis structure.
This chassis is made of metal material of sufficient thickness and strength, and the whole chassis is joined by a frame surrounding the outer circumference and beams before and after passing the front and rear. This structure ensures almost total strength only by this frame and beams.
It is fixed directly on the most neutral beam with low vibration without using any special metal fittings when mounting the mechanism and substrate.
The legs are made of fine ceramic insulators combined with rubber with good braking performance.
The power supply section is equipped with two transformers, one for the interface and the other for the audio, to reduce mutual interference between circuits handling different types of signals. In addition, to reduce the noise of the transformer due to its structure, it is stored in the transformer case filled with resin.
It is equipped with a multi-interface function that automatically responds to 32 khz, 44.1 khz and 48 khz, and is also compatible with DAT decks and BS tuners.
Model Rating
| Type | D/A converter |
| Sampling frequency | 32kHz/44.1kHz/48kHz (auto-compatible) |
| Input terminal | Coaxial Connector (COAX1/2) : 0.5Vp-p/75 Ω Optical connector (OPT1/2) : -18dBm (emission wavelength 660 nm) Optical twin-link connector : Fiber diameter 0.2 mm reciprocal (emission wave length 800 nm) |
| Output terminal | Unbalanced (pinjack) : 2.5V/10k Ω Balanced (XLR terminal) : 2.5V/600 ohm |
| Number of channels | 2-channel stereo |
| Frequency characteristic | 2 Hz to 20 kHz ± 0.5 dB (Sampling Frequency of Input Digital Signal at 44.1 kHz or More) |
| Signal-to-noise ratio | 117 dB or more (EIAJ) |
| Dynamic range | 100 dB or more (EIAJ) |
| Total harmonic distortion factor | 0.002% or less (EIAJ) |
| Channel separation | 110 dB or more (EIAJ) |
| Pwer | 100 VAC, 50Hz/60Hz |
| Power consumption | 19W |
| External dimensions | Width 470x Height 125x Depth 410 mm |
| Weight | Approx. 17 kg |