SONY DAS-R1
¥ 300,000 (around 1988)
Commentary
This is a D/A converter that converts digital signals into analog signals with extremely high precision and eliminates resonance.
The digital filter is an 18-bit type with 8 x oversampling.
The sampling frequency of 44.1 kHz input from a CD player is converted to 352.8 kHz, which is 8 times the sampling frequency. This greatly increases the information density and reduces the load on the analog filter to improve sound quality.
In addition, the DAS-R1 digital filter has an extremely high order of 293 order, so it has excellent characteristics such as a ripple within ± 0.00001 dB within the band, a preecho of -124dB or less, and a displacement of 120 dB or more at 150 kHz. Moreover, the calculation error is much smaller than the final output of the 18-bit calculation value, so it is virtually error-free.
In order to reduce requantization noise, we have introduced a calculation method called noise shaping.
In this method, errors in the data are always accumulated, and the accumulated errors are also considered when rounding to determine the output.
The D/A conversion method uses the overlap staggered D/A conversion method.
In this method, two D/A converter ICs operating at 4 fs per channel are used, and the output is synthesized with the operation timing shifted by half a cycle. The two D/A converters alternately receive 8 times over-sampled data, and overlap operation is performed.
The feature of this method is that the aperture effect, which is a kind of filter characteristic, starts at 4 fs even though it is 8 fs D/A conversion. This eliminates dither noise caused by noise shaping that concentrates near 4 fs.
As a result of the overlapping operation, the distortion and noise are averaged, and the distortion factor is improved by up to 3 dB compared with the case where the D/A converter is used alone. Moreover, the output current is doubled, and the SN ratio is improved by up to 6 dB.
The FB chassis is used to eliminate unnecessary vibration and resonance.
It consists of a frame around the perimeter and several beams connecting the previous and next frames, each of which is thick enough to be firmly joined together.
The power supply section is equipped with dedicated power transformers for both digital and analog power supplies to reduce mutual interference.
In addition, the power supply section has enough space to occupy approximately 2/3 of the internal space to compensate for stable power supply.
In addition to the twin-link optical input terminal for connection with CDP-R1, two coaxial input terminals are installed.
The digital input automatically corresponds to three sampling frequencies : 32 khz, 44.1 khz and 48 khz.
You can also determine the source of the program being played by using an indicator that shows the sampling frequency during operation and the Digital Input indicator linked to the input selector switch.
Model Rating
| Type | D/A converter |
| Digital coaxial input terminal | 2 Systems (Pin Jack) Input signal level : 0.5Vp-p ± 20% Input impedance : 75 Ω |
| Twin link terminal | Twin link jack Light wavelength : 800 nm Fiber Diameter : 0.2 mm reciprocal |
| Line output terminal | Pin jack Output level : 2.5 Vrms (MSB) |
| Number of channels | 2-channel stereo |
| Complex (D/A) | 16-bit straight line |
| Frequency characteristic | 10 Hz ~ 20000 Hz + 0 -0.5 dB (Input digital signal sampling frequency : 44.1 kHz or more) |
| Harmonic distortion factor | 0.003% or less (EIAJ) |
| Signal-to-noise ratio | 110 dB or more (EIAJ) |
| Dynamic range | 97 dB or More (EIAJ) |
| Channel separation | 100 dB or more (EIAJ) |
| Power supply voltage | 100 VAC, 50Hz/60Hz |
| Power consumption | 25W |
| External dimensions | Width 470x Height 125x Depth 410 mm |
| Weight | Approx. 17 kg |