Sony OXF-R3, Brochure & Specs

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FFT plot of a typical 20-bit converter
showing harmonically related distortion
FFT plot of the OXF-R3 D/A converter
showing extremely low level of distortion
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dBr
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The analogue converters are the most crucial link in the digital audio
production chain, and above all else, it is the quality of the converters
that defines its sonic capabilities. Considerable attention is frequently
given to the most fundamental measures of converter performance,
such as the number of bits or the optimised signal to noise performance.
However, it is important to realise that these simple specifications do
not give any guarantee of the actual sound quality of converters.
Distortion performance is extremely important in the subjective
assessment of sound quality because the ear is capable of hearing
signal components at levels well below system noise. The ear can
also detect changes in the ratio of signal to distortion levels as well
as the harmonic content of distortion. There are some important
differences between the type of distortion created by an analogue
system compared with that of a typical digital system.
In an analogue system, distortion is normally limited to the 2nd and
3rd harmonics and the distortion level changes in proportion to signal
level. However, a typical distortion in a digital system is due to
the sampling process, known as ‘quantisation noise’. The level of
quantisation noise remains virtually the same for all signal levels, so
the proportion of distortion increases as the signal level falls and the
distortion is spread across higher order harmonics. An example of the
difference between analogue and digital distortion can be observed in
the decay of reverbs. In an analogue system, the reverb tail normally
OXF-R3 converter technology
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disappears gradually into the background noise floor, whereas in
many digital systems there is an abrupt ‘cut-off point’, where the
signal degrades rapidly below a level where it can be represented
meaningfully in the digital domain.
The design of the OXF-R3 converters is highly specialised to provide
extremely high sound quality with superlative distortion control. As a
result, the distortion specifications for ADC and DAC are given for both
full scale and lower level signals.
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2.5k 20k 5k 7.5k 10k 12.5k 15k 17.5k
Hz