Digital Audio Labs CardDeluxe PC soundcard Measurements part 2
Fig.4 Digital Audio Labs CardDeluxe, D/A 1/3-octave spectrum of dithered 1kHz tone at -90dBFS, with noise and spuriae, 16-bit (top) and 24-bit (bottom) data, 44.1kHz sampling (right channel dashed).
Linearity error (fig.5) was also very low: less than 1dB to well below -110dBFS. As a result of the low noise and superb linearity, the CardDeluxe's re-creation of an undithered 16-bit, 1kHz tone at -90.31dBFS (fig.6) is essentially perfect, clearly showing the three discrete voltage levels described by the digital data. Extending the data words to 24 bits gave a pretty good sinewave (not shown).
Fig.5 Digital Audio Labs CardDeluxe, D/A departure from linearity, 16-bit data (2dB/vertical div., right channel dashed).
Fig.6 Digital Audio Labs CardDeluxe, D/A waveform of undithered 1kHz sinewave at -90.31dBFS, 16-bit data.