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SD Slow and Slow work best at 88.2 and up, because the decrease in the high frequency area
then happens outside the audible range. At the same time the impulse response is near perfect
– caused by both the filter as well as the doubled sample rate.
Note: At 705.6 and 768 kHz sample rate the filter selection is not available. At these rates the
ADC uses an Linear Phase Slow Roll-Off filter. A different choice is not possible.
34.12 DA Impulse Responses
The screenshots show the analog output signal of the oversampling DAC filters, stimulated by a
digital single sample impulse at 44.1 kHz sample rate. While Slow has the most perfect response,
it loses around 2 dB already at 19 kHz, see chapter 34.15. Both Short Delay are IIR filters, the
other two are FIR type. FIR is phase linear over the whole frequency range.
Short delay Sharp
Short Delay Slow
SD LD (Short Delay Low Dispersion)
The filter with the bulky name Short Delay Low
Dispersion attempts a compromise between
linearity, latency and preringing. The filter is
steep, but set comparatively low. It offers very
good stopband attenuation in return.
88
Sharp
Slow
User's Guide ADI-2/4 Pro SE - v 1.0
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