T+A Elektroakustik DAC 8 DSD Betriebsanleitung Seite 60

Oversampling 1 (Standard FIR Filter)
The long FIR filter is the standard oversampling process in digital
technology, offering extremely linear frequency response, very high
damping, linear phase characteristics and constant group delays. The
disadvantage is the pre- and post-echoes which are added to the
signal. These „time range errors" tend to affect the music signal's
dynamics, precision and naturalness, and reduce spatial orientation.
Frequency response and transient characteristics of the long FIR
filter
Oversampling 2 (Impulse optimised filter)
Shortening the filter (lower coefficient) reduces the time range errors,
albeit combined with a slight loss of linearity in the frequency range and
damping performance.
Frequency response and transient characteristics of the short FIR
filter
Oversampling 3 (Bezier-interpolator plus IIR-filter)
In this process an ideal Bezier interpolator is combined with what is
known as an IIR filter. This eliminates the problematic pre-echo of the
FIR method. This process produces highly „analogue" system
characteristics, with a sound quality and measured performance similar
to those of good analogue record players.
Frequency response and transient characteristics of the Bezier
interpolator plus IIR filter
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