Cambridge Audio Upsampling Digital to Analog Converter azur DacMagic User Manual page 19

azur DacMagic
The Linear Phase filter is a highly regarded audio filter offering low ripple in both the pass and stop
bands, and what is known as constant group delay. Constant group delay means that audio signals
of all frequencies are always delayed by the same amount when passing through the filter. All audio
is therefore fully time-coherent at the output.
The trade-off with this type of filter is that due to internal feed-forward in the DSP, its impulse response
will exhibit some pre-ringing. In other words, when excited with a theoretical impulse, the output has
both a small amount of pre- and post-spike amplitude ringing (albeit well damped).
Impulse response
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0 20 40 60 80 100 120 140 160 180
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