APA-4E8 Operator’s Manual
Page 75
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All Pass Filter
The allpass filter has adjustable
frequency and ‘Q’ (or Bandwidth)
controls. These affect the frequency at
which the phase effectively flips 180
°
,
and the ‘speed’ at which this transition
occurs.
The graph shows an allpass filter
centred at 1kHz, with various ‘Q’
settings — the higher the ‘Q’ the faster
the transition.
Phase Filter
The phase filter has adjustable
frequency, and phase shift controls.
This introduces a phase shift that
gradually changes from 180
°
above the
centre frequency to the specificed
value at the centre frequency, and
tending towards 0
°
below the centre
frequency.
This graph shows the phase shift
relative to the input (ignoring
processing delays), in 10
°
steps — the
filter will actually provide higher
resolution than this, operating in 2
°
steps.The filter is centred at 1kHz in
this example.