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CS-8 Series PHS-28 Rev1.01, Dec. 2013
The shown amplitude responses are coming into being when mixing the
original signal with the phase shifted one fifty-fifty. The phase response shown
here, however, is the pure phaser stage output, because it is more of interest
than the mixed result and gives more insight of the system properties.
To shift the current phase angle of a real-time signal is only possible when the
signal becomes delayed. This will be done with units of energy storages the so
called stages. Each stage provides a total phase shift of -180°. Application-
oriented, however, only 360°-units are of interest. Such a unit will be obtained
by cascading 2 stages in serial. The input signal, tuned from the lowest to the
highest frequencies undergoes a full clockwise rotation (delay, negative
phase) of -360°. A superposition of this phase shifted signal with its phase
constantly original signal results in a total effacement (notch) of the amplitude
response as shown in the graphs. This occurs because at one frequency an
angle of -180° or at multiples of it will be achieved, that the amplitude
response is interacting in effacements at these frequencies. With each further
360° unit another notch-frequency will come up. So, as many notches will be
obtained as 360°-units or twice as much stages are cascaded. Exactly this is
shown in the graphs. And one achieved this by dial-in with the regarding
rotary switch
Out Stage (12)
and by mixing of the original input with the effect output at the regarding
Mix A (7)
Mix B (8)
controllers
and
, resp..
E.g., the topmost two graphs represents the amplitude- and phase response at
the second stage (one 360° unit) with exactly one notch at -180° phase shift,
Freq
here at 1 kHz. And this frequency can be shifted with the parameter
. The
upcoming notches by cascading further 360° units will be spread exactly
symmetrically above and below the center frequency and the distance
between the lowest and highest notch increases with every stage pair (360°
unit). The undermost graph at the 16th stage shows that the frequency of the
lowest notch is 10 times lower than the center frequency, whereas the highest
one is 10 times higher. The phase is shifted here at all by minus 2880° or 8·360°.
At least since now it becomes clear why such a large range of the parameter
Freq.
(1 Hz - 200 kHz) is necessary when one wants to shift all notches in the
two directions to below and up from the audible audio range.
-16-
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