User manual

10
Now what happens with both filters being interconnected in parallel? High- and lowpass filter work
as always. When connected in series to create a bandpass, the spectrum is being cut from top AND
below. In parallel connection, there is a highpass filtered signal AS WELL as a lowpass filtered signal
in existence.
Figure 5:
INPUT OUTPUT
FILTER B: Highpass
FILTER A: Lowpass
Parallel combination of low- and highpass filter
The highpass will remove lower frequencies and the lowpass eliminates high frequencies for their
signal path. Both signals are being mixed and as result a section in the middle is missing. This is why
this filter type is called a notch or band reject filter.
Figure 6:
CUTOFF
Highpass
CUTOFF
Lowpass
LEVEL
FREQ.
Notch filter: The green area is being passed through the filter whereas the red area is rejected.
Again, the Action Filter 4 is superior to typical notch filters because of its ability to freely adjust the
cutoff-frequencies as well as the bandwidth for the notch.