User manual

14
Figure 8: The frequency being passed through the filter, shown as “fan”.
☛
To use Action Filter 4 as a classic lowpass filter, select BAND
mode and keep FILTER A fully open (CUTOFF set fully left). Use
FILTER B‘s CUTOFF to control the lowpass filter as desired.
Do the opposite for getting a pure highpass filter.
The lters in NOTCH-MODE
The world upside down: With MODE set to NOTCH, the filters work inverted. FILTER A controls the
lowpass while FILTER B adjusts the highpass (see figure "Parallel combination of low- and highpass
filter" on page 10). This wasn’t done to annoy you but for technical and practical reasons. Here
too, the “fan” comparison might help you to understand the underlying principle: FILTER A cuts
the higher, FILTER B the lower frequencies. This results in a V-shaped center-notch. The further
the CUTOFF marks depart (fan opens), the wider the notch in the frequency spectrum that filters
out a larger midrange section.