Audio Damage Phosphor - Manual (Page 17)

Phosphor has low-pass and high-pass filters which come after the delay lines in the signal chain. These filters
can be adjusted to alter the timbre of the delayed signal. For instance, you can use the low-pass filter to
create a “darker” sound, or the high-pass filter to create a “thinner” sound.
The filters are controlled in tandem with the graph-like controls labeled, appropriately enough, FILTER. Since
the filter controls change the low- and high-pass filters simultaneously the filters act like a band-pass filter
with a variable width. Dragging the white circle in the control changes the corner frequencies of both filters.
Dragging up and down moves the corner frequencies farther apart and closer together; dragging left and right
moves the frequencies in the same direction. As you pull the white dot downwards, the filters move together
and allow only a narrow band of frequencies to pass through. You can then move the dot left and right to hear
that band move up and down in frequency.
Moving the white dot horizontally changes the filter
frequencies in the same direction, moving the frequency
pass-band higher and lower
Moving the white dot vertically moves the filter frequencies
together and apart, making the frequency pass-band
narrower and wider