1. First steps in Reaktor Core - Native Instruments

The value of the coefficient b can be taken equal to the normalized circular
cutoff frequency, which can be computed using the following formula:
F c = 2*π*f c / f SR
where
f c is the desired cutoff frequency in Hz
f SR is the sampling rate in Hz
π is 3.14159…
F c is normalized circular cutoff (in radians)
In fact, the coefficient b is equal to the normalized cutoff only approximately,
the error increasing at high cutoff values, but it should be
more or less OK for our purposes, especially if we do not need to have
a precise setting of the cutoff frequency for our filter.
We start by creating an audio core cell with two inputs: one for the audio
input and one for cutoff. We are going to use an event input for the cutoff in
this version of the module.
Actually, because we think it’s a good habit to build Reaktor Core structures
as core macros to enhance their reusability, we a going to create our filter as
a macro. So we create a new macro inside the structure and create the same
inputs for that macro:
Now let’s build the circuitry for converting the cutoff frequency into the normalized
circular cutoff:
102 – REAKTOR CORE