Analog offers each of the four basic filter types low pass, high pass, band pass, and notch pass. These intuitively named configurations function just as they sound. Low-pass filters allow only the lower frequencies to pass and be heard silencing anything above the cutoff frequency. Inverse to this the high pass filter allows only frequencies above the cutoff to be heard while silencing those below it. Finally band pass filters allow only a narrow “band” of frequencies to be heard between a low and high cut. The fourth type is called a notch filter and simply removes a small portion a frequencies from the overall sound. This is much more subtle but can be used to create some interesting effects when automating the cut off with an lfo.
Low Pass
High Pass
Band Pass
Notch Pass
Another common type that you will come across is the SVF or State Variable Filter. This filter type dynamically morphs shape according to settings of various filter attributes. You can get a visual representation of this in Ableton sampler which has an actual morph dial and a graphic representation of how this affects the filter profile. In operator the SVF filters will alter the attenuation slope depending on where the frequency is set. A synth by Spectrasonics called Omnisphere contains myriad filter type options which caused radically different sounds in your patch. Different synthesizers will have different tweaks to their filters so it’s a great place to dive in, experiment, and learn the nuance of the instrument you’re using.