Generally, after you've selected your waveforms, the next step you find in your synthesizer is your
Filter. Most synthesizers have a low-pass filter, which is the basis of all subtractive synthesis. Some have band-pass, notch, comb, and high pass filters, although it is unlikely you will find much more than a low pass and high pass filter on an analog synth. The picture above shows the frequency response of a low pass filter. If you picture this overlaid on the graph of the frequency spectrum of the
sawtooth wave you can get an idea of how this works. The low-pass filter literally means the lower frequencies will be passed through, and the higher frequencies will be filtered out. This same naming principle applies to all filters, as a high-pass lets through higher frequencies, etc.
