Filter

The 12 dB/octave low-pass filter is one of the most important components in the synthesizer. Especially when using the modulation features, it is the key to creating great sounds.

The Frequency knob adjusts the cut-off frequency. Basically, all sounds below the cut-off frequency will go through the filter, but sounds with higher frequencies are damped. At position 10, the cut-off frequency is far above 20 kHz and therefore the filter will allow all frequencies to go through unchanged. At position 0, the cut-off frequency is just a few Hz and the filter will block almost all sound from the oscillator.

The wave forms produced by the oscillator contain many harmonics: high frequencies that are multiples of the fundamental tone. Therefore, they sound bright and a little harsh. By turning the Frequency knob to the left, you reduce the number of harmonics to change the character of the wave forms and create warmer sounds.

The Peak knob adjusts the filter resonance. A little resonance will cause the filter to create warmer and more characteristic tones. Around position 8, the filter starts to self-oscillate at the cut-off frequency which creates terrific effects in combination with the sound from the oscillator. At these high peak values, the filter produces deep, ringing bass tones if you set the Frequency knob around position 3 or 4.

We've carefully tuned the filter to avoid the whistles and other digital artefacts that are common with other digital filters when you change the cut-off frequency at maximum resonance. Our filter sounds crazy but never over the top!

You can modulate filter cut-off frequency with the modulation generator (the MG knob), the envelope generator (the EG knob), and with keyboard velocity. Read the modulation basics section to learn more about the modulation features of the FabFilter One.

Next: Envelope generator

See Also
Modulation basics
Overview