Vacuum features two separate filters, one a high pass filter (HPF), the other a low pass filter (LPF). The sound of each filter is affected by volume of incoming oscillator signals. Lower mixer levels give the filters a clean response and a sharper resonant peak. Increasing mixer gain can overdrive the filters, adding character and de-emphasizing resonance.
Sets the frequency at which the given filter begins to “cut off” part of the signal’s frequency spectrum. In the HPF, frequencies below the chosen frequency are affected. In the LPF, frequencies above the chosen frequency are affected.
Sets the curve of the filter slope. At higher settings, the slope is steeper, and more of the spectrum is cut off. At lower Settings, the slope is more shallow, and more of the spectrum is allowed to pass.
Affects the filter resonance, which is the amount of signal fed back into the filter circuit around the chosen frequency. At higher values, a pronounced peak is created, which can range from a subtle “edge,” all the way to a sine-wave-like tone. At lower values, the filter simply cuts off the specified frequencies.
Controls the amount that the filter cutoff frequency is modulated by Envelope 1. At its center, no modulation occurs.
As the control is moved to the right, more and more modulation occurs, moving the cutoff frequency up when a MIDI note is received, then down, following the envelope’s movement over time.
When the control is moved left of center, the same occurs, only the modulation is negative instead of positive, so the envelope’s effect is inverted.
Sets the amount that the currently playing MIDI note’s pitch affects the filter’s cutoff frequency. At zero, there is no effect. At 100%, the frequency moves in direct relationship with the keys played.
This is most apparent with high Res values, as the tone created may be made to move in tandem, harmonically, with the notes that are played, thus acting almost as an additional oscillator, with interesting sonic possibilities.
Adds saturation to the resonant feedback loop, changing the tonal quality of the current filter from soft to aggressive and distorted.