Microfreak/UG/07 Filter

• 07 The Filter: sound in close-up

  • A filter emphasizes or suppresses harmonics in a sound, changing its timbre. It is traditionally paired with an oscillator; the MicroFreak's analog filter shapes the sound of its Digital Oscillator.
  • The Analogue Filter
    • 
  • Think of the Analog Filter as a searchlight moving over the oscillator's waveform, revealing its harmonic content. Its beam can be broad or focused; the focused width is called Q or resonance.
  • A sound contains sine-wave frequencies at different loudness levels. These frequencies often form families around a fundamental frequency, with related harmonics above it. The mix of odd and even harmonics largely determines a sound's character. A filter favors some frequencies and attenuates others.
  • Microfreak/UG/07 Filter/01 Modifying Sound

    • 07.01 Modifying sound

      • The MicroFreak has a Low Pass Filter (LPF), a Band Pass Filter (BPF), and a High Pass Filter (HPF). The Type button switches between them.
      • A low-pass filter attenuates frequencies above its cutoff; a high-pass filter attenuates frequencies below it; a band-pass filter attenuates frequencies on both sides of the cutoff.
      • With a low-pass filter open at maximum cutoff, all frequencies pass. Lowering the cutoff removes the highs first, then the midrange; closing it completely leaves silence. In high-pass mode, maximum cutoff removes all frequencies; lowering it lets frequencies above the cutoff pass. In band-pass mode, frequencies near the cutoff remain audible, and resonance sets the width of that range.
      • Microfreak/UG/07 Filter/01 Modifying Sound/01 Low Pass Filter

        • 07.01.01 Low Pass Filter

          • A Low Pass Filter removes frequencies above its cutoff. It is central to subtractive synthesis and selectively reduces a sound's high frequencies. Modulating the cutoff over time varies the sound's timbre.

          • Note/Info The MicroFreak filter has a 12 dB-per-octave roll-off. Its slope is gentler than a 24 dB filter, which suits oscillators with rich, complex harmonics such as grains, wavetables, shapers, and FM.
            

      • Microfreak/UG/07 Filter/01 Modifying Sound/02 Band Pass Filter

        • 07.01.02 Band Pass Filter

          • A Band Pass Filter lets only a narrow frequency range pass. At minimum resonance, all frequencies pass; turning Resonance clockwise narrows the range. At its maximum, the filter self-oscillates and can act as a sine-wave oscillator, while blocking the Digital Oscillator's sound.
      • Microfreak/UG/07 Filter/01 Modifying Sound/03 High Pass Filter

        • 07.01.03 High Pass Filter

          • A High Pass Filter removes frequencies below its cutoff. Raising the cutoff removes the lows first, then the midrange, leaving the highest harmonics.
          • Use it to accent beats in an arpeggio or bass loop, or to clear low frequencies from a solo sound that competes with a bass part in a mix.
          • Its main controls are Cutoff frequency and Resonance.
      • Microfreak/UG/07 Filter/01 Modifying Sound/04 Cutoff Frequency

        • 07.01.04 Cutoff frequency

          • The cutoff frequency is where filtering takes place. Feeding a filter's output back into itself creates a resonance peak around the cutoff. The Resonance knob controls this effect; the LFO or envelopes can also modulate resonance when assigned in the Matrix.
          • Filters attenuate frequencies gradually above or below the cutoff. This slope, or roll-off, depends on the number of poles: a four-pole filter has a steeper roll-off than a two-pole filter. The MicroFreak filter rolls off at 12 dB per octave.
          • The Cutoff knob moves the cutoff point from about 30 Hz at its fully counter-clockwise position to above 15 kHz at its fully clockwise position.
      • Microfreak/UG/07 Filter/01 Modifying Sound/05 Resonance

        • 07.01.05 Resonance or Q

          • Resonance, also called Emphasis or Q (for quality of filtering), amplifies frequencies close to the cutoff. Turning the Resonance knob clockwise makes the filter more selective and gives the sound a stronger ringing character. At its extreme setting, the filter self-oscillates.
  • Microfreak/UG/07 Filter/02 Animating Sound

    • 07.02 Animating sound

      • Changing the cutoff and resonance dynamically makes the filter a musical tool. The MicroFreak can use an LFO, an Arpeggiator, or an Envelope to control these parameters. See Microfreak/UG/08 LFO for the LFO; the Arpeggiator and Envelope chapters cover the other modulators.
      • Microfreak/UG/07 Filter/02 Animating Sound/01 Cutoff Modulation

        • 07.02.01 Cutoff Modulation

          • Moving the cutoff changes the sound's timbre. The most effective and musically pleasing way to modulate it is with an envelope generator. The MicroFreak connects the main envelope to filter cutoff; the Filter Amt knob beside Sustain sets the modulation amount.

          • Note/Info Changing Filter Amt lights the corresponding point on the Matrix. The filter amount can also be fine-tuned there.
            

      • Microfreak/UG/07 Filter/02 Animating Sound/02 Emphasis Resonance Modulation

        • 07.02.02 Emphasis/Resonance Modulation

          • Increasing emphasis focuses the filter's response around the cutoff, boosting nearby frequencies.

          • Note/Info A sequencer modulation track can create stepped harmonic effects by assigning a different filter-cutoff modulation amount to each step.