Spectral Gate

The Spectral Gate is an unusual filter effect that can be used as a tool for creative sound design.

It works by dividing the incoming signal into two frequency ranges—above and below a central frequency band that you specify with the Center Freq and Bandwidth parameters. The signal ranges above and below the defined band can be individually processed with the Low Level and High Level parameters and the Super Energy and Sub Energy parameters.

Spectral Gate Parameters

The Spectral Gate panel includes the following parameters:

Figure. Spectral Gate window.
  • Threshold slider and field: Sets the threshold level for division of frequency ranges. When the threshold is exceeded, the frequency band defined by the Center Freq. and Bandwidth parameters is divided into upper and lower frequency ranges.
  • Speed slider and field: Sets the modulation frequency for the defined frequency band.
  • CF (Center Frequency) Modulation slider and field: Sets the intensity of center frequency modulation.
  • BW (Band Width) Modulation slider and field: Sets the amount of bandwidth modulation.
  • Graphical display: Shows the frequency band defined by the Center Freq. and Bandwidth parameters.
  • Center Freq. (Frequency) knob and field: Sets the center frequency of the band that you want to process.
  • Bandwidth knob and field: Sets the width of the frequency band that you want to process.
  • Super Energy knob and field: Controls the level of the frequency range above the threshold.
  • High Level slider and field: Blends the frequencies of the original signal—above the selected frequency band—with the processed signal.
  • Sub Energy and field: Controls the level of the frequency range below the threshold.
  • Low Level slider and field: Blends the frequencies of the original signal—below the selected frequency band—with the processed signal.
  • Gain slider and field: Sets the output level of the Spectral Gate.

Using the Spectral Gate

One way to familiarize yourself with the operation of the Spectral Gate would be to start with a drum loop. Set the Center Freq. to its minimum (20 Hz) and the Bandwidth to its maximum (20000 Hz) value so that the entire frequency range is processed. Turn up the Super Energy and Sub Energy knobs, one at a time, then try different Threshold settings. This should give you a good sense of how different Threshold levels affect the sound of Super Energy and Sub Energy. When you come across a sound that you like or consider useful, narrow the Bandwidth drastically, gradually increase the Center Freq., and then use the Low Level and High Level sliders to mix in some treble and bass from the original signal. At lower Speed settings, turn up the CF Mod. or BW Mod. knobs.

To acquaint yourself with the Spectral Gate
  1. Set the frequency band you want to process by using the Center Freq. and Bandwidth parameters.

    The graphical display visually indicates the band defined by these two parameters.

  2. After the frequency band is defined, use the Threshold parameter to set the desired level.

    All incoming signals above and below the threshold level are divided into upper and lower frequency ranges.

  3. Use the Super Energy knob to control the level of the frequencies above the Threshold, and use the Sub Energy knob to control the level of the frequencies below the Threshold.

  4. You can mix the frequencies that fall outside the frequency band (defined by the Center Freq. and Bandwidth parameters) with the processed signal.

    1. Use the Low Level slider to blend the frequencies below the defined frequency band with the processed signal.

    2. Use the High Level slider to blend frequencies above the defined frequency band with the processed signal.

  5. You can modulate the defined frequency band using the Speed, CF Modulation, and BW Modulation parameters.

    1. Speed determines the modulation frequency.

    2. CF (Center Frequency) Modulation defines the intensity of the center frequency modulation.

    3. BW (Band Width) Modulation controls the amount of bandwidth modulation.

  6. After making your adjustments, you can use the Gain slider to adjust the final output level of the processed signal.