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The Filter module is a simple programmable second order (12 dB/oct) filter designed for general tone shaping. It allows a variety of different filters along with real-time control of the filter parameters. You can use the Filter module for quick, static tone shaping or for elaborate, dynamic tone manipulation.

It can be used as a straight gain block by setting the filter type to NULL. Another possibility is to use it as a treble booster (with more programmability than the one in the Drive module).

In the 60's guitarists began experimenting with booster pedals to increase the signal level into their amplifiers. This increased the amount of distortion their amps would produce. The more popular booster pedals had extra treble boost in addition to overall boost. This technique was essential to Brian May's tone on the early Queen recordings where a treble booster into a Vox AC-30 gave that unmistakable sound.

To use the Filter/Boost module as a treble booster set the TYPE to either HIGHPASS or BANDPASS. Experiment with the Q and FREQ controls to achieved the desired effect. Increase the level to increase the overall signal level out of the block.

The FREQ, Q, GAIN, LEVEL and parameters are all controllable. To attach a modifier to these parameters select the parameter and press ENTER. This brings up the MODIFIER menu. When any of these parameters are attached to a modifier an asterisk (*) appears after the name indicating such.


  • TYPE - Sets the type of filter. All the standard filter types are available. A NULL type has a flat frequency response characteristic.
  • FREQ - Sets the center frequency of the filter.
  • ROFFS - Sets the right channel frequency offset as a multiple of the left channel. A setting of 0.5, for example, would set the right channel frequency to half the left.
  • Q - Sets the ‘Q’ of the filter. Higher values give sharper responses.
  • GAIN - Sets the gain at the center frequency for the bandpass, notch, low-shelf and high-shelf types. This control has no effect with the other types.
  • LEVEL - Sets the output volume level of the block.
  • PAN - Sets the output panning of the block.
  • BYP - Sets the bypass mode.


You can attach modifiers to the filter. There was no room on the display for the little symbol but as usual you press enter. When you've attached a modifier an asterisk (*) will show up next to the parameter.


A boost effect can be easily achieved using the Filter block. Simply set TYPE to NULL and adjust the LEVEL control for the amount of boost desired. Bypass the Filter for normal operation, then engage it for a boost. For a gain boost, place it before a Drive or Amp block. For a simple volume boost, place it after those blocks or at the very end of the chain. Keep in mind the boost will push the drive in a Delay placed after it, but cutting the volume of the output of a delay or reverb could sound unnatural.

Useful applications for filters

  • Your tone is distorted (which is how you want it to be) but the tone is ugly, too much bass, it sounds like it is farting.
    • Add a highpass filter as the first block, start with the frequency 100 Hz and higher (sometimes you can go up to 400 Hz) and play around with the Q
    • Try the same with a Bandpass filter, but with a higher frequence (600 Hz maybe).
  • For solos you want a mid boost:
    • Add a peak filter with gain boost 6db, frequency 600 Hz - 1000 Hz. Put the bypass on an external switch.
  • If you play alone your sound is great, but playing together with the band you get into sonic conflict with drums and bass.
    • Add a highpass filter as last block, frequency 140 Hz, Q = 1.
    • As an alternative, you could try a lowshelf, same settings, with gain -3db.
  • You want to emulate a small wooden cabinet, you want your sound to become "boxy".
    • Add a lowshelf around 200 Hz, gain -3 db to -12 db, with higher Q setting like 1.4, so you have a little peak there.

Note that it makes a big difference if you put a filter before or after the compressor, especially with highpass filters or lowshelf filters with negative gain. Most of the time it is better to put it before the compressor. Otherwise the compressor reacts to bass signals, which are filtered out, resulting in odd volume jumps (like e.g. the pumping synthie pad in Eric Prydz ugly remix of "Call on me".)