Unify's built-in FilterMax effect is a multi-mode filter with up to four (identical) cascaded stages.

The two pop-up menus along the top of the GUI allow selecting the type of filter and the number of stages. Filter type options are:

• OFF: the filter is effectively bypassed
• Low Pass, High Pass, Band Pass: traditional filter types
• Notch: inverted band-pass filter, aka band-reject filter
• Peak, LoShelf, and HiShelf: Equalizer (EQ) filter types

The “EQ” filter types are similar to traditional band-pass/band-reject, high-pass, and low-pass filters, but have unity gain outside the pass-band. You can basically build a custom parametric equalizer by using multiple FilterMax instances on a layer, each set to one of the EQ filter modes. (For most uses, it will be simpler and more efficient to use a single instance of the built-in FlexEQ effect.)

The menu on the right allows you to select the number of filter stages:

• 12 dB: single stage, 12 dB/octave roll-off (when Q=0.707; see below)
• 24 dB: single stage, 24 dB/octave roll-off
• 36 dB: single stage, 36 dB/octave roll-off
• 48 dB: single stage, 48 dB/octave roll-off

The three knobs allow adjusting the filter parameters as follows:

• Frequency is the filter's cutoff frequency in Hz
• Q, aka resonance or emphasis, modifies the shape of the response curve near cutoff frequency
  • The default value 0.707 provides no emphasis
  • Higher values create a resonant “bump” in the frequency response just before the cutoff, and a slightly sharper roll-off slope
  • Lower values reduce the roll-off slope
• Gain (calibrated in decibels) is interpreted differently for different filter types:
  • For traditional filter types, this is simply a gain stage after the filter. Positive gain values can compensate for reduced overall gain when filtering aggressively, especially using high-pass or band-pass modes. Negative gain values are very useful for taming the effects of high Q settings.
  • For “EQ” filter types, the Gain knob sets the filter's pass-band gain. At the default value of 0 dB,

you will not hear any effect from “EQ” filters.