NoizBox is a creative distortion effect consisting of an input filter, a nonlinear wave-shaper, and an output filter, with a Dry/Wet Mix control to adjust the balance between the “dry” unprocessed signal and the “wet” distorted signal at the output.

The GUI consists of three sections, described individually below.

The PreFilter section of the GUI represents the input (pre-distortion) filter. This is actually a chain or cascade of up to four identical, two-pole recursive digital filters.

• The left menu allows selecting the filter type:
  • OFF disables the pre-distortion filter block entirely
  • LP: low-pass
  • HP: high-pass
  • BP: band-pass
  • BR: band-reject (aka “notch”)
• The right menu allows selecting the number of stages in the filter chain:
  • 12 dB: one stage, yielding 12 dB/octave roll-off
  • 24 dB: two stages, yielding 24 dB/octave
  • 36 dB: three stages, 36 dB/octave
  • 48 dB: four stages, 48 dB/octave
• The three knobs adjust the frequency response and gain of all active stages:
  • The Freq knob adjusts the filter's characteristic frequency (e.g. cutoff or center frequency)
  • The Q knob adjusts the amount of resonance (aka “emphasis”) near the characteristic frequency
  • The Drive knob adjusts the filter's gain. It's called “drive” because it affects how hard the nonlinear waveshaping block is driven.

The PostFilter section of the GUI represents the output (post-distortion) filter. Like the pre-filter, this is also a chain of up to four cascaded filter sections, and the controls are the same.

The Mix knob adjusts the balance of unprocessed (“dry”) and processed (“wet”) signals in the final output.

• When the knob is all the way to the left, only the dry signal is heard
• When the knob is all the way to the right, only the wet signal is heard
• Intermediate positions set the mix of dry and wet.

The graph section in the middle of the NoizBox GUI represents the nonlinear wave-shaper block, which is the heart of the distortion unit.

The graph itself represents the positive half of the distortion response curve, i.e., how the wave-shaper responds to positive-valued input samples. The negative half of the curve is identically shaped, but reversed in both X and Y directions.

Clicking on the graph pops up an editor window like this:

The pop-up menu at the top left allows you to select the basic curve shape:

• OFF disables the Distortion entirely
• Exponential and Power Curve are two variants of a convex curve
• Hard Clip provides a variable linear gain segment with clipping at maximum amplitude
• Soft Clip provides a high-gain segment and a low-gain segment, with a smooth “knee” between them
• Quantize yields an adjustable stair-step curve
• Custom yields a curve you can edit into just about any shape–see below.

Immediately to the left of the large graph box is a vertical Strength slider. For the exponential, hard clip, soft clip, and quantize shapes, this adjusts the amount of distortion, ranging from linear response (no distortion) when the “thumb” (green dot) is all the way to the bottom, to extreme distortion when all the way to the top.

When you select Custom from the curve-shape menu, the large graph area becomes an interactive curve editor which works basically the same as the editors for MIDI-velocity curves in Unify.

• Drag either endpoint (circles) up or down to change the output range
  • You can drag the right-hand endpoint below the left one for an inverted response (increasing input signal results in decreased output signal, aka “fold-over”)
• Drag up/down on the line between the endpoints to adjust the shape of the curve (convex or concave)
• Double-click between endpoints to add a new “split point”
  • This splits the curve segment in two
  • Split points can be dragged up/down and left/right
  • Individual curve segments can be dragged up/down to adjust shape
• Double-click any split point to delete it
  • This merges two segments back into one

NoizBox allows you to save distortion curve-shapes individually as Distortion Curve Presets. Note all of the different curve-types can be saved this way, not just “custom” curves.

• Click the Reset button to reset the distortion curve to a straight line (no distortion at all)
• Click the Save… button to save the current curve shape to a new preset file
  • A standard file-save dialog will pop up, allowing you to choose the file name and location
  • It is recommended to stick with the default location, which is a folder called Distortion Curves within the main Unify Presets folder
• Click the Load… button to re-load a previously saved preset
  • A standard file-open dialog will pop up, with the standard Distortion Curves folder already selected