Rectifier

A bipolar piecewise-linear shaper with independent scaling for positive and negative input halves.

What it does #

Rectifier separates the waveform at zero and applies a different factor to each side. It can preserve, attenuate, mute, invert, or emphasize either polarity, covering half-wave and full-wave rectification as well as asymmetric level shaping.

Controls and ports #

Control	Label	Official description
positive_amount	Positive Amount	Scaling for all positive values
negative_amount	Negative Amount	Scaling for all negative values

Practical uses #

• Mute one side for half-wave rectification.
• Flip the negative half upward for a full-wave absolute-value shape.
• Use unequal sides to introduce even harmonics or reshape bipolar modulation.

Things to know #

• Changing the two sides independently can add DC even when the input is centered.
• The transfer is continuous at zero but its slope can change abruptly there.
• The AA mode uses previous-sample state and differs most when the input crosses the kink quickly.
• Rectification changes fundamental frequency content: full-wave rectifying a sine emphasizes twice its frequency.

Technical details #

A high-confidence Nitro implementation candidate supports the technical summary, but the visible-module mapping remains inferred.

The exact direct equation is out = pos*max(x,0) - neg*min(x,0). Its antiderivative is 0.5*(pos*max(x,0)^2 - neg*min(x,0)^2). With AA enabled, the body divides the antiderivative difference by x-lastIn; below a difference threshold of 0.0001 it evaluates the direct function at the midpoint instead. This is first-order antiderivative antialiasing around the zero kink.

Nitro port	Type
in	InputAudioPortType
pos	InputAudioPortType
neg	InputAudioPortType
AA	InputValuePortType
out	OutputAudioPortType

Open questions #

• Map the visible Positive/Negative ranges to preservation, muting, and inversion exactly.
• Measure AA alias suppression, latency, zero-crossing behavior, DC, and response to automated amounts.
• Confirm stereo state, initialization, and treatment of exact signed zero.

Version and sources #

Checked against Bitwig Studio 6.0.6. This page combines Bitwig's module metadata, the existing Grid course and guides, and Nitro analysis where the mapping is strong enough to support a technical statement.

Related material #

• Grid Modules course reference

Return to Bitwig Grid Modules or the Grid Modules course lesson.