Rectifier

1. Bias Knob Applies a bias to the input signal, changing the symmetry of the effect.
2. High Quality Switch Enables or disables oversampling.
3. AC Coupling Switch Enables or disables a DC-blocking filter at the output.
4. Full-wave Rectifier Output Positive signal allowed to flow, negative signal inverted.
5. Half-wave Rectifier Output Positive signal allowed to flow, negative signal blocked.
6. Negative Full-wave Rectifier Output Negative signal allowed to flow, positive signal inverted.
7. Negative Half-wave Rectifier Output Negative signal allowed to flow, positive signal inverted.
8. Boost Knob Adds up to 2× gain to compensate for amplitude reduction caused by rectification.
9. Inputs Signal to be rectified (stereo).

Overview ⚓︎

In an electronic circuit, a rectifier will convert alternating current (AC) into direct current (DC) by allowing current to flow in only one direction. There are two types of rectification:

• Full-wave rectification: The negative part of the signal is inverted, resulting in a fully positive signal. With some input signals, this can produce a frequency doubling effect.

• Half-wave rectification: Only the positive part of the signal is allowed to flow. The negative half is blocked.

The following figure shows the effect of full-wave and half-wave rectification on a triangular wave.

Usage ⚓︎

Connect the input signal to the module. Depending on the desired type of rectification, use one of the four stereo outputs:

1. Full-wave rectification: negative voltage become positive
2. Half-wave rectification: negative voltage is blocked
3. Negative full-wave rectification: positive voltage become negative
4. Negative half-wave rectification: positive voltage is blocked.

Mixing the second and fourth outputs together will reconstruct the input signal.

The symmetry of the effect can be adjusted with the Bias knob, which adds a voltage offset to the input signal. This can be used to simulate the voltage drop of an analog rectifier or to change the frequency spectrum of the rectified signal.

Since rectification reduces the signal’s amplitude, a convenient Boost knob can be used to increase the output volume.

Rectification can cause some aliasing to occur, which is heard as dissonant frequencies added to the signal. This is more obvious on sounds with loud high frequency content. The High Quality (HQ) switch enables oversampling to reduce the amount of aliasing in the audible frequency range and round out the sound. This is enabled by default when adding the module to a patch.

By design, the Rectifier module will also always add a DC offset to the signal, since it eliminates one half of the alternating current. If you’re using the module as an effect on an audio signal, it may be a good idea to enable AC coupling by clicking on the AC switch. This activates a DC-blocking filter, which can prevent problems like a loss of headroom or unwanted distortions further down the signal path.

To see the Rectifier module in action with an oscilloscope, choose All Patches in the Patches Library and open the Basics—Demo: Audio Shapers patch.