Crusher

1. Bit Crush Knob Sets the bitcrusher’s bit rate reduction.
2. Crush Bias Knob Offsets the voltage range over which the bitcrusher operates.
3. Rate Knob Sets the sampling rate reduction.
4. Mix Knob Adjusts the amount of dry and saturated signal in the output.
5. AC Coupling Switch Enables or disables a DC-blocking filter at the output.
6. Inputs Signal to be processed (stereo), with input level trim knob.
7. Outputs Processed signal (stereo), with output level trim knob.

Overview ⚓︎

The Crusher is an effect that can impart a lo-fi digital character to the sound. This is achieved with two different algorithms: a bit crusher, controlled by the Bit Crush knob, and a naive sampling rate reducer, controlled by the Rate knob. This is complemented by a Crush Bias setting that can modify the bit crusher tone, and a Mix control to adjust the amount of clean and processed signal in the output.

The sample rate reduction is applied before the bitcrusher.

The bitcrusher always operates on 10V peak-to-peak signals. By default, the range is from -5V to +5V. Any input signal beyond that is hard-clipped. The Crush Bias knob offsets that range:

• When Crush Bias is 0V, the range from -5V to +5V.
• When Crush Bias is +5V, the range is from 0V to 10V.
• When Crush Bias is -5V, the range is from -10V to 0V.

Usage ⚓︎

On Audio Signals ⚓︎

Audio Sampling Rate Reduction

The main objective of this module is to distort audio signals. As such, its sampling rate reduction is implemented in a way that generates the maximum amount of aliasing artefacts.

In the higher range of the Rate knob, the effect will be heard as a high-pitched digital whine. In the mid range, the aliasing becomes as loud as the input signal. In the lower range, the input signal becomes unrecognizable.

When using the Crusher in a synth patch, you can make the sampling rate reduction follow the pitch by connecting the Keyboard Pitch to one of the Rate modulation inputs and setting its attenuverter fully clockwise. Then, adjust the Rate knob until you hear a harmonically interesting aliasing tone. You can then play that tone over the keyboard; the Crusher becomes a grungy harmonizer.

Audio Bitcrusher

When the Bit Crush knob is fully clockwise, the bitcrusher is turned off. As the knob is turned counterclockwise, the signal resolution goes from 15 bits to 1 bit.

The bit reduction is done without any kind of dithering, creating plenty of digital noise. In the higher range of the Bit Crush knob, this is nearly imperceptible. In the mid range, it’s quite obvious, especially on long release tails. In the lower range, the input signal becomes thoroughly mangled. At 1 bit, the signal sounds like it has been passed through a hard-clipping distortion with infinite gain.

The Crush Bias will change the tone of the bitcrusher. Try modulating it with a LFO: with a low bit resolution, this can sound somewhat like pulse width modulation.

Because the bitcrusher can introduce quite a lot of DC in the output signal at low bit resolutions, a DC-blocking filter is enabled by default by the AC Coupling switch.

Gain Staging

When the bitcrusher is active, it hard-clips the signal to its floor and ceiling voltages (-5V to 5V when Crush Bias is set to 0V). When this happens, the input clips, the LED above the input jack turns on. To optimize the bitcrushing effect, use the volume knob above the input jack to adjust the input level until it clips a little, and dial it back slightly until it doesn’t clip. If you use both channels, you can optimize both channels independently. Then, compensate for the volume loss or gain with the volume knob above the output jacks.

If you plan on doing 1-bit bitcrushing, it’s better to leave all input and output volumes to their default centered position; no matter what the input is, the output will be 10V peak-to-peak which is a fine level in Multiphonics.

On CV Signals ⚓︎

When using the Crusher module on CV signals, it’s important to disable AC Coupling.

CV Sampling Rate Reduction

In Multiphonics CV‑2, most CV signals run at a maximum frequency of 2000 Hz, so the rate reduction will have no noticeable effect at higher frequencies.

CV Bitcrusher

The bitcrusher works great on CV signals. Applying low bit resolutions to envelopes and LFOs give them a stepped character that was a hallmark of early 1980’s digitally controlled analog synths.

For envelopes, set the Crush Bias to +5V to bring the crusher’s range between 0V and 10V.