Stereo Crusher

Type: Module

Category: Processor

Updated: May 01, 2021

Manufacturer: Weevil

Contact Manufacturer

$15.00

Stereo Crusher is a stereo or dual bit-crusher and sample rate reducer.

Check demo patches here: https://www.youtube.com/watch?v=40HbMw0XD3Y

The module has two channels (Left and Right), these can either be modified independently or together. You define this behavior with the dropdown menu at the top left, the options are: OFFSET - In this mode the left controls set the base value and the right controls set the value offset between the left and right channel. DUAL - In this mode the left and right controls are set independently.

Most of the controls have different modes that you set with a button below the control. By default, the right channel is set to the value MAIN, this will use the same mode as is assigned to the left channel. This is indicated in the UI by showing the mode within brackets.

The signal path goes through 7 main steps:

  • Effect - effects can be applied before clipping/folding
  • Clipping or folding - to ensure the signal is within +/- 5V the signal is either clipped or folded
  • Sample rate and bit reduction - sample and bit reduction with plenty of options
  • Effect -  bitwise effect can be applied to signal
  • Mod - cross-modulation effect can be applied between the two channels or against a external sources
  • Filter - multiple filter modes to reduce the harshness
  • Mix - mix the clean signal with the processed signal and set stereo width

INPUT AND OUTPUT

You find all input and output jacks at the bottom of the module. In OFFSET mod the input jacks (INPUT, MOD INPUT and ENVELOPE) are normalized to use the left input jack if nothing is plugged in to the right jack.

INPUT - Input for the left and right lane. The "analog" to digital conversion works in the range -5V to 5V. How signals outside of this range are handled is set in the OVERFLOW section, the available options are:

  • CLIP - the signal is clipped at +5 or -5V
  • FOLD - the signal is folded in on itself.

MOD INPUT - Input for the modulation effect section see MOD below.

ENVELOPE - Effects, modulation effects and certain CV input can cause the stereo crusher to output sound even when no input sound is coming in. This is no problem if the module is put before the Amp module, bit the stereo crusher is more suited to be placed after the Amp. To get rid of unwanted sound you can connect an envelope to the envelope input, this will scale down the output based on the envelope signal sent in (so no output if envelope is 0).

OUTPUT - Output for the left and right lane. In general output is between -5 and 5 but some resonance settings can drive it up to around 8V.

BIT DEPTH

Sets the bit depth between 2 and 12 bits, the available options are:

  • DISCRETE EVEN - set the bit depth in discrete values of 1 bit, this will divide the signal in 4, 8, 16, 32, ..., 4096  steps.
  • DISCRETE ODD - set the bit depth in discrete values of 1 bit, after that we reduce the value by that - 1, this will divide the signal in 3, 7, 15, 31, ..., 4095  steps. This mode reduces the long buzzy tail you get with a low bit depth.
  • CONTINUOUS - sets the bit depth continuously, this will divide the signal in 3, 4, 5, 6, ..., 4096  steps.
  • CONTINUOUS ODD - sets the bit depth continuously (odd only), this will divide the signal in 3, 5, 7, ..., 4095  steps.
  • CONTINUOUS EVEN - sets the bit depth continuously (even only), this will divide the signal in 4, 6, 8, ..., 4096  steps.

SKEWNESS

The bit reduction divides the signal in steps on the vertical axis. Normally these steps are evenly distributed. The skewness controls lets you change how these steps are distributed. The effect of this could be that the top part of the signal has a high bit depth and the lower part of the signal has a low bit depth. The amount of skewness is controlled with the knob, how the skewness is applied is set with the button below the control. The options are:

  • UNIPOLAR - distributes the steps between the edged (top and bottom) by turning the knob to the right or to the center by turning the knob to the left.
  • BIPOLAR - distributes the steps between the top half of the curve (knob to the right) and bottom part of the curve (knob to the left).

SAMPLE RATE

Sets the sample rate between approximately 125 and 48000. There are two modes supported here:

  • CONTINUOUS - continuously reduces the sample rate
  • DIVIDE - this mode locks the sample reduction to discrete divisions of the sample rate

EFFECTS

The two effect sections lets you insert effects either before or after bit reduction. The effects applied before bit reduction are:

  • AMPLIFY - below 0 will scale down the signal down to 0 at effect value -1, above 0 will amplify the signal up to a factor of 10 (FOLD and CLIP will give very different results).
  • VERTICAL OFFSET - add or deduct up to 5V from the signal (FOLD and CLIP will give very different results).
  • UNIPOLAR SKEW - change the shape of the signal, same change applied to both negative and positive values.
  • BIPOLAR SKEW - change the shape of the signal, left will emphasize negative values, right will emphasize positive values.
  • NOISE - add noise to the signal (pink noise to the left, white noise to the right).

The pre bit reduction effects together with CLIP and FOLD makes this a fairly flexible wave shaper, either in stereo or connect left out to right in to get a 4 stage shaper.

The effects applied after bit reduction are primarily bit shift effects (these will drastically change the sound and will benefit from some filtering). The knob sets the value you are comparing your signal to, in general they are symmetric to allow 0 to have no effect on the signal. The effect options are:

  • AND - apply bitwise AND between the signal and the effect value.
  • AND SCALED - apply bitwise AND between the signal and the effect value, scale it up to the full bit depth.
  • OR - apply bitwise OR between the signal and the effect value.
  • OR SCALED - apply bitwise OR between the signal and the effect value, scale it up to the full bit depth.
  • XOR - apply bitwise XOR between the signal and the effect value, scale it up to the full bit depth.
  • SHIFT - bit shift the signal.       CV on the effect values can result in sounds from the module even when you have no input. Check the ENVELOPE section to see how to solve that.

FILTER

Available filter types:

  • NONE - No filter
  • LOW PASS TWO POLE - Low pass two-pole filter
  • LOW PASS FOUR POLE - Low pass four-pole filter
  • BAND PASS TWO POLE - Band pass two-pole filter
  • BAND PASS FOUR POLE - Band pass four-pole filter
  • HIGH PASS TWO POLE - High pass two-pole filter
  • HIGH PASS FOUR POLE - High pass four-pole filter
  • LOW PASS TWO POLE SAMPLE REDUCE - Low pass two-pole filter sample reduce mode
  • LOW PASS FOUR POLE SAMPLE REDUCE - Low pass four-pole filter sample reduce mode
  • BAND PASS TWO POLE SAMPLE REDUCE - Band pass two-pole filter sample reduce mode
  • BAND PASS FOUR POLE SAMPLE REDUCE - Band pass four-pole filter sample reduce mode
  • HIGH PASS TWO POLE SAMPLE REDUCE - High pass four-pole filter sample reduce mode
  • HIGH PASS FOUR POLE SAMPLE REDUCE - High pass four-pole filter sample reduce mode
  • SMOOTHER - Smooths the value between 0 and 1000 ms (no resonance)
  • SLEW - Smooths the value (no resonance)
  • SLEW UP - Smooths the value on up but leaves voltage falls unaffected (no resonance)
  • SLEW DOWN - Smooths the value on voltage falls but leaves voltage increases unaffected (no resonance)

The sample reduce filter works the same as the normal filter at high sample rates but if you bring it down and add signals with a lot of overtones like a saw wave you can get some nice formant like sounds.

SMOOTHER and SLEW was added primarily to be used if you use the stereo crusher for LFOs and other control signals but can of course be used however you like.

MOD

The mod section lets you apply cross modulation with another source. The section consists of input jack, a source selection button, a mod effect select button and a mix knob that sets the balance between the modified signal and your base signal.

The input jacks are used for external sources (you need to set the source button to either EXTERNAL or EXTERNAL DRY).

Available sources:

  • DRY - the channel input signal before bit crushing and effects are applied.
  • OPPOSITE - the opposite channel.
  • OPPOSITE DRY - the opposite channel before bit crushing and effects are applied.
  • EXTERNAL - the external signal.
  • EXTERNAL DRY - the external signal without bit crushing applied, not available for the bitwise mod effects (AND, OR, XOR).

Available mod effects:

  • NONE - No effect
  • AND - Bitwise AND
  • OR - Bitwise OR
  • XOR - Bitwise XOR
  • RM - Ring modulation
  • AM - Amplitude modulation
  • MAX - Max of channel source and mod source
  • MIN - Min of channel source and mod source
  • ABS MAX -  Absolute max of channel source and mod source
  • ABS MIN -  Absolute min of channel source and mod source

ENVELOPE

Effects, mod effects and certain CV input can cause the stereo crusher to output sound even when no input sound is coming in. This is no problem if the module is put before the Amp module, bit the stereo crusher is more suited to be placed after the Amp. To get rid of unwanted sound you can connect an envelope to the envelope input, this will scale down the output based on the envelope signal sent in (so no output if envelope is 0).

MIX

Signal mixing happens in three places in the signal path:

  • Mod mixing, the middle knobs in the MOD section sets the mix between your crushed signal and the mod output (basically a dry / wet knob for the mod section).
  • The knobs below the MIX section lets you mix between the unprocessed input signal and the signal processed by the module (wet / dry).
  • The WIDTH slider sets the stereo width of the module, all the way to the left is no stereo, all the way to the right will give you complete separation of the right and left channel.

CV

The module has 8 assignable CV sections with a label (also works as a target selector), an input jack and an attenuverter. The available CV targets are:

  • EFFECT 1 - Effect value of both channels
  • EFFECT 2 - Effect value of both channels
  • BIT DEPTH - Bit depth of both channels
  • SKEWNESS - Skewness of both channels
  • SAMPLE RATE - Sample rate of both channels
  • CUTOFF - Filter frequency of both channels
  • RESONANCE - Filter resonance of both channels
  • WET/DRY - Wet / dry mix of both channels
  • MOD -  Wet / dry mix of both channels MOD section
  • EFFECT 1 LEFT - Effect value of the left channel
  • EFFECT 2 LEFT - Effect value of the left channel
  • BIT DEPTH LEFT - Bit depth of the left channel
  • SKEWNESS LEFT - Skewness of the left channel
  • SAMPLE RATE LEFT - Sample rate of the left channel
  • CUTOFF LEFT - Filter frequency of the left channel
  • RESONANCE - Filter resonance of the left channel
  • WET/DRY LEFT - Wet / dry mix of the left channel
  • MOD LEFT -  MOD section wet / dry mix of the left channel
  • EFFECT 1 RIGHT - Effect value of the right channel
  • EFFECT 2 RIGHT - Effect value of the right channel
  • BIT DEPTH RIGHT - Bit depth of the right channel
  • SKEWNESS RIGHT - Skewness of the right channel
  • SAMPLE RATE RIGHT - Sample rate the right channel
  • CUTOFF RIGHT - Filter frequency the right channel
  • RESONANCE RIGHT - Filter resonance of the right channel
  • WET/DRY RIGHT - Wet / dry mix the right channel
  • MOD RIGHT -  MOD section wet / dry mix of the right channel
  • EFFECT 1 OFFSET - Effect value offset between left and right
  • EFFECT 2 OFFSET - Effect value offset between left and right
  • BIT DEPTH OFFSET - Bit depth offset between left and right
  • SKEWNESS OFFSET - Skewness offset between left and right
  • SAMPLE RATE OFFSET - Sample rate offset between left and right
  • CUTOFF OFFSET - Filter frequency offset between left and right
  • RESONANCE OFFSET - Filter resonance offset between left and right
  • WET/DRY OFFSET - Wet / dry offset between left and right
  • MOD OFFSET - MOD wet / dry offset between left and right
  • WIDTH - Stereo Width

To get you started, get the tutorial preset pack: https://store.cherryaudio.com/presets/stereo-crusher-tutorial