BitCrusher III

Story:

The "bitcrushing" as an intentional effect distorting a bit representation of a sample was first developed many years ago as a plugin in diverse DAW applications. Back then I have been many times asked by a fellow musicians about a hardware equivalent of such effect, something they could use onstage without the need to use a laptop. A lo-fi computer music from the 8 bit microcomputers era was one of my first encounters with making music, so i felt close to this type of sound. Definitely wanted to make it available in a pedal form.

Bitcrushing as an effect is often confused with Downsampling, which is much easier to simulate using various analog methods. A classic bit crusher distorts the bit representation of a single sample. The simplest way of distorting a sample is to reduce it's bit resolution to a lower value, ie from 16 bit to 4-6 creating lots of harmonics. A downsampler changes the sampling frequency of the signal and by doing that creates an effect called "aliasing". In general, both operations are highly unwanted in regular music reproduction and editing. However, the history of rock guitar sound is based on breaking such rules. Bitcrushing combined with downsampling and filtering creates many interesting harmonic structures and finds many uses in todays music.

The first prototype was created in early 2008. From the beginning, the main design goal was to build a real hardware bitcrusher using definitely not the best quality analog to digital and digital to analog converters with variable sampling frequency. The prototype was an 8 bit machine with simple controls for bit depth (Crush), sampling frequency (Downsample), a bandpass lo-fi filter (Telephone) and Level.

As I have quickly realized, the classic approach of reducing the bit depth did not sound particularly interesting or novel (similar to a gated fuzz). I started to experiment with different, more complex functions to distort the bits, finally finding one that was sonically pleasing. It has become the signature distortion model for all the future BitCrusher pedal versions. The new model got an expression pedal input assignable to Crush or Downsample. The pic shows the prototype of the BitCrusher II

And here the final version of the model II:

A few custom models were built for table top use by DJ's, equipped with toggle switches instead of hard to operate by hand footswitches.

Controls:

• CRUSH, bit mess/digital distortion parameter,
• DOWNSAMPLE, sets the sampling frequency, range from 32kHz (at zero) to 1kHz (at max),
• TELEPHONE, bandpass (350Hz-3.5kHz) filter for ultra lo-fi sound,
• BLEND, dry/wet mix ratio knob,
• LEVEL, output volume regulator,
• EXP In, expression pedal input (jack stereo),
• EXP Pedal Assign, switch, allows to assign the Crush, Downsample or both of them together to the expression pedal,
• INPUT GAIN, settings: single coil, humbucker, line level signal.
• MODULATE, activates/deactivates the modulation mode for the DOWNSAMPLE parameter,
• ON/OFF, true bypass footswitch,
• internal FILTER TYPE switch, allows to choose the TELEPHONE filter response (bandpass or lowpass).

Demo videos / Sound Samples:

Click here to listen to the track on SoundCloud.
Bitcrusher III + Roboduck sound sample.

Click here to listen to the track on SoundCloud.
Bitcrusher III on bass, direct Line input recording.