OBC - One Bit Converter

OBC Front Panel

OBC (One Bit Converter) is an hardware emulation inspired by the Motorola MC3518, single bit converter family. It converts digital signal to digital signal by using the single bit conversion emulation.

Principle of single bit conversion

The converter tries to follow an input signal (sample values) by adding or subtracting values (increment and decrement values in OBC).

If the current output sample value is lower than the next input sample value, then an increment value is added to the next output value.

If the current output sample value is higher than the next input sample value, then a decrement value is subtracted to the next output value.

And so on for the next input signal samples.

Here is a small graph that shows this :

Single bit conversion graph

OBC adds a lot of parameters to precisely drive the converter.

The result of this conversion may sound from a slight frequency exciter to a bit crushed and distorted wave.


  • Volume control for the main audio input signal.

  • Threshold detection for input or side-chained signal. Invert mode.

  • Smooth threshold function for smoother transition between original and converted signal.

  • ADSR envelope trigged by threshold or gate CV or Midi note.

  • Adjustable converter increment and decrement, fast increment/decrement factor.

  • Independant converter increment and decrement values.

  • Resolution modes to control how many times the input signal goes to the converter. The frequency can be drive by Midi note or CV In signal.

  • Soft function to decrease auto oscillations that occurs with constant signal (ie square wave).

  • Pan level and resolution to spread sound.

  • Gain and Saturation controlers. Saturation function adds a limiter to avoid converter generate too high signal levels.

  • Dry/Wet mixer.

  • Full CV control.

  • No latency.

One Bit Converter Demo