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Mixer+ Module

The Mixer+ module includes a basic three channel mixer as well as an attenuverter with the option to add distortion to the output signal.

  • Size: 8HP (40mm)
  • Power: 10mA (+12V); 10mA (-12V)

See the design section for details on the theory and implementation of the module. An assembly guide contains the BOM and assembly instructions. The schematic is also available for reference.

Project Source

The project files, including schematic and layout, are available on github.

3 Channel Mixer

Mixer+ Module

The 3 channel mixer is designed for a maximum of unit gain per channel.

  • DC coupled inputs
  • Inverting and non-inverting outputs
  • Simple output level indicator (red LED illuminates when V_{pp} \gtrapprox 9V)

Attenuverter with Distortion and Offset

The input of the attenuverter is connected internally (normaled) to the non-inverting output of the mixer. The internal connection is broken when an external connection is made. The attenuverter output can be optionally distorted or offset with a DC voltage.

  • Input normaled to the non-inverting output of the mixer and is DC coupled
  • Gain from -1 to 1
  • Optional back-to-back diode distortion (dirty/clean switch)
  • DC offset control adds -6 to +6V DC to output signal

References

  1. Moritz Klein, "Designing a 3-channel mixer with diode distortion from scratch", Youtube
  2. Ray Wilson, "Ultra-Simple Mono Audio Mixer 1", Music From Outer Space