Mixer

4-input dc coupled mixer

This module is a DC Coupled mixer with four inputs, attenuators, unity gain and an output attenuator.

Mixers are important for summing oscillators to make more complex sound, summing control voltages for making more complex modulation, or summing audio to combine cables at the output. Level shifting is important in all these applications, so this module lets you control the input levels of 4 signals and the output level after that.

Five knobs in 6HP can be a little tight, so you might want smaller knobs.

It can me easily modded to have various output gain. If R7 is 100K then it's unity gain, if R7 is 200K it's a 2x max output, and the final knob would be unity at 12 o'clock. If for some reason you wanted the output to drop a 10Vpp synth level signal to a 1Vpp line level, put a 10K in for R7.

https://karltron.com/mixer