321 Utility

The 321 is a multi-purpose utility module for processing audio and control voltage. It has three independent sections, and each one can attenuate or amplify a signal (up to 6 dB, or double the level), invert its phase or polarity, and add a positive or negative DC offset. The DC-coupled amplifier works on both audio and CV.

The sections feed two summing stages. One sum carries all three sections, including any offsets. The other leaves out any section whose local output has a cable plugged in, so a dummy cable can be used to remove a section from that sum. Both sum outputs have a -6 dB switch to halve the amplitude when the sum is too hot. The summing design is derived from the maker's CGM mixer series.

A switch plus an attenuator is used instead of an attenuverter, so a channel can be set exactly to zero and fully muted. The offset can be switched off for more transparent audio treatment, and it is useful for turning unipolar signals into bipolar ones and the reverse. With nothing patched into a section, its Offset control outputs a steady positive or negative DC voltage.