Tube is a characterful VCA. A vacuum tube is like a transistor, but analog and imperfect. It can therefore be adjusted to have various tones imparted on your sound.

The Tube waveshaping VCA is a 6HP module with one channel IN/OUT, three input CV jacks with offset knobs, and a switch for activating a feedback path. If you have experience with tube VCAs elsewhere you know the sound is very dependent on the voltage level given, so this module has both a pre- and post-tube VCA to control the gain and therefore the sound.

The two VCAs are configured to have a huge range of CV, to give you maximum option for smashing your sound. When set low, it can be a very clean VCA, or when set high you have the opportunity to wavefold through extreme clipping; this module can output a 20Vpp signal.

The ‘wave’ CV sets a grid voltage that bends your waveform around a centerpoint, adding harmonics. Works best on softer sounds like a triangle, since a square doesn’t fold very interestingly.

The feedback switch optionally routes the output back into the input, running through a diode to censor some of that signal. This can phase-cancel and reduce your volume at many settings of the wave cv, but enable sweet spots with glitchy self resonance for that electric grunge sound. It can even approximate digital noise if fed high frequencies and set on a clipping threshold.

V1 is in good working order and ready to go. V1.1 fixes some tube cathode current issues we’re seeing on some natural tube variation.