Beast's Chalkboard is a two-channel high-precision voltage adder. Each channel outputs from two outputs by adding the voltage value selected from -2V to 2V for the input signal. Also, if there is no input for the second channel, the first channel input signal is routed by internal termination to the second channel. Thru also outputs an input signal as it is.
It is a utility module that can change octaves with simple but easy accuracy and will be very useful even if the frequency of the modulator changes at FM!