Buchla 257

 The Buchla 257 is a really useful module.

The front panel is a bit intimidating, but once you decipher the symbols and letters its not too hard to understand.

[Va * K ] + {[Vb*[1-M]] + [Vc*M]} + Voffset = Vout

 A great module for mixing, scaling, and processing Control Voltages. (the 257T can also be used with audio voltages)

There are 3 inputs: Va, Vb, Vc.

There are 3 knobs: K, M, Voffset

You can add, subtract, scale, invert & multiply voltages.

The above equation can be simplified to:

K + M + V = output

Va * K (Attenuverter): Inverts/attenuates and scales the voltage from input Va.... allows for -10 to zero to +10V control of whatever is plugged into Va

{[Vb*[1-M]] + [Vc*M]}: blends inputs "Vb" and "Vc" . 

The voltages Vb & Vc can be crossfaded with the M knob 

or a CV at the banana input between Va & Vc

There is a switch that when turned on, will apply +0.5-1V (depending on your calibration) directly to the Vb input

V(Offset):  Adds a DC offset to the final output.

                   The V knob when increased will output 0-10V.

                   (with NOTHING plugged into the module, if you turn the V knob to 50% ,you

                   would have +5V show up at the output).

How I like to imagine this module is as a way to sum 3 voltages in creative ways.

Remember that you have two voltage processors. You can combine these.

For comparison see the Buchla 254v,  Buchla 256 & 156.

254v (buchla format)