Buchla 257t Dual Voltage Processor

Tip-Top Audio

The Tip Top Buchla 257t - an essential part of the Buchla ecosystem!

257t is a dual voltage processor - it contains two channels worth of Attenuator, Offset, and a voltage controlled Crossfader (which can be used as a VCA if one side is left empty).  The 257t allows you to combine and bend control voltages into new shapes, or helps sculpt them before CV inputs.  Perhaps you want to combine a 245t sequence with a small amount of random before using it to modulate a 281t decay stage.  Perhaps you want to use the crossfader to blend between two oscillators, or perhaps use it to invert and offset CV to give two oscillators alternating modulation; the 257 is an essential module to get the most out of a Buchla 200 system!  From Tip Top:

"Model 257 Dual Control Voltage Processor consists of two identical sections, each of which permits several applied control voltages to define a single output voltage according to the equation:

(Va * K) + ((Vb * (1-M)) + (Vc * M)) + Voset = V_out

The algebraic manipulations possible with this module include addition, subtraction, scaling, inversion, and multiplication. Also incorporated is the capability of using one control voltage (M) to transfer control from one applied voltage (V_b) to another (V_c)."

The Vk input has an attenuverter calibrated to 1x to maintain tracking.  This is mixed with the crossfader (allowing use as 3 channel mixer.) and then summed with Offset V oset.


14 HP
25 mm deep
Current Draw
45 mA +12V
22 mA -12V
0 mA 5V