Dual Channel CV Processor (Vintage)
The model 156v was likely the first "CV manipulation" tool ever available to modular synthesists. In the original 100 series environment, the 156 was used as a front end to nearly every other module with a CV input. The majority of CV inputs throughout the 100 series do not have associated attenuators or offsets built into the modules, and thus they relied on the 156 to scale, offset, and attenuate the voltages traveling around the system. The 156V consists of 2 independent “voltage processors” Each with a control to mix the two inputs, add a voltage offset (positive only), and then a control to mix between the external CV to be processed and the internal offset. In addition, the "B" channel has an inverting input. The 156V is as close a replica to the original 156 as possible, and is built entirely of discrete analog components.
The Model 156V (Like all 100 Series Modules) is based off of designs originally pioneered by Don Buchla while working with the San Francisco Tape Music Center.