Doepfer A-189-1 Voltage Controlled Bit Modifier / Bit Cruncher

Module A-189-1 is a voltage controlled bit modifier. It offers several voltage controlled algorithmic functions like voltage controlled bit crunching, bit shifting (with/without carry over), bit exchange, rectifying, absolute value and calculating operations like addition, subtraction, multiplication or division.

The module has two control units both with manual control and CV input with attenuator:

• one for the algorithmic function according to the selected mode (e.g. number of shifted bits): BC and BC CV
• and one for the sampling rate (SR and SR CV)

The signal input is equipped with an attenuator. As the module is DC coupled even control voltages can be processed. The mode (e.g. bit crunching, bit shifting, bit exchange) is selected by a 16-position rotary switch:

Bit crushing: BC controls the number of bits (bit reduction)

AND: Signal AND BC

OR: Signal OR BC

XOR: Signal XOR BC

bit shift right: BC controls the number of bit shifts

bit shift left: BC controls the number of bit shifts

multiplication: Signal x BC

compare and complement: if signal > BC then output = bit complement of the input signal, otherwise unchanged

compare and absolute: if signal > BC then output = absolute value of the input signal, otherwise unchanged

addition: output = signal + BC (with overflow/clipping)

addition with BC swap: same as 10 but with nibble swap of BC (nibble = half byte, i.e. four bits)

short delay 1 with dynamic normalization: BC controls the length of the delay memory

short delay 2: same as 12 but different length/feedback

short delay 3: same as 12 but different length/feedback

short delay 4: same as 12 but different length/feedback

four stages FIR filter: BC controls the filter coefficient