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

  • $140.00


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:

Switch position Function Remark
1 bit crushing BC controls the number of bits (bit reduction)
2 AND Signal AND BC
3 OR Signal OR BC
4 XOR Signal XOR BC
5 bit shift right BC controls the number of bit shifts
6 bit shift left BC controls the number of bit shifts
7 multiplication Signal x BC
8 compare & complement if singnal > BC then output = bit complement of the input signal, otherwise unchanged
9 compare & absolute if singnal > BC then output = absolute value of the input signal, otherwise unchanged
10 addition output = signal + BC (with overflow/clipping)
11 addition with BC swap same as 10 but nibble swap of BC (nibble = half byte, i.e. four bits)
12 short delay 1 with dynamic normalization BC controls the lenght of the delay memory
13 short delay 2 same as 12 but different length/feedback
14 short delay 3 same as 12 but different length/feedback
15 short delay 4 same as 12 but different length/feedback
16 four stages FIR filter BC controls the filter coefficient


Remark: Module A-189-1 is the first derivative of the universal AD/DA module. More modules derived from this basic idea are planned for the future (e.g. CV delay, CV modifier including Hz/V-to-V/Oct, digital waveshaper/multiplier, clocked audio dela

Width: 8 HP / 40.3 mm
Depth: 60 mm (measured from the rear side of the front panel)
Current: +50mA (+12V) / -20mA (-12V)