top of page


ARC Klangumwandler eurorack synthesizer module

  • The Klangumwandler is a fully modular analogue frequency shifter, comprised of a Quadrature Oscillator, Dome Filter, Dual Analogue Multipliers, and an Adder.  The module is prepatched with switching jacks as a standard frequency shifter, but allows access to all the submodules for experimentation.


    The Quadrature Oscillator is voltage controlled with four sine wave outputs, each phase shifted 90 degrees apart.  This phase relationship is useful for patching barberpole effects and is essential for a frequency shifter.  The 0 and 90 outputs are prepatched to the Carrier A and Carrier B inputs of the Dual Analogue Multipliers.


    The Dome Filter is a special phase-shift network that performs a Hilbert transform on the incoming signal, producing a 90 degree shifted output across wideband frequencies.  Unlike a low-pass or band-pass filter, the Dome filter is not named for it's response, but rather for it's inventor R.B. Dome (Electronics, Dec. 1946).  Our implementation of the Dome Filter is discrete, with outputs prepatched to the Program A and Program B inputs of the Dual Analogue Multipliers.  


    The Dual Analogue Multipliers are two identical four-quadrant multipliers built using Analog Devices AD633s.  The module is prepatched to multiply a carrier from the Quadrature Oscillator with an output from the Dome Filter.  These can of course also be used as VCAs and ring modulators.


    The Adder is an analogue mixer that is prepatched to combine the outputs of the Multipliers.  To use the Klangumwandler as a frequency shifter, simply patch the signal you wish to process into the "Dome In" jack and the result will be available at the "Mix" output.  Adjusting the "Frequency" control will determine the shift amount. 


    Please note: to use the module with vocal signals, some additional processing is encouraged.  A preamp is likely to be neccesary to raise the input signal up to modular levels.  Likewise, an envelope follower and VCA can help to shape the signal as found in Harald Bode's "squelch" implementation.  ARC will release a 3hp module with these functions in the future, but many such utility modules are already currently available.


    We produced the Klangumwandler to have features and controls exposed that are usually hidden behind the panel on standard frequency shifters and to celebrate the work of Bode and Dome.  The submodules of the Klangumwandler are powerful analogue computer blocks.   Please experiment.

bottom of page