Friday 3 March 2023

1630d Frequency Shifter

 My latest module, the 1630d Frequency Shifter.

This could be considered a "cheat", as the module is a digital interpretation of the Moog/Bode 1630 Frequency Shifter module. For ease of construction and programming I have based this on a standard Teensy 4.0 processor module together with the Teensy Audio Board. A custom front panel PCB hosts these together with the controls and interface circuitry.

The original Moog module requires many careful adjustments, or close tolerance component selection, in order to operate successfully. I therefore thought that the digital approach was justifiable in this case.

Note that this is a "Frequency Shifter", not a "Pitch Shifter". 

There are some differences between the 1630d and the original Moog 1630:

  • The 1630d includes two audio inputs; the 1630 has only has one.
  • There is no dedicated “mix” output on the 1630d – the MIX output can be assigned to “OUT A” or “OUT B” (or neither)  using the “MIXTURE” control and associated push button.
  • The 1630d includes a “MIX CV” input that can control the content of the MIX output.
  • There is no “ZERO” position on the SCALE switch, as this is not required for the digital version. The switch position has been re-used to provide a 1V/octave calibration function (CAL) for the CV inputs.
  • The 1630d uses digital FIR Hilbert filters instead of the (analogue) "dome" filters used in the original. At low frequencies the digital filters are not as flat in their phase and frequency responses as the original analogue ones.
  • The software contains several user configurable options to tailor the module to individual taste.

The module can be build using only though-hole components. Some of the ICs have surface mount options instead of through-hole to ease component sourcing. You will need to be able program the Teensy module using the open source software.

PCBs are in stock, panels will be in stock soon.


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