FREQUENCY SHIFTER 39A

Frequency shifters add an exotic dimension to the world of modular synthesis signal processing.

A basic definition of the Frequency Shifter process:
A Frequency Shifter takes the individual frequency components of the input signal and shifts them by the same number of Hertz, producing a subtle or dramatic effect on the tonal character of the sound.
Unlike a Pitch Shifter, The frequency components are translated rather than transposed.
Harmonic relationships are not preserved as harmonic overtones become inharmonic partials.

Mp3 demos:
S.A.R.S..mp3 441k
An example of voice processing with the FS.
Radio discussion of a disease that has put Toronto on the map.The up and down shifted signals are panned left and right in the stereo field.

Kneel Jung.mp3 1094k
Folky turns Alien. Up and downshift panned left and right.

barberpole.mp3
If the output is patched to a mixer and then feedback to the input and mixed with the source signal, barber pole phaser type sounds with apparent 'perpetual rising' effect
are possible.

Frequency Shifter in use:
Small amounts of shift can be used to produce phasing/chorus effects or alien/chipmunk voices.

Large shifts will impart a metallic or clangorous quality to the signal. Spectral inversion is possible with large negative shifts. The frequency shifting process generates simultaneous up shifted and downshifted versions of the
input signal. Both outputs are available at separate jacks (SUM and DIFF) on the front panel.

Shifting through-zero hertz reverses the function of the outputs making up shift become downshift and vice-versa.
With both outputs panned left and right unusual stereo image effects are also possible.

The Modcan Frequency Shifter 39a features:

Low-distortion wide-range through -zero quadrature oscillator design capable of very stable large or small shifts.

Companding is provided on both outputs for low-noise operation with minimal carrier feed through.
This is a high performance alternative to the squelch approach found in vintage units.

Carefully-selected components and trimming are used to maximize opposite-sideband rejection.

Large graduated shift knob for precision control.

Input
The input signal level is adjusted using the panel control attenuator.

1V/Oct Input
When in EXPO mode the 1V/Octave can be used to
track a keyboard. Interesting results can be had by tuning and tracking an un pitched sound source like pink noise.

mp3 example:
Tuned noise.mp3 547k
Pink noise 'tuned' by the FS

CV Input
Control Voltage input with panel attenuator
for CV modulation of the shift amount.

Response Switch
Select between Exponential or Linear response.
This is a global function that affects the response of
the main shift knob control and the cv inputs.

Sum and Difference Outputs:
Outputs for up and down shifted signal

Specifications:
+/- 5kHz knob shift range (greater with CV)
Output impedance: 1k ohms
Control Sens:
1 Volt per Octave (Expo mode)
1 V per 1kHz (Linear Mode)

Frequency Shifter electronic design by Michael Irwin