- So called DOME filter to perform sine/cosine transformation (Hilbert Transformation, see R.Dome, B. Hutchings, JHaible)
- Two precision multiplier for sin / cosine (AD633)
- Mixer for two audio signals, balance pot from ring-modulation to Single Side-band Suppression = Frequency shifting.
For work you need a quadrature VCO. A Doepfer A110-4 is perfect it produce sine and cosine wave, or a state variable filter is also possible (s/cosine at LP/HP).
The RMO knob allows continues shift between ring-modulation (only one multiplier) to single side band suppression. You can create interest sound in between and enables you to tune exact SSB balance for your signal. The input mixer allows you to insert a digital delay for delayed shifts. Simply use a patch cord from second out to input to get a special kind of phasing. It is a variation of so called „Barber pole“ phasing.
Modulations VCO: For up or down shifts the phase must be inverted. Doepfer’s A110-4 produces sine/cosine and shifts phase with LFrq pot. Modulation for LinFrq and XFM for extraordinary shift sounds get possible. Basic design of A110-4 was intended to use in FS – systems (H. Wamlsley).
Hint: I changed VCO to LFO mode as Doepfer describes on his side, but us 1nF. That is perfect, because we need higher frequencies too.
Module need 10hp and 50mm depth.
Manual and LFO up-down shifts
90 degree phase shift of a sine wave with Dome filter network.
Phase shifting network is a precise double 6-stage band pass filter with matched parts to get shifts over 12 octaves.
With very low modulation and a feedback strip form 2nd output to 2nd input get interesting „phasing effects“ kind of „Barberpole phasing“:
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