September 07, 2018

The ShaperPhaser

The waveshaper is a 'wavefolder'-type waveshaper, that in its simplest form with a pure sinewave as input creates a odd harmonics spectrum similar to 'through zero'-type linear FM modulation, but always follows the input pitch exactly and can never go out of tune, also the waveform will always stay the same. In essence it is comparable with a wavetable containing multiple cycles of a sinewave and where the input signal is used as an 'index' to read values around the centerpoint of the table. But as this is a pure analog module an array of diodes and opamps is used to 'create' the table. The carrier signal is 0Hz so it is not present.

The input is a bipolar VCA. The modulation depth depends on the level of the input signal. This can be controlled by the bipolar VCA or when the SHAPER IN input receives a signal directly from a OscHRM VCA OUT it can be set by the VCA in the oscillator.

The bipolar VCA can also double as a ringmodulator when controlled by a bipolar CV signal, no matter when at LFO or at audio rate. If no signal is connected to the VCA MOD CV input then it fades between no signal and full level. The VCA MOD control knob fades between an input signal in the leftmost position to an unmodulated full output level in the rightmost position.

The output connector of the VCA is normalized to the input of the waveshaper, so if the waveshaper input is not connected it will get its input signal from the output of the VCA. This normalization allows the VCA to be used separately from the waveshaper or as the input level control for the waveshaper.

The SYMM knob is sort of a pre-shaper that will add even harmonics when a sinewave is used as input. It makes the input assymetric. Fully opened, this double sthe pitch which creates the second harmonic.

The OD knob adds overdrive distortion to the waveshaped sound, adding fuzzy sounding high harmonics to the sound, but it does not alter the modulation depth.

You can create very complex spectra when using the the VCA as ringmodulator on the input of the waveshaper with its pre-distort and fuzz options...

The switch routes to the left side of the MIX knob.

In its top position it receives the input signal to the VCA and the MIX knob crossfades between the VCA input and the shaper output. Used this way one can fade between an unaltered input signal and the waveshaped signal where the waveshaping depth is set by the VCA MOD knob and can be modulated by a CV signal on the VCA MOD CV input. One would normally want to route the output to the Filter/VCA module.

In the middle position the switch is off and the MIX acts like an output level control. One would have the switch in this position when using the VCA and waveshaper separately.

In the bottom position the MIX knob leftmost position gets its signal from the waveshaper input and this would be a dry/wet type of efx-mix. One would use this mode e.g. when the VCA and waveshaper are used independently and one would like to have a dry-wet mix control for the waveshaper only, or optionally when the bipolar VCA would be used as an enveloped VCA.

Here is the flowchart of the Shaper :

I was not able to upload the video of the Shaper at Novars Masterclass as I cannot compress it under 100Mo so here is the link : It includes technical information on how it was designed. Very interesting video.

For the Phaser I will only talk about a single Phaser, the DualPhaser is basically 2 Phasers with internal normalization for the inputs and outputs. If you really want to know more about it please let me know.

The Phaser a 8-stage phaser. It has a reasonably accurate 1V/Oct direct control input that can track the keyboard voltage.

Total control range is about 18 octaves. The Freq knob goes over the top 9 octaves of this range. Through the V/Oct and Modulation inputs you can go deeper, but you get into the LFO range and audible phasing effects would disappear.

It is however possible to use the phasing effect on LFO control signals in the 1Hz to 10Hz range by supplying the V/Oct with e.g. a fixed -5V control signal, which can create quite interesting LFO effects on e.g. drones. All inputs and outputs are DC coupled. Only the internal resonance is AC coupled, so resonance drops off below roughly 10Hz.

Additionally the phaser has a modulation input, also at 1V/Oct when the mode is set to sweep. The input is not normalized, in fact if no plug is connected the modulation level knobs receive a fixed voltage so a manual spread value can be set.

Audio input is maximum 12V peak/peak before clipping occurs and there is 6dB attenuation from input to output to enable resonance peaks without clipping. The Phaser can act as a distortion device, where you modulate the cutoff with the audio input.

The MOD input has three functions, determined by a three position toggle switch:
1. SWEEP MODE - Standard frequency sweep, like other phasers, where all peaks sweep up & down as a group.
2. SPREAD MODE - The upper peaks and the lower peaks are spread apart & pulled closer together and cross over each other. This produces vocal timbres/formants and all sorts of complex filter effects and sounds really wonderful.
3. HALF-SPREAD MODE - the upper peaks move further away & closer to the lower peaks and the lower peaks are not affected.

The MIX control is bi-polar which adds even more sonic possibilities. Set straight up at 12 O'Clock you get dry only, no phaser (bypass mode). Turn it clockwise and you increase the phaser mix, and the phased output is positive. The original signal is still present. Turn it counter-clockwise and you increase the phaser mix, but now the phased signal is inverted which sounds very different from positive phasing. The original signal is not present. It then may sounds a bit less louder at higher resonance settings.

The resonance control always provides positive (non-inverted) feedback, regardless if the mix control is set to positive or negative. If the resonance is fully turned, it can produce very nice percussive effects (pings).

There is no flowchart for the Phaser as it is basic and obvious.

Here is a video of the Phaser with great sounds and tips :

Thanks to Todd Barton for providing the picture of the module.

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