Spectra — pitched pinged resonator audio processor/multi-effect

In theory, the best way to describe Spectra is through comparison. At its heart and the genesis of the design was a filter resonator, in the style of the 4MS Multiband Resonator or the Meng Qi Wingie. Unlike other resonators I’ve tried, I took a novel approach with this one: instead of employing bandpass filters, it uses parametric multi-filters (bell filters) in series to produce the resonant peaks. Then, the output of the multi-filters is added to the inverted copy of the input, leaving only the differences between the two audio sources behind.

The filters can be pitched and spread across the spectrum; they are quantized to different scales as they do so, resulting in chords. This was my original intention, to produce plinky little chords from an audio input.

But I also found that the filters could also be used to produce some quite nasty distortion (in a good way; at least, to me). Because the filters are in series, as the Q is decreased, more and more frequencies fall under each filter’s bell curve. Gain cascades. I already had a compressor at the output, set up as a limiter, because the filters can get quite loud. When the Q is low, it acts as a wall, smashing all that cascading gain into a distortion. You can modulate between the two, which can produce some very satisfying sounds.

To this core, I added a “pre-delay” (really just a delay placed before the resonators) with feedback. At the output, I placed a reverb lite, to add air and ambience.

Each can be used together or separately to produce a wide variety of exotic sounds.

Audio is summed to mono before processing and output as a stereo signal via the reverb lite.

Pitch can be controlled by CV or by MIDI. There is a dedicated page for the MIDI inputs, if you are employing them, so you can change the channel to that which you prefer.

Multi-filters……. do not like being modulated. I’ve done my best to keep this patch from clipping, but I can’t guarantee that it will never clip under any circumstances.

Controls:

Moving from left to right, the first set of controls are for the delay. The delay is up to 1 second, so the decimal values should accurately represent the fraction of a second and correspond to milliseconds.

The delay has a feedback control, for determining the amount of regeneration.

The filter has controls for filter gain and Q. When everything is set to maximum, the filter produces the sharp pings originally intended. Adjusting the gain of the filter can soften the pings, and adjusting the Q can make them more rounded. As the Q decreases, distortion can be produced in the style mentioned above; filter gain acts as a gain control here, too, unsurprisingly, moderating how extreme the distortion gets.

The filter gain can also be used negatively. In this case, the filters -remove- frequencies from the signal path, and can be used as an interesting/weird EQ.

The most extensive section governs the quantization of the filters.

Pitch sets the base pitch of the filters when no CV or MIDI is employed. It also provides an offset to incoming CV or MIDI when they are present.

Spread covers the spread of the filters. The maximum spread is across five octaves. It is a bipolar spread, so the filters can be pitched down, as well, but this is probably only useful when the pitch is set high. This control interacts extensively with the filter gain and filter Q.

Key sets the key for the quantization. It is a rescaled value module, so its range is only one octave, A0 – G#1. If you set it to a note in that range, it will adjust the key of the quantizers accordingly. Anything above that range will be considered a G#.

There are five user buttons to select between different scales: Major, Minor, Major Pentatonic, Minor Pentatonic, and Fifths (octaves and fifths). I chose scales I thought would be useful for a lot of circumstances, but changing the scales is not terribly difficult. There is a page marked “Scale select.” On that patch is a CV in switch. Change the bias of the inputs in accordance with the CV values for different scales provided in the quantizer help file to use different scales than the default ones (and then, optionally, change the names of the UI buttons used to select the scales).

There are controls for the reverb mix and decay.

And controls for the wet and dry levels.

CV inputs:

CV 1: Pitch (0 to 10V) — used to control the base pitch of the oscillators (also controllable via MIDI)

CV 2: Spread (-5 to 5V) — with attenuverter located above input, used to control the spread of the quantized filter frequencies

CV 3: Q (-5 to 5V) — with attenuverter located above input, used to control filter Q/resonance

CV 4: Filter gain (-5 to 5V) — with attenuverter located above input, used to control filter gain

The MIDI mod wheel (CC1) is also routed to the inputs of these attenuverters, so when using MIDI, you can use the attenuverters to route the mod wheel to various destinations that may be useful to control.

The MIDI inputs are located on the second page of the patch, so you can set them to the appropriate channels.

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  • Category: Effect Synthesizer
  • Revision: 1.0
  • License: Creative Commons Attribution Share Alike 4.0
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  • Modified: 3 months ago
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One comments on “Spectra — pitched pinged resonator audio processor/multi-effect
  • Juan Abadi on said:

    Wow, sounds amazing (in text and in audio). Downloading it right now!

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