Knobs

Knobs are the primary controls for adjusting values. They come in a few sizes, but the gestures are all the same:

Spinboxes

Spinboxes are used for selecting between lists of discrete numeric values, used primarily in the oscillator transpose controls.

Modulation Sources

Modulation slots are labels outlined with thin borders which represent a routable control signal.

Modulation Slots

Modulation slots are solid rectangles to the right of other parameters. They represent a modulation mapping between a modulation source and a parameter. The gestures are similar to those for the knobs.

Copy/Paste

These two buttons provide a straightforward, simple method of patch sharing. “copy patch” takes the current state of Cadmium and copies it to your system clipboard in a plain-text format, and “paste patch” loads the contents of your system clipboard as a patch. Since the patch format is plain text, you can easily share patches by pasting them into forum posts or messengers.

For the technically minded: Cadmium’s patch format is JSON, and can be freely edited. On load, Cadmium validates and clamps the parameter values, so don’t worry about parameters being out of range.

VPS (Vector Phase-Shaping)

The main course. The pièce de résistance.

Vector phase-shaping.

VPS is an extended and improved form of phase distortion which provides a flexible way to morph and warp the phase of oscillators. During development, we explored a number of different arrangements for VPS modulation and determined that audio-rate modulation provided the widest and most interesting variety of sounds.

Due to the fact that the phase-shaping is modulated at audio rate, there are timbral similarities to both phase modulation (PM) and frequency modulation (FM). However, unlike both PM and FM, the phases of the carrier and modulator oscillators have significant bearing on the synthesized timbre, and changes in phase can have dramatic effects.

To get a feel for VPS, we recommend you give the following a try:

1. Load Cadmium into your DAW of choice and loop some MIDI input.

   It will be easiest to get a feel for the next few steps while just playing a single note.

2. Load the “initialise” preset from the factory bank.

   The init patch has only one carrier oscillator active and moderate-to-mild VPS settings dialled in.

3. In the “osc1” panel, sweep through the “phase” knob.

4. In the “VPS” panel, now sweep through the phases of both X and Y oscillators in turn.

   The changes in sound and waveform are due to the phase offset between the two modulators and the carrier. Hence, modulating or automating these phase offsets is a great way to get variations.

5. In the “VPS” panel, gradually detune the X oscillator. Notice how, in addition to the expected sound of the detuned oscillator, the oscillator is also now gradually falling into and out of phase with the Y oscillator and the osc1 carrier, and as a result the phase offset is changing. Small detunes are a great way to build slowly drifting and morphing sounds, while heavy detunes are great for classic jungle-style basses.

6. In the “VPS” panel, transpose one of the modulator oscillators down one or two octaves for a thick, heavy bass sound. Transpose your MIDI input up an octave or two as necessary.

Shape

These parameters control the overall shape of the curve (that is, they affect both modulator oscillators). Their effect on a timbre may not always be obvious (or expected), so we recommend experimenting with them to see where they take you.

• span

  Controls the “completeness” of the curve.

  Higher values result in a more harmonically rich sound. Lower values result in a reduced magnitude of the modulators, and thus their effect on the sound will not be as pronounced.

• theta

  Phase offset of X relative to Y.

• smooth

  With many combinations of shaping parameters, the curve will become discontinuous – that is, it doesn’t start in the same place as it ends.

  While this adds some nice, bright harmonics, sometimes it can be too harsh, so this “smooth” control adds a short windowing to both axes which rounds off this sharp edge. Since it does change the shape of the curve slightly, it won’t always roll off the harmonics while leaving the sound perfectly intact, but in many cases works well.

Modulation Oscillators

These parameters control the shape and tuning of the individual modulator oscillators separately.

• span

  Phase multiplier.

  Higher values extend the phase of the modulator into additional sine wave cycles and hence add harmonics.

  Note that, since this parameter purposely allows for fractional cycles, it’s very easy to add sawtooth-like discontinuities (especially in conjunction with the below-mentioned phase parameter). These discontinuities add plenty of even and odd harmonics, but if you would prefer to attenuate them, please refer to the “smooth” parameter in the above shape section.

• oct | st | c

  Transpose in octaves, semitones, and cents (respectively).

  Especially for the modulator oscillators, transposition has a huge effect on the resulting sound. In addition to the expected result of detuning a modulator, it also causes the oscillator to fall in and out of phase relative to the other oscillators, and hence also has the effect of sweeping through the phase offset.

  To get a feel for this, load the “initialise” preset from the factory bank and detune either the X or Y oscillators just slightly by turning the cents knob and then play a note.

• phase

  Phase offset.

  Since phase plays such a big part in the shaping function applied to the carrier oscillators, sweeping through the phase offsets is an easy way to discover (sometimes extreme) timbral variations.

Carrier Oscillators

Cadmium has three sinusoid carrier oscillators each with independent VPS modulation.

In the tradition of phase distortion, the waveform is a cosine when phase is 0% (0 degrees), and therefore is a sine at 75% (270 degrees).

Filter

Cadmium’s filter is a multi-mode ladder with internal saturation. While it’s not based on any specific circuit, we did our best to give it a smooth character to complement the digital edge of the oscillators.

The following responses are available:

The standard filter controls are all present and accounted for, and all of them are modulatable at audio rate.

Voice Saturator

A simple soft-saturation with dc offset and one-sample feedback. Good for a little bit of extra dirt on the filter.

As mentioned on the signal flow diagram, this saturator is applied after the attack/decay/sustain phases of env1 and before the release phase. Hence, the amp envelope drives into the saturator harder in the attack, decay, and sustain phases, and the timbre of the saturation will stay constant through the sustain and release of the envelope.

Global Distortion

The global distortion is an asymmetric nonlinearity with several feedback paths for a spicier sound. Each stereo channel has two nonlinearities arranged in a push-pull topology.

During research and development, we narrowed down a few different variations of this algorithm and selected our two personal favourites:

Output

In Cadmium 1.0, env1 and velocity (linearly scaled) are hard-wired to the voice amplifier. This will be broken out into its own control with configurable modulation in later versions.

Voicing

Polyphony

Envelopes

These are standard ADSR envelopes with few surprises in store. They are loosely modelled after the behaviour of real analog envelopes but have been tweaked and calibrated as necessary.

One modulation source is provided per envelope.

LFOs

Despite the “Low” in “Low Frequency Oscillator”, Cadmium’s LFOs will happily sweep up into the kHz range. The LFO speeds can be controlled with two distinct modes: note and frequency (hz).

Host beat-sync mode is planned and in development.

There are several common controls between these modes:

The LFOs each provide three modulation sources: one each for sine, saw, and square.

Note Mode

In this mode, the LFO is just another audio-rate oscillator tuned to the note pitch. It’s particularly nice to use this mode for modulating the filter cutoff.

• oct | st | c

  Transpose in octaves, semitones, and cents (respectively).

  Try going up several octaves for tuned rate-reduction type effects!

Frequency Mode

This mode provides direct control over the frequency of the LFO.

• hz

  Frequency of the LFO in hertz.

  Goes from 0.01hz to 6kHz.