"A Eurorack in your DOM"

A set of components for generating synthesizer patches, similar to a modular synth. Each "tile" in the synth will automatically connect output to the parent element, all the way up to a <audio-out> tag that represents the AudioContext destination. For example, this code will generate a filtered A note:

<audio-out>
  <fx-filter type="bandpass" frequency="440">
    <source-osc frequency="220" type="triangle"></source-osc>
  </fx-filter>
</audio-out>

In addition to mapping output through audio inputs and outputs, you can also assign a signal to a node's AudioParams using slots. This code will modulate the filter frequency by 50Hz every second:

<fx-filter frequency=200>
  <fx-gain gain=50 slot=frequency>
    <source-osc frequency=1></source-osc>
  </fx-gain>
</fx-filter>

All tiles can send a copy of their output to an aux bus by using the send attribute, and the audio can be returned to a different part of the signal graph through an <aux-return> element. This lets you create effect chains and wet/dry mixes. For example, here's a synth with a chorus effect applied:

<!-- original output -->
<source-monosynth send="chorus"></source-monosynth>
<fx-delay time=".01">
  <!-- signal return -->
  <aux-return bus="chorus"></aux-return>
  <!-- LFO tweaking the delay time -->
  <fx-gain slot="delayTime" gain=".01">
    <source-osc frequency="2"></source-osc>
  </fx-gain>
</fx-delay>

Tiles are generally named according to their roles with a prefix: source- elements produce signals, fx- elements mutate signals, and midi- elements are keyed from MIDI messages in some way.

Primitive tiles

These tiles generally host a WebAudio signal node directly.

<audio-out>

AudioNode type: AudioContext.destination

AudioParam slots:

• None

Attributes:

• None

This tag is used to provide an output sink, so it will typically be the outermost element in your synth patch.

<fx-delay>

AudioNode type: DelayNode

AudioParam slots:

• delayTime

Attributes:

• time - controls the delay time in seconds

Delays a signal by a certain amount. Can also be used to set up feedback loops, which will otherwise be muted by the WebAudio API if they don't contain a DelayNode.

<fx-filter>

AudioNode type: BiquadFilterNode

AudioParam slots:

• frequency
• Q

Attributes:

• frequency
• q
• type - selects between allowed filter types (lowpass, highpass, bandpass, notch, lowshelf, highshelf, peaking, and allpass)

Applies a frequency-domain filter to its inputs.

<fx-gain>

AudioNode type: GainNode

AudioParam slots:

• gain

Attributes:

• gain

Amplifies a signal by a given amount. This can be applied to audio, but also to control values. For example, you might put an oscillator inside a gain tile to scale its numerical range for manipulating an AudioParam.

<source-noise>

AudioNode type: AudioBufferSourceNode

AudioParam slots:

• None

Attributes:

• None

Plays a looped noise sample. Each element creates its own noise buffer, so they can be layered without chorusing.

<source-osc>

AudioNode type: OscillatorNode

AudioParam slots:

• frequency
• detune

Attributes:

• waveform - selects a wave type (sine, square, triangle, or sawtooth)
• frequency

Emits a regular audio signal, suitable for subtractive synthesis.

MIDI tiles

These tiles listen to any connected MIDI controllers, providing the ability to trigger parts of the synth from a keyboard. As such, they're intended only as "control voltage" sources, usually hooked into an AudioParam by being slotted into another element. All MIDI elements support a midichannel attribute for selecting a specific message channel.

<midi-vca>

Attributes:

• midichannel
• midicontroller - Select the specific CC id to listen on.
• min - Minimum output value (when the raw CC value is 0)
• max - Maximum output value (when the raw CC value is 127)
• value - Starting output value

This element listens for Control Change messages and outputs a corresponding value. It's useful for setting a knob to tune a synth parameter.

<midi-pitchbend>

Attributes:

• midichannel
• range - specifies how large the output range should be on either side of zero

This element listens for Pitch Wheel Change messages and outputs a corresponding value. By default its range is ±90, for when slotted into an oscillator's detune AudioParam.

<midi-note-frequency>

Attributes:

• midichannel

This element emits the frequency value corresponding the last pressed Note On message as a constant signal. You can use this to patch into the frequency AudioParam slot of an oscillator tile if you're building a synth voice manually instead of using the synth-voice element (see below).

Complex tiles

These units provide more complex functionality, often internally chaining together several AudioNodes, to provide common synth functionality.

<midi-adsr>

Attributes:

• midichannel
• initial - Starting amplitude
• attack - Attack time in seconds
• peak - Amplitude at the end of the attack phase
• decay - Decay time in seconds
• sustain - Amplitude at the end of the decay phase and during note hold
• release - Release time in seconds

This element listeners for MIDI Note On and Note Off messages and emits a control voltage following an ADSR envelope in response.

<midi-envelope>

Attributes:

• Same as asdr-tile

Like an ADSR tile, but with a GainNode integrated into it, so that it automatically controls the volume of its inputs in response to MIDI.

<source-monosynth>

Attributes:

• All attributes from midi-adsr
• waveform - same as on source-osc

Like an envelope tile, but integrates an OscillatorNode. If you just want to make noises when a MIDI key is pressed, this is an easy way to hook that up in a single tag.