tone/Tone/instrument/AMSynth.ts

import { AudioToGain } from "../signal/AudioToGain.js";
import { RecursivePartial } from "../core/util/Interface.js";
import { optionsFromArguments } from "../core/util/Defaults.js";
import { ModulationSynth, ModulationSynthOptions } from "./ModulationSynth.js";

export type AMSynthOptions = ModulationSynthOptions;

/**
 * AMSynth uses the output of one Tone.Synth to modulate the
 * amplitude of another Tone.Synth. The harmonicity (the ratio between
 * the two signals) affects the timbre of the output signal greatly.
 * Read more about Amplitude Modulation Synthesis on
 * [SoundOnSound](https://web.archive.org/web/20160404103653/http://www.soundonsound.com:80/sos/mar00/articles/synthsecrets.htm).
 *
 * @example
 * const synth = new Tone.AMSynth().toDestination();
 * synth.triggerAttackRelease("C4", "4n");
 *
 * @category Instrument
 */
export class AMSynth extends ModulationSynth<AMSynthOptions> {
	readonly name: string = "AMSynth";

	/**
	 * Scale the oscillator from -1,1 to 0-1
	 */
	private _modulationScale: AudioToGain;

	constructor(options?: RecursivePartial<AMSynthOptions>);
	constructor() {
		super(optionsFromArguments(AMSynth.getDefaults(), arguments));

		this._modulationScale = new AudioToGain({
			context: this.context,
		});

		// control the two voices frequency
		this.frequency.connect(this._carrier.frequency);
		this.frequency.chain(this.harmonicity, this._modulator.frequency);
		this.detune.fan(this._carrier.detune, this._modulator.detune);
		this._modulator.chain(this._modulationScale, this._modulationNode.gain);
		this._carrier.chain(this._modulationNode, this.output);
	}

	dispose(): this {
		super.dispose();
		this._modulationScale.dispose();
		return this;
	}
}