message: moving object creation to constructor body
  more consistent style
diff: @@ -49,7 +49,7 @@ export class Synth extends Monophonic<SynthOptions> {
  /**
  * The envelope
  */
  - readonly envelope: AmplitudeEnvelope = new AmplitudeEnvelope({ context: this.context });
  + readonly envelope: AmplitudeEnvelope;
  constructor(options?: RecursivePartial<SynthOptions>);
  constructor() {
  @@ -63,7 +63,9 @@ export class Synth extends Monophonic<SynthOptions> {
  this.frequency = this.oscillator.frequency;
  this.detune = this.oscillator.detune;
  - this.envelope.set(options.envelope);
  + this.envelope = new AmplitudeEnvelope(Object.assign({
  + context: this.context,
  + }, options.envelope));
  // connect the oscillators to the output
  this.oscillator.chain(this.envelope, this.output);
  