Uncheck box labelled '1' to hear carrier with no modulation. Check it again to turn on modulation. EnvelopeEditor - move points, or add new points to shape an oscillator's amplitude. Shift click a point to remove it. Normally set to 1.0.
Envelopes decay rapidly like a bell.
Vibrato frequency does not change with key pressed. Trumpet - You can hear output of Ops 1,2 and 3. Ops 2 and 3 provide slightly detuned harmonics.