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Why did the invention of the triode vacuum tube matter for electronic instruments?

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Moog synthesizer — electronic instrument Moog electronic sound synthesizer

The invention of the triode vacuum tube in 1906 by Lee De Forest was a pivotal development for electronic instruments because it provided developers with the ability to design circuits that could generate and manipulate sound in new ways.1

Specifically, the triode allowed for the creation of two essential types of circuits:
* Oscillators: These circuits could produce repetitive waveforms, serving as the fundamental sound source for early electronic instruments.1
* Amplifiers: These circuits could strengthen and articulate waveforms that had already been produced, enabling performers to modify the quality and intensity of the tone.1

By adding a control grid between the cathode and anode of existing vacuum tubes, the triode enabled small variations in grid potential to modulate larger currents, making it a critical component for amplification. This technology laid the groundwork for a wide range of instruments developed between the World Wars, including the theremin, the ondes martenot, and the Hammond organ, as well as electric versions of traditional instruments like the electric guitar.231