The voltage threshold for triggering a Voltage-Controlled Oscillator (VCO) in Frequency Modulation (FM) synthesis can vary based on the specific design and specifications of the synthesizer or electronic circuit being used. However, there isn't a fixed or standard voltage threshold that universally applies to all VCOs in FM synthesis.
In FM synthesis, a modulating signal (often another oscillator or sound source) is used to modulate the frequency of the VCO. The depth and nature of this modulation can greatly affect the resulting sound. The modulating signal is typically applied to a control input of the VCO, which adjusts the VCO's frequency based on the input voltage.
To determine the voltage threshold for triggering a VCO in FM synthesis, you would typically refer to the documentation or specifications provided by the manufacturer of the synthesizer or electronic circuit. These specifications would detail the voltage range and characteristics of the control input that affect the frequency modulation.
In many cases, the voltage range might be expressed in terms of control voltage (CV) or another suitable voltage scale. It's important to follow the guidelines provided in the documentation to achieve the desired FM modulation effects while avoiding potential damage to the synthesizer's components.