Today, we will talk about control voltages in modular and analog synthesizers. Generally, three different types of voltages are used in analog synthesizers: CV (Control Voltage), Gate, and Trigger. MIDI, on the other hand, is a term used for digital signals.
MIDI stands for Musical Instrument Digital Interface and is found in many electronic devices today. However, MIDI alone may not be sufficient to directly control analog synthesizers. Therefore, there are standalone or module-format converters that convert MIDI to CV or CV to MIDI. MIDI typically includes data such as pitch, velocity, and clock. MIDI to CV or CV to MIDI converters integrate digital and analog systems, enabling them to work together seamlessly.
In Eurorack systems, since the power supply operates between +12v and -12v, the CV voltage range in the system is generally maximum +12v and -12v.
First, let's consider the Gate signal. When you press a key on a keyboard, the output that sends the corresponding on/off data and the voltage from this output is called Gate. Typically, when not pressing the key, it sends 0v, and when pressed, it sends a steady 5v voltage. As long as you hold down the key, it continues to send a steady DC voltage. When playing a melody, the lengths of rhythms and notes are controlled by this voltage. In some systems, especially in additive systems, the Gate signal can range between 0 to +8v or 0 to +10v.
The Trigger signal is similar to the Gate signal but serves different functions. When you press a key, it sends an instantaneous data, but does not send timing information when you release the key. It sends a short Trigger signal for a very brief moment when you press the key to initiate an action. The Trigger signal is typically 5v, 8v, or 10v and is commonly used for clock signals or drum modules.
The CV (Control Voltage) signal typically ranges between +8v and -8v, but sometimes can be higher, such as +5v, -5v, or even 8v. Oscillators are usually calibrated with CVs in a manner called 1V/octave, meaning each volt corresponds to one octave or 12 notes. Most oscillators can be easily tuned within a range of 5 octaves. However, while oscillators can accept higher voltages, they may not produce musically meaningful sounds beyond a certain level.
All these types of CVs generally operate between 0 and positive (+), but in some cases, they can also operate between 0 and negative (-). Envelopes typically operate between 0 and positive (+). LFOs (Low Frequency Oscillators) or some oscillators typically operate between positive and negative (+/-). There is variability in these different DC oscillators or LFOs.
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