Sample & Hold (S&H) is a function or module in modular synthesizers that captures the value of an input signal at a specific moment in time and holds (or maintains) that value for a certain period. The sampling of the input signal is usually triggered by an external control signal, often a clock or gate signal.
In a typical Sample & Hold module, there are two main inputs: the signal input and the trigger input. The signal input can be any continuous voltage signal, such as a noise source, LFO, or an output from another module. The trigger input is connected to a clock or gate signal that defines when the input signal’s value should be sampled.
When the Sample & Hold module receives a trigger, it samples the voltage level present at the signal input at that exact moment and holds that value at its output until the next trigger occurs. The held value can then be used to modulate other parameters in the modular synthesizer, creating a variety of effects and behaviors.
Sample & Hold modules are commonly used in modular synthesis for several purposes:
- Generating random voltages: When the input signal is connected to a noise source, the Sample & Hold can generate random voltage values at each trigger, creating unpredictable modulations or random pitch sequences.
- Quantized modulation: By connecting the output of a Sample & Hold module to a quantizer, you can create stepped, quantized modulation patterns that conform to specific scales or intervals.
- Clock division or synchronization: Sample & Hold can be used to sample rhythmic patterns or clock signals at a slower rate, effectively creating clock divisions or synchronizing different parts of a patch to a common timing source.