A software instrument is a plugin or a DAW-built-in instrument that receives MIDI performance data and generates sound on the computer. It plays pianos, strings, drums, synthesizers, and more, using methods such as playing back recorded samples, synthesizing sound, or physical modeling.
Turning MIDI into sound
A MIDI note contains only instructions such as pitch, length, and velocity. A software instrument interprets those instructions and outputs the audio signal you actually hear. The same MIDI phrase can be played as piano, bass, synth, or drums by changing the instrument or the preset.
Main methods
A sampler assigns recorded instrument sounds to notes and plays them back. A synthesizer creates sound with oscillators, filters, and so on. Physical modeling calculates and reproduces the behavior of strings, pipes, and keys. Tone, controls, and CPU load differ by method.
Start from presets
At first, choose a preset close to what you want and adjust a small number of items such as level, octave, attack, and filter; that makes the changes easier to follow. Before settling on a tone, it is also important to sort out the MIDI phrase, the tempo, and the part’s role alongside the other tracks.
Choosing between instruments and audio
With a software instrument, you can change the performance and the tone later by editing the MIDI. Recorded vocals, guitars, and audio loops, on the other hand, are handled as waveforms. When you want to cut CPU load or lock in a tone, you can bounce an instrument track to audio.
Playing and programming
You can record a performance from a MIDI keyboard, or enter notes in the piano roll. Since response to velocity and controllers and the note mapping of drums differ by instrument, check the manual and the note names. A practical example is introduced in How to build a drum track with Drummer in Logic Pro (Japanese).
