Authoring a pad
A pad is a slow, sustained bed of sound that fills the space behind a track. It swells in, holds, and evolves while you keep the chord down. A pad is mostly movement, so this build leans hardest on the modulation steps.
Voice
Set Voice to Poly so the notes of a chord ring together. A pad is almost always played as held chords, and they need to sound at once.
Oscillator
Use a Wavetable. Its WT Pos can be moved over time, which is what lets the tone evolve as the chord is held, and that evolution is the heart of a good pad. Add wide Unison with a healthy Detune, and push the Curve out so the copies spread to the edges of the stereo image for a broad, enveloping sound. Granular is a more textural alternative when you want a cloudier, less defined bed.
Turn Note Bloom Rate up. This sets how long a held note takes to gain harmonic richness, and it drives the Bloom modulation source described below, so a held chord grows brighter the longer you hold it.
Filter
Use a low-pass filter with low Reso, and keep the Cutoff partly closed so the pad stays warm rather than harsh. Softness is the point of a pad. The brightness should come slowly from movement, not sit there from the start.
Amp envelope
This envelope defines a pad. Use a slow Attack so the sound swells in rather than starting abruptly, a high Sustain so it holds at full while the chord is down, and a long Release so chords overlap and bloom into one another as you change them.
Movement
A pad lives or dies on its movement.
Route a slow LFO to WT Pos so the timbre drifts as the chord holds. Use the Sine shape for a smooth, regular drift, or the Chaos shape for motion that never repeats. Chaos is the better choice for a long pad, because a regular cycle starts to sound looped once a chord is held for many seconds, and Chaos never lands in the same place twice.
For a longer evolving contour, draw an MSEG and set it to loop. To make the sound grow as you hold a chord, use the Bloom source. Use the Chord source so denser, more dissonant chords read brighter than simple ones, which lets the pad respond to what you play. A Fade in modulation on the cutoff opens the sound slowly after each chord starts.
Effects
Reverb is essential to a pad. Turn Long on for a large tail that stretches past the note, and turn Shim up for the shimmer octave that lifts the tail and gives pads their sense of height. Chorus widens the sound further. A Phaser in Organic mode adds slow motion that, like Chaos, never quite repeats.