Every Surge XT LFO has a built-in 6-stage DAHDSR envelope that shapes modulation depth over note lifetime

Each LFO in Surge XT includes a DAHDSR (Delay, Attack, Hold, Decay, Sustain, Release) envelope that multiplies the LFO waveform output. This means you can set a vibrato LFO to fade in slowly (long attack) rather than applying immediately — matching how a performer adds vibrato after a note’s initial attack. When the LFO shape is set to Envelope, the LFO outputs a constant 1 and the DAHDSR completely defines the modulation shape; the system then behaves as a pure dedicated envelope generator. The LFO envelope can be disabled entirely from its right-click menu. All six DAHDSR stages can be tempo-synced. This design means fewer dedicated modules are needed — each LFO slot can simultaneously be a wave modulator with a shaped onset.

Examples

Set LFO 1 shape to Sine, Attack to 500ms, Sustain to full — vibrato will fade in over half a second after each note is played, just as a string player adds it.

Assessment

What would you hear differently if you set LFO Attack to 0 vs. 1000ms when modulating pitch? What happens to the modulation output if you set LFO shape to Envelope?