With the X4 Quad Envelope / VCA, Flame presents a fourfold, morphable envelope, including VCAs optimized for audio signals. The time range, loop on/off and mode are set for all four envelopes using the toggle switch. In Mode you can choose between Attack/Decay, Attack/Release and pure VCA. In the first two modes, the envelope contour can be controlled via CV, whereas the VCA mode ignores the envelopes and requires an external CV signal. The clou of the X-4 are the morphable envelopes; with only one slider the contour can be changed steplessly between attack and decay or release.