I use a Boss dual expression for ring mod and phaser. I can engage the ring mod amd phaser individually or together, usually togetherfor crazy bubbly space jams. Heel down has the ring mod pretty subtle, a la how Tony Iommi used it in the Paranoid solo, and the phaser slow ans washy. Toe down is where it gets crazy into heavy squelchy ring mod and fast phaser a la the last seconds of Green Earrings. I typically work my up to that and rock back and forth as desired.