Door splits are pretty simple, I typically give the headliner 75% if there is only one opener, and 60% if there are two. Guarantees can be a bit more tricky. You’ll need to be pretty confident about a band’s past numbers in order to make sure you’re not left paying more than you earn at the door.
Filter sweeps are most commonly used in electronic music because it’s a popular effect that DJs rely on to impose a sense of ebb and flow on the crowd. It’s that underwater effect of gradually surfacing, or opening up, until the chorus finally hits. It can also be the exact opposite, where a producer will gradually close off a ton of the frequency content so it sounds like it’s getting smaller and smaller,