Thirteen years is an eternity in club years — it's closer to two eternities, in fact. Yet there must be a reason DJ Sep's Dub Mission party has survived for more than a decade in its Sunday night Elbo Room residency. Perhaps it's Sep and her rotating resident selectas' total devotion to dub music in all forms — including roots, dubstep, and experimental variants. Possibly it's the world-class international talent she's brought in over the years. Or maybe it has to do with the effect prolonged exposure to echo, reverb, and bass has on making repeat customers.