A first subwoofer may be configured to output multimedia content in synchrony with at least one other playback device and a second subwoofer. The first subwoofer may, based on a received indication of an acoustic characteristic of the at least one other playback device, determine a crossover frequency of (i) the first subwoofer and the second subwoofer and (ii) the at least one other playback device. After determining the crossover frequency, the first subwoofer may output a first tone set and a second tone set in synchrony with the second subwoofer and the at least one other playback device, and after outputting the first tone set and the second tone set, receive, from a controller device, an indication of a selected one of the first tone set or the second tone set. Based on the selected tone set, the first subwoofer may adjust a phase setting of the first subwoofer.