Clojurians Log v2

In https://github.com/overtone/overtone/wiki/Buffers-and-audio-files there is an example (defsynth sample-player [buf] (out 0 (play-buf 1 buf))) but when I try to execute it I get an error IllegalArgumentException: A synth requires either an even number of arguments in the form [control default]* i.e. [freq 440 amp 0.5] or a list of maps. You passed 1 args: [buf]. Are the docs out of date? Maybe I am missing something?