p1 is an organ/pipe organ/mechanical organ (keyboard musical instrument).
Although "tubnu" implies "pipe organ" (or more loosely, "mechanical organ", as defined by Wikipedia), "tu'urpi'o" may also informally be used to mean non-pipe organs. See also: mrupi'o, balpi'o, sa'irpi'o, cpupi'o, runpi'o, dicpi'o