Tuning bongo drums is a relatively simple process. You need a tuning wrench or ratchet, but one often comes with the set. The goal is to make sure the head stretches smoothly and uniformly, and you do this by gradually tightening lugs or screws around the head. Turn them in equal amounts until the desired tone is achieved, remembering that the smaller drum (macho) should have a higher pitch than the larger drum (hembra). A good rule of thumb is the two drums should be an octave apart, which you can test with a tuner.