The marimba (/məˈrɪmbə/) is a percussion instrument consisting of a set of wooden bars struck with mallets to produce musical tones.Resonators attached to the bars amplify their sound.he range of the marimba has been gradually expanding, with companies like Marimba One adding notes up to F above the normal high C (C7) on their 5.5 octave instrument, or marimba tuners adding notes lower than the low C on the 5 octave C2.