Care and Maintenance of a Marimba
Care and maintenance of the resonator pipes

Metal resonator pipes are affixed beneath the tone plates. Typically, tone plates and resonator pipes are tuned so that they project sound the best when the temperature of the room in which the instrument is being played is 23°C. Thus, if the temperature of the room differs from this, the resonator pipes will need to be tuned.
If the temperature of the room has risen, then the pitches of the tone plates will be lower; however, those of the resonator pipes will be higher. In such cases, lowering the pitches of the resonator pipes will create better resonating.

With resonator pipes, the pitch lowers as the opening of the pipe is brought closer to the tone plates; correspondingly, taking the pipes farther away from the tone plates raises the pipes' pitch. The resonator pipe receptacle on the side of the lower-note tone pipes can be used to change the height of the gap between the pipe and the tone plates to adjust the position of the pipes. In other terms, when the temperature of the room is high, you should set the resonator pipes in a high position nearer to the tone plates, and when the temperature is lower, you should set them in a lower position, away from the tone plates.

Have you ever had the experience of thinking the sound is somehow strange, peeping inside the resonator pipes, and seeing something like a ping-pong ball or eraser stuck inside? Each resonator pipe has a length based on its corresponding tone plate; if something is trapped inside, it will effectively shorten the space inside, changing the sound. The resonators will also not amplify sound well if dust is accumulated inside. From time to time, flip the pipes over and clean out the inside!