How a Marimba is Made
Tuning the tone plates

Tuning the tone plates is one of the most crucial processes during the wider process of manufacturing a marimba. With a marimba, the undersides of the tone plates are sanded down, matching higher notes to lower notes. It is all over if the pieces are sanded down too much and the notes are lower than prescribed. There are no do-overs. Each piece of wood has considerable variations. With rosewood, for instance, less intense color means a higher note, while deeper coloring means a lower note. Adjustments must also be made based on the grain. Because the shape and amount sanded off will differ, a sander is used on the tone plate, and then the sound is checked periodically with a tuner throughout the tuning process.

The tuning of a tone plate is performed carefully while checking both the fundamental tone and the harmonics. Using a mallet, the fundamental tone can be checked by striking the center, and the fourth harmonic can be checked by striking around 1/4 the way from the end. If the note differs horizontally across the tone plate, then the note will not sound clean. Thus, adjustments are made based on the degree of sanding in this respect, as well.