Diamond Marimba


Photo by Will Gullette





Wild Flower, by Cris Forster

Cris Forster, Diamond Marimba
Benjamin Koscielak, Bass Marimba





The Harbor, by Cris Forster

Heidi Forster, Glassdance
Jacob Richards, Diamond Marimba
Benjamin Koscielak, Bass Marimba




Dream Time, by Cris Forster
Jacob Richards, Diamond Marimba






Built:  ..... 1989, San Francisco, California.
Modified: ..... 2008, 2010, San Francisco, California.
Dimensions: ..... Total number of bars: 54.
Longest bar length: 16¾ in.
Shortest bar length: 7.0 in.
Height to first row: 33.0 in.
Height to last row: 39¼ in.
Materials: ..... Honduras rosewood, birch, teak, Delrin, cast acrylic,
aluminum, brass, and stainless steel.
Range: ..... Lowest bar: G below middle C.
Highest bar: Third E above high C.
Tuning: ..... Just Intonation.


          Diamond Marimba II has fourteen rows of Honduras rosewood bars mounted on a terraced platform. Beginning with the second row, each succeeding row rises a half inch above the previous row, so that the difference in height between the first and the last row equals 6½ in. Each bar is equipped with a tuned acrylic tube resonator that amplifies the frequency of the bar.

          The marimba’s central section consists of a diamond-shaped lattice that includes seven ascending and seven descending diagonal rows of bars. Each row includes seven bars. Rows that ascend from left to right sound major tonalities, and rows that descend from left to right sound minor tonalities.

          From my book Musical Mathematics: On the Art and Science of Acoustic Instruments (see M.M. Pages > Musical Mathematics), below please find Figure 12.5, which illustrates the frequency ratios of Diamond Marimba I and Diamond Marimba II. The tunings of the fundamental frequencies of both Diamond Marimbas are identical.





(See also M.M. Pages > Meyer’s Diamond, > Partch’s Diamond, > Forster’s Diamond.)