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:  ..... 1978, San Francisco, California.
5-Bar Extension: ..... 1982, San Diego, California.
Rebuilt: ..... 1989, San Francisco, California.
Dimensions: ..... Total number of bars: 54.
Longest bar length: 16¾ in.
Shortest bar length: 7.0 in.
Height to first row: 34.0 in.
Height to last row: 40½ in.
Materials: ..... Honduras rosewood, birch, teak, acrylic,
delrin, aluminum, brass, and steel.
Range: ..... Lowest bar: G below middle C.
Highest bar: Third E above high C.
Tuning: ..... Just Intonation.


          The Diamond Marimba has fourteen rows of 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 my Diamond Marimba.




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