Bass Marimba


Photo by Will Gullette





The Harbor, by Cris Forster

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





Wild Flower, by Cris Forster

Cris Forster, Diamond Marimba
Benjamin Koscielak, Bass Marimba




Blue Nights, by Cris Forster

David Boyden, Bass Canon
Heidi Forster, Glassdance
Isabelle Jotterand, Just Keys
Benjamin Koscielak, Bass Marimba






Started: ..... 1983, San Diego, California.
Finished: ..... 19851986, San Francisco, California.
Dimensions: ..... Total number of bars: 24.
Longest bar length: 44.0 in.
Shortest bar length: 19 in.
Length of stand: 145.0 in.
Height of stand: 40.0 in.
Width of stand at wheels: 44.0 in.
Height to bars: 36.0 in.
Materials: ..... Honduras rosewood, birch, teak, mahogany, Delrin, Kydex,
Formica, cast acrylic, aluminum, brass, and steel.
Range: ..... Lowest bar: Third G below middle C.
Highest bar: A below middle C.
Tuning: ..... Just Intonation.


          The Bass Marimba is by far the largest and most powerful instrument I have built. It is over 12 feet long, and all of the 24 exceptionally large bars are made of Honduras rosewood.

          This instrument has 19 standard wavelength resonators and 5 cavity resonators. The reason for the cavity resonators is that extremely low frequencies require extremely long tubes, which in turn would require a high stand for the instrument and a high riser for the musician to stand on.

          In all 24 bars on the Bass Marimba, I tuned the first three modes of vibration to produce exact harmonic ratios 1:4:8 in each bar. Therefore, above the fundamental or first mode of vibration, the second mode sounds the interval of the double-octave, frequency ratio 4/1; and the third mode sounds the interval of the triple-octave, frequency ratio 8/1. I developed this tuning technique because in low-sounding bars the higher modes of vibration are clearly audible.

          Despite its enormous size, this instrument requires only a screwdriver to assemble. Hand knobs hold all the large structural components together. (See also Creative Aspects > Instrument Design Features.)