 Photo by Will Gullette |
| The Harbor Music by Cris Forster Heidi Forster, Glassdance Jacob Richards, Diamond Marimba Benjamin Koscielak, Bass Marimba |
| Wild Flower Music by Cris Forster Cris Forster, Diamond Marimba Benjamin Koscielak, Bass Marimba |
| Blue Nights Music by Cris Forster David Boyden, Bass Canon Heidi Forster, Glassdance Isabelle Jotterand, Just Keys Benjamin Koscielak, Bass Marimba |
| Started: | 1983, San Diego, California. | |
| Finished: | 1985–1986, San Francisco, California. | |
| Dimensions: | Total number of bars: 24. Longest bar length: 44.0 in. Shortest bar length: 19½ 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 bars. Birch, teak, mahogany, Delrin, Kydex, Formica, cast acrylic, aluminum, brass, and steel. HR-23 foam supports. | |
| Range: | From G1 (1/1) 49.0 cps to A3 (10/9) 217.8 cps. | |
| 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. So, I tuned the lowest bar to G1, G3, and G4. I developed this tuning technique because in low-sounding bars the higher modes of vibration are clearly audible. Regarding the tuning of cavity resonators and the higher modes of vibration of bars, see Creative Aspects > Instrument Design Features.
Despite its enormous size, this instrument requires only a screwdriver to assemble. Hand knobs hold all the large structural components together.