Fred Carlson, Alex De Grassi and Jeff Titus perform on The Humanitar at the Blitzer Gallery in Santa Cruz, CA, February 2014. Photo by Jim Mackenzie

The Humanitar is a fully acoustic, free-standing, 40-string baritone harp guitar. The body is constructed from recycled paper and aliphatic resin adhesive cast over a clay mold. The resulting shell is supported by an interior wooden framework, and painted with acrylic artists paints. The soundboard is 100-year-old German spruce. The body can be separated from the legs to be held/played in the lap like a traditional guitar. The Humanitar has 6 main strings (on the neck) with a 28-inch scale length, tuned a fourth or a fifth below standard guitar tuning range. On the bass side of the neck are 11 sympathetic harp strings tuned to pitches ranging from sub-bass up to notes in the range of the main strings. On the treble side of the neck are 11 harp strings running over a bridge that divides them at a ratio of 2:3; each string produces two notes. Plucked on the "upper side" of the bridge (toward the peghead) each string's pitch is a fifth lower than that string plucked "below" the bridge (over the body). This gives functionally 22 strings, which extend in pitch to over an octave above the note of the first main string. There is a fourth set of strings attached to the upper leg; these are most similar in character to a "bowed psaltry", and can be plucked or played with a bow. Main strings are classical guitar strings, bass and treble harp sections are mostly Chinese "Gu Zheng" (board zither, similar to Japanese Koto) strings with a few plain steel. Leg psaltry strings are plain steel.

Here's a little video of the debut public performance of The Humanitar featuring Alex De Grassi, Jeff Titus and Fred Carlson

At the R. Blitzer Gallery in Santa Cruz, Californiaduring the February, 2014 Art of Guitar Festival

(thanks to Andrew Revkin)