“Octal: Book One” is Sharp’s second solo recording for Clean Feed. The first was his all-acoustic take on Thelonious Monk. This time around, however, he tackles his own compositions and plays them on a custom-made electroacoustic “guitarbass,” which is a hollow-bodied electric guitar with two extra bass strings. Sharp has long worked with solid-bodied, double-necked guitar-basses, most notably in his noise-rich group Carbon. This new instrument is certainly more manageable than the earlier two-headed monsters, but its real advantage, and the one the Sharp exploits notably on this recording, is its acoustic qualities. He combines the acoustic and electric qualities of the Saul Koll guitar by placing one microphone close its sound hole, processing its built-in acoustic pickups, and running its magnetic pickup into a small amplifier and putting a microphone near that too. The result is a rich sound environment in which Sharp’s every snap, tap, pluck, wiggle, drone, and ebow activation feels completely organic. The eight notated, but spontaneously interpreted, Sharp originals on “Octal: Book One” sing as though they are alive.