Call Frances-Marie Uitti a cellist if you want, but she’s more of an explorer. In her quest to map new sonic territories, she has acquired unusual instruments, invented new ones, and devised a strikingly alternative technique for playing the ordinary cello. Her assemblage of instruments, which she calls a “beastearium,” includes a Stroh cello that has one string and a Victrola-style amplifier horn, “wonderful for lyrical melodies from Mars,” she says in an e-mail. In Richmond, she’ll play three works for cello and electronics: “The Song of Songs” by Karen Tanaka, “San” by Du Yun and “Age of Aircraft” by Ken Ueno, which she describes as “a huge mass of sound with intricate colorings inside the monolith.” Also on the program is “Hommage à John Cage” by György Kurtág and Scelsi’s “Ygghur.” The concert will also feature guitarist Ayman Fanous playing improvisations with Uitti. Fanous, who lives in Washington, frequently brings musicians to town for programs that are off the map of the standard Richmond concert experience. Frances-Marie Uitti performs with Ayman Fanous on Saturday, April 13, at 7 p.m. at St. James’s Episcopal Church, 1205 W. Franklin St. Lecture at 5:30 p.m. 355-1779. Tickets are $10-15.