Local musician Aaron Lipp is a weathered soul in a young man's body. His old-timey quartet, The Mount Pleasant String Band, embodies that feeling by combining traditional string-band instrumentation with fresh folk originality. Influenced by Appalachian bluegrass, the music is a whirling dervish of percussive string textures and bluesy melodic undertones. Saturday's concert includes a square dance, helmed by fabled caller Margaret Matthews. The band's lineup will consist of Lipp and Bobby Henrie on fiddle, guitarist Cap Cooke, Ben Haravitch on banjo — all sharing vocal duties — and Doug Henrie on upright bass. This show is the second of two evenings showcasing Lipp's various projects. Lipp's bluegrass-rockabilly troupe Aaron Lipp & The Slack Tones will play the night before.