Robert Randolph

Dispatch and O.A.R. will present an evening of jam music and roots rock when the two coheadline July 22 at Hayden Homes Amphitheater, the Old Mill District announced Wednesday. The Robert Randolph Band, led by acclaimed pedal steel guitarist Randolph, will play in support.

The online-only presale starts at noon Wednesday and ends at 10 p.m. Dec. 9 at bendconcerts.com, with the password “local,” according to the release. General ticket sales open at 10 a.m. Dec. 10 at either bendconcerts.com or in person at the Ticket Mill in the Old Mill District.