Mike Auldridge, a guitarist who became one of the most distinctive dobro players in the history of country and bluegrass music while widening its popularity among urban audiences, died on Saturday at his home in Silver Spring, Md. He was 73.

He had been treated for prostate cancer for about 10 years, his daughter Michele Auldridge, said.

As a founding member of the Seldom Scene, the Washington, D.C.-based “newgrass” band that fused bluegrass with elements of contemporary pop and jazz, Mr. Auldridge developed a refined, lyrical approach to playing the dobro.

A resophonic (or resonating) acoustic guitar, the dobro produces sound by means of one or more spun metal cones instead of a wooden sound board. (The instrument’s name is a contraction of Dopera and brothers. Dopera was the surname of the Slovak-American brothers who patented an early version of the instrument in 1928.)

Mr. Auldridge’s liquid, round-toned phrasing — a departure from the more clamorous style favored by previous generations of dobrists — proved more appealing to urban audiences and to pop and country-rock performers with broad musical tastes like Linda Ronstadt, Emmylou Harris and Lyle Lovett. Mr. Auldridge appeared on many of Mr. Lovett’s recordings.