WASHINGTON — Mike Auldridge, a bluegrass musician whose broad knowledge of many musical forms helped redefine and modernize the steel guitar known as the Dobro, died Saturday at his home in Silver Spring, Md., a day before his 74th birthday.
He had prostate cancer, said a daughter, Michele.
Mr. Auldridge was a founding member of the Washington-based bluegrass group the Seldom Scene and, in a career spanning six decades, he recorded with Linda Ronstadt, Lyle Lovett, and Emmylou Harris, among others.
He was renowned for his mastery of the Dobro, a guitar with a metal resonator instead of a sound hole. The Dobro, a trademarked name for a resophonic guitar, is held flat and played with a slide over the strings. Unlike other types of steel guitars, it does not rely on electric amplification. The resonator functions as an amplifier and gives the instrument a distinctively warm tone.
Although the instrument was popular in bluegrass music — Dobro player Josh Graves was a featured soloist in the group Flatt and Scruggs — Nashville musicians regarded its sound as clunky and archaic.
Mr. Auldridge’s work in bluegrass helped change that perception as he borrowed ideas from other musical idioms, including blues, jazz, and rock, and helped design and pioneer a model of the instrument with eight strings instead of the usual six.
‘‘He phrased differently,’’ Jerry Douglas, a Dobro player with Alison Krauss & Union Station, said of Mr. Auldridge in a 2011 Washington Post interview. ‘‘He was the first guy to use the Dobro in a more modern way, to phrase it more like a saxophone or some other instrument.’’
In 1971, Mr. Auldridge formed the Seldom Scene with banjoist Ben Eldridge, guitarist John Starling, and two former members of the Country Gentlemen: mandolin player John Duffey and bassist Tom Gray.
The name Seldom Scene was an inside joke, reflecting the fact that all the members were working day jobs. Mr. Auldridge was a graphic artist for the old Washington Star newspaper.
‘‘We initially had three restrictions on what we would do with the Seldom Scene,’’ recalled Gray, the bass player. ‘‘We would only play one night a week, festivals on the weekends, and would only record when we were ready. We would not tour; we would not have a band vehicle. It worked well for those of us who had to keep our day jobs.’’
With a style often described as ‘‘newgrass,’’ the group broadened the standard bluegrass repertoire with selections from contemporary folk singer-songwriters Bob Dylan and Steve Goodman, rockers such as Eric Clapton, and the group’s songwriter, Starling.
‘‘We liked James Taylor as much as we liked Ralph Stanley,’’ Mr. Auldridge once said. ‘‘And we attracted an audience of like-minded people. We were contemporary and urban. We weren’t singing about mother and log cabins because that’s not where we came from.’’
He recorded several solo albums. ‘‘Blues and Bluegrass’’ (1974) featured guest appearances by Ronstadt and guitarist Lowell George of Little Feat, and included Mr. Auldridge’s instrumental interpretation of ‘‘Killing Me Softly,’’ a song popularized by Roberta Flack.
Mr. Auldridge’s ‘‘Eight String Swing’’ (1981) featured such swing standards as ‘‘Stompin’ at the Savoy’’ and ‘‘Caravan’’ performed with bluegrass instrumentation.
Michael Dennis Auldridge was born in Washington and grew up in Kensington, Md. He received a bachelor’s degree from the University of Maryland.
His uncle, Ellsworth Cozzens, a steel guitarist who performed in the 1920s with country singer Jimmie Rodgers, inspired Mr. Auldridge’s interest in music. Mr. Auldridge started out on guitar and later banjo before taking up the resophonic guitar.
As teenagers, Mr. Auldridge and his older brother Dave, a guitarist and mandolinist, formed a bluegrass group, the South Mountain Boys. Michael Auldridge first recorded in 1969 with the group Emerson and Waldron and the New Shades of Grass.
In the mid-1990s, when the Seldom Scene’s leader, Duffey, decided to limit the group’s touring, Mr. Auldridge formed another group, Chesapeake, with bassist T. Michael Coleman and guitarist Moondi Klein — then members of the Seldom Scene — and mandolinist Jimmy Gaudreau. Mr. Auldridge left the Seldom Scene in 1996, although he sometimes performed in reunion shows.
This year, Mr. Auldridge completed a trio album with fellow Dobro players Douglas and Rob Ickes.
He leaves his wife of 51 years, Elise Fox Auldridge of Silver Spring, Md.; two daughters, Michele of Madison, Wis., and Laura of Malibu, Calif.; two brothers, Gene of South Carolina and steel guitarist Thomas of Wheaton, Md.; and one granddaughter.