His death was announced online by the guitarist Steve Cropper, a longtime associate and fellow member of the instrumental quartet Booker T. and the MG’s, who said Mr. Dunn died in his sleep but did not specify a cause. Mr. Dunn and Mr. Cropper had been performing at the Tokyo Blue Note with a Stax Records alumni band.

As the resident bassist at Stax’s studio in Memphis for much of the 1960s, Mr. Dunn provided the solid, bluesy foundation for classic soul records like Wilson Pickett’s “In the Midnight Hour,” Sam & Dave’s “Hold On, I’m Coming,” Albert King’s “Born Under a Bad Sign” and a long string of hits by Otis Redding, with whom he and other Stax studio musicians also performed at the Monterey International Pop Festival in 1967.

Stax recordings were known for their raw, down-home soulfulness, a striking contrast to the urbane slickness of Stax’s friendly rival, Motown. Mr. Dunn’s playing was an essential element of the Stax sound.

Booker T. and the MG’s (the initials stood for Memphis Group), whose members — Mr. Dunn, Mr. Cropper, the drummer Al Jackson and the organist Booker T. Jones — were also the core of the Stax studio band, had a few memorable hit singles on its own, among them “Hip Hug-Her” and “Time Is Tight.” (Mr. Dunn did not play on the group’s first and biggest hit, “Green Onions,” which reached No. 3 on the Billboard chart in 1962; at the time he was a member of another instrumental ensemble, the Mar-Keys, which had a No. 3 hit of its own in 1961 with “Last Night.”) The group was unusual for the era in that it was racially integrated: Mr. Dunn and Mr. Cropper were white, Mr. Jones and Mr. Jackson were black.

After Booker T. and the MG’s disbanded in the early 1970s, Mr. Dunn remained active at Stax as a session musician and occasional producer. He also performed or recorded with a long list of well-known artists, including Eric Clapton, Bob Dylan, Levon Helm, John Fogerty and Crosby, Stills, Nash and Young. Reviewing a concert by Mr. Clapton in 1985, Robert Palmer of The New York Times praised Mr. Dunn as “perhaps rock’s most impeccably springy bassist” and said that his presence raised the band’s “level of playing all by itself.”

One of Mr. Dunn’s most high-profile sideman jobs was with the band that backed John Belushi and Dan Aykroyd in their incarnation as the Blues Brothers, playing a repertory that mixed Chicago-style electric blues with Stax-style R&B. The members of the band, who also included Mr. Cropper, had speaking as well as musical roles in the 1980 movie “The Blues Brothers” and were also in the belated sequel, “Blues Brothers 2000” (1998), which starred Mr. Aykroyd and John Goodman.

“Other than Booker’s band, that’s the most fun band I’ve ever been in,” Mr. Dunn told Vintage Guitar magazine in 2007.

Booker T. and the MG’s reunited periodically, although they were without a regular drummer after Mr. Jackson was fatally shot in 1975. Their later appearances included a tour as Neil Young’s backing band in 1993. The band was inducted into the Rock and Roll Hall of Fame in 1992 and received a lifetime achievement Grammy Award in 2007.

Donald Dunn was born in Memphis on Nov. 24, 1941, and acquired his nickname as a child. After Mr. Cropper, a childhood friend, began playing guitar, Mr. Dunn took up the electric bass — because, he liked to say, it had two fewer strings than a guitar — and the two were working around town while still in high school with the band that would become the Mar-Keys. He followed Mr. Cropper into the Stax studios and was a member of Booker T. and the MG’s by the mid-1960s.

Survivors include his wife, June; his son, Jeff; and a grandson….More at Duck Dunn, Bassist in Booker T. and the MG’s, Dies at 70