Surviving founding members of Jefferson Airplane paid tribute to Signe Anderson, the band’s original female vocalist, after news came that she had died Thursday at age 74, the same day that former bandmate Paul Kantner passed away.

Anderson, who sang on the band’s 1966 debut LP “Jefferson Airplane Takes Off,” died Thursday in Beaverton, Ore., of a heart condition, according to a report Sunday by Psychedelic Sight. Kantner also died Thursday in a San Francisco hospital from multiple organ failure and septic shock. He also was 74.

“One sweet lady has passed on. I imagine that she and Paul woke up in heaven and said ‘Hey what are you doing here? Let’s start a band’ and no sooner then said Spencer was there joining in!,” Jefferson Airplane cofounder Marty Balin wrote on Facebook, referring to the band’s late drummer Spencer Dryden. “Heartfelt thoughts to all their family and loved ones.”

The psychedelic-rock group Jefferson Airplane helped define the San Francisco sound in the 1960s with songs such as “Somebody to Love.”

Jefferson Airplane was inducted into the Rock & Roll Hall of Fame in 1996, and this spring, the band is to receive a Grammy award for lifetime achievement.

Anderson was born Signe Toly in Seattle and raised in Portland. The folk singer was asked to join Jefferson Airplane in 1965 by Balin following a San Francisco performance, according to Rolling Stone.

Married to Merry Prankster Jerry Anderson, Anderson performed her best-known song, “Chauffer Blues,” on Jefferson Airplane’s debut album.

But as Jefferson Airplane was ascending, Anderson gave birth to her first child and realized that life on the road with a newborn wouldn’t work so she decided to part ways with the band.

She helped the group search for her replacement, Grace Slick. Anderson’s final Jefferson Airplane performance was Oct. 15, 1966 at San Francisco’s Fillmore. The following night, Slick made her debut.

Anderson returned to Portland and sang in bands in Oregon over the years. She also made occasional guest appearances with versions of Jefferson Starship.

Airplane bassist Jack Casady wrote on Facebook that he’d been in touch with Anderson this past week when she moved from her home to a hospice. “She was a real sweetheart with a terrific contralto voice coming from a solid folk background,” he recalled, according to Psychedelic Sight.

Lead guitarist Jorma Kaukonen wrote on his blog: “Signe was one of the strongest people I have ever met. She was our den mother in the early days of the Airplane … a voice of reason on more occasions than one … an important member of our dysfunctional little family.”

Martha Ross provides celebrity commentary for the Bay Area News Group. Follow her at twitter.com/marthajross.