And then there are 3: Parting from a quartet

When a string quartet loses a member after 30-some years, you might imagine the players having angst-filled discussions amid moody Rembrandt lighting, much like Christopher Walken and Philip Seymour Hoffman in the 2012 film A Late Quartet.

Real life, however, is more efficient.

Cellist David Finckel broke the news to his Emerson Quartet colleagues with an e-mail, framing it as a 60th-birthday reckoning that reminded him of all the music he wants to play while he still can. As impersonal as it sounds, string quartets have their own singular dynamics.

"I think everybody had time to digest the information at their own pace," said violinist Eugene Drucker. "When we're together we have the immediate pressure of concerts. We wouldn't have gotten any rehearsal done."

"They were shocked but not surprised," said Finckel, who already runs the Music@Menlo festival in California and the Chamber Music Society of Lincoln Center with his wife, pianist Wu Han.

Though not unusual among string quartets, personnel changes are delicate - and sometimes fatal. The Emersons, whose last Philadelphia concert with Finckel is Wednesday at the Kimmel Center - have been more stable than most, and found a replacement in short order.

But the 44-year-old Tokyo Quartet, rather than filling the chairs left behind by two departing members, will disband after the current season. Its local farewell is May 5 at the Independence Seaport Museum.

The St. Lawrence and Artemis quartets also experienced recent changes. The Borodin Quartet has had 10 since 1945. With 11 since its founding in 1946, the Juilliard Quartet almost has to be considered a franchise.

Lucky for the Philadelphia Chamber Music Society, which presents all six locally, the public trusts the various brands.

"We haven't seen a significant change in box office one way or another, which I think is a testament to the history of the ensembles, that they find new players that fit with the concept of the quartet," said artistic administrator Miles Cohen.

Signing up the new Emerson cellist, Paul Watkins, was a coup. Based in England, Watkins is a longtime member of the Nash Ensemble and has a side career as a conductor. What the Emersons didn't know is that he's married to a homesick American.

"I guess it was meant to be," said Finckel. "Now I almost feel guilty for having taken the seat for so long."

Not that musical chairs always works out. The Borodin Quartet's Mikhail Kopelman joined the Tokyo Quartet in 1996 (replacing disabled Peter Oundjian, now a world-famous conductor) with great expectations, but unhappily departed in 2002.

"It's like family. Sometimes you just can't work out the way you want to do something. It was a tense period," said Kopelman, who teaches at the Eastman School of Music in Rochester, N.Y.

Having survived that and gone on to greater visibility with Martin Beaver, the Tokyo Quartet had plenty of reasons to continue beyond the departures of longtime members Kazuhide Isomura and Kikuei Ikeda.

Not only do they play the "Paganini Strads" (four Stradivarius instruments once owned by Niccolo Paganini and now on loan from the Nippon Foundation), but they also record for Harmonia Mundi and have a longtime residency at Yale University. Given that concert fees aren't great - it's a soloist fee split four ways - such academic residencies offer health insurance, among other basics, and are the bedrock of any quartet's existence.

But upon fielding applicants for replacements, remaining members were caught on the horns of a dilemma.

"The name of the group has an ethnic connotation . . . . Should we limit ourselves to Japanese players? Should they be ethnically Japanese? Is this important or not?" said cellist Clive Greensmith. "If all four members are Western, what's that going to look like?"

The Colburn School in Los Angeles offered Beaver and Greensmith faculty posts and a diversity of chamber-music activities. They talk about forming a piano trio.

The remaining Emersons had to-be-or-not-to-be moments. They considered their quartet to be uniquely defined by its individuals. "If one person left, it would be hard for us to imagine going on," said Drucker. "But . . . it's hard to imagine not having this in our lives anymore."

Therein lies the temperamental difference between Finckel and the others: Finckel can't imagine relearning the entire repertoire with a new member. The others are excited at the prospect.

"It will definitely change us," says Drucker. "But we're willing and ready to be changed."