LEONA MITCHELL AT HOME IN L.A.

The nameplate on the directory of the North Hollywood condominium reads “Mitchell-Bush.” It neither stands out nor suggests that the occupants in this well-manicured, residential neighborhood live anything but a quiet, routine existence.

“The truth is,” says opera singer Leona Mitchell, “we are a normal family managing to go unnoticed here. Not many people know I actually live in Los Angeles”--when not on assignment at the Met, in Paris, Covent Garden or Vienna, etc.

But now, the secret is out. With the soprano set to sing the title role tonight in “Madama Butterfly”--the second offering of Music Center Opera in this inaugural season--she happily receives visitors “at home.”

Husband Elmer Bush III opens the door, holding 2-year-old Elmer Bush IV in his arms. A cleaning crew is just backing out of the luxurious apartment filled with Japonoiserie, mementos from Tokyo where she toured as Butterfly with the Royal Opera.

Mitchell, 37, moved to Los Angeles 13 years ago from Oklahoma City, where she grew up, to be near Ernest St. John (Jack) Metz, her longtime musical mentor.

“It was simply easier to live in the same city with him than commute endlessly,” says the diva, leaning against a mohair divan. “Now, things are a little different. Jack travels everywhere with me and we work on roles as the engagements come up.”

As a matter of fact, the Mitchell caravan always includes family as well. Her husband, she explains, not only tends to little Elmer (“and he’s very good at that job since he is experienced as an elementary schoolteacher”) but acts as her personal and financial manager, assuming all the contractual and scheduling responsibilities of his wife’s career.

There are family businesses and family businesses. This one happens to operate in the music world--so successfully that the Mitchell-Bushes keep another residence in Manhattan, a few blocks from the Met.

“There,” says the singer, “people recognize me on the street. In North Hollywood, who knows from opera? I shop Ralphs with complete anonymity.”

But two years ago it was a pregnant Mitchell who had to cancel the first “hometown” venture--the jointly sponsored Music Center-Royal Opera production of “Turandot” in which she was to sing Liu opposite Placido Domingo. She says she wouldn’t miss this second chance for anything.

So determined was she to take part in the premiere season of local productions at the Pavilion that the soprano is shuttling to New York in between her first and third Butterfly performances to sing a long-time commitment at the Met, the title role in “Manon Lescaut.” As a result, the Music Center Opera had to enlist an alternate, Young Mi Kim, for the middle “Butterfly.”

“But I’m not one of these globe-hoppers,” Mitchell hastens to add, explaining that this is a one-time exception. “Even if I approved of overcramming the calendar, it wouldn’t be possible for us. We insist on having a solid family life. That means staying together. That means taking it slow.”

What she has learned since becoming a mother, Mitchell says, is that most singers indulge themselves needlessly.

“Now, after a performance, I don’t sleep in the next day to rest my voice. And guess what? It’s not necessary. I get along just as well without the coddling.”

When she returned to the stage two months after baby Elmer was born, however, Mitchell set herself an enormous challenge: singing Aida for the first time at the Deutsche Oper Berlin.

“The role is extremely difficult even without adding obstacles,” she says. “But there I was, my stomach muscles not yet back to strength and worrying about the forgotten baby formula. Luckily a friend--a general--at the American Army base arranged to requisition what we needed.

“It was hardly the ideal way to make a debut, although the reviews were great.”

Now Mitchell says she is more secure than ever in her move from the lyric to dramatic category. But she likes to do the occasional Mimi “to keep the leggiero part of the voice active” and isn’t interested yet in taking on the Marschallin (in “Der Rosenkavalier”) “because I still have the B-flats and Cs and can put off roles with a lower tessitura.”

Besides “loving” the vocal challenge of Cio-Cio-San, the singer happily reports that the Music Center production (borrowed from Washington Opera), is conventional and doesn’t have her “pouring Post Toasties” a la plot-developed stagings that turn the geisha into a Westerner. As for the fact that both conductor Alexander Gibson and director Peter Ebert are British, Mitchell explains: “Opera is a friends-inviting-friends-business.”

At this point in her career she says she is “no longer thrilled when people ask if I’m Leontyne (Price) or Grace (Bumbry),” in reference to her black operatic sisters.

“I look forward to someone whispering and pointing, ‘There’s Leona.’ ”