Idomeneo’s Voice : Opera: Former bassoonist Siegfried Jerusalem--a <i> Heldentenor </i> now--makes his L.A. debut tonight.

Even for the always curious world of opera, the career of Siegfried Jerusalem is an anomaly. Possibly the leading Heldentenor today, he didn’t begin serious voice training until he was 31. He was 37 before he finally forsook the security of the second bassoon post with Sergiu Celibidache and the Stuttgart Radio Orchestra for the uncertainties of the stage.

Consider further that the Lohengrin and Siegfried of both Bayreuth and the Metropolitan Opera made his stage debut in operetta and is an accomplished Mozartean and a busy lieder recitalist, and you begin to wonder whether we might not be talking about twins, at the very least.

Though already familiar to local audiences as both the Loge and Siegfried of the Met “Ring” broadcast this summer, Jerusalem makes his Los Angeles debut tonight in the title role of the new “Idomeneo” at Music Center Opera.

“I do nothing different,” Jerusalem says of his singing in such varied repertory. “It’s the same voice, the same technique. In Wagner, you have more play with the words, and Mozart is another kind of music, but I think that I am musician enough for both.”

In any case, Jerusalem is not entirely comfortable with the Heldentenor label. “I don’t like this word, this ‘hero tenor.’ What is a Heldentenor ?” he asks, more than a little rhetorically, as he proceeds to answer.

“You need a voice that’s strong enough to stand against the orchestra when it’s loud. But it also needs a good middle and a deep sound, like a baritone. If you don’t have that, you have to push too hard and that makes you tired when the high notes come.

“You also have to be able to sing as in lieder--it must be very clear,” Jersualem insists.

Lieder are the tie that binds much of Jerusalem’s conversation about how he approaches his roles vocally. It also dominates his schedule this season, with some 20 recitals, mainly of a Schumann/Richard Strauss program. He will also be doing concerts--”Das Lied von der Erde” and the Missa Solemnis--another “Idomeneo” in Nice, a new “Parsifal” in Hamburg, “Die Fledermaus” at the Met, and recording Mahler lieder for Virgin Classics and “Siegfried” for EMI.

This kind of variety seems natural in a career that began in serendipity and happy ignorance. Jerusalem’s instrumental work flourished from an early age, but he did not apply himself seriously to singing until he discovered a suitable teacher in Herta Kalcher, after he joined the Stuttgart Radio Orchestra in 1971.

Four years later, the orchestra was taping a production of “Der Zigeunerbaron” for German television, and the tenor did not show up. Jerusalem’s colleagues urged him to try the part, which he did to the director’s satisfaction.

Then the title role in a production of “Lohengrin” in Darmstadt opened up. “Everyone was telling me, ‘We need Heldentenors and you have this big voice.’ I didn’t know what was hard then, so in 14 days I learned Lohengrin.”

A noted Florestan himself, Jerusalem attended Music Center Opera’s “Fidelio,” which he viewed with much sympathy for the tenor but little for Gotz Friedrich’s staging. “It began well, but after a time it became boring. The ‘Leonore’ Overture seemed staged only to make the opera longer.”

Jerusalem has not worked with Frank Corsaro, director of the MCO “Idomeneo,” before, but other than mechanical problems, he says the rehearsals have been going well.

According to Jerusalem, Corsaro has connected the mythological father/son clash between Idomeneo and Idamante in the opera with the often stormy relationship between Leopold and Wolfgang Mozart. The link is made in mime during the overture, and recalled at the end.

“I play the Leopold part, very dark, very heavy,” says the tenor. “The winner is Wolfgang, with his music.”

This opera and this staging has given Jerusalem, 50, occasion to reflect on his own family, who usually travel with him.

“The other morning I played with my son, who is 5. I was remembering that when I was 5, I didn’t know my father, who was a prisoner of war in Russia.”

Finding time for his family and his extra-musical hobbies is important to Jerusalem. From here, he goes on vacation, including an eight-day cruise in the Fiji Islands, another eight days touring New Zealand in a mobile home, and a visit to the Great Barrier Reef to indulge his passion for scuba diving and photography.

Jerusalem believes that his late start may contribute to the longevity of his voice. He certainly is not contracting his operatic horizons. He sings his first Tristan at Bayreuth in 1993, and beyond that he plans a rare foray into the Italian repertory, with nothing less than Otello.

In the long term, he has little interest in staging opera, and conducting is so far proving a resistable temptation.

“As a musician, I know so many bad conductors and I don’t want to add to the number,” he laughs.