I'm reading Nilsson's autobiography, La Nilsson, which (no surprise) is highly intelligent, tactful and gives away few secrets (how she produced that sound, for instance). She doesn't even mention the reason she didn't sing in the U.S. for five years, and she hardly seems to notice her besetting sin of penny-pinching, a standing joke among all her associates and friends. (A natural vice in a farmer's only child, eh?) She likes other singers and loathes singing teachers. Conductors come in half-and-half -- the more famous they are, the more she likes to cut them down to size. And she's still mad at John Culshaw for making the triangle sound more important than the soprano in the Ring.
I did not hear Nilsson till she was 50, and I always found the voice astonishing, its deployment thoughtful, but the sound itself harsh -- I wouldn't call her an ideal Isolde or Sieglinde or even Brunnhilde for that reason, much less Tosca or Amelia or the Marschallin. But she quotes reviews of her early performances in the late 40s and the 50s that marvel at the beauty as well as the size of the voice. (Or just the beauty -- Karl Bohm harrumphed, "She's a soubrette!" when he first heard her sing Wagner.)
But then she made no professional recordings till she was 40 (the Walkuere with Leinsdorf is heaven; she tells a naughty story about it, also her first Turandot recording with Leinsdorf, Tebaldi and Bjoerling -- whom she adored). The other day, on youtube, I found her singing Ozean du Ungeheuer in 1964, and the voice has a richer, fruitier sound than I associate with her.
So I wondered: do pirates exist of her performances before 1960? (she says someone sent her a list of pirated performances that went on for 27 pages -- "that didn't make me happy" -- but it makes ME happy -- and wherever she is, Valhalla no doubt, they don't have numbered accounts). I never hear about them, and I'd love to know what she sounded like in the early years when Wieland Wagner fell at her feet.