Butch Vig was a top record producer in the U.S. underground when he got the call to co-produce and engineer Nevermind in 1991. He has since made three albums with his own alt-pop group, Garbage. But Vig says bands still ask him to produce their records, to make them "sound like Nirvana. I say, 'You want to sound like Nirvana? Write songs as good as Kurt Cobain.'"

You first recorded Nirvana in April 1990 at your studio, Smart, in Madison, Wisconsin, for what was supposed to be their second Sub Pop album.
Jonathan Poneman [of Sub Pop] called up and said, "This band can be bigger than the Beatles." I laughed.

He really said that?
Yeah. The van pulled up, they walked in. I had no preproduction. One of the first things Kurt said was, "We want to sound slower and heavier than Black Sabbath. Turn the treble off on all the tracks."

We recorded eight songs in six days. I mixed the tracks and sent them to Sub Pop. I think Kurt and Krist [Novoselic] had made cassettes and given them out to shitloads of people. All of a sudden, everyone I knew had copies of the sessions.

Five of those songs became Nevermind classics. Could you hear the leap in Kurt's writing from Bleach?
It was much more sophisticated. The melodies were gorgeous. In "In Bloom," the chorus is, "He's the one who likes all the pretty songs." "Pay to Play," which became "Stay Away," was closer to old-school punk but it was less one-dimensional than the stuff on Bleach.

"Polly" on Nevermind is the actual Smart demo. Why didn't you recut it?
I don't know that Kurt heard the song in any other way. He had this old, shitty five-string guitar that he never bothered to tune. It had these nylon strings, this plucky, ukulele sound. He was playing and singing so quietly that there was tons of tape hiss on the track. Being a nerdy engineer, I'm going, "Oh, shit." He was like, "No, that sounds good."

What was Kurt like as a bandleader?
He and Krist had a specific chemistry. Krist wrote a lot of the hooks, which came across on Nevermind. In a lot of the songs, the verses are just chords and melody. The riff is the bass hook. Kurt gave Krist a lot of latitude. I rarely heard him say, "I think you should change that riff."

The hardest thing was that Kurt would go through these mood swings. He would be really articulate and talk about what he wanted. Then, for no apparent reason — I could never tell what triggered it — he would just shut up. He would sit in the corner and not say anything. I'd say, "Do you want to do another take?" He wouldn't even look at me.