Producer Bob Ezrin didn't want to work on Deep Purple's new album at first.

Ezrin -- who's known for his work with Alice Cooper, Pink Floyd and KISS -- said during Canadian Music Week in Toronto, "I wasn’t really thrilled with the idea because I didn’t want to be pegged as ‘the guy who does old people,’ so I said no."

But he changed his mind after going to see them perform in Toronto. "15 minutes into the show they went into this big, long, fully prog jam. Steve Morse stood up and played Rock God and played the most amazing guitar I’ve ever heard, and then Don Airey filled it with these huge keyboards and then the drums and the bass and everything came in and the whole audience went nuts, and then I realized we never see that anymore. That used to be a staple at every concert you went to when I was a kid. The only people doing that are like Dave Matthews and jam bands... This was rock power."

Ezrin had one stipulation when he met with the band. He told them, "If you want to be a contemporary rock band and be relevant, give up, forget it, it ain’t gonna happen and I’m not the right guy to produce it. No one will play this record on radio -- no one will care about it in the contemporary business, but I you want to make that record. If you want to make that unashamed musically brilliant record, I’m in."

Now What, Deep Purple's 19th studio album and first since 2005's Rapture of the Deep, will be out on April 30th.