NEW YORK — One of hip-hop's greatest producers says he's come up with some classic material not just for the rap community, but for pop and R&B fans as well — and it's coming from Christina Aguilera.

Gang Starr's DJ Premier — who's worked with everyone from Notorious B.I.G. to Common, from Jay-Z to D'Angelo, from Nas to the LOX over his two-decade career — has been locked in the studio with Christina for months and he says watch out: The girl's singing better than ever.

"She's mad cool, man," Premo said last week. "She really represents true music and true singing. She can belt out notes. She has true lungs."

Premo's and Christina's first collaboration, "Ain't No Other Man," is already out, and finds both singer and producer trying out something new: soul.

"It' a jump off," he said. "So far, so good. We do it for the money and the sales but we don't focus on that: We focus on 'Can you feel it?' If you can't feel it, it ain't real. Bottom line! You should be able to judge for yourself if it's real, not 'cause it's crammed down your throat on radio. She took a risk and did a whole new style. I appreciate what she's doing, giving me a chance to rock."

Premo said there's a lot more soul to come on Aguilera's forthcoming album, Back to Basics, which is due in August.

"She described to me what she wanted out of the album," he said. "I'm good at tailoring my music to the description somebody wants. Jay-Z used to do that, like, 'I got a record called this, I want it to do this, then I want it to break down and do this and do this,' then I would bring him exactly what he described. She did the same thing. She gave me CDs of joints to listen to, like Al Green and Aretha Franklin. She wanted to shape the style around what I do. I'm from that era and I respect music, and it's always good to work with somebody else who respects music."

Another leading lady Premier will be working with soon is Amerie. She's currently in the lab constructing her next album. "She's funky, got a new style that's dope," Premier said. "I like all her harmonies, and she writes her own stuff."

However, hip-hop fans will be most excited to hear the producer's take on records he's made for Nas' upcoming LP, Hip-Hop is Dead ... The N (see "Nas Says Hip-Hop Is Dead — New Album Due In September").

"Oh yeah," Premier said. "It's on and poppin'. We're just cutting tracks, cutting tracks, cutting tracks. Whatever works, we keep. Whatever don't work, we don't keep. That's always been our formula. It's real fun with Nas. Just like a day hanging out, but a good joint comes out of it. We ain't never did a dud. Every one's been a banger."

Premier says that fans will be pleased at the level of Nas' focus.

"Nas knows what he has to do," Premier explained. "He knows it's a lot of, 'He's older,' or '[Can he still] do it?' or 'That's not my generation.' He knows what he gotta do. I told him, 'If you don't know, let me know. I'll make sure you stay guided,' 'cause I really am a fan of his and I wanna buy a Nas album.

"We always switch up the formula," Premier added. "Guru [Premier's MCing partner in Gang Starr] used to say we update our formula. Nas played me some joints that Salaam Remi [produced]. Tight! He's flowing like crazy. That inspired me to go in there and really hammer something out. I don't like nobody to outdo me on tracks — I'm inspired by other people that do hot tracks. If it's banging, I give it up. I don't care if Mickey Mouse did it."