Last month Neil Fraser, a k a Mad Professor, was playing a concert in the mountains of Brazil, about three hours outside São Paulo. He had brand-new material tailor-made for this audience, electronic "samba dub" remixes that hybridized indigenous Brazilian music with reggae, rhythm and blues, and other Caribbean flavors.

But for reasons he can't fully explain, Mad Professor started tinkering with "early stuff," mixes from his "Dub Me Crazy" series of the 1980s and his "Black Liberation Dub" of the '90s, with some of the songs he remixed for artists such as Massive Attack, Sade and the Orb thrown in for good measure.

"And the crowd went crazy," he chuckled, his satisfaction clear as a bell over the phone from Argentina.

On Monday night, Mad Professor will be in a place far different from that tropical mountainside — the tiny 7th Street Entry in downtown Minneapolis. But one thing won't change: Mad Professor's on-the-spot decision about what to play.

"You never know what mood I'm going to be in," he says.

Now 58, Mad Professor is renowned as one of the leaders of the second generation of dub music artists who followed in the footsteps of King Tubby and Lee "Scratch" Perry. The hallmarks of dub are spacey, stuttering electronic effects, beats and repetitions, either invented whole-cloth or applied to existing pieces of music in ways that can add a mere dash of color or texture or radically transform the entire enterprise. Mad Professor brought dub into the digital age, especially the editing, where layers of sound could be added but still differentiated, resulting in extraordinarily plush, ingenious and invigorating remixes atop the typical reggae and Caribbean musical template.

He was born in Guyana and acquired his moniker as a boy because of his fascination with electronics. He built his own radio from scratch before finishing elementary school, moving between the library and electronic parts stores. Such projects became easier when his family moved to England at the onset of his teens.

"I loved technology before I loved music. That's what led me to music," he says. It was a progression similar to that of his idol, dub pioneer King Tubby, who began as a radio repairman and got into music after fixing sound systems in Kingston, Jamaica. Mad Professor built a four-channel mixer, his first step toward a home studio. He got a job repairing amplifiers and circuit boards, and added echo and reverb to his home studio.

Eventually complaints from neighbors and his ever-sprawling collection of gadgetry compelled him to open up his own Ariwa Sounds studio in 1979, named after ariwo, the Yoruba word for communication. It wasn't long before he was putting his stamp on dozens of popular songs and remixes.

Dub is like the blues, in that it doesn't seem hard to learn. But as with the blues, there are signature styles, and Mad Professor has an arresting blend of warmth and complexity. The first trait comes from his early musical influences, which range from the classic calypso of Mighty Sparrow to the King Tubby remixes, vintage reggae, the lush soul of Holland-Dozier-Holland for Motown and the "Philly soul" of Thom Bell, Gamble and Huff, and British Invasion rock from the '60s and '70s.

The complexity stems from Mad Professor's passion to remain on the cutting edge of electronic technology.

"How do you get your own sound?" he says, repeating the question. "I don't think it ever stops. In the beginning, it was hard to get the sound I heard in my head. I had to learn about microphones, tape recorders, mixers. It keeps going. I [recently] spent five months rebuilding a part of my studio.

"A lot of times it is boredom. I have been traveling for a few weeks. I am thinking, 'When can I start working on my next album?' Because the system I use on the road is a miniature version of my home studio. And my studio is a total love affair for me."

At the Entry, he will have freshly minted copies of his "samba dub" material, his son, Joe Awira, on guitar, and maybe a keyboardist or a vocalist or two. Or maybe not. It depends on his mood.

"I have been doing this for so long that I can't do nothing but dubbing," he says. "I'd have to go and try and get a job with Apple or something if I didn't do this. But I still really like doing this."

Besides, it drives people crazy in the lush Brazilian mountains and the little Minneapolis clubs.