Think big bass. Think big beats. And then think of the disembodied voice of some prophesying Rasta, cut up and flayed by electronics, with shards of echo-laden and flanged percussion rattling around the sonic perimeter. Think Kingston, Jamaica, on a sweltering summer day. Think of a spliff the size of a Schwarzenegger cigar and its head-spinning effects.

You're getting close to the sound of dub–and to the feel of an afternoon at this year's 30th-anniversary edition of the Vancouver Folk Music Festival. For while banjos plunk away in leafy glades and winsome singers mourn Joe Hill, two of the world's deepest beatmakers will be shaking the earth just a couple of duck ponds away.

Within the framework of their chosen field, dub specialists Ryan Moore and Adrian Sherwood couldn't be more different. Moore's a traditionally minded minimalist, whose Twilight Circus Dub Soundsystem productions hew closely to the template set some 40 years ago in various low-tech Jamaican studios. In sharp contrast, Sherwood's recently released Becoming a Cliché includes brass bands, classical violin, and the voices of his two young daughters, in addition to the rhythms that have made him the remix artist of choice for acts as diverse as Megadeth, Shane MacGowan, and the Cure.

But both agree on this: dub has risen from humble origins to become one of the world's most influential musical idioms.

"That's a really strange twist of fate," offers Moore, calling from his Nijmegen, Netherlands, home. He explains that dub began as a cost-effective way of padding reggae singles. Rather than wax a second song, producers simply put an instrumental version of the original tune on the back of each would-be hit. "The whole idea just basically took off from that, from a simple vocal-less instrumental to a psychedelic, cut-up, fragmented sonic meltdown," says Moore.

"I always used to think it was a rip-off that they didn't have another song on the other side," says Sherwood, on the line from London. "They were a bit boring. But as the years went on, they got more and more adventurous."

Adventurous enough, in fact, that dub is the de facto precursor of rap and hip-hop in the United States, as well as various dance-music idioms–drum 'n' bass, jungle, dubstep, and grime–in the U.K.

"Right now, you can even put on Top 40 radio and hear dublike production tricks," says Moore, who attributes the spread of the genre's influence to the large Jamaican communities in London and New York. "If the music had just remained in Jamaica," he notes, "it would have remained completely obscure."

Sherwood also believes that the sonic strategies of reggae and dub, once considered almost insanely extreme, have come to flavour modern pop in a big way. "[Jamaican producer] Keith Hudson was making those mad records with completely vicious guitars with loads of delay on it and people like Big Youth screaming over the top, and they were so far ahead of the time they were alien to everybody's ears," he explains. "But if you listen to the frequencies of sub-bass and extreme treble that were present in the reggae stuff, now you get that kind of thing on pop records."

Pop may be attracting more listeners to dub, but both Sherwood and Moore were drawn to the style while it was still relatively unknown.

The Twilight Circus mastermind notes that he fell in love with dub largely because of its pared-down instrumentation: "It was like one of these things where the clouds parted and a beam of light shone down on me and a voice spoke, drenched in reverb, saying 'Ryan, this is your kind of music.' And I think it was because the genre tends to feature my two favourite instruments, which are drums and bass."

Sherwood is more blasé about his introduction to the form, which happened at around the same time. He'd been running a small reggae label and had a little spare cash, he says, so he decided he might as well take a turn at the controls.

"I paid the musicians, hired the studio, and made my first album when I was 19," he explains. "I called it Dub from Creation, and I called the band Creation Rebel, after the Burning Spear song. It just started off as a joke, but everyone said 'This is fantastic,' and it sold better than a lot of the tapes I released. So I started off by bluffing my way in."

Almost 30 years later, both remain committed to the style and to making sure its founders get their due. Twilight Circus Dub Soundsystem's recently released Rasta International features a host of veteran Jamaican singers, while Sherwood plans to follow Becoming a Cliché by resurrecting the career of the legendary Lee "Scratch" Perry, whose work under the Upsetter pseudonym remains a dub benchmark.

"I've got a new album that I made with Lee that's amazing," he says. "It's the best thing he's done in 25 years, to be honest. It's that good. So I'll be playing lots of new Upsetter, lots of new productions of my own, plus old ones, some new Jamaican tunes, a lot of black junglist dubstep–and even some old roots things as well, just to keep the elitists happy."

You don't need to be an elitist to get happy at Jericho Beach Park, however. Sun, sand, and DJ sets from these two sonic subversives should take care of that for all.

Adrian Sherwood and Twilight Circus Dub Soundsystem play the Vancouver Folk Music Festival on Saturday and Sunday (July 14 and 15).