Walking into Thymeless Bar and Grill at the north end of Toronto's Kensington Market, the first thing that hits you is heat, followed by bass. As with most DJ events, there's no central visual focus; you're as much a part of the vibe as everyone else in the room. In fact, you might even be name-checked in a deafening dubwise style as you walk in. You may even step right up to the mic and spit out a few greetings of your own. The rhythm, even if it's brand new, already sounds classic — it's all part of the intoxicating blend of community, familiarity and experimentation that makes SuperheavyReggae one of Toronto's finest sound system experiences.

The sound system is Jamaica's audio gift to the world, from which countless other DJ styles are descended. It is much more than a selector, their records, and a wall of speakers with lacerating highs and pulverising lows, it is an all-encompassing musical environment expertly manipulated by its selectors.

As described in Lloyd Bradley's reggae history, Bass Culture, the sound system was "the community's heartbeat… a social phenomenon around which Kingston's various inner cities turned." For many years — and this still happens occasionally — these systems contained just one turntable. There was also a hype man (called a deejay in Jamaica, not an MC) to keep the crowd's energy up. By the time the late '60s hit, Jamaica's sound system culture had developed into a state of the art performance. Each operator drew on the talents of DJs, singers, dancers and the calibre of the system itself to set himself apart. Sound systems are found everywhere in the reggae's worldwide diaspora, and Toronto has had its share. SuperheavyReggae's selectors Jeremiah and Friendlyness carry on in the tradition of sound system entertainment.

Jeremiah explains the general flow of the night. "We play modern roots, from the '90s to the present. The event structure is a classic dancehall program; we'll start up early with just some warm up jugglings." (Not the more complex "beat juggling" in hip-hop, just unadulterated spinning.) "Then the selector kicks up the tunes a notch and Friendly will greet the people as they arrive. Sometimes we have guests passing through and that's when we make way for more live performances with DJs and singers. About [midnight], Isax will start to improvise on [alto] sax and flute. We'll drop the A side and if he likes it, we'll flip it and he keeps going."

Isax is hands down the best reggae sax player in Canada and one of the very best in the world. He brings a selector's sensibility to his horn, with an intimate knowledge of the myriad rhythms offered up by the selectors, and combines them with the musical vocabulary of a seasoned improviser. Reggae hornsmen are fairly infrequent on sound systems; Jeremiah can offer up only one other example: Leroy the Hornsman, who appeared with Black Star and King Jammys systems during the '80s.

Each component of a SuperheavyReggae night is a combination of planning and spontaneity. With experience as a drum & bass MC, and as a lead vocalist for Canadian reggae veterans Truths and Rights, Friendlyness is the more technically involved of the two. "We have an SM58 microphone go through a digital delay pedal to give it that [early '80s] dancehall sound. It's not a stereo digital delay; we like it to sound dirty. We do a little fine-tuning on the milliseconds, the feedback and delay. Isax really likes the delay, but other vocalists like to hear themselves more clearly through the system."

The mic feeds into the DJ mixer, which is always controlled by one of the two selectors — in such a setup, with so many people taking turns on the mic, feedback can be instantaneous and brutally painful to the ears and to the vibe of the party. At the same time, the selector is choosing records, flipping them so that the DJ or instrumentalist can play over the B-side version. A selector may string many cuts on the same rhythm together into a seamless flow. Beat-mixing, which is the foundation for so many other DJ styles, is far less important in this context than a sense of drama; abrupt transitions and drop-outs just add to the vibe. To heighten the experience, Friendly is constantly modulating the EQ settings in a live, dubwise fashion to transform even the most popular rhythms into something new. By the end of the night, Isax is playing full-bore into clouds of delay while peaks and valleys of frequencies break like waves over the sound system — superheavy, indeed.

Gimmickry in the form of ear-piercing sirens or machine gun effects does not characterise a Superheavy set. Jerermiah opines, "I think the cornerstone of people creating a nice atmosphere is Friendly's DJing, having his spiritually uplifting chat on the microphone, whether it's greeting people or referencing a positive message in a song, it's all very positive. That's a real key."

The last word belongs to Friendlyness: "It's all through the grace of the most high, Jah Rastafari: he makes all things possible."