"It gives me shivers down my spine today," says Huw Williams, who runs Sheffield's Sinai Sound System. He's recalling his first exposure to Leeds' legendary Iration Steppas system in 2006. The venue was a community centre, with walls hung with pictures of the local cricket club and Black activists like Marcus Garvey. In those humble settings was something magical. "The bass was unbelievable—like nothing I'd ever heard in my life. We went up this wheelchair ramp and it was shaking my feet," he says.

Sound system culture has exploded from its roots in Jamaica into an international phenomenon and DIY movement, fuelled by the Afro-Caribbean diaspora. The system and the party culture it brings with it are indebted to 1940s Kingston, Jamaica. WWII brought an import of American popular dance music with the stationed US troops, and with that, Jamaicans began to build their own sound system scene, powered by big amps, to take the party wherever they wanted. "A lot of it [this practice] echoes of a colonial past," says Williams. "Sound systems were outside because in Jamaica, everything was outside." In the UK, the same approach took hold as it provided an escape from racial segregation, he says. "People [of colour] weren't let into the clubs."

Kebra Ethiopia, a South African sound system whose name means "glory to Africa," writes this story into the public mission for their work. "Reggae's roots stem from the historical conditions of both Jamaican slavery and colonialism by different nations," they write in a statement for the sound system. Reggae is a revolutionary tool for this global scene, they say, "a movement that concerns itself with community upliftment, socio-economic issues, ghetto living and spreading pan-African teachings."

As the Internet has improved accessibility for those wanting to build sound systems, the number of contemporary international crews has grown in turn. Each sound system is specific to a space and context by design, so there's no obvious starting point for those wanting to join in. Operating custom sound systems also demands just that kind of experimentation, error and sense of personal adventure. Resident Advisor spoke to a current generation of sound system leaders from a cross-section of different backgrounds about how they got involved, what makes their approach special and the advice they'd give to others. That included Huw of Sinai Sound System, Sheffield UK, Lekentle Mohlala of Kebra Ethiopia in KwaThema, Johannesburg SA, Sgt. Remo of King Remo Sound System, San Antonio, Texas USA, Ron Schleper of Anode Records who built a DIY system in St. Louis, MO, and Jesper Frederiksen of BQestia Soundsystem in Lima, Peru. They uniformly warned that advice still won't make your system sound like theirs. But that's the whole point.

Anatomy of a sound system

At its most basic, a sound system is defined as any custom-assembled set of PA components matched across different frequencies to produce a certain sonic character. There's no linear path through building a sound system. The best place to start is to understand what the terms mean and what components make up the speaker stack. Here's what to know:

Bass, Mid, Top: Speakers in a sound system are grouped by frequency range and handle different bands of sound. ("Top" is high-frequency.) Dedicated speakers of different sizes specialize in different ranges of sound.

Cabinet: The physical box that houses the driver is the speaker cabinet. This is the bit DIYers enjoy making out of wood themselves.

Crossover (x-over): Crossovers are electrical circuits that route components of the sound to particular speakers and filter out certain frequencies. (The crossover frequency is the cutoff point for the filter.) That way, you send bass sounds to large woofers, and high frequency speakers to smaller tweeters for the most precise, un-distorted sound. These can use passive circuits or active circuits, depending on the application.

Driver: Speaker drivers are the usually cone or bowl shaped diaphragms inside the speakers that convert electrical signals into sound. These are also the bits you'll see moving back and forth when you play loud sounds; they're what physically push the air to produce sound.

Full-range, tweeter, woofer: Full-range speaker drivers are intended to cover a broad range of what you can hear. Tweeters are specialized speaker drivers that handle higher-range frequencies; woofers produce lower frequencies; subwoofers produce lower frequencies still (the "subs").

Hofmann's Iron Law: Named for the founder of KLH, Advent and Acoustic Research, Hofmann's Iron Law is an essential rule that all sound system builders should know. The basic non-mathematical idea is this: with a given amount of power, your sound can be low, loud or have a small enclosure. You can pick two at once, but not all three. It could be small and efficient, or small and handle low-end, but it can’t be small and efficient and handle low-end.

Horn: Just like the bell of a brass instrument, the horn system is shaped to direct the sound. (A megaphone uses a horn in its design.) Horns can take different forms, but cone-shaped high frequency horns are the most common. Some bass speakers use an arcing "scoop" or a "folded" design. The aim is the same: the designs direct the sound laterally out of the speaker cabinet.

It would be a mistake to view a sound system as just the collection of speakers and equipment, of crossover frequencies and horns. "It has to do with chemistry more than entertainment," says Jesper. "The selector and the DJ are a big part of this chemical compound. Understanding this from a fan and a listener's perspective is part of the learning process that makes you a better sound system operator." But that's not to say sound system operators won't immediately get excited talking about speakers and technical details, too.

Thanks to the combination of components across the frequency spectrum, each system is customized to a unique perspective. "If two people were asked to go into the countryside and paint a picture of what we'd see, they'd look completely different, but they'd both be a picture of the same thing," explains Williams. "[The sound system] is someone's interpretation of how the audience should [hear sound.] It's art."

"My goal from the beginning was to get the most powerful, clean, compact sound for as little money as possible, and I'm extremely happy with the results I've achieved," says Jesper Frederiksen of BQestia Soundsystem in Lima, Peru. "My system is currently based on four Keystone subs loaded with RCF LF18x451, four classic HD15 kicks with RCF MB15N401 and six Orbit 4's top/monitors," he says. "It's a fully horn-loaded sound system that goes down to 35hz, and unlike more traditional speakers where the drivers radiate into free air, it's like all the drivers have their own kind of trumpet in front of them. In that way, you can reach high levels of sound with less stress on the drivers and the sound is more focused and directional. For example, the sub design is a three-meter folded tapped horn that by positioning the driver (1/4 of the wavelength of 35hz) in a clever way, uses the positive and negative movement from the driver in a synchronized way so it kind of works like there's two drivers in one box."

Williams mixes DIY and high-end aftermarket components. "I try to marry the two worlds together: expensive equipment with DIY boxes," he says. "I have a hand-built, wooden-looking sound system that sounds as good as a pro audio rig." That also means making trade-offs to ensure mobility, as Sinai Sound has toured all of Europe, from Berlin to Croatia. By leaving out the valves, his 40,000-watt speaker system weighs 25kg; the desk is a digital Soundcraft option to save still more weight. He describes the process of managing these tradeoffs with the attention to detail of a mission planner working on a rocket launch.

Starting your build

For all the shared knowledge and community approach, getting into running a sound system is naturally an expensive and technically challenging hobby. "There's so much to know," admits Williams. "Especially in the reggae world, there's a lot of gatekeeping."

The good news is that the spread of sound system culture has made equipment more available and the economics of getting started more realistic. There has also been a rise in DIY information online, which has led to a bumper crop of message boards and Facebook groups brimming with people eager to share knowledge. Two of the best places to start are speakerplans.com and freespeakerplans.com (separate sites with DIY instructions and discussion).

Williams recommends starting with used gear. Heavyweight vintage amps and mixing desks tend to drop in value and for anyone willing to haul them, savings await. "Because this has existed for decades, there's loads of second-hand equipment that's serviceable," Williams says. "Those big heavy amplifiers—those are perfect for people doing events locally. You can pick up second-hand amplifiers for a couple hundred pounds. That's how I started."

Most of all, trust your ears and don't be afraid to make mistakes. "Don't just go and buy stuff without hearing it," repeats Williams. "A lot of it is trying stuff out, trying it with my equipment. Beg, borrow, steal what you can. It's like a recipe."

Frederiksen notes that there are software solutions like Hornresp that can simulate speaker response, and on a purely aesthetic level, he uses SketchUp to simulate looks. "Make documents and write down all the information. That really helped me a lot," he says. "I suggest having a complete idea about what system you want in the end so you are sure that size and frequency response fit together. Otherwise, you might run into some nasty surprises where there's suddenly a gap in your frequency response or your kicks or tops are bigger than your subs."

Sound systems across genres

Music and talent programming matter, of course, but the sound systems themselves become elevated to stars alongside the people booked to play. Parties book systems the way they book music acts. Williams will go to events to hear sound systems—and even individual components—the way some promoters might scout artists or DJs. "I've even taken equipment to other people's events and taken it to their soundcheck. I've heard stories of people going to dances with tape measures. I talk to people literally all day about speakers."

Sound systems empower artists in a different way as well. "A lot of engineers tell DJs what not to do. I tell them, 'Do what you want,'" says Williams. "I've configured my sound system so DJs don't have to worry about it. You don't have to fight the system with compressors and limiters. You can run it loud and that's fine." CDJs are connected digitally with attenuated output, too, so running in the red isn't an issue.

Sound system culture might be associated with reggae music, but it's spread to genres like techno. Bass in reggae and bass in techno may not be directly comparable, but the approach holds—especially as techno fans care about big bass, too. "The crossover frequencies are determined by the speaker, cabinet, design, frequency range, etc.," says St. Louis sound system DIYer and techno artist Ron S of Anode Records. "For our system, the sub cabinets will cover from 30Hz to about 80 or 90 Hz, [depending] on the room size, shape, etc. We have a DSP processor that performs x-over, EQ, delay, and limiting. I adjust this during soundcheck to react with the space in the way that I want it to."

In Lima, Bquestia Sound System is built with an entirely genre-independent approach, able to handle bass music, but ready for disco and wedding hires, too. Frederiksen goes as far as saying the scene can't happen without the speakers. The sound is more important than the music, because on bad speakers I can't even enjoy my favourite music."

The payoff for the obsessive customization and investment of time and money is that the system fits your specific taste and needs. Just buying high-end components means everyone is the same, says Williams: "If you have the money, you'd have a turnkey system. If you buy a Funktion One, it's been pre-made for you," he says. "What the DIY setup allows you to do is turn it into a level of artistry."

Power and community

Proud as they are of their speaker stacks, sound system operators are quick to talk about the bigger picture: the party, the scene and the community. The music is conscious and accommodates all people. "Sessions are held in community streets, so that also encourages economic activity by offering market spaces for locals to sell their goods in the gathering," says Lekentle Mohlala. "The subject matter in the music and the socializing space both unlock conversations around pan-Africanism, communal living and African history."

"The way I see it," says Williams, "this idea behind what I do—the ecosystem of sound—is to create a coherent relationship between the sound system, the performer and the crowd. If you think of an amazing night, it's when all three of those work in concert."