"Easy Snappin'," recorded by Theophilus Beckford around 1959, is frequently cited by historians as a transitional record between Jamaican R&B/shuffle and the ska sound that would emerge within a year or two - one of the clearest audible steps in ska's formation.

The lacquer-coated disc a studio cuts one at a time, called soft wax because it wears out after a few dozen plays. It was meant as a test pressing on the way to a stamper; Jamaica made it a finished product instead. A dubplate is an acetate, and the whole economy of exclusive versions, specials and clash tunes rests on a format that was never supposed to leave the cutting room.

Late-1950s Kingston sound system remembered as the set where Percival "Sir Lord Comic" Wauchope worked first as a star dancer and then, from about 1959, as a toaster in the style pioneered by Count Machuki.

Adolphus Shawn founded Addies Hi-Fi in Crown Heights, Brooklyn in 1983. It became a central New York clash sound over the following two decades and a fixture of the international clash circuit.

Albert Malawi was a selector and vocalist for the Twelve Tribes sound Jah Love Muzik and a drummer in Augustus Pablo's circle, one of the figures linking sound-system practice to Rastafari organisation.

The iron-cored transformer that couples a valve amplifier to its speakers; in Jamaica the winding of these coils by hand, as King Tubby did to expand bass depth, became a signature electronics skill of the sound-system craft.

The heavy low-frequency loudspeaker at the heart of a bass bin, typically a fifteen-, eighteen- or twenty-one-inch cone, whose size and excursion the box is built around. Sound systems prize robust, high-excursion drivers.

A ported box loading that tunes a port to extend low frequencies, contrasted in sound-system practice with the horn-loaded scoop favoured for reggae weight. Used where a shallower, less horn-coloured bass was wanted.

A Greenwich Farm street cited in sound-system history as the location associated with Coxsone Dodd's early operations and West Kingston dance culture.

Hedley Jones's radio, electronics and record shop on King Street, Kingston; the amplifier Jones built in 1947 to play records outside the shop is credited as the first purpose-built sound-system amplifier in Jamaica.