Born in Sans Souci, Trinidad, Mannette as a young child developed a passion for metal and tools for metalworking, and would become engaged in the evolution of the phenomenon of sounding steel. At the age of 11, he was a member of Alexander's Ragtime Band created by Alexander Ford. From the middle of the 1930s, percussion bands of different quarters of Port-of-Spain were in competition with each other. Legend says that Mannette was the first person to use a discarded oil barrel to build a steel pan: "He sank the lid to create a tensed playing surface and fired the metal to improve the acoustic properties." From about 1939 to 1941, he performed with his own band, the Oval Boys (the name taken from the oval sports pavilion opposite the band's rehearsal space).