Early electric piano recordings include Duke Ellington's in 1955 and Sun Ra's India as well as other tracks from the 1956 sessions included on his second album Super Sonic Jazz (a.k.a. Super Sonic Sounds). The popularity of the electric piano began to grow in the late 1950s after Ray Charles's 1959 hit record "What'd I Say", reaching its height during the 1970s, after which they were progressively displaced by more lightweight electronic pianos capable of piano-like sounds without the disadvantages of electric pianos' heavy weight and moving mechanical parts. Another factor driving their development and acceptance was the progressive electrification of popular music and the need for a portable keyboard instrument capable of high-volume amplification. Musicians adopted a number of types of domestic electric pianos for rock and pop use. This encouraged their manufacturers to modify them for stage use and then develop models primarily intended for stage use.
Digital electronic stage pianos that provide an emulated electric piano sound have largely supplanted the actual electro-mechanical instruments in the 2010s, due to the small size, low weight and versatility of digital instruments, which can produce a huge range of tones besides piano tones (e.g., emulations of Hammond organ sounds, synthesizer sounds, etc.). However, some performers still perform and record with vintage electric pianos. In 2009, Rhodes produced a new line of electro-mechanical pianos, known as the Rhodes Mark 7 followed by an offering from Vintage Vibe.
The Neo-Bechstein electric piano was built in 1929. The Vierlang-Forster electric piano was introduced in 1937. The RCA Storytone electric piano was built in 1939 in a joint venture between Story & Clark and RCA. The case was designed by John Vassos, the American industrial designer. It debuted at the 1939 World's Fair. The piano has normal strings and hammer action but no soundboard. The sound is amplified through electromagnetic pickups, circuitry and a speaker system, making it the world's first commercially available electric piano.
Many types were initially designed as a less-expensive alternative to an acoustic piano for home or school use. Some electric pianos were designed with multiple keyboards for use in school or college piano labs, so that teachers could simultaneously instruct a group of students using headphones.
"Electric piano" is a heterogeneous category encompassing several different instruments which vary in their sound-producing mechanisms and consequent timbral characters.