The Yamaha CP70 is an electric grand piano (also known as the Yamaha CP-70), and was first introduced to the market in the mid-1970s with production ceasing in the mid-1980s. The CP80 was a further advancement and it included an extra octave of keys (the CP70 has a total of 73 keys). The CP70 was a descendant of the original Helpinstill idea to use a magnetic pickup to amplify an acoustic piano. The piano has real strings, hammers, wooden keys, and an internal baby grand piano frame. It was designed to be portable, and could be taken in two pieces. One piece would house the mechanical keys and hammers, and the other could be lifted off to contain just the strings and harp frame. This made for a true piano that was somewhat simple to transport, although it still required constant tuning.
The Yamaha CP70B model (also known as the Yamaha CP-70B) included several improved features such as balanced outputs (hence the B added to CP70) and included an improved preamp.