English: Original description: "Taken at Ginza Sony Building". This is one of the earliest tape recorders by Tokyo Tsushin Kogyo, abbreviated to Totsuko. In 1958 the company will assume the brand name Sony [1][2]. The unit shown here was produced earlier, since 1951. It is a valve single-head (no erase head) portable model for professional field recording (an early densuke). The transport is "powered" by hand-cranking the spring; the valve circuit is powered by two batteries. The M-series continued into the early 1960s, employing the same transport and the same shape and layout but eventually switching to transistors [3].