TDK

TDK Corporation (ティーディーケー株式会社) was founded on 7 December 1935 in Tokyo by the engineer Kenzo Saito as Tokyo Denki Kagaku Kogyo K.K. (東京電気化学工業, “Tokyo Electrical and Chemical Industry”); the TDK initials come straight out of that name (T-okyo D-enki K-agaku). The company was set up specifically to commercialise ferrite, the iron-oxide magnetic material that Yogoro Kato and Takeshi Takei had invented in 1930 at the Tokyo Institute of Technology. By 1945 TDK had produced five million ferrite cores, most of them for radio receivers used by the Imperial Japanese Army. From 1966 the company entered the audio-cassette market; in late 2007 the American firm Imation Corporation bought TDK’s recording-media business for $300 million, and TDK-branded cassettes continued in limited release under the TDK Life on Record name for several more years. TDK Corporation itself continues as a manufacturer of electronic components, with its head office in the Nihonbashi area of Chuo, Tokyo.

TDK was the first commercial ferrite manufacturer in the world - the material that, from the 1930s through the 1950s, came to underpin the transformer cores, chokes, antennas and magnetic media of essentially every radio-electronics product of the twentieth century. That technical base shifted into magnetic-tape production from 1966, when TDK became one of the earliest Japanese makers to enter the Philips compact-cassette format. The SD (Super Dynamic) line was TDK’s first mainstream high-quality music cassette. The SA (Super Avilyn) series, launched in 1975, was TDK’s own answer to Type II: chromium dioxide was both expensive and patent-encumbered, so TDK formulated a cobalt-doped iron oxide called Avilyn, which then became the working model for most of the Type II tapes the industry shipped from that point onward. The MA (Metal Audio) line opened in 1979 to address the Type IV metal format. Its high-end variant MA-XG Fermo, released in 1990 at ¥2,000 per 60-minute cassette, used a five-piece hand-built shell - a composite-resin pair of halves wrapped in a three-part metal frame, with every cassette assembled and inspected by hand.

TDK’s Showa-era cassette catalogue ran on three axes: D and AD on the Type I normal-bias side; SA and SA-X for Type II on the in-house Avilyn cobalt-doped iron-oxide formulation; and MA, MA-X, MA-XG, MA-R and MA-XG Fermo for the top-tier Type IV metal position. The MA shell carried a signature engineering feature from the start - a metal module inside the cassette body to damp transport vibration. By the late 1980s TDK was a major player in the “over-engineering battle” of Japanese cassette makers: the MA-R flagship of 1979 came in a chassis ringed by an aluminium frame, and the MA-XG Fermo of 1990 was advertised as one of the most expensive volume-production cassettes the Japanese market had ever seen - ¥2,000 for sixty minutes (roughly $19 at the time), promoted on hand assembly and individual inspection of each unit. From 1997 onward TDK gradually wound down cassette production, and the December 2007 Imation deal took the TDK name on cassette tape out of the company’s own hands altogether.