KR
Chrome tape using chromium-dioxide magnetic material
Krom・O2
First generation: 1972
C60: 900 yen.
TDK’s first chrome tape was released around 1972. Silver packaging and a black cassette shell gave it a distinctly premium feel. The price was high: 900 yen for a C-60.
Second generation: 1972
C60: 800 yen.
The second generation was released in 1972. When TDK renewed its entire cassette lineup, this model joined the Diamond Series and adopted striped packaging.
KR: explanatory notes
Ordinary Normal tape uses iron oxide as its magnetic material; KR was chrome tape using chromium dioxide. Chrome tapes appeared in the early 1970s and greatly improved the high-frequency performance that had been a cassette weakness.
Exploiting these capabilities required stronger bias than ordinary tape and equalization that attenuated the high frequencies slightly. The deck settings providing these are called the chrome position, or High Position.
TDK’s chrome-position cassettes are usually associated with SA, but KR came first.
The name KR apparently abbreviates Krom-O2, referring to chromium dioxide.
KR had two generations, but naturally faded away after SA appeared.
SA-X
High-quality High Position with a dual-layer AVILYN coating
SUPER AVILIN EXTRA
First generation: 1979
C46: 650 yen.
The first generation was released in 1979. It used the same latest SP mechanism as the contemporary MA, looking more expensive than SA in its older shell. Cassette discussion then focused almost entirely on Metal tapes; this model reminded people that High Position existed at a practical price.
SA-X: explanatory notes
Introduced above SA, this model exploited AVILYN’s ability to have its coercivity controlled precisely. Extensive experimentation and analysis optimized the upper layer for middle and high frequencies and the lower layer for low and middle frequencies. AVILYN was applied in two layers of optimum thickness. Each layer accurately recorded the corresponding distribution of the head’s magnetic field, further improving audio-cassette performance.
This produced a higher-energy tape than SA, with high output and sensitivity. MOL rose by 1 dB across the frequency range. Sensitivity increased by 1 dB at low and middle frequencies and by 1-1.5 dB at high frequencies. These comparisons refer to first-generation SA-X and its contemporary SA. Although the layers served different frequency regions, both used AVILYN, extending frequency response in a balanced way.
By the third generation, bias noise reached -63.5 dB, making it an exceptionally low-noise tape at the world’s highest level.
Second generation: 1981
C46: 650 yen.
Released in 1981, the second generation increased AVILYN orientation and density in both layers, raising remanent flux density and achieving even better-balanced magnetic characteristics. Alongside physical specifications, listening evaluation was given great importance in the pursuit of faithful reproduction.
Third generation: 1985
C46: 680 yen.
The third generation was released in 1985, achieving exceptionally low noise at the world’s highest level. Its dual-layer AVILYN used TDK’s smallest particles, developed in pursuit of the limit of particle refinement. The shell featured the precise, rigid SP-X mechanism. A Sound Stabilizer sheet prevented small vibrations and sharpened sound images.
Fourth generation: 1987
C46: 700 yen.
The fourth generation was released in 1987. Exceptionally low noise was retained while AVILYN packing density was increased further to reduce perceived noise. The shell adopted the integrally molded dual-layer SP・AR II mechanism with an exceptionally wide window. Suppressed resonance reduced modulation noise and, together with the tape’s low noise, delivered clean sound.
Fifth generation: 1990
C46: 730 yen.
The fifth generation arrived in 1990 under the slogan Super Presence with an exceptionally clear sound range. Its world-class low noise was retained. Rows of small transparent square dots in the Multi Dimple shell further reduced resonance. High-quality cassettes could not withstand the market’s decline, and this was the final generation.
HX: 1983
A new dimension in High Position using metal powder
HIGH-POSITION EXTRA
C46: 750 yen.
An insider’s recollection
The development concept was to use metal powder at the High Position setting for decks that did not support Metal! Perhaps because it was not a mainstream approach, the market did not accept it. I still think it was a good idea (laughs).
Yoshino (吉野), former TDK employee.
HX: explanatory notes
Released in 1983, HX stands for High-Position Extra. Its metal-powder magnetic material makes it a Metal tape, but bias and other parameters were tuned for High Position (Type II), so it was used as a High Position cassette. It brought some Metal tape capabilities to older decks and radio-cassette recorders that did not support Metal.
The magnetic material was developed specifically for High Position. This high-performance metal material had a large particle aspect ratio: the crystals were twice as long as those in Metal material while retaining the same thickness. Coercivity remained within the High Position range, while remanent flux density matched Metal, providing high output. Its high MOL and sensitivity distinguished it clearly from ordinary High Position models such as SA.
The price also differed from ordinary High Position, matching the Metal tape MA. The shell used the same SP mechanism as MA and was dark blue with a slight light-blue tint. Perhaps it would be more accurate to call it a Metal tape variant than a High Position tape.