SF
TDK’s first economical High Position cassette
SUPER FIDELITY
First generation: 1985
C46: 500 yen.
The first generation appeared in 1985. Light blue packaging and shell colors created a casual impression. The shell used an SP-X mechanism, but of the earlier type.
Second generation: 1986
C46: 470 yen.
Released in 1986, the second generation reduced noise with ultrafine AVILYN. The shell gained an H-shaped window and SP-RL mechanism. The price was also reduced, delivering excellent value.
SF: explanatory notes
From chrome tape’s arrival in the early 1970s, chrome-position or High Position tapes long remained expensive, high-grade music tapes. Around the mid-1980s, relatively inexpensive, economical High Position cassettes began appearing and gaining popularity. TDK entered this market too, with SF as its first model.
SF stands for Super Fidelity. Like SA, it used AVILYN. Whether the material was specially formulated for SF or the coating method differed, the first generation’s packaging graph showed slightly less high-frequency extension than SA. This apparently distinguished the models. Yet some specifications put SF ahead in MOL and noise. Perhaps it was no worse than SA overall?
On introduction, the first generation cost about 10-20% less than SA, matching the high-grade Normal cassette AR.
SR
More advanced High Position at a low price
SUPER RESPONSE
First generation: 1988
C46: 450 yen.
The first generation appeared in 1988. New surface-modified AVILYN provided low noise and high output. The shell used the new low-resonance HP・AR mechanism.
SR: explanatory notes
The first SR generation was released in 1988 to succeed the economical High Position cassette SF. As competition over value intensified and various manufacturers offered economical High Position models, TDK’s entry appeared under a new name.
SR stands for Super Response. Its magnetic material was AVILYN, familiar from TDK’s High Position tapes. High output, low noise and high MOL gave no sense of a budget model in the specifications. The first generation’s shell and packaging looked as expensive as the high-grade Normal cassette AR, updated at the same time, and did not suggest an economical product.
The second-generation SF price had already fallen to AD’s level, but first-generation SR was cheaper still.
Many playing times were offered, including C22 (half a C46?)*, later replaced by C20.
* The question 'half a C46?' appears in the original article.
According to the Museum administrator's observations, 22 minutes is an exceptionally rare cassette playing time: apart from TDK SR22, only a Sony karaoke version is known. This duration has not been encountered in other standard ranges, including TDK's own. The photograph shows an actual exhibit from the Museum collection.
Second generation: 1990
C46: 430 yen.
Released in 1990, the second generation’s improved high frequencies made it a clean-sounding High Position tape with a live-performance feel and beautiful sound. Its price matched the contemporary AD-X. Two shell materials were molded integrally to reduce resonance, greatly lowering modulation noise. A rounded case was used.
Third generation: 1992
C46: 470 yen.
Released in 1992 as Powerful High Position with resounding deep bass. The base film was reinforced for car and outdoor use, resisting deformation during repeated use. A small additional feature was an index card that could be printed on a word processor.
Fourth generation: 1993
C46: 480 yen.
The final generation appeared in 1993. Low-frequency dynamic range was extended further. It used the integrally molded dual-layer Aero Arch shell and a short leader. Reflecting the CD era, eleven playing times were offered: 40, 46, 50, 54, 60, 64, 70, 74, 80, 90 and 120 minutes.
SR-X
High Position with better performance than SR and a lower price than SA
SUPER RESPONSE EXTRA
First generation: 1989
C46: 480 yen.
The first generation appeared in 1989. Ultrafine, high-output AVILYN was densely coated onto the tape. Overflowing power, clear high frequencies. High Position with a sense of strength. The low-resonance HP・AR mechanism reduced modulation noise. Seven playing times were available from C40 to C90.
SR-X: explanatory notes
SR-X was introduced as a model above SR.
When SR appeared, the price gap to the higher SA was substantial: 150-200 yen or more. This made it an economical High Position, but competition with other manufacturers presumably called for a grade to fill that gap.
Released in 1989, first-generation SR-X resembled SR in shell shape, packaging and overall impression. Its price was not halfway between SR and SA either, but closer to SR, at about 50 yen more. The image was of a slightly more luxurious SR.
This model also used TDK’s proprietary AVILYN. By then, AVILYN tapes had almost reached perfection, but small distinctions between grades apparently remained. I feel this model’s tape performance was close to SA.
Second generation: 1990
C46: 530 yen.
The second generation appeared in 1990. High Position full of strength realistically conveyed musical energy. A rounded Fit Case was used. The price gap to both SR and SA was 50 yen, placing it midway between them in price as well.
Third generation: 1992
C46: 530 yen.
The final version appeared in 1992. Its shell used heat-resistant plastic, joined by both screws and ultrasonic welding. This AR・HP mechanism combined heat resistance, low resonance and high rigidity. Reinforced base film made the tape reliable and resistant to deformation even with repeated car-stereo and outdoor use.
SR-Limited: 1991
A compact SR with a side-loading case
SUPER RESPONSE LIMITED
C46: open price.
A version of SR released in 1991. It used a side-loading case described as the world’s smallest and lightest. The cassette slid in and out at the short side; the plastic case resembled CD packaging. Portable-use features included three-way labeling, visible from three vertical and horizontal directions to help locate a cassette. Tape and shell performance appear identical to SR. There were only four playing times, fewer than SR. The price was set by the retailer.