TDK SAC-90 (1980–1981)

Two dollars and ninety-nine cents bought a Type II cassette in a jewel case - and that's about all the record will tell you.

Overview

The TDK SAC-90 is a blank audio cassette, a Type II high-bias tape in the familiar 90-minute length, sold in a standard jewel case. That much the record supports. Beyond it, this is one of the thinnest entries in the Archive. No spec sheet, no catalog page, no independent bench review, and no owner testimony have surfaced. What exists is a handful of dealer price sightings in the consumer audio press, and a naming problem that collectors should understand before they go shopping.

The same tape turns up under several spellings. "SAC-90," "SAC 90," "SA-C90," and "SA 90" all appear in period advertising and in marketplace listings, and the Archive has not been able to confirm that they are all one product rather than a family of related ones. The 90-minute capacity is consistent across the sources that state it - the model number carries the length, as TDK's numbering always did. One vendor description lists the tape at 120 minutes, which contradicts the "-90" designation and reads as a listing error rather than a spec. Treat 90 minutes as the working number and the 120-minute claim as noise.

What's left is a price history. Audio (June 1980, p.131) advertised the SAC-90 at $29 per ten through a New York mail-order dealer, with the SAC-60 at $21 per ten. The long tape cost roughly $8 more per box, which was the usual premium for the extra fifteen minutes per side. A High Fidelity dealer list (December 1981, p.143) later showed the SAC-90 at $2.99 apiece. Those two figures bracket the tape's commercial life: a ten-pack price at the start of the run, a single-unit price near the end.

Key Features

Type II High-Bias Formulation

The SAC-90 is a Type II tape, the high-bias formulation that cassette decks select with the CrO₂/Type II switch. Listing titles describe it as "Type II High Bias" and, in one German-language case, "IEC II/TYPE II" - the international standard designation for the same thing. That's the tape's whole technical identity as far as the record goes: a high-bias cassette meant to be recorded and played back with Type II equalization.

Super Avilyn Descriptor

Marketplace listings for the tape carry the phrase "SUPER AVILYN high resolution super precision" - TDK's formulation branding, the same particle-technology name the company used across its tape lines. Whether the SAC-90's coating was identical to any other TDK product's is not documented here, and the Archive won't guess. The descriptor is what the packaging said. The formulation details behind it are not in the record.

Jewel Case Packaging

The SAC-90 shipped in a standard jewel case, per dealer listings. That's the ordinary plastic library case with the hinged lid and the J-card insert. Collectors will find it when they open a box, assuming the case survived, which after four decades is never a given.

90-Minute Capacity

The tape runs 90 minutes, the standard long-play length that fit a full album per side with room to spare. One vendor page gives a frequency response of 20 Hz to 15 kHz and a "recording density of 15 ips." The latter is a tape-speed figure that has no meaning for a cassette, and the former is a single-source claim the Archive cannot corroborate. Treat both as unverified vendor copy, not specification.

Historical Context

The SAC-90's documented life runs from roughly 1979 to 1982. A German dealer listing gives 1979 as the year of manufacture, while an image caption elsewhere places the tape in the 1975-1977 window. The Archive cannot resolve that conflict and flags it rather than papering over it. The consumer-press record begins in 1980: High Fidelity (July 1980) listed "Tdk sac-60 tdk sac-90" among its cassette specials, and Audio (June 1980, p.131) carried the ten-pack pricing. By November 1982 the tape was still being advertised, appearing in a Rolling Stone (November 11, 1982) spot alongside the SAC-60 and TDK's MAX series.

Pricing varied wildly by market and by year. The German Audio (1981) listed ten SAC 90s at 85 DM. The Australian ETI (1982) gave a per-tape value of $6.38. The American mail-order price in 1980 worked out to $2.90 a cassette. None of these are directly comparable, with different currencies, years and dealer margins, but together they sketch a tape that sat in the middle of TDK's lineup, above the budget D series and below whatever flagship formulation the company was pushing that season. One further sighting, a HiFi-Stereo price list (July 1980, p.112) showing an "SA-C90 (New)" at $1.05, may or may not refer to this same tape. The scan is garbled and the figure looks like a promotional or multipack unit price. The Archive lists it as an open question.

Collectors will find the SAC-90 sold in "vintage" and "retro style" lots, and used examples turn up in mixed groups. One eBay lot bundled twelve used SA-C90s with eight SA 90s, which at least confirms that the two spellings circulated as the same family. No dated current asking prices have been captured, and no common failure modes or maintenance notes are documented. The record says nothing about how these particular shells and coatings have aged.

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Related Models

• TDK ADC-60
• TDK C-90
• TDK DC-90
• TDK L-500 (1979–1986+)
• TDK LX-35
• Akai CS-M40R (1983)
• Akai GX-7 (1970)
• Akai GX-8 (1975)
• Akai GX-F44R (1979)
• Akai GX-F71 (1982)