Ampex C-90 (1973–1987)

The Ampex C-90 was a blank compact cassette. It was a standard 90-minute tape sold through the 1970s and 1980s as a consumer recording medium.

It is a simple product: a cassette, not a machine. What survives is a trail of period advertisements, archival use notes and the occasional live-taper's log. There are no service manuals or performance measurements.

It appears to have been a mid-market or budget tape. A 1972 advertisement in Audio listed the low-noise high-output C-90 at $2.34 each (Audio, June 1972, p.82). A 1973 advertisement in The Massachusetts Daily Collegian listed Ampex C-90 cassettes at 95 cents each. By 1978, a 3-pack with a plastic storage "stackette" was advertised at $4.99 (Audio, February 1978). A 1986 price from Mix showed the single cassette down to 69 cents. One forum reference mentions an "educator grade" variant, which suggests the tape was also sold in bulk or institutional packaging.

The C-90 saw real archival and live-recording use. The Museum of Modern Art's Avalanche Magazine archives note multiple artist interviews "originally recorded on Ampex C-90 cassette," including at least one conversation about the sculptor George Warren Sharp. Bootleg concert recordings from 1969 - a Grateful Dead show and a Led Zeppelin performance - were captured on Ampex C-90. One of them is labeled "Master Cass" and was transferred via DAT and CD-R in later years. One taper noted recording "no dolby," which suggests the tape was used without noise reduction as a matter of course.

No technical specifications have been located in any period review or manufacturer publication. That includes frequency response, signal-to-noise ratio and tape formulation. The C-90 was a blank tape, not a component that earned lab tests in the hi-fi press. It was sold alongside BASF, Fuji, Maxell and TDK in dealer price lists. Its place in the Ampex product line, relative to Grand Master, Chrome, or low-noise/high-output variants, is not well documented.

Type: Blank compact cassette, C-90 (90 minutes total)
Period known in production: At least 1973–1987
Known packaging: Single cassette; 3-pack with stackette storage container
Documented prices: ~$0.95 each (1973); $4.99 for 3-pack (1978); ~$0.69 each (1986)
Known variant: "Educator grade" (referenced anecdotally)
Attested use: Archival interviews (MoMA Avalanche archives); live concert bootlegs (Grateful Dead, Led Zeppelin, 1969)