BASF Cassette history
There are six basic categories of BASF true chrome tapes for compact cassettes:
- chromdioxid SM 1971-80 are singe layer true chromes, with magnetial properties according to DIN reference tape C401R. 1971-74: 1974-76: 1976-77: 1977-80: (77-79 without "hifi stereo cassette" badge, 79-80 with "hifi stereo cassette")
- chromdioxid super SM 1977-80 are double layer true chromes with off-standard magnetical properties, still close to C401R, but higher sensitivity and a non-linear frequency range on DIN-aligned recorders: 1977-80: (77-79 without "hifi stereo cassette" badge, 79-80 with "hifi stereo cassette")
- chromdioxid II SM and Cr Extra II 1980-ca 1993 were single layer true chromes, with magnetial properties according to IEC II reference tape S4592A. 1980-82: 1982-85: 1985-87: 1987-89: 1989-91: 1991-93: 1993-95:
- Cr Super II 1980-ca 1995, as well as Cr Maxima II 1982-ca 1994/95 are double layer true chromes with off-standard magnetical properties, still close to S4592A, but higher sensitivity and a non-linear frequency range on IEC-aligned recorders: S 1980-81: S 1981-82: S 1982-84: S 1984-85: S 1985-87: S 1987-89: S 1989-91: S 1991-93: S 1993-95: M 1982-85: M 1985-87: M 1987-88: M 1988-91: M 1991-93: M 1993-95: The last examples of the 1993-95 line-up had already the next generation of tape described below.
CE II 1995 until the end: "single-layer chrome/ferric cobalt mix (85%/15%)" (quoted from Wilhelm) with higher sensitivity compared to the older models, magnetical properties close to IEC II reference tape U564W
CS II and CM II 1995 until the end (plus some 1994 Chrome Maxima II): Double layer tape, the lower layer being the same mixture of ferric cobalt and chrome as in the CE II, and the upper layer pure chrome. Frequency response nearly as flat as a single layer tape, magnetical properties close to IEC II reference tape U564W
With the last series of CS II during the Emtec era, I am not sure what tape they used.
All four Maxima Design Editions had the contemporary Chrome Maxima tape.
All budget chrome cassettes with different names, such as Chrome Standard II, ReCorD II, Sound (Level) II, the 353 Cr II Live as well as the Disney series and other printed shell promotional cassettes had one of the single layer chrome tapes, either the old Chrome Extra II or the new CE II formulation.
The Chrome II Super _Quality_ was specially made for Lidl discounter stores, and despite having the "Super" shell, I am not sure whether they had single layer CE II or double layer CS II tape inside: 1995-97: 1997-2002: