I can’t, unfortunately, give much information about the period of manufacture for this Akai SX 90 audio tape. I’m guessing it’s not any earlier than 1987, and it can’t be any later than 1999, because that’s the year the cassette was given to me. Sorry I can’t be more specific.
What I can say is that this is a normal bias Type I audio cassette, and it sounds well within the bounds of acceptability. It’s been used for music recording, and whilst the frequency range isn’t brimming with definition, I’ve heard much worse Type Is, and the noise levels are low. There’s no warble I can detect, or drop-outs of any prominence. This cassette reminds me of a mid 1980s Sony HF in the way it renders recordings, which isn’t bad at all. The only thing that is a bit suspect is the way in which this Akai SX90 distorts relatively low down on the level meter. The Sony HF could in my experience take quite a bit of level for a Type I, but this is the opposite. The meter does get into the danger or warning zone before obvious distortion sets in, but only just. Technically, it’s acceptable, but there’s no margin for error, and the distortion comes in very heavily indeed once you exceed that point.
There is a slight brownish tint to the colour of the casing. I can’t be sure whether the tint was there from new or if it’s just the ageing process, but since it’s so uniform across all areas of the plastic, I’m thinking the casing was never really devoid of a tint.
All in all, obviously a tape which did the job. No more, no less. I wouldn’t go mad and buy a pack of them, but I wouldn’t refuse one if it was going free.