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Back in the early days I monopolized the family’s VM714 tape recorder. This is a mono vacuum tube unit which I still have and it almost works since the rubber parts have turned to clay.
When I could afford it I would buy Scotch brand audio tape but usually I had to resort to an unbranded type which was rumored to be sliced to 1/4 inch from surplus or out of spec computer tape. At the time this sold for about $1.25 for a 1200 foot reel when the Scotch was about double this. There was a slight difference in the sound quality with the gray unlabeled tape being a bit harsh in comparison but perfectly usable.
The major difference between the two types is that the Scotch, after 50 years, is flaking the oxide from the mylar or acetate while the mystery tape is perfectly OK. Nonetheless, I went through about 40 reels and digitized what was worth saving. A lot of the content was nothing special but there were a few keepers which I had recorded live in HS and college.
When I upgraded to a good reel to reel in the ’70s I bought TDK and Memorex brands and they are still in good mechanical shape.
One thing which is easier to do than to describe is to “clean” the tape before first use by mounting the reels and using a cloth held against the tape as it is run in fast forward through the machine. This partly removes any loose oxide remaining from the cutting process. Even the expensive brand tapes back then had loose oxide when fresh out of the box.