I've just finished digitizing about 50 cassettes. About half are commercial albums and the others were blank cassettes that I recorded music onto back in the '80's. Almost all of them are 90-minute cassettes. Most of them ran ok and a few required repeated rewinding before they played smoothly. These cassettes include Sony, BASF, Maxell and Memorex. There are also three Ampex 20:20+ cassettes. These three have resisted all my efforts to get them to run, or run without lurching to a stop. I have tried rewinding, lubricating, knocking, loosening the screws and putting the reels in a known-good case. They didn't have mylar liners to remove. All of them wind forward and reverse fine. Yet when the pinch roller presses against the rotating capstan in Play mode, they won't run. Or run for long. What's with these Ampex cassettes?
Sorry I can't help you but I've been facinated by AMPEX Tapes for years, I've never seen or held one but they were one of the first and they advertised like crazy. You might be able to find info on their R2R Tapes and see if they had issues with those, there some threads on the internet that list common R2R tapes and the issue they now have after 50 years.
Hmm, It didn't even occur to me that the old cassettes might be anything special. I also have a few Memorex, which came in an unusual side-opening case. Then there are some Kelly Deyong "Sound House" cassettes, which look like a brand local to Vancouver Canada. Some of the old self-recorded cassettes sound awful. Like audio mud. Hardly worth listening to. Poor frequency response and high levels of accumulated background noise. Some of them aren't even stereo. But some are amazingly good. There is some electronic music, but most of the songs were recorded during the heydays of live DJ's. Who had a dismaying habit of talking over the beginnings and ends of songs. At New Years the FM pop music stations would do countdowns of the most popular 100 or 500 songs. I would record the songs then. I recall Hey Jude often topped these lists.
Tape collectors are popping up all the time, some going after the very early ones which are hard to find. It was hard to get a great recording without good equipment, my friends and I all had cheap piano key recorders and we taped everything with dime-store cheap tapes. Most sounded like crap until the late 70's when it all changed and everyone had a nice home deck, usually one in the car and maybe a boombox. My DJ buddy said they had a intro song timer, they knew how long they could talk before the lyrics began, the "good" DJ's would talk as close to that as possible, meanwhile the listening audience mostly hated it. Make sure you check the foam pad on the cassette, they go bad or fall off and the tape doesn't make good contact with the deck head.
Ampex has a bad rep for sticky shed tape....the tape degrades badly over the years and it just falls apart....so basically the capstan is just grinding the coating without moving the tape...probably left some residue in your deck...i avoid Ampex r2r tape/cassette's, every review i read about them is bad... There are some other brands that are loaded with Ampex tape, MagnaX (not to be confused with Magna) is one of them...Japanese company did a coop with Ampex under the brand MagnaX, later that Japanese company became Konica.... MagnaX made some lovely looking cassettes, got to GMI (Grand Master) coming my way, probably will ditch the tape and load it with TDK/Sony chrome tape.... So 80's
This is what was going on. The capstan was rotating the pinch roller ok. But instead of having traction against the tape to move it, the tape was shedding the coating. I suppose applying more power to the takeup reel could overcome this, at the risk of creating other tape speed problems.
Well if 45 tapes played well and three aren't, it is not your deck that is at fault. I wouldn't go adjusting my deck to a tape that woldn't play. You could try playing them in another deck where the pinchroller has more force....but again it will be metal grinding against plastic because the coat is shedding.... From what i've read it's the binding agent that Ampex used that degardes and causes the shedding....i think this fault can be tracked back to production errors, wrong formulas.....who knows it was the 70's, maybe some hippy put some hoffmann in there....
Just found this interesting site with measurments of cassette tape http://audiochrome.blogspot.com/2018/03/cassette-tape-measurements-agfa-denon.html
