You most likely have a Stenorette tape.
Stenorette was a German dictation format made by Grundig in the 1960s. It came as a 3” reel inside a plastic cartridge, BUT very often, Stenorette reels came as regular-looking 3” reels. The machine had no capstan — it was pulled by the reel motors, so the speed would drop as the reel played on. Normal playing speed was 1-7/8 ips. There is also a loop of tape at the start of the reel for threading the cartridge onto the machine.
The caveat to this is the reel itself. On the bottom side, it’s a regular cine hub. But the top side is a round hole that will not fit on a regular tape deck. Stenorette decks are on Ebay fairly cheap so that’s probably the way to go.
On Fri, 12 Jul 2019 14:30:22 -0400, J. D. Mack <[log in to unmask]> wrote:
>I'm looking for some advice/info. I sometimes transfer reel-to-reel
>tapes to CD or digital files for my customers. Frequently, I receive 3
>inch tapes from the 1960s that start at one speed and gradually speed up
>or slow down substantially as the tape plays. The speed range is usually
>between 1 7/8 and 3 3/4, but never landing on either speed. I can
>correct for this using Adobe Audition's gliding stretch, but it takes
>quite a bit of trial and error. What sort of tape player would I need
>to hunt down to play these tapes correctly without having to resort to a
>software solution? My customers never have any idea what brand and
>model was used to make the recordings.