via this auction
"This is a really odd item, can't find any info about it online!?
So what i can tell you is: it's a 1980's boombox with built in analogue drum machine!
I've recorded the output here so you can get an idea of the presets:
This device can also be used as a 2 track recorder, featuring a guitar and mic inputs.
I think this could make the basis of a really interesting circuit bend or just a super unique addition to the collection of a drum machine/ 1980's/ analogue recording enthusiast.
More photos here"
Update: some additional info via Jan:
"this boombox was also distributed in Germany under the "Lehnert" brand and was called the "Lehnert Studio-5000". My parents bought one in 1978 or 1979, I can't remember exactly. I tried to find more information about it and the company in the web a while ago, but alas no success. And my mother threw hers away some years ago…
More pics on [via this auction]
Judging from the German labeling with the correct Umlaut usage, and the more detailed description of the device's functionality on the lower left of the German front panel (compared to the English Tensai version), I assume that "Lehnert" might be the original (German? Austrian?) manufacturer.
More pics of the machine's guts: [link]
On [link] you can see the manufacturing date of the tape motor is 1977.
The 2 way speaker system sounded really nice, the rhythm section allowed pressing multiple buttons simultaneously to combine rhythms, the external input allowed to use it as an amp for my first synthesizers (Casio VL-Tone and Korg MS-20), and you could use is as a limited 2 track recorder. I had a lot of fun with it 30 years ago."