
via this auction.
Details:
"I have only seen 3 of this unit in my 20 years playing synths. Its very rare, and Vintage. Its the Cass-1 Interface for the OB-1 and the 4, 6, 8 Voice SEM synthesizers. Its the only way to load, save sounds into the memories of these synths. It also has check errors for the sound memorries. I dont have my 4 Voice any more so I am selling this unit. I cant test it , as I sold my 4 voice so its as is. It worked fine when I had my 4 voice. I have a copy of the manual that I will send with it. The Cass-1 came out in 1978 from Oberheim. I have only seen 3 unit total, and have never seen one on Ebay. A must if you have a 4, 6, 8 voice Oberheim. I payed $500 and it was worth every penny."
via brian comnes