This amazing vintage thing had several different incarnations.
This one, labelled Conditioning Panel Model 101, and made by B&K's American wing in Cleveland Ohio, has microdot sockets as opposed to Hainbach's 1/4 inch jacks ( https://www.instagram.com/p/CxNNs7JNtvt/ )
Inside are 29 beautifully encapsulated differential opamps by Philbrick Researches - a firm linked with Nexus, Alan R Pearlman's firm, and often called Philbrick/Nexus.
These opamps themselves are probably very collectable.
Here is another example of a similar machine:
https://www.facebook.com/photo/?fbid=1553652231455816&set=gm.2249783151984679
Dani at Hideaway believes there is nothing inside to create frequency-changing control. If, as generally reported, IRCAM and the Radiophonic Workshop used machines like this, either B&K must have added components inside, or IRCAM and the BBC must have modified them.
There are miniature pots with screwdriver slots to control something, though! And the frequency bands are clearly shown. Puzzling.
There is no mains power supply lead.
Sold as is, not tested in any way, but very intriguing. Packing 18GBP.
