Stephens Electronics 821-B

American professional 2-inch multitrack studio recorder from Stephens Electronics (Burbank, California; founded by John Stephens in the early 1970s) - the company's workhorse, typically configured as a 24-track (the frame also took 16/24/32-track headstacks). Used to record Pink Floyd's 'The Wall' (Bob Ezrin), and competed with the Ampex MM-1100 and 3M Series 79. Drive: distinctive iso-loop transport with no pinch roller; tape speed sensed by an optical pickup under the reversing idler, with servo current-steering controlling back-tension and speed - clever, and known to be flutter-prone and tricky to service. Speeds 15/30 ips; variable-pitch; independent per-track electronics with sync/repro select; balanced XLR I/O. Solid-state (c.1973-78).