Armoured Colliery Tannoy. Commonly known as a DAC. Mini-Amp type BMA. Derby Automation Consultants Ltd, Burton-On-Trent, Staffs. Made from Iron, Rubber and Brass. Size 11″ x 7″ x 6″ inches. Date 1970s-1980s.
These Tannoys were placed at all major transfer points, headings and coal faces etc and used for communication between such places and the surface Control Room.