In the early 1970's, BBC UK decided to develop their own studio and outside broadcasting (OB) monitor speakers. A small format monitor speaker was needed to give consistent sound reproduction quality across their many studios and field-based recording and broadcasting facilities. This gave rise to a design using KEF drivers and custom designed crossovers using no less than 30 components, to ensure a smooth and linear response across the usable frequency range. The design became very popular, and was licensed in 1975 to several companies to produce the units in quantity. The LS3/5a model code designates this as “Outside Broadcasting model 5, revision A” miniature monitor loudspeaker.
The Rogers LS3/5a 60th Anniversary Edition bookshelf monitors are quite sturdy, with solid plywood and real veneer, bolted-through rear connections (bi-wirable) for the amplifier connection, and 10 screws holding the baffle into the enclosure from the front. The stiff but light cloth grille is attached around the edge by Velcro into the recessed front of the box. A square ring of acoustically absorbent material fits over the tweeter’s face plate, and surrounds the tweeter diaphragm. The woofer is mounted from behind the baffle.