Hi-fi editor Kashfia Kabir on the LS3/5A’s history and continued charm
The LS3/5A were never meant to be heard by the public. The iconic BBC speakers were born out of the broadcaster’s research and development department in the 1970s, whose engineers were tasked with designing and creating broadcasting equipment that the BBC needed but couldn’t source from external suppliers. In this instance, they were after highly accurate small monitors that could be used in the limited space within the outside broadcast vans.
Nothing commercially available at the time was good enough for the BBC’s needs, so the engineering division invested in a huge amount of research to find out what makes a good sound in speakers.
Until this point, the concept of a small hi-fi speaker didn’t exist. You’re looking at fairly large cabinets for your average speaker before the ’70s; the LS3/5A were attempts to get very high-quality sound out of shoebox-small nearfield monitors. Many of history’s successful small speakers, such as the Linn Kan, the Neat Petite and models by Spendor and Harbeth, owe their existence to these original LS3/5As. The BBC never actually made these speakers, but licensed out the specifications to various manufacturers, including Rogers Hi-Fi, Falcon Acoustics, Chartwell, Goodmans, Stirling, KEF and Spendor, while Musical Fidelity’s versions are inspired by those original R&D specs.
Those research findings
First, the BBC’s engineers discovered that a very rigid cabinet wasn’t very good for sound. If the box is too rigid, the frequency at which the cabinet resonates keeps rising into the midrange area where you are more likely to hear its effect. If you make a less rigid box that is heavily damped, it will resonate at much lower bass frequencies, where the human ear is far less sensitive. The BBC decided to use cabinets with thin flexible walls and damp them heavily inside to move the resonance frequencies to the lower bass. The original designs had 9mm walls but changed to the now standard 12mm birch ply walls. The result? A lovely midrange, with a slightly plump bass.
The front and back panels of these early designs were also fixed with screws rather than glue, which allowed for a small amount of flex, compared with the more rigid design when the baffle is glued on.
At the time, paper cones dominated driver designs in speakers, but the BBC wanted
