Original and matched pair The LS3/5A were designed by BBC engineers for mobile monitoring use. They needed to be compact, so they could be fitted into BBC vans. The speakers feature 5l sealed enclosure with 110mm bass driver and 19mm dome tweeter. There is nothing particularly special or amazing about each of these drivers. On the other hand, the crossover is quite complicated as most of frequency equalisation (flattening) happens there. I personally believe that the crossover changes these ‘ok sounding’ drivers in to great sounding speaker. The BBC did not produce the speakers themselves, instead, they outsourced production to number of British companies (e.g. Rogers, Kef, Spendor, Goodmans, Chartwell, etc.). From what I gathered the Rogers LS3/5A are most popular, and therefore, cheapest to buy. The other brands are more sought after, and consequently, more expensive. All of these manufacturers used Kef drivers (T27 SP1032 for tweeter and B110 SP1003 for bass). It is important to mention that not all of the B110 drivers product by Kef were the same. The variations on the production line where quite high, which meant that only small percentage of these drivers were approved by BBC and used for LS3/5A production. CHARTWELL LS3/5A SPECS Frequency Response: 80 – 20,000Hz Sensitivity: 82.5dB (1W input, measured at 1m) Impedance: 15Ω Power Capacity: 25W (continuous program) High Frequency Driver: T27 SP1032 19mm (0.75″) Mylar Dome Low Frequency Driver: B110 SP1003 110mm (4.5″) Bextrene Diaphragm Crossover Frequencies: 3,000Hz Enclosure Type: Closed Enclosure Dimensions (HxWxD): 300x190x160mm (12×7.5×6.25″) Weight: 5.5kg (each speaker)