Lots of BBC monitor speakers were lined up in one of the rooms of the Design Department. In this room, they adjust speakers (adjustment of crossover network etc) and the speakers are checked with simple measurement tools.
As described previously, the BBC monitor speaker has a classification called LS3 and LS5, and the additional numbers or letters are attached to the end of the name like LS3/4C or LS5/5. Letters are attached, if improvement is added to an original model, or if the units are changed.
Although there are many types of BBC monitor speaker, the basic philosophy is the fidelity of male announcer's voice. The sound of the voice is always checked in the development stage. Moreover, a unique way is to bring in general listeners, and ask them to choose a model which sounds most natural. Then they adjust and develop again.
For monitor speakers, the important point is that they can reproduce the same sound consistently. Although it is a matter of course, since they are played for a long time (unlike home use), the stability and durability are beyond imagination. To avoid monitor speakers playing different sounds in the same studio, checking the sound whether they are comparable with the sound of a reference BBC monitor speaker is also important.
There is a tale about the excellence of the BBC monitor, born out of this severe testing. When stereo was introduced, two monitor speakers LS3/1 which was made before introduction of stereo (1958 or before), were paired. It is said that both of the pair had the same quality and that a wonderful stereo image was reproduced. (Although they are replaced by LS 3/7 today.) We were impressed by their steadfast confidence and somewhat stubborn and thorough investigation, and were touched by the British soul that lives in their history and tradition.
(English translation to be continued)