Watkins WE-1 loudspeaker
First I should clear up what may be an ambiguity in the driver-lineup spec for these speakers. In each system, three 8" cone units serve as woofers. Two of these crossover from the midrange drivers at 100Hz. Crossover to the third 8-incher, the subwoofer, is at 40Hz. Thus, two woofers are active from 100Hz down to 40Hz, and all three are active below 40. In other words, the third woofer does not come into play until the frequency drops to the point where the radiating area of two 8-inchers starts to become inadequate for moving air, at which point the additional area of the third speaker is thrown in. Below 40Hz, all three are working together.