The Universal Microphone Co. Ltd was out of Inglewood California. We couldn’t find a ton of information on these mics. Just like American Microphone Company, information is rather sparse on Universal.
Universal Microphone made several different iterations of at least 3 different double button microphones. The model X, model XX and the model BB double button microphone from the late 1920s – 1937. The model BB were rather hefty spring carbon mics usually about 5″ in diameter x 2.5 deep. The model X and XX were a little lighter. From the advertising we have found, it appears the model BB was made prior to the model XX. We are not exactly sure where the model X falls. Ours looks rather old, so it may have been made prior to the BBs.
Here are some early ads from Shortwave Craft, Radio Craft and Radio World for the Universal Microphone. These are from 1931 – 1934, but our guess is this microphone was made in the 1920s.