The NBC Chimes were the first ever “Audio Trademark” accepted by the US Patent Office. As a trademark, the tones had to be done right. In the early days this was usually accomplished by an announcer tapping out the sequence by hand in front of a microphone in the broadcast studio.
The JC Deagan company of Chicago was the largest manufacturer of dinner chimes, and produced many of the sets used by NBC and their affiliates. Several photographs show 3, 4, and 5 tone chimes being used, with the chime plates arranged in chromatic, largest to smallest, order. Many custom chime sets were produced with the chime plates arranged in the G-E-C, largest-smallest-middle, configuration. These were used both for broadcast and promotional purposes. Today these sets are highly sought by collectors.
In 1932 the chimes were mechanized. Captain Richard Ranger, an inventor who had worked for RCA, developed a rack mounted system of revolving studded wheels. The studs plucked three sets of tuned metal reeds that produced the tones. Several of the Rangertone sets produced and placed at major network locations across the country, including LA, New York, Chicago, and San Francisco.
In 1953 NBC Television adopted a graphic trademark of three colored chimed bars colored red, green and blue, to mark the advent of Colored Television. Promotional sets of these chimes were also produced. Using different alloys and thicknesses of the chime plates, the G-E-C tones were produced while keeping the largest to smallest sizing.