The Radio Historian

The sound of the NBC chimes is the sound of radio history itself. Probably no single sound better recalls the golden age of radio. The NBC chimes – the musical notes G-E-C – were played at the end of every NBC radio program beginning shortly after the network's inception, and continued in daily use on NBC radio and television until 1971.

Shortly after the formation of the National Broadcasting Company in 1926, network executives became aware of confusion among the affiliate stations as to the exact when a program ended, and when it was safe to cut away for local announcements. The problem was assigned to a committee of three: Oscar B. Hanson, NBC's Director of Engineer and a former AT&T engineer; Earnest la Prada, an NBC orchestra leader; and Philips Carlin, an NBC announcer. They decided that a musical signal of some kind would be an appropriate way to indicate the ending of all programs. At that time, it was common for radio stations to use the sounds of chimes, gongs, sirens and other mechanical devices as a signature sound for their station, so the choice of a chime by NBC was not unusual or particularly innovative. There is in fact some evidence that the chimes may have been inspired by a similar chime sequence used at that time by NBC affiliate WSB in Atlanta.

During 1927 and 1928, the committee experimented with several combinations of notes, played by the announcer on a set of hand-held dinner chimes. A seven-note sequence which was first used, G-C-^G-E---G-C-E, was determined to be too complicated for the announcers to play correctly on a consistent basis. It was first simplified to G-C-^G-E, and finally to just G-E-C. This latter familiar sequence was heard for the first time on November 29, 1929.

In this recording from 1929, you will hear the 7-note chime sequence used by NBC shortly before it was changed to the familiar three-note version.

And here is a recording of the Rangertone chimes machine on a network program from 1948.

The chimes were sounded at :29:30 and :59:30 of each hour, indicating the start of the 30 second local station break. They were initially struck by hand by the announcer, using a set of hand-held chimes held up to the microphone. But, there were inconsistencies in the chimes' tempo, volume, and exact timing. It was finally determined that the best way to solve these problems was for the chimes to be generated mechanically.

The chimes machine was developed by Captain Richard H. Ranger, who was also the inventor of the electronic organ and the RCA facsimile. Ranger created a device resembling a music box, where fingers on a revolving drum plucked a set of reeds. There were three sets of eight reeds, one for each note, allowing the generation of the fundamental note plus several overtones. Each reed formed one plate of a capacitor in an oscillator circuit, and the signal generated by all reeds was amplified by a single 6C6 pentode tube. It was activated by a timer, which would cut off the program two seconds before its end (whether it was finished or not!) and feed the chimes to the network.

NBC built a limited number of chime machines. NBC in San Francisco had two of them - the main and backup machines. Others were installed in other cities around the country where network programs originated – Los Angeles, Chicago, New York, and perhaps a few others. It is likely that not more than a dozen chimes machines were ever made.

The photos on this page show one of the few chime machines still in existence, until recently in the hands of a private collector. (NBC had the short-sighted habit of discarding large quantities of historical artifacts throughout its history. It's only through the far-sightedness of a few NBC employees, who saved some of these items from the trash bins, that we can today experience many recorded programs, photos, and other memorabilia from that era.)

The unit shown is the chimes machine serial number 2, probably from the first group ever made. Its mechanical parts, although finely crafted, appear to have been hand made. This unit is no doubt the original chimes machine placed in operation at NBC's studios at 111 Sutter Street in San Francisco. The schematic diagram, also shown, indicates that serial number 5 was fabricated in 1933, so this machine would have predated it. The main cabinet contains the motor drive reed mechanism and amplifier, which is accessed by removing the front panel's four thumbscrews. The unit operated from an external power source, no doubt the same battery and motor generator system that operated the audio amplifiers in the studios. The smaller box contains the timer and switches that operate the chimes for both studio and "NEMO" broadcast lines. ("NEMO" was a term used in early radio to indicate a remote broadcast. It comes from a telephone term, and stands for "Not Emanating Main Office".) The chime machine could be operated in an automatic mode by the clock, which was the usual method of operation, or manually by the announcer in the event of programs with imprecise ending times, such as sports broadcasts.

The NBC chimes were officially registered with the U.S. Patent Office in 1950 as a registered service mark, the first known case of a sound receiving trademark protection. They were last heard regularly on NBC television in 1976, used to mark the 50th anniversary of the network.

In 2018, the private collector donated the machine shown in these photographs to the California Historical Radio Society, where it is now on display at the organization's museum in Alameda, California.

Here is a remembrance of the NBC Chimes Machine from Rick Greenhut - February 3, 2013:

Just saw your page on the Bay Area Radio Museum dedicated to the NBC chimes machine, and I wanted to give you another historical fact to add. In 1969 when I went to work as a summer replacement engineer (board op) at NBC-owned WKYC Cleveland, there was still a chimes machine back in the racks. Since all the O&O's originated programs like NOTH (New On The Hour) and Monitor inserts, they all had 2 chimes machines. Besides WNBC/New York, WMAQ/Chicago and KNBR/San Francisco, WKYC/Cleveland and WRC/Washington also had chimes machines.

By the next summer I worked there, the chimes machine was gone - whether thrown away or taken home by one of the old-timers, I couldn't say.

Last bit of radio trivia: I was doing Affiliate Relations for the NBC Radio Network in August of 1987, and during the NABET engineers strike those of us in management with technical backgrounds were taking shifts running the board for the NOTH and manning the ROD (Radio Operations Desk) in Radio Central (network master control). I was the first management person on the board when the engineers walked out at 6:00 AM that morning, and engineered the 6, 7, 8 and 9 AM NOTH (the talent was Gary Nunn, now heard on the CBS Radio Network). At 8:30 that morning I was told by the General Manager, Craig Simon, that the network had been sold to Westwood One, and that the chimes were not part of the sale, so I was forbidden to play them at the end of the newscast like we usually did.

I ignored him, and "chimed out" at the end of the 9:00 AM newscast as per usual. He came up to the studio a few minutes later with a funny smile on his face, and told me to make sure no one else did that. I made sure by taking the chimes cart and backup out of the studio. I bulked the backup, and have the last remaining cart with the NBC chimes (recorded directly from the WNBC chimes machine) in my collection.

Rick Greenhut

Director – U.S. Broadcast Sales
iBiquity Digital Corporation