In honor of the invasion of spooks and ghouls tomorrow on Halloween, I thought we’d focus on bells representing the profane. I give you . . . “Hell’s Bells” by AC/DC.
That is a real, honest-to-goodness one-ton bronze bell hanging above the stage. Michael Milsom, former bellmaster at Taylor foundry in Loughborough, England, gives us the details of creating the bell.* The firm got an inquiry about casting a very large bell for AC/DC in April 1980. Milsom talked them down from a two-ton bell to one-ton, ringing a note E instead of C. After all, a one-ton bell is easier to manage for stage shows than a two-ton bell, and the pitch could be changed to C with studio recording equipment. The band wanted the bell pronto for the recording, so the Taylor foundry got to work quickly.
There was a danger that the bell would not be done in time in order to record it. Taylor considered recording a C bell from one of their nearby carillons, the Loughborough World War I Memorial Carillon. This idea was scuttled when Milsom pointed out the difficulty of deleting the sounds of traffic and pigeons from the recording. Taylor did in fact complete the AC/DC bell in time to record it in their foundry, despite media reports that the nearby carillon bell was used.
Milsom was tasked with ringing the bell on the recording, but this is not as simple as just grabbing the clapper and banging it against the bell. For any tuned bell, the clapper needs to strike at the thickest part of the soundbow (the “lip”) of the bell for the best tone to develop. But with this bell, they had to be even more careful. The large AC/DC logo in raised relief on the outside actually made it slightly lopsided. This small weight discrepancy affects the vibration patterns of the various partials in the bell, resulting in two hum tones at slightly different frequencies. When heard at the same time, two pitches just slightly apart create a wobbling sound.
To remedy this defect, Taylor identified the four locations on the soundbow where the desired pitch has an antinode (point of maximum vibration) and the undesired pitch has a node (point of maximum stasis). These are not eight different spots, but four; the antinodes of the desired pitch and the nodes of the undesired pitch are located at the same spots. Striking the bell at one of these specific spots results in a clear, wobble-free tone. Milsom recounts that they marked the four spots on the bell with red paint and he struck the bell (not too hard!) precisely there. He also explains that he reduced the tin proportion to make the bell somewhat less fragile and supplied the managing company with many hammers, of which the stagehands broke a couple and lost several more. It seems they learned their lesson . . . I don’t see a clapper or hammer in the 2016 video above, so that the bell sound is being played from a recording.
*Information for this post taken from Michael J. Milsom, Bells & Bell Founding: A History, Church Bells, Carillons, John Taylor & Co., Bellfounders, Loughborough, England (2017).