The Sound of Bells

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Dunham Massey, Greater Manchester, St. Margaret, 10, 25-2-24 cwt in C

Recorded: WAH 29/1/01
Analysed: WAH 12/2/01

These bells are a complete Taylor ten of 1854. The tenor is said to be the lightest bell for its note in the UK. Originally there were an additional 14 bells in the tower, cast at the same time and used as a chime. These were sold in 1914 to pay for a replacement clock. The ringing bells were rehung in 1974 by Taylors. Though the bells went to the foundry, the local ringers asked for them not to be tuned to preserve their unique sound. The ringers believe that only the third was tuned, though this bell shows little sign of it, whereas the prime of the 8th is close to the octave and may have been tuned. New clappers have recently been fitted to all the bells by Eayre and Smith. The sound of the bells, especially the tenors, is most distinctive and it is illuminating to analyse them to understand why. Here is a slightly muffled recording of the bells being rung in rounds. Here is the tenor rung alone.

Bell Founder Tuning
1 - 10 Taylors 1854 see text

Tuning of main partials

Tenor nominal: 516 Hz (with a small doublet at 519 Hz)

Bell Hum Prime Tierce Quint Nom'l S'quint O'nom.
1 -2270 -1462 -890
-897
- 1616 669 1191
2 -2266 -1492
-1502
-915 -427 1414 687 -
3 -2168 -1301 -867
-861
- 1208 676 1217
4 -2259 -1163 -851
-857
- 1105 684
679
1218
5 -2235 -1212 -855 - 906 664 1202
6 -2309 -1169 -865
-856
-424 702 684 1228
7 -2219 -1226 -857 - 517
512
656 1194
8 -2302 -1200
-1187
-853 -417 410 684 1230
9 -2281 -1106 -839 -420 216
208
669
673
1207
10 -2461 -962 -819 - 0
10
692 1234

(The figures in this table are all given in cents. For all partials except the nominal, the partials are given from the nominals of the bell. Cents of the nominals are relative to the tenor. Pairs of values indicate a doublet. Frequencies for the quint are often not given, especially if inaudible.)

Intensity plots

Here are the spectra of the front six shown together:

Dunham Massey front six

and here is the tenor:

Dunham Massey tenor

Commentary

These bells are very interesting - but then, I always say that! The tuning of the nominals is quite good - the maximum out from equal temperament is 17 cents, and certainly in the tower there is nothing exceptional to be heard in them. The tuning of the hums in the front nine is typical old-style, but the tenor hum is over half a semitone flat of the double octave. This is unusual. Finally, the primes start flat in the trebles, as is expected, are quite good in the middle bells, and in ninth and tenor are quite sharp. The flatness of the treble primes means that in fact the fourth's prime is sharper than that of the second and third. The tenor has by far the sharpest prime in my collection (of 320 bells) to date. The superquints and octave nominals are old style, with the octave nominals nicely near the octave.

The front six at Dunham are quite a pleasant, tuneful little peal for their date, and looking at the spectra it's clear why. They all have very subdued partials above the nominal (compare the trebles at Greenwich and Egham) and octave nominals close to the octave. This all makes for a mellow sound. Primes and hums of the back three (i.e. bells 4 to 6) are quite close to true-harmonic. Tierces across all six are pretty comparable. Although the hums and especially the primes of the front three are a bit wild, this does not seem to spoil them when rung with the others. If these bells were a six only one would be quite glad to have them.

The intensity profiles of 7 and 8 are fairly similar to those of the front six.

The tenor is in a class apart. As explained above, it has the sharpest prime in my bell collection, and in fact the interval between prime and tierce is only 25.5 Hz. This has two effects. First, although the beats between prime and tierce are too fast to hear, acousticians tell us that tones of about 25 or 30 Hz apart are maximally discordant. Secondly, since prime and tierce are similar modes of vibration (each having a single nodal circle, but at a different height above the soundbow) they may interfere if the frequency is this close and reduce the bell's resonance. Certainly, it is noticeable that both partials have the same intensity, as if they were interacting. Whatever the explanation, a prime as sharp as this is going to make for a bell with a most unusual timbre. In addition, this bell has a very flat hum, and no sooner has the ear recovered from the jarring strike but the hum chimes in and makes the tone of the bell sag mournfully.

The ninth has a sharp prime, though not as extreme as the tenor. It's saved a little by not having a flat hum. The tenor, being light for it's note, is presumably very thin. I wonder if there is enough metal in the ninth and tenor to allow the primes to be flattened, which is usually done by tuning high in the waist? One suspects this was done for the eighth in 1974, given its accurate prime. The bells go well, and despite their tuning are well worth ringing.


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Last updated August 16, 2001. Site created by Bill Hibbert, Great Bookham, Surrey