bill at ib_OriRs5rEZVHbFBoXTAQM1fSj1F5G8RsCXS9fW0OiDEvC1xP2-1yJTgrxr5FpXNfIzhI963w7HGfklOw.yahoo.invalid
Thu Dec 6 09:42:31 GMT 2007
Responses to various posts and questions:
> CSZ's question on the history of stretch tuning:
Stretch tuning (of e.g. 20 cents per octave or more) was the common
practice for higher numbers in the 18th and 19th centuries. Taylors
in particular used a huge amount of stretch in peals such as St
Pauls Cathedral and the old Worcester 12. Whitechapel (as RO's
posting of some while back showed) were tuning strike notes, not
nominals, until the 1920s which guarantees stretch if the trebles
are thicker than the tenors. Stretch tuning stopped with the
introduction of true-harmonic tuning, but as Andrew Higson says,
Taylors re-introduced it from the early 1950s until the 1970s. I am
aware of one stretched peal from Whitechapel from this period
(Cornhill 1958) but perhaps there are others I haven't come across.
> Rod's comparison of bell stretch with piano stretch:
In pianos, stretch tuning arises because the upper partials and in
particular the 2nd harmonic are slightly sharp due to the stiffness
of the piano string as it crosses the bridges. As a result, if the
octaves in a piano are tuned for zero beats, they will be slightly
stretched. The amount of stretch depends on the quality of the
piano's construction; high quality grand pianos need less stretch
than cheap uprights. As Rod says, a few cents in the octave is the
Stretch in bells arises for a completely different reason;
compressed upper partials (which occur in thick, heavy bells)
flatten the strike note. The effect is large: 25 or 30 cents is not
uncommon. Therefore, in a peal with thick trebles and thinner
tenors, if the trebles are not stretched some people will say the
trebles are flat, or dull sounding. I wrote an RW article on this a
while ago, I don't have the reference with me. My PhD research has
now proved the effect beyond reasonable doubt and provides a way to
calculate the effect, though you'll have to wait until it's
published to read the details. Investigation of half-a-dozen
stretched 19th and 20th century twelves gives satisfactory
correlation between theory and practice.
Stretch tuning is not at all to everyone's taste. In fact, there are
two modes of pitch perception experienced by different listeners,
and sometimes the same listener under different circumstances. Most
listeners hearing bells rungs close together in changes experience a
holistic effect (the strike note, shifted by the upper partials).
Other listeners, especially bell tuners, hear the individual
partials, particularly if one or two bells only are being rung.
> Richard Offen and St George's Perth:
Richard's comment that the trebles are thin is an important clue. If
this is so, the strike notes will not be flattened to the same
degree as for thick trebles. It sounds as if stretch has been
applied in a formulaic way to these bells when it was not needed.
Tuning figures (especially the octave nominals) would settle the
matter. Plus, Richard used to be a bell tuner ...
> CSZ quoting from Frederick Meyer, on carillon stretch:
This was an interesting account, which I had not heard before. In
carillons, of course, the little bells are not thickened up as they
would be for change ringing, and so the pitch shifts are much less.
Another experiment written up in the thesis investigates which
partials determine pitch in bells. In little bells (e.g. the top end
of carillons), the prime and/or hum take over from the nominal.
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