A carillon is a musical instrument composed of at least 23
bells, arranged in chromatic sequence, and tuned for concordant
harmony. Chances are, you have listened to a church or university
carillon in the past, and didn't realize it. Many carillons play
church hymns and patriotic tunes, but it is also common to hear
Westminster chimes and bell strikes to announce the hour. The
sight and sound of a carillon tower is something you don't forget.
Many carillon towers are several hundred feet high, and contain
bells weighing over 10 tons. It has been reported that some of
the larger carillon and church bells can produce enough sound
energy to rattle the windows in nearby homes. These mammoth instruments
can reach audiences over great distances and yet have the ability
to produce pleasing music that has captured the attention of
people for many years.
A
mechanical carillon contains cables connected to wood batons
that are mounted in a carillonneurs keyboard. When the operator
strikes a baton with a closed fist, the cable and pulley mechanism
causes a clapper to strike a bell. Mechanical carillons have
been used for centuries, however, many improvements in sound
and mechanical design have occurred over the past few decades.
It is common these days to see a carillon or church bell containing
electrical wires and clapper solenoids instead of the cable and
pulley mechanisms used in the past. Bell designs and tuning have
also improved considerably in recent years. Hammer and chisels
have been replaced by lathes as the preferred technique for tuning
bells. Tuning forks have been replaced by spectrum analyzers
and computer modeling programs for characterizing the performance
and partial tones of a bell.
Electronic carillons
are another type of instrument that have gained popularity in
recent years. These designs
consist primarily of electronic components, but may also contain
some mechanical hardware. The success of the electronic carillon
is due in part to their low cost, flexibility, and automated
time scheduling of carillon music. In some instances, an electronic
carillon costs less than the price of a single bell in a mechanical
system. Many electronic carillons use a technique known in the
audio industry as "digital sampling". If you were to
record each bell sound from a nearby carillon tower, and placed
each bells recording on a separate CD track, you would have a
digital sampling of this instrument. If you we were able to connect
your CD player to a keyboard, you could play a carillon tune
that would sound just like the bells from the carillon tower.
Digital sampling may also be applied to other instruments like
church bells, tube chimes, harps, hand bells, and a host of other
instruments used by the church community. This kind of flexibility
has contributed to the popularity of electronic carillons in
the last couple decades.
One
of the obvious requirements for creating pleasing music is to
start first with a well tuned instrument. Many articles have
been written on the subject of bell tuning in the past and present.
Many bell manufacturers tune their bells by turning them upside
down and removing metal from the inside of the bell with a lathe.
The location and amount of metal removed from the bell changes
it's pitch and harmony characteristics. Each bell manufacturer
has their own technique and criteria for making what they consider
the correct bell tune. Bell tuning becomes a complicated process
due to the multiple tones produced when a bell is struck. These
multiple tones are referred to as partials. The frequency of
each partial is related to the metal alloy, thickness, dimensions,
and profile of the bell. During the tuning process, it is common
for more
than one partial to be effected at one time. Therefore, the bell
manufacturer must anticipate changes to all partials while tuning.
The connection that exists between multiple partials sometimes
requires a compromised tuning of the bell to satisfy requirements
for each. The correlation between these partials does not exist
when tuning bells in the digital domain. The frequency and amplitude
of each partial may be individually adjusted using digital processing
techniques. Therefore, it is possible to create a large variety
of bell and instrument sounds when working with digital sampling.
The bell partials may be adjusted for any desired amount of tint,
muffle, bass, flat or sharpness.