The European Timpani KETTLES
AND ACOUSTICS
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KETTLES
AND ACOUSTICS : Many
different factors influence how the kettle of each timpani will sound; the
many possibilities with regard to the size, shape, construction, bearing
edge (lip), thickness and composition of each bowl all influence the sound
of the drum. Over the hundreds of years of the history of the timpani as
an orchestral instrument, there has been much documented about the steady
increase in the diameters of each drum. Timpani makers were also
experimenting with the depth of the bowl, and how changing the ratio
between these two factors, diameter and depth, affected the sound. For
baroque timpani, where the depth and diameter are often close to equal,
the sound of the drum is clear and direct. A contributing factor in the
case of baroque timpani is the tension on the skin, which is less because
of the smaller diameters. With
timpani of the Dresdener design, the drum’s diameter and depth increased
at an equal rate, so that shape and profile of the kettle, either
hemispherical or parabolical, remained more or less the same. The Viennese
timpani on the other hand kept the same diameters as from early romantic
times, but the depth of the kettle increased dramatically giving it
something of an egg-like shape, or that of a vase (this design of timpani
can be seen in the televised concert given by the Vienna Philharmonic
every New Years Day). In this way was the volume of the drum increased –
but not its diameter – producing a full, round sound which is still very
defined and focused, and impossible to overplay. ‘The
fundamental difference [of
the Viennese timpani] to the Dresdner timpani consists of the
circumstance, that the skin is not drawn down over the kettle at the
tuning, but the free swinging kettle is moved up an down.’ – Prof.
Wolfgang Schuster, maker of Viennese timpani Dieter
Dyk - ‘One
can with whole strength can play it [the
Viennese timpani] in the largest
Fortissimo – still of course in a musical way - without it the sound
becoming overly loud, ugly or noisy.’[1] The
sound of these drums has also been described as “dark”, and so
maybe the depth of these kettles contributes to this tone colour, as
timpani with “multi-elipse” shaped kettles (straight sides angling
inwards before rounding out at the bottom, see below) have also been said
to have this type of sound. A parabolic reflector is the most effecient shape for the reflection of light waves, and some would say that this also holds true of sound waves. The curve of a parabola is such that all waves are reflected through a single focal point. The original Ludwig balanced action timpani were built with parabolic kettles and many, if not all, balanced action timpani available today also use this kettle shape. Finally note the distinctive shape of the Viennese timpani, egg shaped but still basically a parabola.[2]
Different Shapes of Timpani Kettles With
regard to how each kettle is constructed, there are two common methods.
One entails the pulling of a single sheet of copper over a mold, creating
a kettle that is not of uniform thickness, and in the other method the
sides and bottom of the kettle are formed from separate sheets of copper
which are then joined, a process which may inhibit the vibration of the
resulting kettle. ‘When
you shape a kettle by spinning [or
stretching] one single piece of
copper, the result is a kettle with a very thick bottom but thin sides,
which is not able to resonate evenly’[3]
Steve Schiffer, D. Picking & Co. (USA) In
the second half of the 20th century scientists began looking at
musical instruments, applying objective tests to determine how a
“good” sound is created. For the timpani kettle, they spoke of ‘ideal
depths’ and ‘proper
reflection of sound’. But the scientific information available on
bowl acoustics and the affect of design and construction on the sound is
scarce and often contradictory. So
we look to the players, who make little mention of construction processes,
or scientific models, but instead speak of how the shape and the thickness
of the kettle contribute to the sound of the drum. Conical shaped
kettles, such as those of the Ringer design, are said to have a more
focused and bright tone. Such kettles, also referred to as
“parabolic”, have a shallower curve in the shape of the base of the
kettle, which some players also attribute to giving the drum a darker and
heavier sound. On the other hand timpani with a more hemispherical curve
at their base give a ‘round, full
and warm sound’. The
thickness of the kettle has a major impact on how the instrument is able
to support the sound that the timpanist wishes to produce. One maker,
Christoph Dörfler, whose instruments are designed along the lines of the
Ringer timpani, builds the larger timpani with a thicker kettle to support
the volume of sound often required from these drums, and uses thinner
copper for the smaller drums so the sound is not thick and tubby. Dieter
Dyk -‘Thin material : more
sensitive in soft passages, not so strong in fortissimo. Thick material:
stiff sound played softly, with no good attack up to mezzo forte, but very
strong in fortissimo.’ The
bearing edge (or rim or lip) of the kettle, being the point where the skin
meets the kettle, and also the point at which the skin is stretched,
giving it tension, has an affect on the shape, or definition of the sound.
A sharp or hard lip will produce a much clearer and more articulated tone
than a soft lip, which makes the shape of the tone rounder.
Again the bearing edge can be tailored
to the size of the drum; a rounder bearing edge on larger timpani gives a
full sound to the low notes, with sharper bearing edges on the higher
drums producing a more defined articulation. Maarten
van der Valk – ‘The
lip has an influence by how the skin folds over the whole timpani. I
believe that with goat skin for instance a thicker lip works better for
the sound, rather than a thin lip’ Finally
regarding the materials used, the kettles of almost all professional
timpani are made of copper, a metal chosen for its ability to resonate
with a full and round tone (brass kettles also exist). For the older
timpani, which were produced individually by coppersmiths, a thorough
hammering of the kettle to bring out the richness of the drum sound was
considered a very important part of the construction process. Many of
these drums, considered vastly superior to their factory produced
counterparts, are still used in orchestras today. Peter
Offelder – ‘The
form and the hardness of the kettle make the sharpness of the tone. Also
the hammering!!’ Many
manufacturers also produce drums with fiberglass kettles, but their sound
is ’dull,
no strength, no real power’ and these instruments are only used by
amateur ensembles such as school bands. |
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