Tag: problems

…How your timpani has gone from sounding good to bad.

(Every Percussionist Should Know…)
…How your timpani has gone from sounding good to bad.

My intention with this article is to explain how your kettle drum works acoustically to create a harmonic pitch.  I have simplified everything considerably for clarity and brevity.  Once the fundamentals are understood you will then be able to find out what has happened to your drum, and come to the realisation that you really do need expert help!

Right at the very beginning, Preschool Paul, whilst out walking with his parents threw a stone into a pond and watched the ripples.



Because this pond just happens to be perfectly round, the ripples bounce back off the banks uniformly.  It creates a nice symmetrical pattern.  When applied to your kettle drum, this would represent the perfectly pure note.  The stone represents the timpani stick and I know a timpani is played at the edge, but that is because of more advanced acoustical reasons which do not contradict this acoustic model.  The ripples are sound waves.

However, if the pond was elliptical then some sections of the circular sound wave would be reflected off the bank before other sections.  Your drum now sounds awful because the interaction between the original and reflected sound waves are inharmonic. (This will be explained in another article if I ever finish it!)  The same thing would happen if your timpani bowl has been squashed and you have a flat spot.

wpid-wp-1435049671973.jpg

However it gets more complicated, because we live in a three dimensional world.  In the diagram below, the drum looks circular when viewed from directly above, but as the image rotates around the centre line as if to view the bowl from the side, it can be seen that the top half creates the expected ellipse, whereas the bottom half undulates up and down.  This could be because something has dropped onto the drum from above.  At the bottom left you can see the “acoustic” shape that this bowl would create.

wpid-wp-1435050147365.jpg

Because the bowl shape doesn’t vary when timpani are played, then any defect in the roundness of the bowl will affect the entire playing range.  It is relatively easy to return an elliptical bowl back to round – I do it every time I change a head, however if the bowl is egg shaped things suddenly get harder, and if it’s not flat they become harder still.

Timpani don’t just play one pitch, they have pedal mechanisms that adjust the tension of the head.  Now we know how to get a good note, it is easy to understand that if the tuning linkages are pulling one part of the head harder than another, then acoustically, this is like changing the shape of the bowl away from circular and harmonic.  This manifests itself when the kettle drum sounds good at one pitch, but gets worse as you move away from that pitch.

However, timpani always sound better at lower pitches, so a 26″ will always start to sound a bit iffy at higher pitches because they are no longer capable of working properly from an acoustical stand point, and anything smaller just doesn’t work.  As players, you will probably agree with me in wishing that composers would stop trying to get timpani to play top A’s and above – they would be better using a roto-tom!

…How to adjust Ludwig Timp pedal.

(Every Percussionist Should Know…)
…How to correctly adjust the balancing action on a Ludwig timp so the pedal doesn’t creep.  The video below explains how to do it properly.



Below is a cross sectional drawing of the ludwig mechanism:

wpid-img_20150115_0902542.jpg.jpeg

So as the pedal (1) pushes down it pulls the central tuning rod down (5), which stretches the head to get a higher pitch.  The spring adjustment screw (2) winds the spring towards itself making it tighter, so the spring is pulling in the same direction as the pedal movement, ie. pulling in the opposite direction (in the mechanism) as the drum head.

The problem in the design is that the elastic properties of the drum head change with the diametre of the drum, but the same spring is used throughout.   The further a spring is stretched, the harder and harder it becomes to stretch it; these properties of a spring were used to good effect in exercise products:

wpid-screenshot_2015-01-15-09-23-102.jpg.jpeg

What this means in the real world is that on the larger drums the spring is too powerful, and on smaller drums not powerful enough.  It is however way more complicated than that, but you just don’t need to worry about it, let’s face it, the manufacturers don’t even understand it, otherwise they would use the correct springs!

Obviously this problem quickly became apparent as Ludwig increased the range of drums they made, so the solution was to put a bicycle brake caliper in the only place they could put it, between the pedal and the balancing mechanism.  And there it has stayed ever since, through many “completely new designs” that the company have launched over the years.