“In tuning timpani, the accuracy will depend ever so much on how absolutely clear the head is tuned at every spot. There must positively be no falseness and this is one of the most difficult phases of timpani playing to master.”
For timpani to produce a true pitch, a sound that is rich with near harmonic overtones, the instruments must be adjusted or tempered properly. I use the term temper which means to adjust. By this I mean the process of adjusting the head so that the pitch is uniform and consistent throughout the range of the instrument. You may also hear or use the terms clear or balance when working with timpani heads. These terms refer to the process of adjusting the tension at each lug until the pitch is uniform and consistent, but not necessarily for the entire range of the instrument. Well-tempered with respect to timpani pitch, means that all notes within the normal range of any drum can be tuned in such a way that the principal tone and upper partials will not sound perceptibly out of tune, and will blend well with the other pitched instruments in a ensemble.
Well-tempering will result in the drum having a long sustained principal tone, and a pitch rich in near harmonic overtones. When the instrument’s heads are well-tempered, the instrument is easier to tune, blends better with the ensemble, and is much easier to play. You will be able to produce a pure and focused pitch as well as a beautifully sustained principal tone throughout the range of each drum. The strong near harmonic overtones produced will not compete with those of your colleagues, but rather compliment them.
The full tempering process should always be done when you install and mount new heads or when a drum has lost its pitch center. How does one tell? Generally, if you hear any flatting or sharping after the drum is struck, or consistently sense a lack of definite pitch, or you have a difficult time tuning and blending with an ensemble, your drum needs tempering. A more precise way to check is to pick a benchmark position (usually your normal playing area) and strike the drum a few times softly and then once loudly and listen for a consistent, unwavering pitch (no rise or fall). You want the principal tone to sustain and predominate as well as have a good blend of upper partials which sound harmonic. You also want to make sure that the second of the preferred modes (mode 2,1) does not overpower the principal tone (see Pleading the Fifth).
Repeat this process at each lug position and compare. Your drum doesn’t need any adjustment if you hear the same strong predominant principal tone and similar near harmonic partials at each lug. If you hear any pitch wavering (flatting or sharping) at any lug or even a slightly different principal tone, then you will need to spend some time tempering the head. The color of the sound, i.e. the overtones or upper partials will vary at each lug, but the principal tone should be the same or vary by only a few cents.
Bear in mind, however, that Mother Nature will always have the final say in the harmonicity of your pitch because of the air loading of the head. As the density of the air fluctuates, so does the pitch and the harmonicity of the preferred modes. Knowing when to temper is as important as knowing how to temper.