Step No. 1
Centering The Head
N.B. Before beginning this process, make sure that the drums are acclimated to the environment, the room is quiet and between 72 and 78 degrees Fahrenheit, and no air is circulating directly above the drums. (see Environment and Timpani Pitch)
1. If at all possible, the day before you start the tempering process, clean the surface of the head thoroughly with a non-caustic glass and surface cleaner to remove any salt, dirt or grease which may have accumulated. Excessive dirt and other unwanted residue can keep the head from vibrating evenly. If the head shows any dryness or damage from indirect sunlight or heat, evenly apply liberal amounts of a vinyl protector such as Armor All®; let it set for at least ten minutes, then work the protectant into the head evenly, and then completely wipe off any excess. It is recommended to do this both before after you have completed the tempering process. The vinyl protector will help restore some of the natural elasticity in the head. It helps to apply this to the heads routinely to keep them flexible. The heads come from the factory with a film coating on them but it dissipates over time. Be sure that the protector has been worked well into the head and that no excessive residue remains.
For balanced action timpani (Ludwig, Yamaha, Adams, Ajax, Majestic etc.), set the foot pedal all the way back to the floor with the heel of your foot. This will remove the head tension and should place the drum near the low-end of the MSR. For drums with a master tuner, loosen until the drum is at its threshold of pitch. Leave the drum(s) overnight in this position with all the tension off of the heads.
Center the head & check for a uniform collar.
The head can become off-centered simply by moving the drum improperly. If the head is not centered, loosen each lug the same amount and center the head on the drum. Measure the distance from the lip of the bowl to the counterhoop at four points on the drum (north, south, east and west) making sure that they are exactly the same. With a felt tipped pen, place a small mark on the head directly where the at the lip touches the bowl at these four points (NSEW). Use these marks as reference points to make sure that the head is always centered. It is best to place these reference marks on the head before it is mounted on the drum in which case you would simply measure the diameter of the drum at two adjacent points at the lip and then the diameter of the head. You then find the difference of these two measurements and then divide that number by two. Use this measurement and mark on the head at four points (NSEW) measuring from the very edge of the head in towards the center. When you mount the head, center the head on the drum making sure that the NSEW marks are right at the lip. For more information on this process, please see my article on mounting mylar/plastic heads.
If the head is not centered, the drum cannot be tempered properly and will never be able to create a desirable overtone series throughout the range of the drum. This crucial step, which is often overlooked, is easily fixed and “makes or breaks” the overall sound of the drum. This process insures the even tensioning of the fundamental (mode 0,1) frequency of the drum throughout the range of the drum; a frequency which is not heard as being the actual pitch of the drum yet it has a strong influence on the preferred modes that do. The principal tone or what we perceive as the pitch of the drum is determined by mode 1,1, which is actually the second partial of the vibrating membrane .
diagram courtesy of the Yamaha Corporation
Return the lugs to the low note position of the MSR (the lowest and highest pitch at which you want the instrument to sound) once the head is centered. For drums with a master tuner, leave the instrument at its threshold of pitch.