Drum Tensioning and Tuning
By Prof. Victor E. Lopez / Bomba Drum Artisan
“From our experience and library, as a contribution to keeping our Bomba culture alive. This article is written with emphasis on the Bomba drum as a percussion instrument.”
VL Tensioning and Tuning
Every musical instrument needs correct tuning in order to produce the desired sound and, as a result, excellent harmony. Percussion instruments are no exception. Proper tuning of a percussion instrument produces a combination of sounds that is in tune with the music it accompanies. For the hide (skin) to remain properly tensioned and produce the appropriate sound, the percussionist must have the knowledge to determine how far the adjustment should be taken so that the instrument sounds harmonious with the music.
Today, there are methods for tuning percussion instruments, such as tuning forks and electronic tuners, which are used to test sounds in relation to the instrument until the desired sound or timbre is achieved. However, tuning by ear continues to be the most common way to obtain the desired sound, especially with Bomba drums, because they follow a tradition in which tuning has historically been done in an indigenous and traditional manner.
Drums, timbas, bongos, drum sets, and related instruments can be affected by and are sensitive to changes in temperature and humidity, just as string instruments are. These changes can cause the hides to lose tension and the instrument to go out of tune. The lower the temperature (cold), the lower the tension; warmer or higher temperatures generally improve the sound. In several countries, fire or light bulbs are used to help maintain the sound of the drum. It is not recommended to over-tighten a drum when the temperature is cold. Moisture tends to stretch the hide, increasing the possibility that it may break.
Each drum has its own tuning system. Many are tensioned with heat, since higher temperatures can benefit the sound. For example, a wedge-tension Bomba drum is limited to a maximum tension. Other drums use screws or other adjustment elements that allow the hide to be tightened or loosened. There are also drums in which the skin is tensioned with ropes; in some cases, even animal gut has traditionally been used.
Tuning and Tensioning Methods
For fixed-tension percussion, it is recommended to apply heat before playing; this may even be done with a light bulb. Mechanical percussion systems using screws (eyebolts) are ideal because they allow adjustment as needed, always keeping in mind that the tension must remain uniform. The tensioners should be adjusted progressively in a triangular pattern, giving the nuts the same number of turns on each side. This helps produce a good sound and extends the life of the hide by maintaining equal tension in all directions.
Rope-tension drums lose pressure during use because of elasticity. Ideally, the ropes should be replaced when they are no longer applying sufficient pressure, or whenever necessary to maintain a good sound.
Fixed-Tension Percussion
The only way to tension the membrane (hide) is through exposure to heat, and the drum is tuned by ear. Fires may be prepared and the drums positioned at an angle near the heat. The hide loses moisture and contracts, becoming tighter. This is how the drum is tuned. This method is still used in some countries depending on the type of drum, although today most drums use adjustable tensioning systems.
Tensioning by Means of Wedges
Ropes are tied to the main ring surrounding the hide and extended at several points around the hoop so that the hide can be stretched and adjusted evenly. Wooden wedges are made and inserted at an angle through the side of the drum. The rope extensions tied to the hoop are secured to these wedges. By striking the wedges so that they move farther into the drum through openings made for this purpose, the hoop is pulled downward at each point, tightening and stretching the hide.
Using Screws or Mechanical Elements (Mechanical Tension)
The hide is mounted over a metal ring, providing greater stability for tensioning. The tensioning system operates through screws. A side plate serves as the base for the screw (eyebolt) and maintains the force applied by the eyebolt to tension the hide. Bomba drums generally use five to six screws, depending on the size of the drum, distributed at equal distances around the body.
The side plates vary in shape, material, and size. The eyebolts hook into V-shaped metal hooks welded to the main hoop or metal band. There may be five to six hooks. To apply sufficient pressure for tuning, an inner metal rod is used and the hide is interlaced with the main hoop, which sits above the inner rod, securing the hide between both elements so that tuning remains uniform around the drum.
Rope Tensioning
Tensioning with hemp rope is another method used on drums. In some cases, animal gut and natural leather tensioners are used. Ropes are tied to the main ring around the hide with double extensions long enough to pass through the inside of the drum and return through another opening so they can be tied under tension.
Holes are made according to the diameter of the rope, approximately at the center of the barrel and, on some drums, closer to the lower section. These openings allow the rope to pass into the drum and return outward. They are positioned perpendicular to the rope location on the main ring.
After the ropes are tightened, a piece of wood at least 1/2 inch in diameter and 4 to 6 inches long is woven between each double rope. The wood is rotated, twisting the rope into a tourniquet; with each turn, the tension increases. This stretches and adjusts the hide and helps achieve the proper tuning of the drum. In some cases, a tool may be needed to move the piece of wood from side to side and increase the adjustment and tension until the hide is evenly tensioned.
By Victor E. Lopez / Written: 7/25/2023 / Bomba Drum Artisan - CFI #24310