Drum Mechanics
WHAT IS A DRUM?
It is a cylindrical object (also know as a shell) with an open top that has a membrane (also known as a head or skin) stretched across it. That is known as a membranophone. The drum is struck on the membrane to produce a tone.
WHAT ARE DRUMS MADE OF?
Drums can be made from any material that can be formed to meet the above description. The main materials used are wood laminates (maple, birch, beech or mahogany). Cheaper sets are made of lauan (mormally called hardwood). Top end kits are made of jarrah or ironwood. Drum makers can make drums from solid pieces of wood either glued together or hollowed from a single log. Less known drums can be made out of plastic or fiberglass.
WHAT CAUSES THE TONES?
A drum is fitted with either one or two heads on the open ends of the shell. The drum is struck which creates vibrations that are modulated and radiate out from it. These vibrations are heard by the ear as a single note plus harmonics and overtones. The shell and head properties dictate the timbre and tone in a manner which will vary with many factors. A lot depends on the bearing edge, diameter, thickness, depth, internal construction, number and type of laminate plies, internal shaping, choice of heads and how you have tuned the drum.
The bearing edge is the only spot on the drum that the head touches. The top of the shell is cut so that it comes to a point between the outer edge and the inner edge. Normally it is at an angle of about 40 to 45 degrees and have it offset towards the outside of the shell. The sharpness of the edge is important to how the drum will sound. A sharper point will make the resonance within the head greater. It will also allow more of the vibration to be passed to the hoop, which will give more to the drum sound. A more rounded edge will be less bright in tone and a more woody sound because more of the vibration is absorbed into the drum. Check the bearing edges every time you change your heads. They are fragile and any dips, cracks or divots will definitely affect the tone of the drum.
RACK TOMS AND FLOOR TOMS
Rack toms are the toms mounted (usually) on top of your bass drum. They will range from 6 inches to 18 inches. Just like the name suggests, floor toms sit on the floor supported by 3 legs. They usually range from 14 inches to 20 inches. Both types of toms are made in the same manner as previously described. They are usually used for fills and patterns. You can tune your toms melodically.
BASS DRUM
It is usually the largest drum to the set, ranging from 18 inches to 24 inches. Although you can get bass drums larger than that. It sits on the floor with the heads in a vertical plane. They are made the same as previously described. For most drummers, the bass drum is tuned just above its lowest tuning point. The front head usually has a small hole in it to accomidate micing etc. It is played by a foot pedal that has a beater on it (the beater is made out of either wood, felt or rubber) and it strikes the center of the drum.
SNARE DRUM
It is the heart of the drumset. The head sizes range from 10 inches to 15 inches. The most commonly used sixe is 14 inches. Depths are as follows: 3 inches to 5 inches (piccolo), 5 inches to 5.5 inches (standard) and 6 inches to 12 inches (deep). The snare is almost always played with a single ply head. Although there are a lot of drummers that use twin ply batter heads to extend the life of the head. The bottom side of the snare is where it differs with the rest of the drums.
First the snare has a number of wire coils stretched across it. These vibrate and snap against the resonant head underneath. The bearing edge has a shallow flat cut spot into at two opposite points falling between tuning nodes. This is known as the snare bed. The resonant head underneath is only 3 to 4/1000ths (3-4 mils) of an inch thick. Being this thin makes it more responsive to the vibrations. IT 3 inches TO 5 inches (piccolo), 5 inches TO 5.5 inches (standard) AND 6 inches TO 12 inches (deep).
ONE OR TWO HEADS?
The choice of using either one or two heads is up to the drummer.
Using only one head will give you a clean and bright sound with a shorter sustain.
Toms with one head are known as concert toms and are less common than toms with two heads.
With two heads, you have a surface that is parallel to the batter head against
which the vibrations caused by striking the drum are reflected back and forth
against both heads. The vibrations are retained inside the drum longer.
The level of control that the drummer can exert over the movement and duration
of the tone, is a main advantage. For toms that have both heads tuned the same,
the vibrations bounce back and forth with each vibration quieter than the last,
until the sound dissipates. For toms that have the bottom head tuned either higher
or lower than the top head, they will be out of phase, giving a tone that decays
faster with a greater attack.
THE DIFFERENCE IN DRUM DEPTH
The depth has an effect on the overall sound of the drum. A longer drum will have a more and full and rounded tone to it. Longer drums take more of an effort to play because you have a greater distance of air between the heads. A longer drum will have less attack. It will be slower to respond but will have a fuller tone and longer resonance. A shorter drum will have the reverse effect.
HEAD ATTACHMENT
The head should be horizontal and centered on the drum.
RIMS (hoops)
The most common type is the flanged hoop. It is rolled into a shape by
a single strip of metal. Holes are punched into the hoop. These holes are
for the tension rods that hold your head and hoop on to the drum.
The flanged hoop is cheap and has a degree of flexibility, which will allow
it to sit evenly on your drum. Another type of hoop is the die-cast hoop.
It is cast from molten metal to a mold, which is the exact shape and size of the hoop.
It is a very solid piece of hardware.
There are also wooden hoops. The plies give the hoop strength to withstand the battering they will take and they
are very durable. These are the most expensive hoops to but with the
exception of gold platted hoops.
RODS AND LUGS
They are placed vertically in the holes of the hoops.
The tension rod fits into a lug, which it can be screwed into.
The lugs are attached directly to the shell of the drum.
It's always good to know the parts of your hardware.
