Drum Shells

I would like to give credit to Gene Okamoto and David Howe of Pearl Drums for giving permission to use information from their web site for this page. If you want to check out their site, it's at: pearldrum.com



Why are drum shells made of wood?

I will say that, in general, the harder the wood, the better it sounds. The harder and more dense a material, the more evenly it will vibrate. When it vibrates evenly and as a whole, it helps to create even tones when struck or during coupled vibration, as with a drumhead. There are all kinds of exotic hardwoods in the world and many of them are harder than what is generally used. But in order for a wood to be considered economically feasible for mass production, it must be inexpensive, workable, and attractive. To be inexpensive, a wood must be in great quantity in the world. To be workable, a wood must have a long, straight, tight grain, with few knots. It must also be dense enough to be hard and strong, but not so dense that it can not be bent into a circle. To be attractive, it must have the same characteristics as for being workable, as well as a pour structure that is pleasing to the eye and takes stain well.

Some woods that fit these categories are Maple, Birch, Beech, Poplar, Ash, and Mahogany (or Luan). There are different species of each of these, grown in different areas of the world. Each will have differing characteristics, but still close enough to be thrown in with their respective names. ie: We won't be differentiating between Canadian Rock maple and any other kind of maple, or between Scandinavian birch and any other birch. Many low end drums are made of wood such as eucalyptus, basswood, tulipwood. Some companies combine these woods with Maple or Birch outer plies. Since these woods are not very tonally pleasing, and are only used to lower the cost of the drum, at the sacrifice of the sound, we won't get into them.

Maple, Birch, and Luan.

But Maple, Birch and Luan each have different tonal characteristics, so lets take a look at those.

The diagrams below were provided by Gene Okamoto and the folks at Pearl Drums. Keep in mind that what most companies are using for their Mahogany shells, that we refer to as Luan, is not the same African Mahogany that Pearl is referring to in these diagrams, but a much cheaper, less attractive, and less tonally pleasing species.



Slightly boosted lows with smooth

mid and high frequencies for all

around applications.



Boosted high frequencies, slightly

reduced mids, and a good low end

punch for applications requiring

extra presence and cut.



Extremely rich low end frequencies,

with beautifully smooth mids and a

slight roll-off in the higher frequencies

for applications requiring ultimate

"bottom" and punch.

Many people describe Maple as being "warm" and even in its frequency response. Birch is often described as "bright," because it produces more high end than Maple. The bottom line is, like most musicians, we can get pretty anal about our equipment. Because of this, we hear minute little differences that most normal people would never distinguish. Any of these woods, with the exception the luan that budget drums are made of, will produce an equally wonderful tone. If you have certain preferences about the frequency response for your drums, choose accordingly.

Shell Thickness

Making shells from many plies, instead of one thick piece of wood, adds strength and stability to the shell. By alternating the grain of each ply, a thinner shell can be made that ends up being stronger than a thicker, solid piece of wood. It also will resist warping, as each ply has a different direction to the grain.

Gene Okamoto at Pearl Drums, provided the following diagrams about how shell thickness effects the sound of a drum:

The number of plies effects how readily energy is transferred from the

heads to the shell. This single factor has a profound effect on the tonal

characteristics and projection of the drum.



Thin shells (4 ply, 5mm) enable relatively easy energy transfer from the

heads to the shells thus causing the shells to vibrate. This vibration

imparts a very rich "wood" tone to the overall sound that can be most

appreciated in near-field applications and especially in recording.



Medium thick shells (6 ply, 7.5mm) have greater stiffness and resist

energy transference from the heads. With less shell vibration, a trade-off

is achieved: the sound is slightly "cooler" than thinner shells but

projection is greater. Drums made to this thickness are ideal for

general-purpose applications and / or situations requiring more

"horsepower."



Thick shells (8 ply, 10mm and 10 ply, 12.5mm) are extremely "efficient"

and allow most of the player's energy to be focused to the audience. These

drums are ideal for coliseum-type venues and other applications requiring

high sound pressure levels. Snare drums made in this thickness rival metal

snare drums in intensity and projection.

Shell Sizes

We all know that the bigger the diameter of a drum, the deeper it will sound. For example: a 16 inch floor tom sounds much lower than a 12 inch tom. The depth of the shell also effects the tone, as well. The deeper the shell, the lower the sound and vice versa. But the depth effects more than the tone of a drum. A deeper drum will also be louder and therefore project more. A shallow drum won't project as well, but it will have better resonance and a purer tone. This is why power toms became so popular in the 70's, for rock music-- projection and low end thud. This is also why smaller drums are so popular with jazz music-- cleaner, fundamental tones.

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