3. Materials & Components
The top, or belly is made of spruce, a timber of plain, straight grain, while the ribs and back are invariably made of maple, often spectacularly figured. On student and generally cheaper instruments, it is not uncommon to see tops and even the whole body made of laminated wood. This is not entirely a bad thing while they might not make quite such a good sound as a natural timber bass, laminated instruments are substantially stronger and less prone to cracking with changes in temperature and humidity.
A bass with a well-figured maple back
The only other permanent external fixture is the fingerboard, which is made of ebony. Ebony is an extraordinarily heavy, dense timber - drop a piece into water and it will actually sink. The best ebony, after long seasoning in the sun, is a startling blue-black colour, and is used for the fingerboard because it is one of the few woods hard enough to cope with the wear that this part of the instrument is subjected to.
Machine Heads or Machine Tuners
Most other members of the string family tend to have one or more metal adjusters, or fine tuners fastened to the tailpiece, in order to make tuning the instrument a little easier. Not so the bass, which has an altogether more elaborate system of machine tuners built into the scroll. They are made of brass with steel worm gears and use a mechanical action to adjust the strings with relative ease and accuracy. While machine tuners can be entirely functional in appearance, some makers go rather more to town in this area, with elaborately engraved brass side plates and decorative shaped keys.
Spike or Endpin
Both cellos and basses are fitted with a spike which retracts into the body of the instrument when not in use. While cellists use it to raise the body of the instrument up for ease of playing, on a bass, the spikes main function is to locate the instrument safely on the floor. As it has a sharpened point at the end, it is best treated with the care and respect appropriate to all sharp steel objects. It is probably worth mentioning that most bass players will, at least occasionally, have fallen foul of the owners of the various floor surfaces they play on. Some people, not unreasonably, will object to holes being made in floors that may be fragile, or old, or constructed from expensive materials. Fortunately, there are various options available to avoid this problem (see Accessories). By connecting the instrument firmly to the floor, the spike also improves sound projection. Anyone who has spent time in a room with a cello or a bass being playing upstairs will be well aware that most floors/ceilings become excellent sounding boards!
Unlike the bridges of violins and violas, which sit very close to the body of the instrument, bass bridges are raised up on what amount to a built-in pair of legs. All bridges are made of a specific type of maple and cut from the timber in a particular way, its design - like many of the apparently more decorative parts of stringed instruments - is the result of years of trial and error on the part of makers, and is largely functional.
Like the bridge, the soundpost needs to be positioned with great care to ensure the instrument sounds its best - a job that should be done by an expert using a special tool designed for the purpose. Very roughly, it stands close to the right foot of the bridge to share the tension of the strings between the back and belly of the instrument, and avoid the wood cracking under the strain. Remember, if you completely slacken or remove all four strings at the same time, it is very likely (without the considerable pressure of the bridge bearing down on it) that the sound post will fall over. Should this happen, do not, under any circumstances re-tighten the strings the potential consequences are obvious and repair will be expensive! Instead, take the instrument to a repairer to have the soundpost re-fitted - a very much cheaper alternative. The situation is best avoided in the first place by making sure that at least two strings remain taught at all times.