Access to the adjustment nut is on most truss rod systems possible either from the peghead end or the body end of the neck. Peghead-end nut adjustment cavities should be kept as small as possible in order to not weaken this part over and above what is necessary. Avoid hex nuts, if possible, as they require a lot of space (which is not easy to find at the peghead side) to allow getting at them with an adjustment wrench. Allen nuts on the other hand make ideal adjustment nuts as they require no room around them and the allen key can be inserted right into the nut (similarly with cross slot nuts).
When access to the nut is on the body end of the neck a small cavity can be made in the body so that the neck does not have to be removed to allow adjusting the nut. If the guitar is to have a front pickup, at least 20mm (3/4") of space should be left for a recess to allow getting at the adjustment nut and adjusting the truss rod with an allen key or a wrench without having to take off the neck. If necessary, the allen key can be shortened with a metal saw to enable access to the nut. Another option would be to install one fret less on the neck and to make an adjustment cavity in its place. Cover the cavity with a small metal plate. This makes it possible to place the pickup right next to the fingerboard.
Some effects on sound
The position of the pickups has a strong influence on the sound. Since there is only a limited amount of space left between the bridge and the end of the fingerboard, guitars with more than three pickups are very rare. A pickup fitted closer to the neck sounds bassier, whereas one mounted at the bridge sounds brighter. The front pickup is fitted in an area where the strings vibrate more, while the pickup further back picks up the less wide vibrations of the strings. Normally, the rear pickup's output is somewhat higher to compensate for differences in volume levels.
Due to the fixed distances between their polepieces conventional pickups do not allow much variation with regard to positioning - as already mentioned, the strings have to be precisely above the polepieces. Pickups with blade polepieces leave more options for positioning, but the blade always has to be wider than the distance between the two outer strings.
Sustain |
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Sustain is the length of time over which a string sounds after |
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being plucked - the longer it does so, the better. Getting a lot of |
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sustain is one of the declared goals of guitar-building. Stopping a |
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vibrating string, on the other hand, is no problem. The length of |
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sustain depends less on the density and weight of the body or the |
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material used for making the neck than on the stiffness of the |
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entire system. Here's an example: a string mounted on the |
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narrow side of a piece of wood (a) will vibrate longer than one |
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mounted on its broad side (b). Although the mass is the same in |
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both cases, the first way of mounting gives a much stiffer system |
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as less energy is withdrawn from the string. When mounted on |
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the broad side the resistance to bending is much lower and the |
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board “swallows” the energy of the vibrating strings far more |
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quickly. This explains why a guitar with a stiff and firmly fixed |
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neck and a body made from a lighter type of wood such as alder, |
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swamp ash or even poplar can give more sustain than a guitar |
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with a heavy, dense body and a “soft” neck. |
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Because the neck-body joint is approximately in the middle of |
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a string, it is extremely important to have a good, firm joint to get |
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maximum stiffness and a long sustain. This is easier to achieve |
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on guitars whith stiff, straight-through neck, but is also possible |
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on guitars with bolt-on or glued-in neck as long as the joint is |
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well made. |
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Consider every detail that might withdraw energy from the |
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strings' vibrations: inserting a cardboard shim under one of the |
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saddles can be sufficient to dampen the strings' vibrations and to |
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give a strongly reduced sustain. A loose saddle or tuner shaft |
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vibrating with the strings can have the same bad effect. A well- |
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fixed solid brass bridge will give more sustain than a thin metal |
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plate with saddles. |
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Making the system too stiff, however, is not advisable, either, |
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as it would then not be sufficiently stimulated by the strings and |
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a loss of some of the elements of the sound would be unavoida- |
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ble. Although an electric guitar made of stone would most |
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certainly have an “endlessly long” sustain, we would no doubt be |
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less impressed with its lifeless, sterile sound, let alone the weight |
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of such a guitar which nobody could put over their shoulder. |
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Mahogany necks can be made stiffer by using a quartersawn |
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neck blank. Conversely, a very stiff maple neck can be made less |
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stiff by using flatsawn timber, resulting in a mellower, warmer |
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attack. |
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