An acoustic guitar is so named because the hollow design of its body provides a natural means by which the acoustics can be optimized, so that the sound of the guitar is naturally amplified, and therefore needs no exterior or additional means of amplifying the sound. Electric guitars are quite different, and without an external, electrical amplifier, strumming or picking the strings will make almost no sound at all, and certainly nothing much more impressive than pinging a rubber band! It is for this reason that electric guitars do use external amplification, but there is a common misconception or misunderstanding as to what exactly the external amplification does.
Many people believe, quite wrongly in fact, that the external electric amplification of an electric guitar simply makes the sound of the string much louder. If you switch off the amplifier, you'll notice that simply making the resulting sound louder would be a pitiful quality of note, and despite its name, the amplifier does not simply make the sound produced by the string louder.
It is actually not the sound that the string makes which is detected, but its movement. An electric guitar is so named because effectively, each of its strings is a wire in an electric circuit, and it is by strumming or picking these wires or strings that movement is created. The harder the string is plucked, the greater its movement, and it is this movement or resonating that is detected.
The part of an electric guitar which detects this movement is called the pickup, which are basically magnets wrapped tightly round with very fine wire. As any electrician will tell you, a magnet wrapped round with coils of wire is an electric generator waiting to happen, and the vibrating movement of the string next to this mini generator is enough to create an electric current. This electric current is sent as a signal to the amplifier, and it is at this point that the tone, voice, sound, colour, and any distortion effects, are generated, and of course, the volume boosted.
Of course, many factors affect the eventual sound of the note, in addition to simply how hard the string is plucked. The thickness and manufacture of the string, how close it is to the body, the body's shape and design, the type of pickup, the number of pickups, to name just a few. Once the signal reaches the amplifier, all manner of different effects and distortions are possible to create an individual voice for the instrument.
Because the strings of a guitar are close together, and the pickups use magnetic vibrations, there is a natural tendency for these magnetic pickups to detect and pickup electromagnetic signals from other nearby sources - anything from nearby microphones, to other electric equipment in the area - even lighting. This extra noise is generally not overly distracting, but does tend to create a kind of background hum. Single coil pickups tend to create the most amount of background hum, and the fact that most electric guitars tend to be incorrectly shielded against any interference of this kind, this can be quite unwanted.
A solution to this hum was the development of a pickup which was created slightly differently to the normal ones. Instead of a single coil of wire wrapped round the magnets, two coils were used, but each wired to the opposite polarity, both electrically and magnetically. This meant that any electromagnetic noise that was detected by both if these coils was effectively cancelled out - like adding minus five and positive five, the answer is zero. This also had the added effect of creating a much fatter sound to the guitar too. Because these pickups were designed to cancel out the hum, they were named humbuckers, and are still extremely popular today. |
