The banjo is a four-, five- or (occasionally) six-stringed instrument with a thin membrane stretched over a frame or cavity as a resonator. The membrane is typically a piece of animal skin or plastic, and the frame is typically circular. Early forms of the instrument were fashioned by Africans in Colonial America, adapted from several African instruments of similar design.
The banjo is frequently associated with country, folk, Irish traditional and bluegrass music. Historically, the banjo occupied a central place in African American traditional music, before becoming popular in the minstrel shows of the 19th century. In fact, slaves both were influenced by and influenced the early development of the music, which became country and bluegrass, particularly in regards to the innovation of musical techniques for both the banjo and fiddle. The banjo, with the fiddle, is a mainstay of American old-time music.
Though many people think that the banjo is the all-American instrument, born and developed in the good ol' U. S. of A., they're only telling you a partial truth and a very small part of the whole story. What they are thinking of is the 5-string banjo donned by such greats as Earl Scruggs and Bela Fleck. It's the most prevalent type of banjo in many popular styles of American music such as Bluegrass, Dixieland, and Country, so naturally, being exposed to no other types of banjos, one would assume that the 5-string IS the banjo.
In reality the banjo originated hundreds of years ago somewhere on the African continent. These instruments were quite simple and rough - an animal skin tacked on to a hollowed half of a gourd with three or four strings stretched over a planned stick (keep in mind, too, that there were no such things as frets back then). The strings were often made from waxed horsehair or gut. One name for this instrument was the banjar. (Isn't it interesting that the pronunciation of this native-African word from ages ago is still being used by the back-woodsy American folk of today?) Anyway…
The banjo didn't actually make it to America until the African slaves were forced to come here in the 17th Century. Because the materials used to make a crude version of this instrument were readily available, it spread among the plantation workers in the South quite easily. Eventually, in the early 1800's, a few whites learned to play, such as the notable Joel Walker Sweeney, who learned the instrument from the people working on his father's farm. Because the instrument was a novelty to many Americans, Sweeney was able to tour the East Coast in the 1830's with some success. He played in a style that is similar to what is known today as "clawhammer" or "frailing." This technique was the standard for the Africans of the day. Clawhammer (my personal favorite - you should all try it some time!) is a very rhythmic way of playing. It is achieved by striking down on the strings with the nail of one of the fingers and plucking back up with the thumb. It is not understood for sure who developed the short fifth string, but by this time it was definitely in use.
As the Civil War rolled around, some musicians (probably influenced by the guitar) turned away from the old style of playing and started finger-picking the banjo. Players such as Frank Converse started publishing instructional books in this new style and thus it gained great popularity rather quickly. Interestingly, the people isolated in the Appalachian Mountains were not privy to this new technique and, as a result, we still today have the old African style of playing represented in clawhammer.
Simultaneously, major changes to the banjo were happening elsewhere. Having had much success in America, the minstrel performers of the 1830's, 40's and 50's traveled over to Europe and the British Isles. As the popularity of the banjo spread there, novel approaches to the instrument were developed. By the early 20th Century, these changes had taken hold both in Europe and in America. The most important invention was the use of metal strings and a pick (also called a plectrum). With the use of a pick, the need for the short fifth string was no more, so new banjos were made with the same neck length, but with only four strings. This came to be known as the Plectrum Banjo. Tuning for this instrument was similar to the 5-string (but I'll map that out down below). The Plectrum Banjo gained great popularity among American Jazz players and Vaudeville entertainers in the early 20th Century, but nearly died out until it experienced a revival in the 1960's and 70's.
Another spin-off of the plectrum banjo was developed in the early 20th Century. This was known as the Tenor Banjo. The need for this instrument arose from the plectrum players who desired an instrument that catered more to the styles played at the time in Ireland and England, as well as to some entertainers in America. As a result, the length of the neck was shortened and the tuning was altered to something akin to the fiddle.
Fortunately for us, all three of these banjos (the 5-string, Plectrum, and Tenor) have not died out. Today they are used in many different musical genres and in many different countries.
But enough storytelling….
Here's the breakdown of the basic differences between the three types of banjos:
The Plectrum Banjo: It has a full-scale neck with 22 frets. Most often it also has a resonator (that wooden bowl on the back) and a tone ring (a metal ring placed under the head that affects the volume and tone). It has four strings and is played with a pick. The strings from high to low are tuned: D G B C.
The Tenor Banjo: It usually has the same construction as the Plectrum (resonator, tone ring, four strings, etc.), but the neck is shorter and has between 17 and 19 frets. From high to low, the strings are tuned: Either A D G C or E A D G (often by Irish musicians).
The 5-String Banjo: The 5-string actually can be broken down into two major types: the Open-Back and the Resonator.
Open-backs are generally more simply constructed. These banjos are less expensive because they require fewer materials and are easier to make. They are popular among Clawhammer players and Old-Time musicians. Clawhammer players who seek a more "plunky" tone often put skin or synthetic-skin heads on these banjos and can even use nylon strings. Usually open-backs don't have a tone ring, either. Old-Time musicians use a number of tunings, but these seem to be the most popular: The standard g D G B D, the modal g D G C D, or the "Double-C" g C G C D.
Resonator Banjos are much more complicated. They too have 22 frets and five strings, but that's where the real similarities end. As the name suggests, they have resonators, the wooden back that projects the sound forward. They always have metal strings. Most have a tone ring, but all have a flange (that's the metal around the body that extends to the edge of the resonator). This feature can be highly decorative, but is primarily used to attach the resonator to the banjo. The heads are synthetic and are stretched much more tightly than on an open-back. This is preferred by Bluegrass musicians for the volume and "pop" that it gives when using finger picks. The standard tuning is: g D G B D.