Dating a gibson 4 string tenor acoustic guitar
The tenor banjo's sharp and cutting sonority, partly derived from its tuning in fifths, compared to that of the more mellow six string guitar, was particularly suited to the newly emerging, but still primitive, technology of acoustically recording this type of music onto acetate or metal discs which were then used as moulds for pressing the familiar black discs.
It is not surprising, therefore, that some of the earliest tenor guitars were also built by banjo manufacturing companies which they could possibly have seen initially as a way to expand their markets, and then eventually maintain their markets.
The tenor guitar (and the tenor banjo) are thus tuned CGDA which is in "fifths", where the C is the note one octave below middle C and the A is referenced as an A440 because it has a frequency of 440 Hertz (Hz) where 1 Hz is one cycle per second.Because it is tuned in fifths, chord voicings are much more spread out than they are on a 6 string guitar.This is why if a "C" chord played on the six string and a "C" chord played on the four string tenor guitar, the tenor guitar "C" will sound much more 'open'.Two of the major guitar manufacturers of the twenties that still exist today, Martin and Gibson, along with some other banjo manufacturers of the period, started to manufacture tenor guitars in significant numbers towards the end of the 1920s.
In the case of Martin and Gibson this was in 1927, and it is undoubtedly linked to the beginnings of a trend away from the banjo, as the main rhythm instrument in jazz bands and dance orchestras, and towards the guitar, whether four or six string.
The violin, viola and cello all have four strings each, whereas mandolin family instruments have eight strings in four pairs or 'courses' that are each tuned to the same note, usually in unison but sometimes an octave apart, similar to what is seen in the tuning of the various pairs of strings on the twelve string guitar, the two highest of which are unison and the four lower of which are octaves apart.