It is an alternate tuning that is constructed from ratios using only the prime numbers 1, 2, 3, and 5 as factors. It uses 19 tones that are harmonically related to each other rather than the 12 equal-tempered tones (12-TET) used in most western music today. Since the tones are harmonically related, chords using them sound richer than the same chords using 12-TET. The designation “5-limit” signifies that 5 is the largest prime number used as a factor.
To create your own sequences, follow these steps:
First, ratios of 3/2 and 5/4 are selected for the perfect 5th and major 3rd, respectively. Fifths are taken then from 1 below to 3 above giving tones 9, 1, 12, 5, and 16. From these, thirds are taken from one below to 2 above, except that 2 above tone 16 is omitted. This results in the remaining 14 tones. The following table illustrates this process.
Why do we stop at 19 tones? Well, the 20th tone would be an F lowered one tenth of a step. This difference is generally imperceptible and so we stop at 19.
To hear a comparison 5-19 JI to 12-TET, click on this short demonstration. First, a flute plays a series of chords switching from 12-TET to 5-19 JI at midpoint. This is then repeated by guitar. Then the flute plays a series of ascending fifths in 5-19 JI switching to 12-TET in the middle of the final chord.
All MIDI sequences are copyright © 1998, Brian M.Ames. Permission is granted for non-commercial use only. All other rights are reserved.