The Prime and Subprime Octaves in Tuning
The Prime Octave
In discussions about tuning, it is common to use descriptive shortcuts to simplify communication. One such shortcut is the term “Prime octave,” which specifically refers to the A3/A4 octave or the A3-A4 octave. This designation helps clarify which octave is being discussed without repeatedly specifying the notes or the note range.
Definition and Notation
The Prime octave encompasses the notes from A3 up to and including A4. A hyphen between two musical notes (e.g., A3-A4) indicates a range of notes. Therefore, A3-A4 represents the complete span of notes from A3 to A4.
When a slash “/” appears between two notes (e.g., A3/A4), it refers to the interval between those notes. In this context, A3/A4 denotes the interval of an octave, referred to as the Prime octave. Thus, the Prime octave is both the interval between A3/A4 and the range of notes stretching from A3 – A4.
The Subprime Octave
Following the same logic, the term “Subprime” is used to describe the octave immediately below the Prime octave, specifically A2 – A3. Like the Prime octave, the Subprime octave can refer to both the interval (A2/A3) and the range of notes (A2-A3) between and including A2 and A3.
Intervals Within the Octaves
Within the Prime octave (A3-A4), there are two important intervals known as the “Prime 5ths.” The lower Prime 5th: A3/E4, and the upper Prime 5th: D4/A4.
Similarly, the Subprime octave (A2-A3) contains its own pair of “Subprime 5ths”. The Lower Subprime 5th: A2/E3 and the upper Subprime 5th: D3/A3.