Augmented seventh Adding a diesis to this makes up an octave. Hence, this interval's complement, the diminished second, is often referred to as a diesis. Augmented seventh In classical music from Western culture, an augmented seventh is an interval produced by widening a major seventh by a chromatic semitone. For instance, the interval from C to B is a major seventh, eleven semitones wide, and both the intervals from C to B, and from C to B are augmented sevenths, spanning twelve semitones. Being augmented, it is classified as a dissonant interval. However, it is enharmonically equivalent to the perfect octave. Since
Octave mandolin distinction is not crisp, and there are cases of each term being used in each country. Jimmy Moon, a Scottish luthier calls his version of the instrument by both names and Paul Shippey, an English luthier, uses the term octave mandolin. Confusion will likely continue as the terms continue to be used interchangeably. Octave mandolin construction is similar to the mandolin: the body may be constructed with a bowl-shaped back according to designs of the 18th-century Vinaccia school, or with a flat (arched) back according to the designs of Gibson Guitar Corporation popularized in the United States in the early