F+ (pitch)
Musical pitch for Northumbrian smallpipes / From Wikipedia, the free encyclopedia
F+ is a musical pitch approximately 20 cents sharp of modern concert F (500 + 20 = 520 cents), and is primarily associated with the Northumbrian smallpipes.[1]
![Thumb image](http://upload.wikimedia.org/wikipedia/commons/thumb/f/ff/Wolf_fourth_on_C.png/320px-Wolf_fourth_on_C.png)
Similarly, composer Ben Johnston uses a "−" as an accidental to indicate a note is lowered 21.51 cents, or a "+" to indicate a note is raised 21.51 cents (which is the width of a syntonic comma.[2][3] 498.04 + 21.51 = 519.55 (Just perfect fourth + syntonic comma = F+).