This thread actually seems to be about tempered and untempered pitch. Any fretted or other non adjustable (by the player) instrument is, these days, invariably tempered - where all the semitones are of equal size to each other. A tempered scale uses notes that fall on the harmonics of the root (tonic) note. People who are particularly sensitive to natural harmonics find equal temperament offensive. As stated above - equal temperament is a compromise designed to allow changes of key with the least offense! J.S. Bach wrote his 48 Preludes and Fugues to argue (or demonstrate the need for) for equal temperament when a keyboard instrument changes key. (For anyone who is wondering about 'cents' as cited above - a 'cent' is one hundredth of a tempered semitone) TomB