whole tone lower than the tonic to one octave above it. The drones are tuned to this tonic note, called A (specifically A4). The nine notes of the chanter scale are "low G, low A, B, C (sounds as a C), D, E, F (sounds as a F), high G, and high A". However, the A pitch of most pipers and pipe bands currently is somewhere around 470–480 Hz, which is actually sharper than standard pitch B4 at 466.16 Hz. So the scale actually sounds closest to A, B, C, D, E, F, G, A, B, and can be considered a transposing instrument in D-flat major. Historically it was indeed flatter, as evidenced by recordings, and extant instruments. Highland bagpipe music is written in the key of D major, where the C and F are sharp (despite the key-signature usually being omitted from scores), however only some tunes are in D major. Due to the lack of chromatic notes, to change key is also to change modes; tunes are in A Mixolydian (most commonly), D major, B minor, or occasionally E Dorian. In concert pitch (notes on the piano) it will be B Mixolydian, E major, C Aeolian, or occasionally F Dorian. Traditionally, certain notes were sometimes tuned slightly off from just intonation. For example, on some old chanters the D and high G would be somewhat sharp. According to Forsyth (1935), the C and F holes were traditionally bored exactly midway between those for B and D and those for E and G, respectively, resulting in approximately a quarter-tone difference from just intonation, somewhat like a "blue" note in jazz. Today, however, the notes of the chanter are usually tuned in just intonation to the Mixolydian scale, with the G tuned to the harmonic seventh which is significantly flatter than the just minor seventh or the equal temperament minor seventh. The two tenor drones are an octave below the keynote of the chanter (low A), and the bass drone two octaves below. There are some documented examples of other tunings: Forsyth lists three traditional drone tunings: Ellis, A3–A3–A2; Glen, A4–A4–A2; and Mackay, G3–B3–C2. Modern developments have included reliable synthetic drone reeds as well as synthetic bags that deal with moisture arguably better than hide bags. The chanter reed is typically made out of cane. It is possible to get synthetic reeds for chanters but it is not very common.