diatonic

i was curious about what diatonic actually ment so i went to the glossary on this site and it wasnt there, i wasnt really that shocked though. does anyone know? ive been watchin a tv series called how music works and the guy says "a system where all singers and instruments could play together" although everyone relates to it as the major scale, but it could be almost any scale (not melodic minor though) couldnt it?

The word Diatonic means to stretch or stretch out. In music it's relating to a musical scale, major or minor, but consisting of intervals of 5 whole steps and 2 half steps. If this is the basis then melodic would be in that group.

Diatonic scale refers to a group inside another group (Heptatonic or seven note scale) of scales. Other scale groupings include Melodic and Harmonic Minor and Hungarian Minor.

Diatonic refers to a particular grouping of notes. There are loads of different opinions, as with most things in music. Some people will tell you that diatonic refers to every scale in western music because, in the end, they are all connected via the chromatic scale. Others will say, only the "White Tones", i.e. C Major or C D E F G A B.

To me, however, when something is diatonic is means whatever you make it mean. For example, If I were to be playing all the "white tones", then everything relative to C Major would be diatonic... D Dorian, E Phrygian, F Lydian, G Mixolydian, A Aeolian and B Locrian.
The same thing would apply if I were playing in A# Major or F Major; all relative scales would be considered diatonic.

Basically, I believe to play diatonic is to play within a tonal expression or voice. If I am playing a riff that is voicing the chromatic scale, then any note I play will be diatonic. If I am playing something that voices C major, then, so long as the notes I am playing still voice C major, I am playing diatonic; even if I play notes outside of C Major.

Hope that helped.

«Rock on!»

I think a more simple way of looking at it is to look at the opposite of diatonic which would be atonic or atonal. Atonal is without a central tone or key Like the chromatic or whole-tone scale. Diatonic scales have a central tone or key like in all the modes.