I'm fairly new to learning music theory at a basic level. I understand notes, triads, intervals and how to read sheet music but I am struggling to understand key scales and how and when they apply and how to use them correctly to create melodies. I understand chords and how key scales affect the tone/emotion of the chords and overall track. I've written a melody that I like which is: A# F# F D# C# D# F# F G#

I believe it is a A sharp minor scale. Would I need to change the natural F as it isn't in that scale in order for it to work, is that what you would call out of key? Can you play one note out of the scale if it sounds better to you or fits better with what you are writing, would that be out of key or is there a name for this? Do you need to apply the same scale to every instrument you're working with?

Is my thought process and understanding correct? If not, please could someone explain?

  • One point: Yes, F has to be notated as E#. Commented Jan 10, 2021 at 21:27

3 Answers 3


To try to help you understand - had you written this in key Am, the notes would be ABCDEFG. Making them all sharp takes the 'E' to E♯, while the F becomes F♯.

However, as Aaron states, that key, same sounding notes in 12 tet would be better known, written and read as B♭m. Reason being, two fewer 'accidentals' in the key sig.

So many questions here seem to be based on the 'rule' that pieces need to only contain diatonic notes - those which belong in the scale of the piece's key. Whilst generally speaking, lots of tunes actually do that, there are many that manage to fit in some of the five that are 'out of the scale'. I mean 'not included in the scale'. There is no such rule, although possibly it's a safe guideline for beginners!

Usually, when other instruments join in, they will all be playing in the same key. Bit like language - it's easier if during a conversation, the partcipants all use the same. Having said that, let's say a piece is in key C, Then actually, a trumpet would be looking at dots written in key D, although what notes that come out at the end actually belong to key C. Trumpet is a transposing instrument.


The A# minor scale is more typically written as Bb minor -- A# and Bb being the same pitch.

Bb Minor
Bb C Db Eb F Gb Ab Bb

A# Minor
A# B# C# D# E# F# G# A#

Note that the two scales comprise the same pitches, spelled differently, and in particular F and E# are equivalent.

One can certainly use pitches that are out of the main key -- or even change keys altogether -- if that's what best serves your music. And separate instruments can play "out of key" pitches as well. Should you consistently have instruments playing in two different keys from each other, the music would be "bitonal". Multiple instruments consistently in different keys from each other would be "polytonal".


The scales are just a formality. Yes, you can play notes not from the scale. Try like beat the drums only on the keys-that's how to play the piano.

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