Is it OK to Notate Accidentals in a Sharp Key Signature?

Tom is correct, it is perfectly fine to have a flat accidental in a key with sharps in the key signature. However, it's important to note that if you are writing a flat accidental for a note that is already a sharp in the key signature, you should use a natural sign rather than a flat. For example, if you're in the key of G major and you need to write a C minor 6th chord (Cm6), you must spell it as C E-flat G B.

It is perfectly acceptable to mix and match accidentals as the situation demands. But if the situation doesn't call for it, you shouldn't combine sharps and flats indiscriminately. This is a common practice in traditional notation, although some modern composers have pushed the boundaries.

Conventional Notation Rules

Conventionally, a key signature will consist of either sharps or flats, but not a mixture of the two. For instance, D minor and G minor have flat key signatures, but because of the seventh note, they contain sharps. D minor starts with B-flat, but the seventh note C is raised, and G minor starts with B-flat and E-flat, but the seventh note F is raised.

Harmonic Chromatic Scale and Borrowed Notes

The harmonic chromatic scale includes borrowed notes from the subdominant and dominant minors of the home key. In the case of G major, these borrowed notes are from C minor and D minor. Generally, the harmonic chromatic scale uses the tonic and dominant notes only once in succession and no other note more than twice.

Practical Considerations in Musical Orthography

Musical orthography, the process of writing music, is a complex subject with countless instances where composers have not notated chords correctly. It’s important to understand the rules of proper musical spelling. The key signature is a convenient shortcut, but it does not inherently dictate the use of sharps and flats in the music. Rules about enharmonic spelling are based on function and identity, not the key signature notation.

Examples and Exceptions

For instance, when writing a C minor 6th chord in G major, you must spell it as C E-flat G B. This is due to the key of G major, which has a natural E and a flat A. However, in modern music notation, composers may occasionally mix sharps and flats for artistic reasons, even though performers may prefer not to see this.

Understanding these rules and exceptions is crucial for both composers and performers. It ensures that music is written and heard as intended, even as modern practices challenge traditional conventions.