b flat major and other key signatures

[matt7777]

Hello , i hope someone can help. i have got back into writing music after a 20 year absence and need some help. i am writing a piece in b flat major. the question i have is, if i use a c sharp , do i write it as a c sharp or a d flat? can it be either?

the same in other signatures, if i use a note that is not in the scale, say a b flat in the c major key, do i write it as a b flat or an a sharp , or does it not matter?

[mikeowski]

Ex. 1: It really depends on what you want to do. For example if you use a c# in Bb-major, it would probably be for modulating to either d-minor or D-major. But if you modulated to Db-major, you should obviously use a Db.
In a diminished chord the choice of accidental doesn't matter as far as I'm concerned.

In ex. 2 it's pretty much the same. If you modulate to the very close F-major, then obviously use a Bb. But if you want to modulate to B-major or b-minor, use a#.

[gregh]

Besides the above, use what is easiest to interpret. For instance, in a descending sequence, you would probably want to write F-E-Dflat-C rather than F-E-Csharp-Cnatural, just because a skipped line and then the same note twice with two accidentals isn't as clear about what the music is doing.

[quantum]

Another possibility is if you are moving into Bb minor harmony, then it would make more sense to write Db and not C#.  But as others above have pointed out, it depends on the context and the functional purpose of the C#/Db.

If you are unsure about which to use, try transposing the passage into a familiar key to you.  Does that same note make sense in the familiar key? 

[Bob]

One general idea -- If the note resolves up, use a sharp.  Down, use a flat.  Makes it easier to read.

Or if you want it to be easier to analyze, use what the chord function actually is. 

[matt7777]

Thankyou for all the replies. what about the melody line. same example, playing in the key of b flat major , would you write c sharp or d flat?

i like the idea of using a sharp for going up and a flat for going down. i think i'll use that if there are no set rules, as i guess it doesn't really matter too much as i doubt anyone else will read it, i just like to do things properly.

 it's been so long since i have read or written music that i'm rather rusty at the moment and am even struggling to read the melody line i have laid down on manuscript paper!

[quantum]

Again, as others have mentioned above it depends on context.  One cannot give a hard rule for a single melody line note.  One needs to know where in the phrase the note occurs, what is the predominant harmony surrounding the note, the direction of the harmony in the following measures.  If this note in question is part of a repeating motif throughout the piece, it may also be good to know how one intends to develop such motif.  There are just too many variables for us to say use C# or use Db. 

Perhaps if you give us the entire phrase and harmony in which you want to include the note in question, members here will be able to offer a more focused response. 

[Bob]

Ex.'s

If it's in Bb and you want a Db chord, then it's a Db.

If it's with an A Major chord, then it's C#.

[matt7777]

Perhaps if you give us the entire phrase and harmony in which you want to include the note in question, members here will be able to offer a more focused response.  

right hand the melody in the key of b flat in 4/4 time is:

 f (minum and quaver) , f (quaver), dflat, c, b, (triplet) f (semibreve)

left hand, (one crotchet continually)  c sharp/ b flat/ f sharp/ c sharp, chord changes on the semibreve f to f/ d/ b flat/ f


not sure if that's clear and i must also say i haven't cracked the bass clef yet so am writing both as treble clef.

[Bob]

Not quite clear....

If it's a c# with an F above it, I'd say that's a Db Major chord.