I was reading some online music theory lesson and this came across. What is the reasoning and would it be wrong to use one over the other?

Along the same lines can anyone recomend any free online music theory lessons or a good music theory book?

I found this site useful:
http://www.dolmetsch.com/theoryintro.htm
As far as your question, I'll go out on a limb - typically, one will see sharps being used if the key signature contains sharps, and vice versa, of course. Could be wrong - just a guess.

HM

It doesn't matter which one you use. It's just an enharmonic change. The use of either a sharp or a flat depends on which one fits into that harmonic sequence.

The way my teacher described it is that it's a matter of spelling. For example, an 's' and a 'c' can have exactly the same sound. But the word is only spelled correctly with one or the other.

Likewise, for a given scale, the notes are spelled a certain way. The same way that you can double-flat a note. If you're double-flatting G, then the note is Gbb and not F.

Scales are the building blocks of harmony. One learns the C# Major scale to learn the notes used in C# Major harmony.

This, obviously, begs the question: Why use C# Major harmony instead of Db Major harmony?

The answer lies in the harmonic direction the entire section, movement or piece takes. It is rare for even a short section of a work to remain in a single harmonic key, and the keys to which the harmony migrates usually dictate which "spelling" of a scale is used in order to make the notation simpler as the harmony modulates. For example, if the harmony starts in C# Major and modulates to F# Major, the notation would involve placing naturals on the B's (C# Major = 7 sharps / F# Major = 6 sharps). However, if the harmony were to move to G# Major, one would need to double-sharp the F's (kind of ugly); if one started with Db Major and moved to Ab Major, one would only need to put a natural on the G's (Db Major = 5 flats / Ab Major = 4 flats).

Hope that makes sense.

whoa, i must have read that 4 times and its still confusing. but hopefully with some reading i will understand better. Thanks for taking the time to explain it though.

Let's see if I can use a really bad metaphor (don't think I'll have any problem with that!) to explain a little further.

If one were to stand in the middle of the intersection of two roads (Fast Rd. and Wide Rd., if you like), you wouldn't be able to say with certainty which road you were on. At that point you are on both roads equally. This is the situation with enharmonic equivalents: you can't say that there's any actual difference between them.

Now, say you want to travel down one of those roads away from the intersection, let's say down Fast Rd. Would it be easier to describe your starting point in the middle of the intersection as being on Fast Rd. or on Wide Rd. instead?

This kind of decision is based on where you may end up going, and folks that write music take this into consideration when putting the notes on paper. So, when the starting point is C#/Db, it's a matter of knowing whether you're going to be headed into keys with sharps in them or into keys with flats. Keeping the number of accidentals (i.e., notes not in the key signature) to a minimum is usually the goal. If the music will head off into sharp keys, start with a key containing sharps (C# in this instance); conversely, if headed into keys with flats, start with a key using flats (Db here).

I guess the point here is that (using the metaphor again) if you never leave the intersection, there's no difference between the two choices. It's when you move away from there that it becomes an issue.

I like the metaphor!

Yea, but what if Wide Street is a really REALLY really REALLY[/b] wide wide Wide-wide-wide street? Then no matter how far you went on Fast Street, you'd still be on Wide Street,too. (unless maybe you went REALLY really REALLY[/b] fast fast Fast-fast-fast.)


What do you think? I got possibilities at least as a drummer maybe? (I already KNOW how to deliver pizzas and steal!)

I just love this theory stuff! It just, oh I don't know,...wow, just exPANDS your mind so much, I guess. Jeepers.

I like the intersection metaphor. Thats a very good way to explain it.

Do the streets have to be perpendicular?

I like that metaphor, too! But, alas, I'm still confused . . .

Well, OK, that makes sense. But do all sharp keys have a corresponding flat key signature? If so, then you could start with a sharp key signature because you'll be using a sharp key signature later. But couldn't you also just change both key signatures to the corresponding flat key signature and write the piece that way?

Right? No?

Ugh.

In theory (no pun intended), all keys can be written in either sharps or flats, but many of the variants would require excessive respelling of notes just to work. For example, you could write a piece in E# Major, but doing so would require 4 double-sharps and three sharps (!), whereas F Major only requires one flat. Clearly, from a legibility standpoint, simpler is better. When the number of sharps or flats reaches 6, it's a wash (compare F# Major with 6 sharps against Gb Major with 6 flats); anything beyond six means there's a simpler way. But because of the desire to keep the score simpler, one might actually use a key of 7 sharps or flats if the direction of the piece moves into areas with fewer sharps or flats.

Changing the key signature is a sort of last resort, used when the harmony has veered so far afield from the original starting point as to create far too many accidentals. If a piece starts in Bb Major and wends its way into A Major, a change in key signature would be far better than putting naturals on all the B's and E's and sharps on all the F's, C's and G's. Even so, the composer (or editor) might not bother with a key signature change if the new key doesn't stick around very long.

Clearer?

No. In fact, if you want to create a visual map of how it might work, and give yourself nightmares at the same time, consider this:

The road map resembles Paris, after a fashion. There are 12 roundabout intersections, each having 11 roads leading to each of the other roundabouts. The spoke roads emanating from the roundabouts can intersect with each other at any angle.

Hey, you asked! :p Besides, shouldn't you be working on your cadences?

Stop this incessant whining about the French!

This whole discussion is sooooo neat. I love theory!

Thanks Matt. The metaphor makes it a lot more understandable.

I have been watching the exchange of ideas here on the side. Matt, I'd like to commend you for your patience in explaining those hard to understand stuff. I understood it better with your metaphor.

I'm a real real beginner and I'm learning a lot from you guys. I have just been taking lessons for about a year. A real rookie.

I know this is an old topic but I'm new to the forum and this is my first post.
Therefore I beg your indulgence and ask your forgiveness if I mess this up.

I asked my piano teacher the exact same question a while back. She explained that when you transpose to a key all the notes shift in that direction.
Going from C major to D major scale you are moving to the right of the keyboard therefore you end up with C sharp and F sharp not D flat and G flat although they are essentially the same keys.
Also she said some notes are self defined. If you type a B flat chord your thumb hits a B-flat. Calling it an A sharp note confuses the issue. This stuff is hard enough already!

My understanding of this (though simplified)is that the scale of what ever key you're playing in is alphabetically arranged so that you can't have , say a G and a Gb (has to beF#)...or B and B#(Has to be a B and C). Only one note name per scale, not just a good idea it's the law . Hope that makes some sense.

The notes played in a C# scale are different than for a D flat scale.

http://www.music.vt.edu/musicdictionary/appendix/scales/scales/majorscales.html

If you are writing a piece that has accidentals outside of the key signature, than you simply write a sharp if you are ascending the scale, or a flat when descending.

C## = D on a piano, but is this correct for every other music instrument ?

Which notes are different? As far as I can see you are hitting the same notes on the keyboard (all the blacks, plus C and F), but just thinking of them differently.

BINGO !

That is reasoning behind it.

The major scale for every key must contain all of the note names (ABCDEFG) whether or not they are sharped or flatted.

This is a little difficult to explain in writing.

Here is one way to experience it ...

Sit at the piano and play a major scale, any one except the C major scale.

As you play the scale, say the name of the note you are playing with the understanding that you must not skip any letters of the alphabet as you progress. This will cause you to have to attach the proper flat or sharp extension when naming them.

For example: The D major scale.

D ... E ... ?

Since the next key falls on a black key (between F and G) you must attach either FLAT or SHARP to the next note you name. It could be F# or Gb. Using Gb would violate the rule of not skipping any letters or the alphabet so you name it F#.

D ... E ... Gb (Wrong)

D ... E ... F# (Correct)

Simple ?

I felt guilty resurrecting such an old thread but look at all the excellent information obtained!
I like the reply above the best.
It will help a lot with scale building
Thanks so much!

OMy gosh. I never even thought about that! I feel nuts that I didn't recognize that! ha!

Guilty?!? Goodness, gracious... I'm so glad you resurrected this ancient thread. I certainly never would have seen it otherwise.

Matt's explanations re: why certain key signatures are chosen have helped make clear something that was otherwise very mysterious to me. I never knew it was so logical!!

I couldn't get Matt's explanation at all. Since the development of equal temperament major key pieces move first to the dominant (or sharp side) at the beginning and generally pass through the subdominant (or flat side) before finishing back in tonic.

Looking at Bach's C# major Preludes and Fugues, both books, the notational awkwardness becomes apparent as the F double sharps are marked, in my copy, with both a natural and a sharp when they return to F sharp and the preponderance of double sharps, unusual in my normal literature, make for a very difficult experience in reading - not that Bach is normally easy in that respect.

In Liszt's Un Sospiro the simplicity of the accidentals of D flat, by comparison, is evident. The first page (in my copy) is without accidentals - I had to double check it was Liszt! There are however only eight bars on the first page as much of the étude is written using three staves instead of the usual two.

In contrast, Chopin's Db major Waltz, Op. 64 No. 1 introduces G natural on the second note! In fact there are more G naturals in the piece than there are G flats. It emphasises that the choice of key signature is more important than notational convenience.

As an aside, I wondered if perhaps the characteristic sound of Db is preserved in C# major - it should, they're the same keys on the instrument - so I listened to Bach's C# Preludes and Fugues and Ravel's Ondine from Gaspard de la nuit, also in C# major, and thought I could detect that characteristic poetic quality of D flat.

So as an experiment I listened to more preludes and fugues and discovered that very D flat poetry in ALL the major key pairs! Ah well, back to the drawing board.

Matt's explanation is perfectly clear to me too. You are looking at it from a different angle, Richard. At this moment I'm trying to sort out what those angles are.

Hm. Matt is describing how music gets messy once you have a large number of flats or sharps. The forks in the road are the places where you can decide to switch key signatures or decide to convert flats to sharps. As an example, B major with its 5 sharps - in the key signature or in accidentals - is easy to navigate. In terms of piano keys/"equal" temperament, Cb major with its 7 flats has the same sound as B major. Here's one fork in the road. If your music has started off in a flats signature and it's been modulating like mad so that suddenly you find yourself in Cb major, do you want to wipe the slate clean and start with a new key signature in sharps? It does seem wise. Let's go for B major at this point!

Richard, you are describing the history part. Before well temperament and "equal" temperament came along, keyboard music could not modulate very far before the music sounded dreadful with wolf tones and whatnot. Other instruments were also limited - a look at Tuckwell's history of the French horn is an eye opener on that. So if music didn't modulate a lot, you didn't find yourself in the predicament that I hypothesized along Matt's lines, of the Cb major and worse. They are two sides of the same coin.

No, I still don't see it, keystring.

Whatever you're writing, if it's going to modulate them it will most likely modulate to the sharp side first. As an explanation of why a composer might choose to start with seven sharps over five flats Matt's explanation doesn't cut it for me.

If the music does get messy there's always the option of a key signature change. Un sospiro goes to F# minor (three sharps) instead of G flat minor (five flats plus two doubles), for example. Didn't Liszt go from six sharps to six flats in one of his Hungarian Rhapsodies?

I wasn't intent on describing the history, I merely mentioned it BECAUSE music didn't modulate before the advent of the mean and equal temperaments.