# Choosing a key signiture



## LordBlackudder (Nov 13, 2010)

What are the rules when choosing a key signature?

Does the composer decide this before composing or just stick to one they like?

Is there a chart or understanding of what emotional use each key signature has in music?


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## millionrainbows (Jun 23, 2012)

One possible answer is, the key signature is chosen based on what the destination key is, and how to get there.

In older music, a limited range of keys sounded best, because of keyboard tuning.

Here's a note I wrote & posted on *Amazon*, then *facebook.* Forgive me if it's too lengthy.

We'll start on *C,* project a minor third from that, yielding an* Eb*, then another minor third from there, giving us *Gb.* From *Gb,* up a minor 3rd is *Bbb,* or enharmonically, an *A,* giving us the familiar *'diminished seventh'* chord. As you can see by the *'Bbb/A,'* the _glitch_ in our diatonic 7-letter-name scale system is revealed by this. *A scale must consist of seven different letter-names.* This is a good time to discuss this in more detail.

On a keyboard, *Gb* and *F#* are the same note, physically.

If one starts building fifths from a starting point of *C,* then going "forward" or clockwise around the *"circle of fifths"* would yield *C-G-D-A-E-B-F#(C#*-no need for* D#*).

If, on the other hand, you go in reverse (counter-clockwise), you travel the *"circle of fourths", *which yields *C-F-Bb-Eb-Ab-Db-Gb (Cb).*

As you can see, there are three keys which "overlap" under two different names:* B (Cb), F# (Gb), and C# (Db).* The reason it goes no further has to do with the physical layout of the keyboard itself (there are two semitone steps in the letter sequence), and the subsequent "letter-naming" of notes which results. *To be a diatonic scale, you must have seven different letter names. *

For example, there is no key of *"Fb"* because this is* E,* a sharp key; but if we named it anyway, we would get *Fb-Gb-Ab-Bbb* (you can't repeat *A* - there must be seven different letter names with no repeats),* Cb-Db-Eb-Fb. *This "repeating letter or double-flat" dilemma does not arise on the three "repeat" keys of *B (Cb), F# (Gb), and C# (Db), *because this is the _"seven-letter limit"._

In equal tempered tuning, both end points *(F# and Gb)* are identical, because all the "fifths" have been adjusted flat by 2 cents, to keep from "overshooting" the mark. Otherwise, instead of a closed circle which repeats from octave to octave, we would have an endless spiral, and an infinite number of different notes.

In other tuning systems, which I am just now beginning to understand & study, the physical layout of the keyboard must remain as 12 notes (7 white and 5 black), regardless of what tuning we use.
We don't want to have a separate *"F#" *and *"Gb"* black key, although this has been tried.

In either mean-tone or Bach's tuning, what remains consistent in a "key signature" is the *relationships* or intervals produced in that octave or key, all in relation to the "key" note.

For instance, in mean-tone tuning, starting from* C *and building our fifths, we have* C-G, G-D, D-A,* and *A-E. *The fifths are adjusted in mean-tone, made smaller, in order to create a good-sounding major third of *C-E,* which without adjustment would have been too sharp. This was a limited tuning, since going in fifths clockwise yields* C-G-D-A-E-B-F#-G#(Ab),* or counter-clockwise yields *C-F-Bb-Eb.* This sequence produces in *G#- Eb (or Ab-Eb, or G#-D#)* a "wolf" fifth. So there is the limit of mean-tone tuning.

Bach's tuning was not "equal", but it was "well" tempered, meaning that, unlike mean-tone tuning, he could get a decent sound in all twelve keys.

In mean-tone tuning, there IS no *"Gb",* only* F#.*

In the Bach tuning, the difference in *F#* and *Gb* would show up as the OTHER keys those notes are in; for example, in the key of *D *(a sharp key), the* F# *is the major third. This would be a different-sounding major third than the *C-E* in the key of *C,* it might be a wider or narrower interval span.

Similarly, *F#* could be the fifth in the key of *B *(also a sharp key). This *B-F# *fifth is unique to this key.

*Gb *could be the fifth of the key of *Cb, *because a fifth below *Gb* (keeping our letter rule) would be *Cb.* This would be a unique fifth for that key, maybe more "perfect" and restful, or "sharper" and restless.

*Gb *can't be the major third in any key; there is no key of* "Ebb".* This is really *D,* in which case we must call it *"F#",* not Gb.

In Bach tuning, the keys of *F#* and *Gb* would also be identical.
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A while back, I got interested in tuning systems as applied to keyboards, and found this guy's site, (PHD) Dr. Bradley Lehman. He's a very friendly guy, younger than I, and his name will now be forever linked with J.S. Bach.

The title-page of the original manuscript of Bach's "Well-Tempered Clavier" contained what for years was thought to be a "decorative flourish" by the title.

It turns out that this was actually a graphic representation of Bach's tuning method! Not "equal-tempered" like ours, but nonetheless "well" tempered, meaning that all 12 keys would sound good.

Not only that; but for years, people puzzled over various 19th century writers and musicians describing how different keys sounded different, or had a certain "color" or mood. Well, now we can see what they meant: each key in Bach's tuning system sounds slightly different, with a different "character;" some have purer major thirds, while others favor other intervals. Flat sevens sound real good in Bb, for instance.

This may have affected the way Bach composed the pieces; in certain keys, he would linger on certain intervals longer, or zip by those that sounded weird.

The development of truly 'equal' temperament took all this "affekt" away.


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## LordBlackudder (Nov 13, 2010)

very interesting


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## TresPicos (Mar 21, 2009)

In the old days, there was indeed a notion (how widespread, I don't know) that keys had their own emotional characteristics. One example is the list made by Christian Schubart, a Haydn contemporary. Eb major was the key of love, for example. 

Also, synestethic composers like Scriabin might have had their own reasons for choosing certain keys (or colors).


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## millionrainbows (Jun 23, 2012)

http://amzn.com/0393334201
I found this book to be very informative, as well as making a strong case _against_ equal temperament.

After the demise of "mean-tone" tuning, in which only 7 of the 12 key areas were usable, efforts were made towards equal temperament. Although many people from 1850 onwards called these attempts "equal," a universal standard was not achieved until 1917, with the publication of William Braid White's "Piano Tuning and Allied Arts." _True_ equal temperament was only really realized in this century. Before this, the tunings approached ET, but were actually compromises containing a mix of flatted and pure fifths (our ET fifth is 2 cents flat).

Bach's tuning was like that, a "well" tempered tuning in which all 12 keys sounded good, but different from each other, some key areas having different, flatted fifths, or some having pure fifths and different major thirds or flat-sevenths. Bach's method was discovered from the graphic flourish on the cover-page of the WTC by Dr. Bradley Lehman. The flourish turned out to actually be a small tuning chart. Here is his site, with video demonstrations of him tuning a harpsichord.
http://www.larips.com/


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## PetrB (Feb 28, 2012)

Through the early romantic period, key for orchestral works was often determined by the technical limits of winds and brass - the quality of their intonation, what would 'sound well.' Later, as technology developed - valve Horns, flutes which could play more reliably in tune and more equally in any key, that changed.

There are probably hundred of lists of key association: some may show points of agreement from one list to the next:
Eb is supposed to be 'heroic,' but that is because, coincidentally, Beethoven's Eroica and many other works of a more overt nature have been cast in that key - to return to the former premise, it was practical to cast a work in Eb to get full use out of the technically limited winds and brass of the day. 

So 'traditions' are born.

There is nothing 'heroic' about the key of Eb unless you write 'heroic sounding' music in that key. No reason 'Heroic Sounding music could not be in F# minor, either 

Still many a musician and avid listener is 'key sensitive.' One particular key, for a particular musical idea, may seem a little high, the body of the sound too thin, another, too low, the body of sound too muddy.

Robert Schumann thought that most composers intuitively chose the 'right key' befitting their original musical idea.

For millennia, people have had notions about a mode or key having particular emotional qualities, and sometimes an actual color, ala the synesthete crowd's mixed sensual perception.

For millennia as well, no group of 'experts' have been able to agree as to which emotional quality goes with which mode or key, 
and a room full of synesthetes may not find agreement, each individual thinking of F# major as a different color.

The idea, then, is empirical, idiosyncratic from individual to individual. F# (major or minor) is neither bright, happy, sad, or Naples Yellow. It is just F#: it is what the composer writes in that key which determines its 'emotional' import or especial timbrel
color.


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