Reasons to compose in various keys

[tac-tics]

I have a question that I'm sure has a very deserving answer, but one that confuses me a bit.

To put it bluntly, why do composers compose in different keys? To put it in a way that will probably make me sound quite unintelligent, what reason is there to ever write a piece in a key other than C major or A minor (or whatever key you would argue the easier to play).

I understand there are obvious historical reasons related to tuning, especially on non-keyboard instruments. As far as I understand, many instruments have a "home key" which is easier to finger than others (violins in G and carlinets in Eb), but since the keyboard is very roughly the same to play in every key, why do composers use other keys?

Maybe this has to do with my lack of perfect pitch or the fact between three of my music books, I have the first movement of Beethoven's Moonlight Sonata in 3 different keys. But what considerations besides technical ambition does one decide a piece's key on?

[musik_man]

Take the extreme example of transposition, moving it up an octave.  Virtually every piece in the literature would sound much worse.  To a lesser extent, moving a piece say a fourth up or down would change it's character.  Would the first movement of Moonlight sound so misterious if you moved it up a 6th to A minor? 

There are also considerations of how easy certain figures would be to play in each key signature, and the range of the instrument.  Not every type of technical challenge is easiest in C major(in fact C major is one of the harder ones to play in, I like 3 flats or 3 sharps.)

[allthumbs]

As far as I understand, many instruments have a "home key" which is easier to finger than others (violins in G and carlinets in Eb), but since the keyboard is very roughly the same to play in every key, why do composers use other keys?

You've answered your own question.

[timothy42b]

A given piece might be easy to play in any key on piano.

Guitar is a little trickier, some keys really are much harder than others.

But singers!  If a piece is too high or too low, it may not just be hard, it may be impossible. 

Now that we have equal temperament, there is no reason to write in different keys for sound purposes.  But anything that accompanies singers has to fit their range.

Yes, we could write it all in C, use a digital piano, and just hit the transpose button.  There is no longer any real need to have different keys.  But it is tradition. 

[alzado]

I can play in most keys, but I will shy away from pieces written in keys with --say-- 5 or 6 sharps or flats. 

Some of the hardest scores to play are in a "nominal" key (in the signature) but the measures are just peppered with accidentals, to include double sharps and double flats.

This is very true of some pieces by Edward MacDowell. 

[cfortunato]

1) Different keys sound different.

2) Composing in different keys breaks you out of your patterns, and helps keep you from doing the same sort of thing over and over.

[tompilk]

I can play in most keys, but I will shy away from pieces written in keys with --say-- 5 or 6 sharps or flats. 

Some of the hardest scores to play are in a "nominal" key (in the signature) but the measures are just peppered with accidentals, to include double sharps and double flats.

This is very true of some pieces by Edward MacDowell. 

hehehe.. check out the middle bit of hungarian rhapsody no 6 - seven sharps!!!
Tom

[g_s_223]

Certain piano sonorities are only possible in certain keys, due to the fact that there is by defintition a lowest pitch A on the (normal) instrument. If you want the most profoundly dark and weighty sonorities from the instrument, you would be looking at keys A/B/Bb/C/Db say. These would allow you to have a deep-sounding low octave in the LH.

If you chose Ab or G for the tonic, on the other hand, you would be forced up 6-7 tones from the lowest note on the instrument to have that octave. It would inevitably sound much lighter in tone. I don't think it's any accident that B minor is considered possibly the 'blackest' key in piano music.

The available notes in the upper register of the piano does not generally affect the choice of key in quite this way, but does affect how elaborate arpeggiated figuration is presented, e.g. some bars in Chopin's Op.10 No.1.

[fencingfellow]

Well...
On a purely aesthetic note, think of how boring it would be for every piano work (or step back and say every piece of music) to be composed in the same key!  Even without perfect pitch, it is easy to hear a difference between each of the keys.

Now on a more theoretical idea: a huge percentage of compositions written in C Major or A minor modulate into other keys, often to distantly related keys.  This concept immediately undermines any notion of works being easier if transposed to C Major.  Take for example the Waldstein Sonata (1st mvt).  It begins in C Major, though after a time has moved to E Major.  What would be gained by transposing the work?

[tac-tics]

due to the fact that there is by defintition a lowest pitch A

I think this was the answer I was looking for. Very interesting explanation.

Thank you all for your replies.

[Derek]

I compose a lot of music for piano. The reason I personally use different keys is that it is fun. Different keys feel differently to my hands, because the patterns of white black white black etc. have different "grips." This physical aspect of the piano suggests certain figures which fit better in some keys than others. Therefore,  writing in different keys tends to help suggest new ideas to a composer.

[timothy42b]

Certain piano sonorities are only possible in certain keys, due to the fact that there is by defintition a lowest pitch A on the (normal) instrument.

Same as a soprano, then;  they can only go so low.