# Topic: Picking the right key!

1. ## Picking the right key!

Hi guys,

First off, just want to say thank you everyone; I find these forums extremely insightful.

Now, I have a quick question regarding a symphonic piece I'm (attempting) to write. On piano, I'm playing the piece in F Major, with a key change to D Major. However, I need a bit of a brighter sound for the symphonic work...

But here's the thing:

It's for high-school orchestra, so I'm trying to find all combinations of two keys a minor third apart that would be playable by both orchestral and band instrumentalists. So look at this as a sort of riddle... anyone up for the challenge?

Thanks, and all help would be greatly appreciated.

Chris

2. ## Re: Picking the right key!

I like puzzles.

Since you said this was a high school orchestra, I assume you don't want too many flats or sharps. So let's start by eliminating any key with more than three sharps or flats.

That leaves us with C, G, D, A, F, Bb, and Eb. Now if you pretend for a moment that they're notes and compare each note with every other note, you discover that there are only 4 pairs of notes that have a minor 3rd relationship:

[C A] [C Eb] [G Bb] and [D F]

Hooray, we're done! Well, not quite. What about transposing instruments? Your trumpets are in Bb (notated a full step higher) and your french horns are in F (notated a fifth higher). So, let's see what keys we'd be in if we transpose each of the above by a major second and a fifth.

C becomes D and G. That's ok.
A becomes B and E. Oops, your trumpets now have 5 sharps and your horns 4 sharps. So we can't use that pair at all.

C is ok.
Eb becomes F and Bb. ok. So we have a winner! [C Eb] works.

G becomes A and D. ok.
Bb becomes C and F. ok. Another winner!

D becomes E and A. Hmm, E has 4 sharps. No good. So it doesn't matter whether the F works (it does).

So, only 2 pairs of major keys fit our requirements: [C A] and [G Bb]

If you're willing to have more than 3 sharps or flats, you will have more choices. Got any Eb instruments? That changes things again.

- k

3. ## Re: Picking the right key!

If you don't care how many sharps or flats your poor players have to deal with, there are 12 pairs of keys you can use. I can explain how I arrived at that answer if you're curious. But in the interest of not putting everybody to sleep, I'll leave it at that.

- k

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