Key choice for brass instruments

Question

I've been told several times that brass instruments prefer to play in keys with flats, rather than sharps. As a trumpet player myself, I cannot relate to this preference. E major is just as easy or hard as A flat major. I interpreted it as being the playing key, not the concert key.

I'll take that the preference is true, since I've heard it from several trustworthy sources, but why is that? I have several hypotheses:

1. Tradition. Bands (brass bands especially?) usually play in keys with flats, therefore that is what the players are used to, and more comfortable with. But how did the tradition start?

2. Intonation. The construction of valve instruments make the intonation better in keys with flats. For example in A major: the low C# of the trumpet is naturally high, whereas a good intonation should have it low as the third of a major chord. I cannot think of a counterexample right now.

I welcome guess answers, but please mention that you are just guessing if you do not actually know for a fact.

Answer 1

Adding to the narrative in other answers, here is a chart that might help further explain why brass players tend to prefer sheet music written in keys with flats. As is shown, written keys that exclude the “worst-to-play usual notes” (elaborated below) on common brass instruments (except French horn) are overwhelmingly keys with flats. This is especially true for almost all lower-brass parts, in which even the written-and-concert key of C, with no flats, includes the worst-to-play notes for all but C tuba and triggered trombone.

The specific keys mentioned in the question as being equally playable on B♭ trumpet—written keys E and A♭ —serve well to demonstrate this chart. The row for B♭ trumpet recognizes the note scored as C♯ or D♭ as the most troublesome to play, so keys with at most 1 sharp or 3 flats are likely to be favored because they exclude C♯/D♭. The aforementioned keys of E and A♭, however, contain 4 sharps and 4 flats, respectively, and thus include C♯/D♭ and are equally disfavored here. If you are comfortable with music in these keys, you are no doubt an experienced musician. Not only are both keys relatively difficult to play but trumpet music in A♭ (concert key G♭) is also quite rare.

                                                                   Written keys WITHOUT
                                                Worst-to-play         worst-to-play
  Name of        Version of      Open key         usual note           usual note
 instrument      instrument    ------------    ----------------     ------------------
  on score       considered    Con-   Writ-    Writ-    Valves/     How many  How many
                               cert    ten      ten    position      sharps    flats

F French horn      4-valve      F      C       G#/Ab     2-3         2,1  0  1,2
 Bb Trumpet        3-valve      Bb     "       C#/Db    1-2-3          1  0  1,2,3
Baritone T.C.         "         "      "         "        "            1  0  1,2,3
Eb Mellophone         "         Eb     "         "        "            1  0  1,2,3
Alto/Tenor horn       "         "      "         "        "            1  0  1,2,3
    Tuba            C tuba      C      "         "    1-2-3, 2-4       1  0  1,2,3
    Tuba           Eb tuba      Eb     Eb       E/Fb      "          6,7       2,3,4,5,6
    Tuba           Bb tuba      Bb     Bb       B/Cb      "            7     1,2,3,4,5
Baritone horn      4-valve      "      "         "        "            7     1,2,3,4,5
  Euphonium           "         "      "         "        "            7     1,2,3,4,5
Baritone horn      3-valve      "      "         "      1-2-3          7     1,2,3,4,5
  Euphonium           "         "      "         "        "            7     1,2,3,4,5
  Trombone        slide only    "      "         "       7th           7     1,2,3,4,5
  Trombone        F trigger     "      "    C#/Db,F#/Gb  5th              0  1,2,3

“Worst-to-play usual note” is an ad hoc designation likely to find agreement among many players due to some of these factors:
• The note is in the range usually scored for the instrument.
• With 3 valves but no fingered slide, timbre is compromised when a note is lipped into tune.
• With 3 valves and a fingered tuning slide, coordinating the slide quickly is difficult.
• With an in-line 4th valve, pinkie-vs-ring-finger agility is anatomically hampered.
• With an opposite-hand 4th valve, coordinating the hands quickly is difficult.
• On a trombone, a quick slide excursion is a gymnastic feat.
• French horn players have a right to complain too.
Admittedly: 
• Some fingering/position sequences and almost-worst notes play circumstantial roles as well.
• Some rarer fingerings/positions are worse than those shown, but tend to also avoid flat keys.
• A trombone's 7th position is the worst of the worst. An F attachment/trigger alleviates this.
• As French horn typically plays high in its range, its usual worst fingering is relatively benign.

Have another usual note that you least favor or instrument that would help to mention? Please comment or edit.

_{This comes from a community band and orchestra member who fills for whatever non-percussion parts are needed during rehearsals, playing the most appropriate brass instruments that happen to be along or available.}

Answer 2

Most wind instruments transpose in a way that adds sharps. Horn and English horn are in F (add 1 sharp); trumpets, and half of the clarinets and saxes in Bb (add 2 sharps), and the other clarinets and saxes in Eb (add 3 sharps). The low brass reads concert pitch, but tenor trombones and euphoniums are actually Bb instruments as well. Bassoons are sort of in F by this same logic. Tubas come in C, but also in each of the 3 listed transpositions. Aside from some very esoteric instruments, nothing transposes the other way.

So if, for whatever key you choose for your composition, the winds are mostly adding sharps, then flat keys are friendlier. Concert C puts trumpets in D and alto saxes in A. So while E major might seem like a perfectly reasonable key for strings or piano, your trumpets end up in F# and alto saxes in C#. Of course, a good player should be able to play in any key, but it's just not as easy.

Furthermore, brass instruments work by adding tubing to lower the pitch, so unless you're already at the bottom of the partial, you can always flatten a note. But on trumpet, even just C -> C# or G -> G# is crossing over a break, going from the highest note of one partial into the bottom of the next. And then there are the tuning issues you already mentioned.

Answer 3

I interpreted it as being the playing tonality, not the concert tonality.

There is your mistake. As a comment about brass players, this statement is for the benefit of those not playing the instrument and consequently is about concert pitch.

Indeed, it does not make much sense to speak about playing pitch in this context since the playing key differs even within the brass section.

Answer 4

All answers (and their up-voters) up till now fail to take into account this essential parameter: I am talking about playing key, not concert key. A comment from @jjmusicnotes made me think of this possibility (a wild guess):

For the same amount of flats or sharps, more flat keys feature the open C and G.

F major or G major have both C and G, so they're not relevant.

2: Bb major has both C and G, while D major misses the open C (it has the middle E though, which Bb major lacks).

3: Eb major has C and G, A major has neither.

4: Ab major has both, E major has none.

5: Db major has C, not G, B major has no open tone.

The hypothesis is that the keys that feature open tones are preferred because the instruments resonate better on open tones.

Answer 5

This seems much more of a worry to composers/arrangers than to brass players! OK, ask for a preference, we'll come up with one. But it's not important.

There are two notes on trumpet that require all three valves to be depressed. Written low C# and the F# below. All but the cheapest student instrument have the technology to extend the 3rd (and sometimes 1st) valve slides so as to play them in tune. They aren't hard to play. But that range of the trumpet has neither the brightness of a trumpet's higher notes or the appealing flatulence of a trombone's low register. Write it if you want, but know what you'll be getting.

Answer 6

Here's the test - ask a bunch of brass players to first sight-read a passage with n sharps in the key signature and then a different passage of similar difficulty with n flats in the key signature. Count the number of errors for each performance and collate the results.

My expectation (contrary to the received wisdom quoted in the OP) is that the accuracy would fall as the n increases, but would not depend on whether the key contained sharps or flats.

My feeling is that brass players, in common with most other musicians, prefer keys with few sharps or flats. Keys with lots of sharps or flats aren't innately harder to play - but because they often get less practice they're less familiar and so don't fall automatically under the fingers.

Answer 7

My preference ,as a tuba player, I can't really read more than two sharps. Yet I can read down to all flats fairly easy. Its just much more common to see flats than sharps. This is of bably likely do the jump from bass clef to treble. I only have a sharp if say like a sax has four sharps.