I often write music for orchestras, and I was wondering what is the largest number of parts I should assign to one instrument. For example, I'll often write 5 french horn parts, and sometimes up to 6 or 7 viola parts. Is there a practical limit of parts I should write short of the number of instruments in the section?
6A great deal of things may be possible that are a bad idea. You could write on your orchestral score that there are 100 bass saxophones arranged in a circle around the audience, each playing a different microtonal note... The laws of physics don't prevent it, it could be notated and it could be performed... But I don't think anyone will perform that piece.– AJFaradayMar 1, 2022 at 12:57
6You might want to think long and hard about why you are writing 6 viola parts. I've played in orchestras, on various instruments, for 50 years+ and almost invariably multiple-divisi parts represent composer wanking rather than tonal creativity. Yes, there are exceptions, such as cello divisi in Rachamaninoff symphonies, but these are rare.– Carl WitthoftMar 1, 2022 at 16:01
If it clears it up, the times I will write a large number of parts for a stringed instrument is usually for one section of the piece when I want to utilize the range/tone of the instrument or have a very specific chord in mind; For most other sections of the song, I will use maybe one or two parts. French horns I utilize a lot for chords.– violetoriginMar 1, 2022 at 17:28
I was curious to hear six violas... youtube.com/watch?v=UMMG216i_RQ– Michael CurtisMar 1, 2022 at 21:40
Brass and woodwinds are always one player per part, so you write as many parts as there are players. Four horns is standard for a symphony orchestra.
Strings are nearly always multiple players per part. You can divide them as much as you like, up to the number of the players in the section. If you want to divide the violas six ways, then the orchestra needs at least six violas (and the other string parts in proportion). You need to stipulate, for example, "strings: at least 10-8-6-5-3".
Be aware that amateur string sections might have trouble if you divide the strings so much that every player has to play a part by themselves. And if you ask for too large a string section then some orchestras will not be able to play your piece, which is going to reduce the chance that your piece will be played.
Percussion parts are more complicated. There are in general two approaches to writing these. Stipulate how many players are needed and exactly which instruments they play, or alternatively just write all the parts and leave the percussionists to figure out the logistics. The first approach is preferable, but even then the logistics might require more players.
"Brass, woodwinds and percussion are always one player per part": unless, we'd like it. Especially percussions. I've seen so many oddly (or terribly) written parts, even for strings, in which it's really unclear if the "part" has to be considered for distinct players or not. And with percussions it's even worse: even ignoring parts that could be (theoretically) played by fewer musicians as long as equipment allows it, there are lots of occurrences in which it's absolutely unclear who should play what. Yes, player's experience helps, but that shouldn't always be an assumption as -too often- is. Mar 1, 2022 at 5:02
2@musicamante: I would expect the number of performers required to handle a set of percussion parts to vary considerably with the skill of the performers, range of instruments, and the amount and shape of the space to set up the instruments. If someone is scoring music to be played by a particular group in a particular venue, that person could figure out exactly who will be playing what, but in some cases it might be necessary for the marimba and vibraphone to be played by the same person, while in other cases it might be necessary to have different people play them.– supercatMar 1, 2022 at 7:33
1@musicamante The question is about divisi parts. Percussion writing is a lot more complicated, and I don't think a complete discussion of that is necessary here. I have amended my answer to at least mention the problem. Mar 1, 2022 at 10:13
2In the days of writing music on a computer, make sure to keep an eye on the cost of performing your work. It can become surprisingly expensive when you work in a vacuum for while.– ThomasMar 1, 2022 at 11:10
3Just for completeness, you might point out that oboe, flute, clarinet, bassoon standard setup is two each, but adding a piccolo, or a bass clarinet, etc., is relatively common. Mar 1, 2022 at 16:03
There is no "practical limit". As usual, you can do anything you want or need, as long as it makes sense.
If the reason for more players is for the sound "mass", then there is no need for a divisi part, just specify the preferred number of players for each instrument/section in the performance notes of the composition.
If you are actually writing so many separate and unique parts, then you should consider if they are worth it: maybe you need separate parts only in small sections of the composition, then you just merge the common parts and eventually go for small divisi sections. If their parts allow it, you can even write more voices in a single staff by specifying "divisi", and also add an indication about the minimum number of players for that instrument in the performance notes as written above.
I have seen french horn parts with a single staff for two players, and a shared 2-staff part for four players. They usually know how to manage it, but notes in the score will certainly help to indicate which player has to play when not all voices are present.
But, as said, there is no limit.
Consider, for instance, Strauss' Metamorphosen: it is actually written for 10 violins, 5 violas, 5 cellos and 3 double basses, each one with its own separate part.
It is sometimes performed by a full string orchestra with doubled parts.
There's no theoretical limit, but there is a practical limit: the number of player you have available. Even if four horns are written on one staff, they are still four separate parts. Mar 2, 2022 at 10:19