Why is it so that there are often two identical oboes, two identical clarinets, two identical bassoons and two identical trombones in a symphonic orchestra?

Is it just because one instrument is not loud enough and both are always playing exactly the same line? Or does each one of the pair play different lines?

  • Is your question about number of players per part comparing winds to strings? Pairs for the winds, but many more players for the strings. May 13, 2022 at 13:51
  • @MichaelCurtis - My knowledge about symphonic orchestra is rather limited. Somebody told me in the past that many violins in an orchestra is solely for the sake of volume. So, I just wanted to find out if it was also the case with the winds.
    – brilliant
    May 13, 2022 at 14:19
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    Probably would be better worded as "what is the history behind the makeup of a "standard" symphonic orchestra?" May 13, 2022 at 15:14
  • Tradition plays a big part. Just like the String Quartet is a standard, but there are pieces written with a second cello added, or a bass added. Random works exist for mixed string-wind sextets and octets, and so on but the quartet and the trio (violin , cello, piano) are far more common. May 13, 2022 at 15:25

4 Answers 4


Both. When they play in unison it’s louder. When they play separate lines it’s a richer sound. There’s also usually two flutes, two trumpets, and four French horns.

And I think the word “identical” might be overstating it. Yes, generally the second chair will be asked or expected to play the same or similar make and model of instrument, but no two instruments or players are identical. Having the slightly different tone between the two instruments adds to the richness of the orchestra.

It’s similar to there being two violin sections. And 6-10 violins in each section. They can play together or divisi or one can play solo, etc.

The overall size of the orchestra is to fill the concert hall so everyone can hear in a time before electronic amplification. The relative numbers of instruments create a mostly balanced level across the orchestra, at least within reason.

Studying scores while listening carefully to symphonic works will help make this all clearer. Also going to see live symphonic music would give you a first hand understanding.

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    It would be interesting to also explain why there aren't more than two (typically). Two is richer than one, but then why not twelve (as the norm)?
    – Aaron
    May 13, 2022 at 3:55
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    @Aaron If I’m reading the Wikipedia article right, the popularity of pairs of winds and brass comes from Beethoven’s specifications for his symphonies. It claims that the standard of four horns comes from his ninth symphony. I can only guess that the romantic composers often used the Beethoven orchestra as their starting point. Certainly by the 20th century things got much more eclectic (e.g., Ravel’s Bolero). And for those who don’t know, three of each wind and brass and 6-8 horns is common in film scoring orchestras today. May 13, 2022 at 4:19
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    @Aaron beginning in the mid to late 19th century it was common to have three or more instruments of each woodwind family; the first piece I looked at as a quick sanity check was Parsifal. Todd, as to the fashion for pairs arising with Beethoven, that can't be right. Look at Mozart's and Haydn's symphonies and at late baroque orchestral works. They often have winds in pairs. Even the standard woodwind choir of pairs of flutes, oboes, clarinets, and bassoons predates Beethoven -- See Haydn's London symphonies, written before Beethoven was 5.
    – phoog
    May 13, 2022 at 13:30
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    I cannot believe this answer is voted up so highly when it's almost 100% wrong. I challenge anyone out there to identify the difference in tone between a Selmer and a Buffet clarinet (unless radically different mouthpieces are used). It's easy for a trumpet or French horn, or clarinet to play over {the entire violin section playing forte} . Volume balance comes from everyone adjusting their sound level so the music as a whole has the desired balance among all themes & backgrounds written in the score. May 13, 2022 at 15:20
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    @CarlWitthoft In every symphony that I've reviewed, there are unison passages and non-unison passages for pretty much every wind and brass pair/group except for horns, where rarely do all four horns play unison (although it does happen). So you're right that the entire parts are never identical, but there are many unison passages. And of course the final balance of the orchestra is created by the playing, not the instrumentation. Also keep in mind that this answer is pitched to the apparent level of understanding of the asker, so I've over simplified many concepts. May 13, 2022 at 15:28

Much (?) more frequently they play different voices; note, that as for all wind instruments only one tone can be produced at the same time. So if the composer desires an additional tone of that same color, there is no choice but to add another player. The first position typically has a bit more to play, especially in pianissimo he/she may play alone.

(For super-difficult passages the conductor may even instruct the player of second instrument to stay silent in unison passages, since differences are far easier to spot than wrong notes. This, as correctly commented, is no issue for professional orchestras, but applies to student and amateur ensembles.)

  • "since differences are far easier to spot than wrong notes" - Can you, please, elaborate on this sentence?
    – brilliant
    May 13, 2022 at 14:22
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    @brilliant I agree with you. What he should have written is that two identical instruments in unison will sound worse when slightly out of tune than two instruments (in unison) from different sections of the orchestra. May 13, 2022 at 15:16
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    @brilliant One errant note may not be noticed by people unfamiliar with the piece, a wrong note/rhythm may fit into the context of the music and not sound obviously wrong. But if two players playing the exact same line suddenly play something different, it's more obvious that one of them is wrong. May 13, 2022 at 15:28
  • I suspect your last point may be more true in student ensembles. I would expect this to be less of a problem with professional musicians.
    – A. R.
    May 13, 2022 at 20:24

My understanding is you have enough players per instrument to cover the number of written parts, except for the string which used large numbers of players, not because there were many more written parts, but for the special timbral quality of a large group of strings.

Lots of classical symphonies have just two parts per wind instruments. Two parts meaning two notes to be played simultaneously. So just two players was enough to handle to two written parts.

Strings were different. Especially the violins. Lots of violins were used. Not because there were many more written parts, not for volume, but for timbre. The group sound is "richer", "warmer", also the bow attack become a little softer, more diffused. However you describe it a large group of strings sounds timbrally different that just one string player per part.

You can also think of it in terms of instrumental genres too. The symphonic orchestra is essentially a string orchestra and the winds just augment that string orchestra for timbral color. The large group of strings distinguishes the symphony orchestra from instrumental groupings like a concertino group in a concerto or chamber ensembles like a string quartet. So, many strings versus single string players distinguishes some genres, but the number of wind players doesn't. You only need the number of wind players to fit the number of wind parts.

In my mind that makes the distinguishing factor about how many players per instrument to be mostly about the timbral expectations of various instrumental genres.

  • How true -- since a "wind ensemble" aka "concert band" might have 6 flutes, 6 to 12 clarinets, and yet only one or two tubas, one bari sax, and so on. 3 trumpets plus 3 cornets May 13, 2022 at 15:22
  • This is also why a solo violin sounds different from the ensemble. A great example of this is the first allegro from Vivaldi's La primavera, which alternates between duet violins and tutti sections. In a good recording, you can really notice the difference in timbre.
    – A. R.
    May 13, 2022 at 20:30

Reed instruments have keyed pitches. As opposed to bowed strings (and incidentally, trombones) that means that to a certain degree the pitch relations between instruments with purportedly identical pitch are mostly fixed, but since expressiveness and volume typically impacts pitch as well, expressive melody lines don't add up to a rich complex texture like with violins (also aided by a comparatively rich overtone spectrum) but contain some non-organic semi-systematic beatings. At the same time, any multiplication of instruments diminishes expressivity by averaging it out.

2 is a compromise that still provides redundancy (and differentiation from a solo voice, even though orchestral woodwinds are all expected to be able to carry a solo, something not to equal degree the case with strings) while not attempting to compose a complex sound texture which does not work all as convincingly with reed instruments as with some others.

I am fuzzy about trombones.

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