I have been receiving conflicting information from orchestration bigwigs. Some say that composers should never orchestrate two stringed instruments together because they will be ever so slightly out of tune with each other. But then there are compositions like Vivaldi's Violin Concerto Op 3 No 8 that have two violins playing in unison. What's the scoop?

Okay there seems to be confusion as to what I mean. I have read that for smaller ensembles, one section of stringed instruments should either consist of one or more than three because only two stringed instruments playing together would sound out of tune. Is that true?

  • Which is the issue: orchestrating two stringed instruments (pretty general and would seem to rule out string quartets and many other genres) or two stringed instruments in unison? Mar 26, 2020 at 16:02
  • I'm wondering how that interpretation would work on a 100-piece orchestra… they all have to be playing something different, all the time…?
    – Tetsujin
    Mar 26, 2020 at 16:05
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    To expand on @Tetsujin 's comment, I am guessing you are referring to something like the first and second violins playing in unison, but you have to take into consideration that in an orchestra, the first violins aren't just one violin, they are numerous and they all have to play in unison with each other, so there is no reason why they can't play in unison with another group of string instruments Mar 26, 2020 at 16:16
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    This is supposed to be regarding never arranging exactly two instruments in unison. Supposedly more than two makes a nice sound as a section, and one is a solo, but two is a weird out-of-tune thin section, I would assume the logic goes.
    – user45266
    Mar 26, 2020 at 17:03

2 Answers 2


Two string instruments in unison don't blend well. But in the concerto for two solo violins, you don't want them to blend. You want them to remain individually recognisable. Which is tricky in a unison passage, so such passages are short.

There are also tutti passages where the solo violins are joined by a section: of course there the blend is intended.


This is dangerously close to "feng shui" territory. But I suspect that, rather like the infamous Bose 900 series speakers, his point is that 3 or more instruments produce enough interferences that your neuroacoustical interpretation is that of "smoothed" sound. When there's only 2 instruments the beat frequency (difference of the two pitches) is much easier to pick out. When you have 4 or 5 instruments, the collection of beat frequencies (go ahead and do the math of combining 5 separate complex waveforms :-) ) crushes your ability to notice them.

footnote: Bose 900 "Direct-reflecting" speakers drive 9 identical elements. The company and some listeners found them delightful; Consumer Reports slammed them & pointed out the guaranteed phasing mismatches. and that most of the subjective likes were due to the high volume output. Lawsuits ensued.

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