Strings in an orchestra?

Just wondering a few things... do composers ever specify in their scores how many desks there are to be of each string instrument? Some orchestras seem to have so few violas compared to other string instruments. When writing for strings do we have to be aware that one section might not be as loud as another section or are they designed to all be represented equally? For example, if the melody is played by the violins which are doubled in octaves and the cellos and double basses have something completely different and the violas have a part which is in harmony with the melody will it come through over the violins? Thanks for your time.

generally, you "assume" that the string parts are balanced.

this assumption is that there are considerably more violins than any of the other string instruments.

A composer MAY specify a minimum number of strings or desks, but that could probably reduce the number of performances as well. The reason? A conductor looking at a new work, seeing "10 violas" will assume that it means there is at some point a divisi which requires 10 viola parts. His orchestra has 8 violas, and in reality COULD have played your piece perfectly well (since there wasn't any divisi of the sort)... and that equals one less performance.

Student and community-based orchestras are not the barometer upon which you should base your orchestrations (unless we are talking about a specific commission BY one of that type of ensemble).

Therefore, always consider the "perfect" ensemble when orchestrating.

As for your question about string balance, well, celli and basses in octaves, with 1st and 2nd violins in octaves, your violas, if their melodic material is very important, MAY very well get lost in the fray, depending on the dynamic.

That is part and parcel of the craft of orchestration.

As you yourself noted in the thread on your Music of the Spheres, if the accompaniment and melody are within the same range, then one of them risks getting lost in the mass of sound.

However, I can perfectly well imagine 1st and 2nd violins playing long held notes in harmonics, in the high register, ppp, while the celli and contrabasses play delicate off-beat pizzicato notes in their lowest register, the whole time the violas are right in there around middle C playing a more prominant melody in 1/4 and 1/8th notes that would come out quite well against the rest of the string texture.

With this example, extra care must be taken when you start adding any woodwinds, brass, harp, etc.. to the texture. the same consideration for register and texture must be taken - held notes will not detract, rapid figurations WILL distract from the main melody unless very carefully constructed.

The idea in orchestration is to create planes of sound that will support one another. You will have foreground planes, background planes, and mid-ground planes (depending on the complexity of your orchestration).

Thanks very much for your advice. Good luck with the Canadian Symphony, by the way. I hope to hear it performed one day.