Really good question @florent83!
I try to explain my point of view as a composer and a mixing-engineer (2 views):
If you go to a classical concert, you always see the instruments positioned in groups somewhere. This “somewhere” actually was a long process which was created by super talented composers like Bach, Mozart, Beethoven. What you need to know, that there are two different concert positions used. The one which is used more often is the “American”. Violins, Violas left, Cellos, Basses right. And then there is the so called “German” one. This one splits the violins. Violins 1. are sitting left, Violins 2. are sitting right (mirror). Basses are behind Violins 1., Violas on the right where the 2nd violins are and the cellos in the middle. Horn section is changed as well. If you are interested, you can google it
Whenever you change a position of an instrument, you change the “feel” of how you react to a composition, because you deal with different frequency responses / octave changes, sounds, and so forth. Another thing to have in mind, people who play in there are used to sit at their “standard” position – they always have a reference group of instrument to refer to. If you change the group positions the orchestra will play the piece different, due to the “wrong” hearing, as what they are used to. There are pieces which are composed exclusively for the American / German. It was a really long process to figure out, what sounds best for the composition, which orchestra position. Really a “physical” thing.
A super good example of how much an orchestra sound can change if you just let them sit wherever but not at their usual position. If you know Hamburg, Germany, you might know the “Philarmony”, a new concert hall for classical music, but for other “bands” as well. So the idea was to make it “super special”. So they decided to place people around the orchestra. The consequence was, that you need to change the orchestra positions as well, so all people can hear the same music performance. If you don’t change it, you can hear more brass, or strings or woods, or percussions, due to how near you sit to the section. So they need to “mix” the groups to make it sound more or less equal. They did. But then the musicians said that it’s just not working for them, as they are not used to play like this. The one said: “I hear now only the horns.”, another: “I hear only distracting flutes???..”. So what did they do, they start to build “reflection walls”, so the musicians could hear the other instruments through reflections. Extremely difficult to make. And of course hundreds of millions €!!! So now you know, why changing positions can be difficult in real life.
But it wasn’t your question, I know I make it short, if you keep your orchestra either “German, American or just your own”, then you make your music much more interesting, as you can play with the panning a lot.
Point of view as an engineer: Let’s say your composition has a beautiful violin melody. We know that a melody is the most important element at that point. But if you place this melody on the left side, as your typical position you will lose attention, because it’s only heard left and all other panning-spots are filled with everything else, and this “everything else” is much more stuff, then the violins. So you need to focus your melody somehow. What do you need to do, to accomplish that? You need to pan the melody to the centre, to make sure it’s heard on both ears. It will be louder as well when you hear it in mono. If it’s only left, you lose gain, when you play in mono back (panning something to a site = lost in gain), so lost of focus twice actually.
What I would suggest. Narrow down your “real orchestra” by max. 50% pan. The other space you either use lite percussion or wide pads, etc. At the point when you focus your orchestra it becomes more as “one”. Especially on headphones it’s really hard to make “pans” work well. What I found out for me, which works for me fine and I don’t overthink the “pan-problem”, I use only 5 pan positions:
- Hard-Left (L100)
- Half-Left (L50)
- Half-Right (R50)
- Hard-Right (R100)
If you take single mono sound like snare, you can almost hear all the positions, as the sound is concentrated to just one point. But I realised that if you start to add more and more sounds you can’t hear these small steps anymore, your ear is “oversaturated” with information, so I just don’t waste time on the .10 or .25. I call it for now “Advanced Old School”, in the 60s you had either L/C/R, nothing in between. And many engineers still work like this, for example: Chris Lord Alge.
Point of view of a fan/listener:
Last words: focus more on your music first of all, the feeling, the small nuances, which make people get emotional…if you make a killer track, do you really think people care about which “mic positions”, pan-pots or EQ moves you did? You know the answer