SleepDeprived said:
I listen to rock music and usually in the musical mix, the drum is placed at the center/back of the soundstage, the vocal is at the center/front, and other instruments like guitar, piano are either are the left or right and slightly up front. So this gives a nice weight to the soundstage with the drum and vocal act as a foundation upon which others are built.
I notice that in an orchestra, the light instrument such as violin are placed on the left side, whereas the heavier instruments such as the cellos are on the right? Is that the usual convention? Are there any reasons for that? Whenever I listen to a classical piece, I also get this odd feeling like I am listening to the bass part on the right and the light part on the left as if I am listening to two separate events. Can the cellos be places at the center/back of the orchestra? Are there any reason why not?
There are many factors involved in the layout of the orchestra, and many varying opinions on the best layout. There is certainly no single ideal layout.
The first thing to note is that orchestral layout assumes that the listener will not be too close to the orchestra. The best seats are typically something like half way back in the concert hall. The sound should normally be primarily central in front of one, but it is sometimes helpful to have some stereo separation for passages where different parts play alternately, especially for higher pitched instruments (where human perception of direction is more accurate). Some devices and even recordings use "wide" stereo techniques where the difference between the left and right channels is artificially amplified, which doesn't often work well for orchestral music.
Some of the factors involved are as follows:
1. Section principals within a given instrument family (strings, woodwind, brass) should be as close together as practical, for best coordination.
2. Players of a given instrument part normally find it most practical to be grouped together (although some orchestras split double basses or even cellos between the two sides).
3. It is often easier for players and the conductor if instrumental parts with more closely related pitch are placed adjacent to one another, as it is common for two or more such parts to play closely related music. In particular, the first and second violins may sometimes be subdivided (into three, four or more individual lines) which may be easier to perform and better blended when the relevant players are tightly grouped. For example, one movement of Shostakovich Symphony No 5 is scored for 1st, 2nd and 3rd violins (of equal importance) playing in harmony, which typically requires some 1sts and some 2nds to play 3rd, so it is obviously more practical when the 1sts and 2nds are seated next to each other.
4. The sound from string instruments is somewhat directional, being stronger and more clear when facing the front of the instrument (with the holes in), although this effect decreases with lower pitch. In particular, cellos and double basses can sound stronger when placed towards the middle facing forwards, but second violins and violas sound a bit less strong when placed on the right facing the first violins. (On the other hand, the fact that second violins are facing the other way can help to provide a contrast in the sound for antiphonal sections).
5. Certain composers like to use antiphonal styles where two different parts alternately play similar music. In such cases, it may enhance the effect to have those parts well separated on the stage. However, different works may have different requirements.
Before the 20th Century, orchestras were typically small and the layout was often defined by the convenience of grouping around the keyboard/conductor. It was common to have the first and second violins on opposite sides for antiphonal effect, with cellos and basses somewhere in the middle facing forwards. J C Bach (youngest son of J S Bach) even wrote some works for double (string) orchestra, which are typically performed with a mirror image arrangement.
In the 20th Century, influential conductors Henry Wood and Leopold Stokowski decided to switch to what is now the common modern layout, with the strings going down in pitch from left to right, with the first and second violins together, then the violas, then the cellos on the right with the basses behind them. This is very practical for the players and conductor, but has this effect that one side is predominantly high pitches and the other is predominantly low pitches. Whether this is a good or bad thing generally depends on the work, but provided that one is not too close the effect generally blends well anyway. This blending may of course be undone by recording techniques which separate parts too much, simulating being too close to the orchestra.
Different orchestras may choose different layouts (often selected by the conductor), and this may also vary depending on the musical period of the works involved, but the Henry Wood arrangement is the most common at present.
The Hallé orchestra (based in Manchester) is well known for trying out alternative arrangements. They currently usually use first and second violins facing each other, with cellos and basses either in the middle or split evenly between the sides. (One of the co-principal second violins is the daughter of the couple who make up the other two players of the string quartet in which my wife and I play).
From some Googling I have found an interesting paper which covers these aspects and many more:
Orchestral Seating in Modern Performance by J D Smith:
http://www.jdsmusic.co.uk/Orchestral Seating - JDS 2009.pdf
