Since the 1990s, musicians have increasingly used sequencers or notation programs in conjunction with synthesizers or software instruments.
The advantage is that it has been possible to work on the "almost finished sound" during the entire design process.
The sequencers from then on have developed into powerful workstations with notation modules and are an integral part of the studio and production environment.
Music notation programs today are effective graphic work surfaces, which can reproduce the created music realistically through corresponding interfaces.
Composers and arrangers decide on which surface their music is to be created
The interaction between notation programs and virtual instruments allows musicians to make musical scores sound - long before the first rehearsal with live musicians or an orchestra. Unpleasant surprises for a live performance should be avoided - ideally.
Does the notation correspond to the sound?
The moments of surprise have been reduced but have not disappeared completely. Despite the amazing sound quality of virtual instruments, many productions suffer from a aural deficits. This is usually less due to musical material, stylistics or the quality of the mix.
Do deficits have to do with the workflow?
Deficits can often already be found when dealing with individual instruments or ensemble sounds and add up rapidly. This reduces the quality of music created. The variety of playing techniques and articulations that sound libraries offer, leads to "try" instead of the conscious "selection" of sound colors. Today's methods of work have changed significantly compared to "traditional instrumentation".
Very exaggerated: "In the past you had to study various textbooks for orchestration, read scores and listen to countless recordings, while today you can search on a computer screen through menus with countless samples and make your selection with a mouse click."
What do sound libraries contain and how do you deal with the diversity?
For production without live instruments this is not a problem at first. It can be critical if acoustic instruments are involved in the production process. A composer or arranger should have a clear idea of sound of his music. He really needs to know exactly what he writes in the score, so that what he wants also sounds. Discussions with the players waste time and money.
Sound libraries often contain gigabytes of samples, sometimes for only "a single" instrument. If you listen to productions with virtual instruments, you sometimes ask yourself - where have all the gigabytes remained?
Music can still be so good when you have "no happy hand" when selecting and using sounds, or if you still use the recipes that many other colleagues have successfully used.
Is there a "standard orchestral sound"?
No - that would be terrible. Countless (film) composers have made it clear how diverse instrumentation can be. So many composers can be recognized directly by their instrumentation. And what is true to an orchestra also applies to the use of virtual instruments:
Poorly instrumented music sounds bad too!
The starting point was a simple piano score. The later orchestrated versions use this basic material and the same instrumental cast. Nevertheless, they clearly differ in their sound.
Comment: Here can be heard the basic musical material (beats of the strings, piano, bass and clarinet motifs). The instruments start one after the other, there are no duplications. No fading effects were used. This version contains the actual basic atmosphere: piano sound above a strings surface with a woodwind motif before the ending.
Comment: The basic musical material is still present; in addition single notes have been doubled, long-held notes of violins are superimposed with faded sound variations (eg. a simple vibrato is superimposed by a non vibrato, played on another string), piano bass notes are doubled by weak pizzicati of violoncelli, etc. This kind of instrumentation can be easily realized by instrumentalists or higher quality sound libraries.
However, the instrumentation can be made more refined.
On the Internet there are numerous sites of varying quality, which deal with the subject of orchestration. They are usually suitable for a "quick answer" to specific questions. Basics for orchestration could be found, for example, at selected online orchestration courses:
Thinkspace Education Composition & Orchestration
Berklee Online Courses Orchestration
Audiocation Soundtrack Composer
Vienna Training Center Courses
audio workshop Courses and Tutorials
And then there’s the good old textbook on the subject orchestration. There is a list on Wikipedia.