Hey Friend,
So where were we? Oh yes, scaling for music...
We were talking about how composers need to understand the venue that houses their orchestra. It's not enough to pull a bunch of musicians together and sit them down in sections. They had to know how many of each instrument would be need to make sure they would be heard.
On top of that, they needed to have enough of each instrument to make sure the song was served properly.
With guitar and piano, we can create and play chords all day long pretty easily. Not so with other instruments. Most musical instruments can only play one note at a time. If you want any sort of harmony, you have to have at least one other instrument to provide the third or fifth note from the key.
That isn't to say that they HAD to have two or three of the same instrument to provide harmonies, but with larger orchestras it's certainly possible. Otherwise, as long as there are a number of instruments from the same class, the composer could accomplish what they were trying to do.
For example, consider the brass section. You'll have trumpets and flugelhorns, coronets and French horns, trombones and tubas. Each of these covers a set of frequencies in the sound spectrum and are directed to play various musical sections to fill out what is needed sonically.
The composer makes sure that there are enough instruments to fill out each range - the bass, middle range and treble tones.
They also take timbre into consideration. Obviously, a violin sounds much different than a piccolo or clarinet, so instruments are chosen to based not only on their frequency range but also o their unique sound properties. Each instrument's timbre is a result of the materials used to make the instrument and by its size.
Because we have amplifiers, effects and microphones, we don't necessarily have to worry about doubling or tripling our guitar sound when playing live, but it's a trick we can use to give a single guitar more fullness and depth. Adding some reverb, delay and compression to an amplified guitar signal can really enhance it.
I sometimes think about how cool it would be to get a bunch of guitarists together to play orchestra-style, where each guitar takes on an individual part and plays as if they were in one of the designated chairs in an orchestra.
I know it's not an original idea - I shared a video a while back by a guy that does ust that. He plays each orchestral part on guitar and then mixes it all together as a final piece. I don't remember the guys name, and I know I shared it fairly recently, but I'm drawing a blank right now.
Anyway, can you think of other ways we fill out the sonic spectrum in Rock? Let me know what you think - have a great one!
Peace~
Dave | 
