What led to the changes in instrumentation of the Romantic orchestra?

Answer 1

The changes in instrumentation were the result of MANY different things.

Following the French Revolution, the rise of the middle class meant that there was more demand for concerts, and as a result, larger concert halls were made. Because musicians needed to make a larger sound for concert halls, they turned to brass instruments and percussion instruments to give the orchestra more sound.

Also, the industrial revolution changed MANY things as well. Valves were invented for the horn and other brass instruments, allowing them to be more flexible. This was very attractive to composers, who wrote more for them.

There was a massive upsurge in the popularity of the piano now because of both the rise of the middle class and the industrial revolution. The piano was now a better, stronger instrument, and because it could play many notes, every household had one for domestic music making.

Another reason is that composers sought to create new soundscapes. Remember this is the Romantic era, and tone colour was starting to be explored fully now. Composers wanted to evoke sounds that had never been heard before. Hector Berlioz is the famous one for this. Look at the colours in his Symphonie Fantastique. The E flat Clarinet and other instruments in there are very new additions to the orchestra. And Wagner was another one. I mean, he INVENTED a type of French Horn, called the Wagner Tuba, to appear in his Ring Cycle.

There are probably one or two other reasons but I can't remember them.