By the times of Bach, most orchestras consisted of strings of the violin family, woodwind section of flutes/piccolos, bassoons and oboes and a harpsichord-led continuo. Some orchestras added brass section of trumpets and sackbuts (trombones) but brass instruments had not yet come into their own. The cornet—a post horn with valves added—would not be invented until 1814. French horns existed but not as we know them and would not until the 19th century. Likewise, the tuba—descended from the ophicleide and the serpent, both huge ungainly instruments—was not known until patented in Prussia in 1835 as a basstuba. As it stood, the trumpet at this time was a fixed-key instrument and would not become chromatic until more valves were added in the early 19th century.
17th century trumpet. Louis Armstrong couldn't have done much with this thing.
Some early orchestras may have had percussion sections—drums and cymbals—but not tympani as these were still a ways off from being added to the orchestra.
The orchestra seemed to set the standard for the future was that at the court of Duke Carl Theodor at Mannheim in 1742. They introduced ideas of tone coloration by combining different instruments playing in unison and using dynamics of soft passages interspersed with loud, clashing ones to excite the audience. This was departure from other orchestras that played pieces where one section of instruments could do as well on a certain passage as another—winds instead of violins, for example. The instructions indicate that these different sections play in unison and rarely did one go out of the range of the other. But with the introduction of brass, harps and that new-fangled clarinet, more differentiation not only crept in, it was rather necessary.
Instead over-relying on violins as before, a scene in a meadow, for example, would rely on flutes and piccolos to provide bird-like notes while the strings played lower and in the background like wind occasionally rustling through the trees and grass. A scene taking place in the heavens or celestial realms would rely on harps with brass providing sound of an angelic host, etc. This was where the concerto grosso came in. By answering or backing the soloists and the small choir, great variation in tone coloration was achieved. True orchestration can be said to have arrived in the second half of the 18th century.
The difference between a Mozart piece and a Bach piece was that the instrumentation in a Bach piece could be supplied by any number of instruments. An oboe could do as well as a flute or a trumpet playing high up. But by the time of Mozart, orchestration provided enough tone coloration that parts written for flute could only be played by the flute or parts written for strings could only be played by the strings and so on.
Concomitant with the development of
Pièces à Grand Orchestre, was the development of the double bass. The assumption that it descended from the bass viol is erroneous. The bass viol was intended to provide soft music for intimate settings such as chamber pieces. The double bass was intended to be loud enough to fill a hall. There was not a lot of use for it until
Pièces à Grand Orchestre because it was loud enough to be heard by all the players. A good player could keep the entire orchestra in time which was essential for a large ensemble (there were no conductors yet).
The following two pieces illustrate the difference between baroque period music and that of the classical period which followed:
Giovanni Valentini - Sonata à 5. Forgotten early baroque music - YouTube
Christoph Willibald Gluck - Fruhlingsfeier - YouTube
Notice in the Gluck (an early composer of the classical era) piece, the addition of expanded instrument sections to the orchestra, most notably brass and tympani which add tremendous punctuation inconceivable to the baroque era. Note also the addition of the choir. What we hear is a whole new style of music, whole new dimensions opened to the listener.
Notice also the difference in length. The baroque piece lasts only a few minutes while the classical piece lasts 20 minutes. What was the rationale for the expansion?
All music from the early religious hymns to classical to the latest pop consist of repeating themes but the themes are much longer in classical and so one must listen with more attention to catch the themes repeating whereas with pop the themes are so short that they take no real effort to catch where the themes repeat.
People of the past paid a lot more attention to the “music-scape” of a piece than people do today. Imagine walking in a big circle through a detailed landscape and so one must to pay strict attention to landmarks to figure out where one is and to know when one has passed by this area before and all along the way there are little side paths and what not to walk through. One may not walk the side paths on first listen but only on subsequent listenings or may not have even noticed except another pointed them out. Composers used to delight in taking the listeners on these long, long musical journeys and the listeners had fun to navigating through them. People today often hate these long passages and find them exceptionally boring.
Art Buchwald once wrote an article about his visit to the Louvre in Paris. He said only three works are worth seeing—the Winged Victory of Samothrace, Venus de Milo and the Mona Lisa. He said everything else in the museum is “just so much window dressing.” One must arrive by taxi, stopwatch in hand, and then enter the museum in a walk, no running allowed. By keeping an even but quick tread one can see each of the three masterpieces in a quick glance. Buchwald wrote of Peter Stone who had tried before but failed to set the record of seeing the three masterpieces faster than anyone but who finally broke the record at five minutes and 56 seconds. Stone’s advice was to not look at any other exhibit but to shut them out or one will get caught up in actually enjoying the art and will lose the race.
The point of Buchwald’s article was to point out what has become important to modern society and it is just as true of music as painting or sculpture: It's no longer about enjoying the landscape as you journey slowly to take it all in and imprint it in your memory but rather how fast you can get to the end, how fast you can whiz through it. That's why rap is so stripped down and bare-bones minimal. There is no point to creating rich textures that the listeners aren't going to notice anyway or understand even if they did notice them. The idea of a modern songwriter deliberately creating repeating themes that take 10 or 20 minutes to cycle through just once to give the listener an hour or two of enjoyment is completely alien to people today. Classical music today is “tl;dl”—too long; didn’t listen.
Ironically, the huge amount of available music today is largely what is wrong. People of medieval times or the 18th century were not bombarded from all sides with a zillion songs and jingles from a zillion forms of media blasting it at them 24/7. Music was comparatively scarce so they paid a lot more attention to it. The symphonies were something new and exciting to them. Couple this with the lack of visual stimuli that we have today with television and movies and the internet and a million magazines on the store shelves.
The people of old had to use their imaginations way more than we do now and so they took delight in losing themselves in this glorious music. They couldn't wait for the next symphony to take them somewhere new and exciting the way we might reserve ONLY for the next over-hyped big blockbuster movie today.
And remember also that they had no way of hearing it except to attend the performance. They couldn't just throw on the cd or the mp3 and listen back as many times as they wanted to catch everything. They attended these symphonies with the full knowledge that they might never hear this particular piece again and so they struggled to remember as much of it as possible on the first and possibly only listen.
They did the same with books and all the arts. Most of the population couldn’t even read and, in fact, regarded it as something akin to magic. But music? Anyone could listen to music and so I imagine the masses took great delight in it. It may have been one of their few true diversions.
Today, we revel in our ignorance because it takes too much time to study anything. If it takes time then it is a waste of time. That is the path to doom.