Know Music Theory But Still Can't Write Symphonies

I have lost my composition book years ago. Musescore is good but still if I even think of writing a symphony I get overwelmed with questions.

I know music theory and can easily look up amateur and professional ranges for certain instruments like the flute. I can also transpose. It isn't always easy when transposing from something like C to something like F# or Major to unrelated minor. But I can do it.

The questions I get are things like "What instruments should I use?, What instrument/instruments should I use first?, Should I add piano as accompaniment?, What key signature? Major or minor?, What time signature?, How many movements?, Where should the forte go?, Should I add a repeat? How fast or slow? etc."

Which they are good questions to have in mind when writing a symphony. The problem is I get overwelmed because most of those questions are being asked at once.

I know that Beethoven had to go through that trouble and I wanted to be like him, that is symphonies first, than piano sonatas.

So how can I not get overwelmed by all these questions since listening to orchestral music has not helped?

Beethoven was the most prolific sketch maker in musical history. Throughout most of his career he worked on as many works as his muse dictated, sometimes five or six at a time. A sonata, a symphony, a choir, a string quartet. Somehow he was able to juggle all of these and keep track of everything. The man was posessed! And as far as I can tell, there ARE no lesser works in his vast repetoire.

The questions you ask yourself are troubling. Most composers don't bother with such questions because they aren't important. Don't make them so important, just play.

But I know that a symphony needs to sound good in at least the last movement. So that is why I ask myself all those questions is because I want a good sounding symphony. Perhaps listening to an analysis of symphony no 5 by Beethoven and symphony no 40 by Mozart will give me some ideas for my first symphony.

You can't simply want it and hope it will happen and you can't put such standards for yourself for when you write your first symphony. It may not sound good at all, however you mustn't let that stop you from trying and trying again. Beethoven and Mozart both wrote tons of pieces, both good and horrible, before any of their first masterpieces were even thought of as simple musical ideas prior to their making. They spent years, even decades learning and mastering their craft before writing those pieces.

I'm saying that you can't hope to understand music and write down an entire symphony in one huge step. It takes time - years even, before a person has enough compositional experience and knowledge to write even a decent sounding symphony. If I were you, I wouldn't start with a symphony. I would start with mastering the basics like melodies, harmony and counterpoint. Once you have mastered those and laid your musical foundation, only then can you go on and build the fountain of ability you so desire. 

Remember that Rome wasn't built in a day, and neither is musical ability. Learn to crawl on your hands and knees, then walk, then run, then jump. It's all a process and you can't skip any one of those steps no matter how much you want to. We all have to go through it, friend.

Good luck friend!

Beethoven did symphonies before sonatas and Mozart is not all that far off from symphonies first. Both are really famous. And I bet some modern composers have started with symphonies before sonatas. And I didn't realize it at first but in my thunderstorm piano piece I used the same rhythm for my lightning as Beethoven used for his 5th symphony.

It's also possible that Beethoven and Mozart wrote some really awful things first, which they tore into tiny pieces and threw into the fire once they learned enough to write better music, don't you think?  (;  I know I don't have all my third grade writing assignments any more.  The better you get at anything, the more you cull the proof of your early days.  

Mozart and Beethoven wrote many (MANY) smaller works before tackling the symphony and sonata. I don't get what them having written symphonies first (they composed them and many other works simultaneously) has anything to do with it. Plus, you need to expand your horizons...Beethoven and Mozart weren't (aren't?) the only "famous", "perfect" symphonists. 

I agree with MuseScience, you need to start off small, master the basics of melody, harmony, and counterpoint first. Then read orchestration books, study scores, keep listening to different music. Remember, Brahms took 21 years to write his first symphony. The questions you posed show that you are not ready to write a large scale symphony, since those questions are pretty meaningless in the scheme of things.