Q:

Will a forte tympani overpower a quiet orchestra?

So far, I have been mainly using the tympani in my orchestration of the Pathetique Sonata for the purpose of adding an accent. It might change later on to having a more important role but right now, it is just an accenting instrument. Because of this, I feel that I can give plenty of time for the tympanist to retune the drums if I have to to keep the accent consonant with the rest of the orchestra. I also think that most likely the tympanist would have tympani pedals to raise the note without retuning the instrument. So far, I have been keeping it forte because of its accenting purpose.
But I'm wondering whether it would simply overpower an orchestra that is at piano if the tympani stays at forte. I mean, the distance between the tympani and the woodwinds and strings and the sheer power of the brass makes me think "No, of course not. It is too far from the more mellow instruments of the strings and the woodwinds to overpower them. Besides, the brass, even at a piano dynamic is very powerful, especially if you include the heavy brass(tuba and trombones) as I do in my orchestration.
But, am I right in that assessment? Or should I lower the dynamics of the tympani a bit to something like mezzo piano when the orchestra is at piano so that it still sounds accented, but not overpowering? 

A:

Yes, timps at forte would dominate an orchestra at piano.  Give them the same dynamic as the rest of the orchestra unless you're looking for a special effect.
Trombones can play very loudly, but also very softly.

