No system in the room. Totally acoustic.
Are you trying to get the sound of the room and actual orchestral micing or are you looking for a Broadway pit orchestra sound where everything is close miced and instruments are individually defined with no natural room sound?
What you want to achieve determines how you'll mic.
Is this a professional orchestra, community orchestra, college or high school?
Where is it being broadcast?
What genre of "orchestral music" is this?
Do you know the works being performed?
Mahler is very different than Debussy who are both worlds apart from a modern composer like John Adams.
I assist at a large professional symphony with their live broadcasts secondary to my main design and engineering job. We broadcast live every regular season concert. We won a Grammy this year for one of our live recordings.
I am happy to help with pointers but can't help much without answers to questions.
Lee