Originally a place where dancers and musicians gathered, an orchestra now symbolizes the group of musicians itself. Such an image suggests that we are capable of operating in spiritual harmony.
Psychological / emotional perspective: When we wish to orchestrate something, we want to make it happen. This means that we must take action that enables us to be heard and to have people understand us. When we find we are conducting an orchestra in a dream, we feel we can accept we are in control. When we are a member of an orchestra we are simply part of a greater task.
Material aspects: We all have certain aspects of our personality that must work in harmony with one another for us to function properly. Dreaming of an orchestra represents ways in which we are capable of bringing all those aspects together and making a coherent whole.
A discordant orchestra suggests that we have not succeeded in integrating all aspects successfully.
A disciplined orchestra suggests that we have succeeded in that integration.