You've gotten great advice -- I'm going to go out on a limb and point out that it's quite possible to make such a transition overnight, and even within the same day, if you go about it properly. Many professionals can go from a hard-rocking, loud, ragged blues band tone recording session in the morning to a brass quintet with classical tone rehearsal in the afternoon to a big-band lead trumpet tone in the early evening and end up with a small-combo jazz tone for a late-night club. Tone is in your mind, your concept of breathing and tone, and you can change tone quite easily, provided you've been practicing all your various types of tones at the same time all along. During your marching band season you should be practicing with your concert band tone every day, and not compartmentalize them into different seasons of the year. Keep them current with each other and you can turn them on and off at will.