The sound booth is commonly referred to as the MIX on concert seating charts. For most end-stage concerts, the MIX is behind floor seating - directly head-on to the stage. However, the exact location does vary by concert.
At Gillette Stadium, the sound control is usually in front of Sections 142 and 143, which may cause a slight obstruction for fans in the lowest rows in those sections. Those sections are elevated above the field, which does reduce the obstruction.