HD 4 has been completely refurbished in 2017 (formerly known as DBlux OB4). The audio control room is designed to meet high requirements during larger live entertainment music shows. HD 4 has its own, custom-built semitrailer that functions as a storage and transport vehicle for all of the peripheral equipment that is required for a major production whether it is sports or entertainment. All technical equipment in HD 4 production unit is protected by UPS (3x 11 kVA)