All the new subwoofer's electronics are fully integrated into the cabinet, including the active crossover filters, driver overload protection circuits and power amplifiers. The integrated bass management system with its six inputs and outputs (L/C/R front and L/C/R rear), plus LFE input and summed signal output connectors is very flexible. The dedicated LFE input (which can be set to two bandwidths, 19-85 or 19-120Hz) has a low-pass filter selectable to 85 or 120Hz, plus a +10dB sensitivity switch. When the LFE channel carries frequencies above the crossover frequency, the system's 'redirect' function automatically sends these signals to the centre front output to ensure they are audible.
There is an integrated 85Hz test signal generator, making it easy to set-up the crossover alignment. Dual bass roll-off and phase matching controls mean the sub-woofer can be accurately tailored to different environments. The bass roll-off can be adjusted in 2dB steps, while the phase matching controls offer four positions, from 0 to -270 degrees. The low pass section of the bass management system has adjustable sensitivity for simple level matching with the main loudspeakers in the installation. The six HPF sections have 0dB passband gain and can be bypassed with an optional switch for accurate assessment of the sub's effect on the overall system. The amplifiers on the 7073A produce a total of 1kW of short term RMS power for the four 305 mm (12") cone drivers. Driver overload protection and power-on signal muting are included in the amplifier circuitry.
(Ruth Rossington)
