134STACKED SUB CORRECTIONThe Stacked subs option is designed for stacked multiple-subwoofers configurations.When multiple subwoofers are used to reproduce the same signal, the perceived level increases. The SDP-75automatically decreases the signal sent to each subwoofer to maintain the same perceived level depending on thenumber of subwoofers used to reproduce the same signal. The attenuation varies, depending upon whether thesubwoofers are located very close to each other, or are located well-away from each other, which is typically the case.In such multiple subwoofers configurations, two typical cases are handled by the SDP-75:• If subwoofers are considered as decorrelated (away from each other), their power add up.• If subwoofers are considered as correlated (positioned next to each other or stacked), their amplitude add up.Therefore, whether the stacked subs option is disabled (default) or enabled, an automatic attenuation of the signals willbe calculated accordingly to maintain a consistent level.Number of subwoofers inthe systemAttenuation if “Stackedsubs” disabledAttenuation if “Stackedsubs” enabled2 subwoofers -3 dB -6 dB3 subwoofers -4.8 dB -9.5 dB4 subwoofers -6 dB -12 dBFigure 99: Level of attenuation and the Stacked Subs option
