Coherent Summation Across BASSBOSS Models
BASSBOSS subs include processing that allows any combination of cabinets to be combined (on the same plane) and their output to sum coherently — providing an increase of SPL in their common passband.
Example: Combining a ZV28 with an SSP118
Combining a ZV28 with an SSP118 will result in an increase of SPL capability only in the operating range of the SSP118. Filtering the upper frequencies out of the ZV28 would simply remove its capacity to add SPL in the upper range — effectively the same as eliminating the SSP118.
That said, retaining the SSP118 and adding the ZV28 does provide extended LF response AND additional SPL capacity, and distributes the thermal and physical stress over more drivers. Thus, combining the boxes and using EQ to reduce non-linearity yields a system with flat response AND greater headroom — generally translating to longer service life and reduced distortion.
Using ControlBASS to Flatten the Response
Combine the boxes, measure the result, and apply the same EQ filters to both — ensuring they remain in phase, with each providing 50% of the resulting output.
Understanding Effective Crossover Frequency
When subwoofers are providing more SPL than tops, the effective crossover frequency (the point at which each passband is contributing 50% of the energy) moves up in frequency. Increasing sub output by 6dB shifts the effective crossover frequency up by approximately 1/4 octave.
To reduce any resulting boominess, lower the HPF filter frequency of the subs and/or raise the LPF filter frequency of the tops so the transition is more gradual.
