Cardioid Versus Omni - Spl Differences - JBL VTX Series User Manual

11.4 CARDIOID VERSUS OMNI - SPL DIFFERENCES

Cardioid stacks are not lossy. Using the proper JBL preset, rear-facing subwoofers not only reject sound at the back of an array they also
contribute positively to the sound pressure at the front of the array, though not as much as an array in which all subwoofers face forward.
2 x Forward Facing B18s
The curves below compare the performance of the three examples illustrated above. The 2:1 cardioid stack produces marginally less
SPL than the all-forward stack of three cabinets (about 1 dB), but significantly more SPL than the stack of two forward-facing cabinets.
This shows that cardioid arrays actually redirect energy from their rear to their front.
5
0
-5
-15
-25
-35
20 100
TIP: The point of maximum rejection of a cardioid stack is about 3 meters (9.8 ft) behind the array.
2:1 Cardioid Stack
B18 SPL: Cardioid versus all-forward (measurements taken at 10 meters)
1000
Frequency (Hz)
VTX B18 | User Manual
(3) VTX B18 all forward facing
2:1 Cardioid Array
(2) VTX B18 all forward facing
10000 20000
28
3 x Forward Facing B18s