d&b MAX2 - Manual (Page 7)

CPL circuit
The CPL (Coupling) circuit compensates for coupling effects
between the cabinet and close boundary surfaces or when the
cabinet is used as a stage monitor. CPL begins gradually around
1 kHz, with the maximum attenuation below 400 Hz. To achieve a
balanced frequency response, the CPL circuit can be set to dB
attenuation values between 0 and –9.
Positive CPL values create an adjustable low frequency boost (0 to
+5 dB) and can be set when the system is used in full range mode
without subwoofers.
2.4. Dispersion characteristics
Due to the conical coverage pattern of the coaxial driver design,
the horizontal and vertical dispersion characteristics of the MAX2
are largely identical (slight differences which occur are attributable
to the cabinet shape). The diagram below shows dispersion angle
versus frequency plotted using lines of equal sound pressure
(isobars) at –6 dB and –12 dB. The nominal 75° dispersion angle
is maintained from 1 to 16 kHz.
Isobar diagram
Frequency response correction of CPL circuit
d&b MAX2 Manual 1.1 en 7