10
Unmute the subs and employ the low cut filter on the appropriate channel of the LD-1A. Measure the PSW-6 and
the MSL-6 together. The frequency response should look flat through the crossover. A noticeable reduction of
SPL at 125Hz is caused by one of two problems. The first is that the microphone is positioned too close to the
near-field of the speaker which can be solved by moving the microphone further away from the speaker. The other
probable cause of the cancelation is a reversal in phase somewhere in the signal path.
To test for a phase reversal, use the polarity reversal button on the Sub section of the LD-1A channel 1. If this
causes the response to become smooth through the cross over region, there is a phase reversal in the signal path
check the wiring and input polarity switches of all components in the system. While not good practice, in an emer-
gency the polarity reversal switch can be used throughout the performance.
Adjust the gain of the Mid-High cabinet and Sub cabinet using the LD-1A to optimize the phase and frequency
response so that the acoustical crossover point is close to 125Hz.
The illustrations shown below represent general guidelines for appropriate LD-1A settings for various combina-
tions of PSW-6s and MSL-6s.
1 PSW-6 on the ground
for each MSL-6 in the air.
4 PSW-6s on the ground
for each MSL-6 in the air.
Note that the Lo-Cut filter is engaged and all the other
buttons are out. The Sub output gain is set to 0 dB and
the Mid-Hi output gain is set to 0 dB.
Note that the Lo-Cut filter is engaged and all the other
buttons are out. The Sub output gain is set to -9 dB and
the Mid-Hi output gain is set to +3 dB, resulting in a
relative Sub to Mid-High gain difference of 12 dB.
Input Signal
CP-10
LD-1A
MSL-6
PSW-6
Mid-Hi Out
Sub Out
House Curve
Crossover
