Nexo GEO T - Manual (Page 47)

NEXO NX242 D IGITAL C ONTROLLER FOR GEO T Page 47/67
• Should you want to restrict the bandwidth with a low pass filter, you can introduce a phase
difference of up to 180° (completely out of phase) at the cross over point.
• If the signal is passing though any digital equipment you are adding between 1.4ms and
2.2ms (around 70° phase shift at 100Hz) due solely to the converter delay! The additional
delay due to the processing itself (look ahead compressor, delay…) can be quite important
as well.
If both outputs are not measured in the actual configuration, it is very likely that phase alignment will not
be correct.
5.6.3 Consequences of badly aligned systems
Mis-aligned systems have lower efficiency: i. e. for the same SPL you would be obliged to drive the
system harder, activating the displacement & temperature protection at lower output levels. Both sound
quality and reliability will decrease as the system is stressed. In certain situations you will even need
more speakers to do the same job.
5.6.4 Precautions & Checks
• Before using the AUX send of your desk, ensure that the outputs are in phase (you can
feed a 1000Hz signal at the input and monitor the MAIN and AUX outputs on a dual trace
oscilloscope).
• Always apply EQ or processing on both channels at once, so that the phase relationship will
not be altered.
• Never add additional low pass filtering on the SUB or high pass filtering on the main
system.
• Inverting polarity on one channel should always result in a massive difference near the
crossover point. If the sound is more or less the same the system is no longer aligned.