System information
X-Array Touring Loudspeaker Systems – Applications Notes – Page 27
if one loudspeaker was suspended directly above another. (The most common example would be the
Xds subwoofer systems sitting on the ground with the Xf, Xn, Xb, Xcn and Xcb systems suspended
overhead.) Whenever enclosures are physically misaligned, signal delay must be introduced to compen-
sate for the misalignment.
Consider the case of an array of Xf, Xb and Xn systems suspended in an array overhead (for the primary
coverage of the venue) with a ground stack of Xn systems (for front-fill coverage). The front seating rows
would typically be much closer to the Xn ground stack than the overhead array. Therefore, the Xn ground
stack would have to be delayed to bring it into alignment with the overhead array in the seating areas
where their coverage patterns overlap. Failure to delay the ground stack would result in decreased intel-
ligibility in the overlap region. Furthermore, the apparent sound image would shift from the overhead ar-
ray to the ground stack as one walked through the listening area.
Another example would be that of a full-range array of Xf, Xb and Xn systems suspended overhead with
a stack of Xds subwoofers on the ground. If the full-range array was suspended directly above the Xds
subwoofers, then the Xf, Xb and Xn systems must be delayed 2500 microseconds (as describe in the
previous section) to bring them into alignment with the Xds systems. If the full-range array was sus-
pended downstage relative to the Xds subwoofers (i.e., closer to the audience), then the signal delay to
the Xf, Xb and Xn systems would have to be increased beyond the basic 2500 microsecond to bring
them into alignment with the Xds systems. (One strategy that is often employed in portable systems with
ground-stacked subwoofers and overhead full-range arrays is to purposely add a fixed delay to the over-
head array that is greater than the requisite 2500 microseconds. With this approach, signal delay ad-
justments need only be made to the ground-stacked subwoofer outputs to bring them into alignment with
the overhead array – thus, simplifying the set up procedure.)
The amount of signal delay required for compensation for enclosure physical misalignment (for atmos-
pheric pressures of 1.0 and ambient temperatures of 20°C/68°F) is as follows:
Signal Delay for Loudspeaker Physical Offset:
2910 microseconds per meter
887.1 microseconds per foot
HELPFUL HINT: When tuning an X-Array system, the user should make adjustments to the input and
output signal delays to compensate for any physical misalignment of loudspeaker enclosures. Failure to
compensate for the physical misalignment of systems can result in uneven frequency response and un-
even pattern coverage. Failure to compensate for the physical misalignment of the low-frequency sys-
tems with the subwoofer systems can result in reduced bass output and impact
D.8 Limiter Parameters
The limiter in the DN8000 is fast acting and is used for preventing extreme (and potentially damaging)
voltage peaks from reaching the loudspeaker. The limiters may also used for minimizing amplifier clip-
ping. The limiter-threshold settings shown in the digital-parameter spreadsheets are calibrated for opti-
mal protection of the loudspeakers when used with the Electro-Voice P3000 amplifiers (which have built-
in analog limiters to minimize amplifier clipping).
As noted in the Power Amplifier Recommendations section, the recommended large amplifiers have a
very-high-voltage capability that can damage the loudspeaker drivers. The X-Array™ loudspeaker sys-
tems are can handle large, clean, instantaneous-voltage peaks from those amplifiers; however, the driv-
ers cannot withstand repeated clipping (140-volt square waves!). Although the SUB, LF and MB drivers
are somewhat tolerant of such abuse, the HF compression drivers are considerably less so. To minimize
the possibility of loudspeaker failure, the user must make sure that the limiter thresholds in the digital
crossover are calibrated to minimize amplifier clipping.