Xt System Operation; Recommended Maintenance Procedures - L-Acoustics 112XT Operator's Manual

6. XT SYSTEM OPERATION

Connect program signal lines (L/R outputs from a mixing console, for example) to the A and B channel
inputs of the digital signal processor (XTA DP224, DP226 or BSS 366).
With reference to the output channel assignments given in the Preset Description sheets (see also
Figures 5, 6 or 7), connect the outputs of the DSP unit to the corresponding amplifier inputs (directly
or via your signal distribution / return snake multicore system).
For 6 channel units (XTA DP226 and BSS 336 or 366) outputs 1, 2, 3 correspond to Sub, XT low, XT high
for input A while output channels 4, 5, 6 correspond to Sub, XT low, XT high for input B.
Power up the DSP unit and select the appropriate preset for 2-way operation (FRONT, FILL or
MONITOR) or 3-way operation (3W or 3WX for 112XT or 115XT plus SB115, SB118, SB218, dV-
SUB subwoofers).
Perform the following steps as a system check:
1) turn down the level of all amplifier channels before turning the amplifiers on
2) un-mute the HIGH crossover channel
3) send a pink noise signal to the crossover
4) turn up the level of each HIGH amplifier channel individually and check that this provides
the expected frequency band in the expected loudspeaker component. Test each HIGH
amplifier channel individually until all HIGH amplifier channels have been tested.
5) mute the HIGH crossover channel
6) repeat steps 2-5 for LOW and SUB channels
7) turn off the pink noise
Set all amplifier output levels to 0 dB gain
Un-mute all crossover output channels and the system is ready for use.
Remember the old saying: "amps on last, amps off first" in order to avoid component damage due to power
on/off transients.

6.1 RECOMMENDED MAINTENANCE PROCEDURES

a) HF diaphragm replacement
To access the HF compression driver diaphragm, the front grille of the XT enclosure should be
removed and the entire 12" or 15" coaxial assembly de-mounted.
To remove the front grille, lift the edges of the acoustic foam and remove the screws. Screws can be
found where the edges of the foam are not glued onto the grille (there is no need to completely
remove the acoustic foam in order to remove the loudspeaker grille).
Once the coaxial assembly has been de-mounted, unscrew the back cover of the rear-mounted
compression driver assembly to obtain access to the compression driver diaphragm.
Remove the damaged diaphragm and before installing the replacement diaphragm ensure that the
voice coil gap is free from any metallic particles, dirt or other debris by using 2-sided tape and
acetone, if necessary, to thoroughly clean out the gap.
After installing the replacement diaphragm, apply a low level, low frequency sine wave sweep (for
example: 4 volts from 100 Hz - 1 kHz) to ensure that the diaphragm is properly centered in the gap
before reinstalling the compression driver back cover. Make sure all compression driver diaphragm
and back cover mount screws are securely fastened (loctite is optional but recommended).
L-ACOUSTICS XT Manual V1.1 11-02-03 41