Page
8
VTX
Series
Laser
Accessories
User
Guide
August
2012
USING MULTIPLE VTX-LZ LASERS
For advanced system tuning, multiple LZ lasers can be deployed to serve as site angle
references for individual array circuits, assisting in physical measurement microphone
placement to correspond with virtual measurement microphones shown in LAC.
Using JBL HiQnet Performance Manager™ control software and with reference to
measured spatial response, circuit level gain shading and JBL Line Array Control Panel
(LACP) frequency tapering adjustments are performed as a first step in system tuning.
This initial step is referred to as array calibration and JBL LAC II / LACP simulations
provide a good starting point. For the actual real world installation, VTX-LZ lasers
mounted on array circuits can be used as a reference for microphone placement to
verify and further refine the starting point gain shading and tapering parameters that
were pre-determined in JBL LAC II / LACP and Performance Manager.
Once SPL and frequency response has been optimized on a circuit level, global
equalization can then be applied to the entire array to compensate for room-related
effects. For this step, global equalization can be based on the spatial average of all
measurement microphones that were placed throughout the audience area with
reference to VTX-LZ laser aiming locations. This patented approach to system
measurement and tuning has been specifically designed into the workflow of
Performance Manager (US patent 2008/0170729).
LAC II Frequency Response Probes
(virtual measurement microphones)
Refer to VTX-LZ focal points for actual
measurement microphone placement
Note: It is only necessary to deploy multiple microphones on one array of a FOH L/R
system (FOH L or FOH R) and a single VTX-LZ laser unit on the other array to verify
that vertical site angle focus is matched for both arrays. Once basic testing verifies that
FOH L/R arrays are acoustically-matched, detailed calibration and tuning can be
performed based on measurements conducted on the side of the FOH L/R system that
has multiple measurement microphones (adjustments are simultaneously applied to the
other array using stereo linking features available in Performance Manager).
