Nexo GEO D - Manual (Page 74)

Page 74/97 S YSTEM ALIGNMENT GUIDELINES
Consequences of badly aligned systems
Mis-aligned systems have lower efficiency: i. e. for the same SPL the system will have to be driven
harder, activating the displacement & temperature protection at lower output levels. Both sound quality
and reliability will decrease as the system is stressed.
Precautions & Checks
Before using the AUX of a mixing desk, ensure that MAIN and AUX outputs are in phase;
Always apply identical EQ or processing on both channels, 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 that is not the case, the system is no longer aligned.
7.6 Recommended installation tools and equipment
• Tape measure – should be 30m/100ft in length and be of durable fibre material. Have one per
array available to speed up the installation process.
• Laser Inclinometer – For measuring vertical and horizontal angles in the venue. An ideal product
is the Calpac ‘Laser projecting a dot’ version which costs approximately 60 €.
• Digital remote inclinometer – with a remote sensor in the bumper and a meter unit at ground level
to ensure precise installation of the cluster. NEXO GeoSight system predicts the stationary angle
of the array, even while it is swinging, and has a green laser mounted coincident to and parallel
with the axis of the topmost cabinet.
• Spirit level – used to ascertain the trueness of the surface from which the angle measurements
originate.
• Rangefinder measuring device – either a Disto type laser measure or an optical laser rangefinder
can be used. Devices such as the Bushnell ‘Yardage Pro’ sports rangefinders provide sufficiently
accuracy and are easy to use. They have the additional advantage of working very well in bright
sunlight.
• Electronic calculator with trigonometric functions to calculate the height from ground level to
points in the room. The formula to calculate height of a point from measured angle and distance
is:
• Height of point = Sin(vertical angle in degrees) x distance to point
• NB: Take care when using spreadsheets as they calculate using radians by default. To convert
degrees to radians use the formula:
• Angle (in radians)=3.142 x Angle (in degrees)/180
• Computer – Laptop or Desktop PC running Windows 2000 or XP with the current version of
NEXO GeoSoft2 installed. It is not possible to configure a Geo tangent array properly without
using GeoSoft2. Note that, when GeoSoft2 designs are prepared prior to arrival at the venue, it is
often necessary to modify or update the design to accommodate special circumstances. A PC is
absolutely essential to make such changes.
• Audio Analysis Software – recommended but not absolutely essential, programs such as SIA
Smaart Pro, Spectralab or Spectrafoo enable rapid and detailed analysis of the installation.
Consider taking a training course in using one of these tools if you are not already competent
with them – it will pay dividends in increased performance of the system.