RAY SUB IMPLEMENTATION
Page 52 / 76 System Manual RS Series
7.5.2 Alignment with phase measurement
Phase measurement with real time FFT analyzer can also provide reliable measurements, provided:
• measurement microphone is set on the ground to avoid floor interference in the reading
• floor is perfectly rigid (concrete)
• measurement microphone is set far from any walls / ceiling, or inside angles / corners
• coherence values are high (typically above 75%)
If one of above conditions is not respected, then distance measurement should be preferred.
7.5.3 Driving RS from the AUX send
It is common to use the AUX send of a mixing desk to drive the Sub section of a PA system. This gives the mixing engineer
more flexibility to set the level of the subbass relative to the main PA, apply special effects, or to use a different EQ on the
Sub. However, it also raises some serious issues for the performance & safety of the system (mostly time alignment).
At NEXO, great care is taken to design optimum phase alignment from one octave above to one octave below the crossover
frequency point. By doing so, drivers are working perfectly together and providing the best efficiency possible. It is then up
to the user to adjust the delay on the NX TDControllers to match the physical path difference of the different systems. It is
thus possible to get a well-adjusted system, even without measuring instruments.
If RS subwoofers are driven form an AUX output, NEXO TDController is fed with two signals coming from different sources.
If those two sources (MAIN output & AUX send) are not exactly in phase, delay is introduced into the crossover between
main system array and RS subwoofers. It is then mandatory to use proper measurement tool to optimize phase response.
IMPORTANT
Before using different outputs of a mixing desk, ensure that MAIN and SUB outputs are in phase.
Never add additional low pass filtering on the SUB output or high pass filtering on the MAIN output.
Always apply identical processing (EQ etc…) on both outputs, so that the phase relationship between
MAIN and SUB is not altered.
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.
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 8 with the current version of NEXO NS-1 installed. It is not possible to
configure a GEO tangent array properly without using NS-1. Note that, when NS-1 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 Systune
TM
, Smaart
TM
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.
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