Master audio Xcellence Serie Manual Usuario página 19

Master Audio
7. CARDIOID SUBWOOFER X18WE
The X18WE enables the combination of three or multiple of three subwoofer cabinets
in an array to provide exceptional directivity at low frequencies.
High directivity at low frequencies has two main effects on the sound field: firstly, the
low frequency level behind the subwoofer cabinets is greatly reduced; secondly, in
closed venues the diffuse sound field at low frequencies is reduced so the low
frequency reproduction is much more precise.
The typical operating range of a traditional subwoofer tends to be like a monopole,
i.e. tends to radiate with the same energy in all directions. This behaviour implies that
the control of radiation at low frequencies is very difficult because the wavelengths
are very large compared to the size of the source (8.5 m at 40Hz).
Fig.12. Traditional polar pattern of a subwoofer at 40Hz
To increase the directivity at low frequencies we must transform the omnidirectional
performance into a cardioid performance. This can only be achieved by various
sources, arranged in a certain position, to which we apply a specific phase, filtering
and delay. That is, we need to reproduce two signals with the same frequency and
similar amplitude which will have a difference in phase of approximately 180º at a
certain point of the sound field. If the phases and delays are well calculated the result
is a system in which we cancel the energy of the back and not the one of the front.
This can only be achieved with cabinets that incorporate independent delay units on
their DSP, as X18WE.
Fig.13. Cardioid pattern
7.1. The CARDIOID preset
The X18WE can generate an uncompromised cardioid behaviour, which means that
there is no need for special cabinets, enabling the use of the system's full efficiency
with just "one finger".
Xcellence "E "Series. Ver1.3 Des13 19