Previously, we have discussed low impedance speaker system options. Most consumer audio systems are low impedance in operation to provide higher audio quality and power output requirements, and these concepts scale up to larger Professional level PA systems. In this issue, we will discuss the concept of speakers in a ‘line array’ setup, the benefits of this arrangement and where these should be used.
A Line array is a specific arrangement of multiple speaker boxes or speaker drivers which are referred to as elements, that cause the sound waves emitted from each individual element to interact with their neighbours in a specific way. These interactions are engineered in such a way to tailor the line arrays ‘dispersion angles’ to suit a particular space or environment, dispersion angles being the angle at which the full range of audio is emitted from the speaker. This engineering involves selecting elements with specific characteristics, angling them in certain ways and applying processing such as equalization and delay to the audio signals.
In smaller spaces we commonly use column speakers due to their unique dispersion patterns, and in many ways a line array is simply a customizable, large scale column speaker. To this end, line arrays are often used when we need to direct sound in a specific way that a conventional box speaker cannot do efficiently.
An example of this could be a performance space that has tiered seating and needs to employ only front of house speakers. Such a space would require a higher sound output level (SPL) for live music which a traditional column speaker would be unable to reproduce. A common box speaker would be able to produce the SPL required but it would not offer the listeners in the tiered seating a linear level of SPL across the venue, meaning those closer to the front would experience higher SPL than those further back. In this instance a Line array can be used, with a number of elements coupled together at specific angles to ‘throw’ the sound waves into the space more effectively, ensuring a more even SPL coverage.
The term ‘throw’ here is also important, as it touches on the second feature of a line array we can use. A line array can be used to throw sound a longer distance with a lower rate of SPL loss than a traditional box speaker by altering its dispersion characteristics.
An example of where this would be of use is a multipurpose sports venue, such as a large school hall. The speakers may need to be mounted up high, out of the way of flying basket balls, but still need to be efficient at reproducing audio for school performances. Mounting a conventional box speaker at a great distance from the audience would see the majority of the sound energy from the speaker dissipated and wasted. In this instance, the tight ‘pattern control’ of the line array would focus the sound energy in such a way as to not have it dissipate as greatly. The extreme of this example is large sports Stadiums and outdoor music events, where the speakers could be mount 30 – 50m away from the audience.
Line array systems are less common than conventional box speaker systems, but are the perfect solution to many spaces. They do require more planning and time spent in engineering to implement properly, Most line array manufacturers provide access to ‘modelling’ software that allow you to design the space you need to service, insert their products and will work out how well the setup will perform, to allow changes to be made to the setup of the array prior to installation. We can provide our industry leading engineering to ensure you can provide the best result for your customer.
