TECHNOLOGY FOCUS WIRELESS SYSTEMS Expert Witness
The early drawbacks associated with digital wireless systems have been overcome creating a reliable, capable technology, says Gear4music’s live sound expert, Ashley Smith.
Ashley Smith
WIRELESS AUDIO systems have become a fundamental tool in modern day live performance. Removing many of the restrictions imposed by cables, wireless systems have not only changed how live audio set-ups are designed and implemented, but how artists deliver the performance itself. From offering the freedom of the entire stage for vocal and instrument reproduction, to providing a controlled monitoring environment, wireless audio technology is being called upon more and more frequently. With ever- increasing standards in live production, from grass roots through to professional levels, so too is the demand on wireless audio systems, their technical capabilities and financial viability.
DIGITAL Since the relatively recent shake up of bandwidth allocation in the UK by the communications regulator Ofcom, we have seen a rise in the number of wireless systems operating via digital signal transmission available on the market. A significant
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benefit of digital wireless systems is the fact that they offer licence-free use, with the majority of systems in Europe operating at 2.4GHz (as used by WiFi networks and Bluetooth devices). One major drawback of digital wireless systems operating in the busy 2.4GHz range can be signal interference. Unlike an analogue system, where interference may just cause degradation of audio quality, interruption of a digital signal is much more likely to have the effect of total audio drop out. To overcome this problem, manufacturers have had to engineer beyond the analogue method of connection redundancy, often known as “diversity reception”. Systems such as the Shure GLX-D have been designed to combat this problem effectively by transmitting on three frequencies concurrently. It automatically returns both the transmitter and receiver to clear frequencies if interference is detected, thus maintaining a constant and uninterrupted audio signal.
This method of operation
also removes the need to scan manually for clear air space, making the system much more user-intuitive and potentially shortening set-up times. Another key benefit of digital wireless is increased data security. Many high-end systems such as the Sennheiser 9000 series offer encrypted signal transmission, preventing interception by third parties (intentionally or not) and maintaining privacy.
AUDIO QUALITY A major drawback of early wireless systems was the lack of dynamic audio range, with minimal control over AF and RF signals provided.
Nowadays, even entry-level set-ups include features such as equalisation, audio level attenuation and RF signal (squelch) management, providing audio quality much superior to the early systems. Many manufacturers also offer interchangeable capsules featuring different pick-up patterns for their microphone handsets. This allows a single system to be used for a variety of different vocal or instrument applications and offers a much greater level of flexibility. The Line 6 XD series of handheld mic systems take this in a unique direction by offering capsule simulation presets for a selection of popular microphones. Presets for models such as
the Shure SM58, Sennheiser e935 and Audix OM5 are included allowing users to quickly achieve different frequency responses without using EQ further down the audio chain. Recognising a historical difference in frequency response between wired and wireless counterparts, the Shure BLX/GLX-D systems feature corrective equalisation, designed to accurately match the response curve for the corresponding capsule model. In situations where multiple transmitters and receivers are used in co-operation, greater system planning is required to overcome the issues inherent to areas busy with radio frequency transmissions. With advancements in wireless electronic design, many manufacturers include the option to connect multiple wireless systems together into a single combined network. Management software then allows engineers and technicians to monitor the AF and RF performance of each system in one centralised point, programming
adjustments as required. This level of control is invaluable in ensuring radio reliability and audio stability for productions utilising a large number of wireless systems.
IEM Wireless in-ear monitoring can offer huge benefits over speaker-based monitoring systems. Creating a controlled listening space by blocking out external noise sources, wireless in-ear systems provide a consistent mobile monitoring environment for the performer. The lowering of on-stage volume by the scaling down or even total removal of monitor loudspeaker systems offers other benefits too. Past the obvious advantage of cutting the risk of audio feedback, a drop in stage levels can also greatly reduce microphone bleed, resulting in a cleaner and more defined sound through both the FOH and monitor systems.
Although for many in-ear
monitoring is an instant solution, many find the ‘sterile’ environment created by this method of monitoring isolated and removed from the atmosphere of the live performance. One way of countering this problem is introducing a dedicated crowd or ambient microphone signal into the monitor mix. The Audio-Technica M series of wireless monitoring systems offers a straightforward solution to this problem by allowing the performer to control the mix between the transmitter’s two inputs from the beltpack receiver while on stage, giving the control to cut or boost the ambient signal level as required. The risks associated with listening to audio for extended periods of time or at high volume are well known.
Established in 2003, Gear4music now has over 300,000 registered customers. Alongside musical instruments, including the company’s own brand of great value beginner gear, Gear4music retails a large selection of pro audio, live sound and recording equipment. Working with more than 400 manufacturers, Gear4music has developed a choice of over 18,000 products to cover the vast majority of audio applications. Gear4music prides itself on its customer service, with no fuss returns and money back guarantees and warranties available, as well as offering customers a wide selection of convenient delivery options.
www.gear4music.com
www.audiomedia.com
This combined with the potential for interference in wireless systems to cause unexpected spikes and noise makes protection of hearing an important aspect of in-ear monitoring systems. Signal limiting is employed to ensure the performer’s hearing is safeguarded in the event of any such incident. Historically wireless in-ear
monitoring has been regarded as an option for professional productions, but, as with wireless microphones, the technology is becoming more and more accessible. At Gear4music we offer our own wireless in-ear monitoring system, which although an entry-level system, at under £55 is fantastic for its price point, testament to the increasing availability of wireless audio systems to meet every technical requirement and come in on every budget.
The Expert Witness
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