Wireless In-ear Monitoring Systems
Oct 12, 2009 12:00 PM, By Bennett Liles
Clarity and comfort have brought stage monitoring under control.
In-ear monitoring (IEM) is at the apex of a series of tech advances that have led up to the ability of stage performers having their own customized monitoring environment in a live music situation. In the ’60s, stage monitoring was a radical, new-age concept at a time when even the Beatles were miking drums in live concerts with a single omnidirectional EV635 overhead. It didn’t matter because no one could hear them playing above the usual adolescent shrieking. As their music and that of other performers became more sophisticated, the live stage systems used by such performers had to evolve to deliver to paying concert crowds the same sound quality and definition that had been heard on the groups’ records.
By the ’90s, enough performers had put together do-it-yourself IEM systems that manufacturers recognized the trend and produced wireless models with better control, while the firms that had been making custom interruptible feedback (IFB) earpieces for TV anchors and reporters found a new market in stage musicians and vocalists. The same technology that was pushing the envelope on wireless microphone systems with frequency agility, improved receiver selectivity, and more recently, automatic frequency assignment, was used to deliver better performance for rapidly evolving IEM systems. Now these systems are everywhere providing much better monitoring clarity, eliminating feedback, and drastically reducing the hernia factor for stagehands and roadies.
Most of these systems include in their feature set a multimode operation with a choice of one mix in both ears or separate, customized monitor feeds in each ear—an ambient microphone feed that some performers prefer in order to avoid feeling isolated from the onstage environment—along with connection loop-through, switchable RF output power, pilot tone muting, limiting, and infrared transmitter/receiver sync brought over from the modern wireless microphone advances. Of course, battery power is critical, and these systems also employ the same power-monitoring features in the body-pack receivers that are used in wireless microphone transmitters.
The IVM 4 set from AKG is an in-ear monitoring system that includes the SS 4 stereo transmitter and the SPR 4 body-pack receiver. The SS 4 allows up to 14 channels within a 30Mhz UHF band. Any of the 1,200 frequencies can be manually selected using the unit’s front-panel controls, providing compatibility with AKG’s WMS 400 or WMS 4000 wireless microphone systems in frequency selection and in the use of an adjustable RF output level. The SS 4 also features an audio input loop-out to feed multiple units with the unprocessed input audio signal, and the input level to each unit is individually adjustable ±20dB. Using the optional Hub 4000 Q, the SS 4 can be integrated into a Harman Professional HiQnet system, controlled and remotely monitored with a PC through the System Architect software with control features that include RF monitor, device manager, environment scan, and auto setup. The transmitter operates on frequency bands from 500MHz to 865MHz with an audio frequency response from 35Hz to 20kHz. The SPR 4 body-pack receiver has auto setup and environment scan in addition to RF-signal-strength indicator and the Smart Battery Management System. The BP 4000 battery pack charged by the CU 4000 charger can keep the unit up and running for up to 7 hours.
The M2 wireless in-ear monitoring system from Audio-Technica consists of the M2T UHF stereo transmitter and the M2R stereo receiver. The M2T, with its 100 UHF channels, has an interesting front-panel display with a dual peak meter and left/right signal indicators along with three operation modes: personal mix, stereo, and mono. The unit features a switched limiter, pilot tone muting to avoid RF blasts when the transmitter is turned off, and an XLR loop-through to feed up to 10 additional transmitters. It also has an auxiliary input for connection of ambient mics, click track, or other sources. The audio frequency response of the M2T is 60Hz to 13kHz ±3dB with a maximum dynamic range of 90dB. Depending on local availability, the system can be capable of operating on any of four 100-channel bands between 575MHz and 865MHz. The M2R receiver uses a 3.5mm TRS headphone connection, and it can operate up to 8 hours on two AA alkaline batteries. The included EP3 headphones have proprietary dynamic drivers, three sizes of rubber ear tips, and an ear-conforming foam tip.
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