Zen On Stage: The Latest On IEM & Personal Monitoring
Ways manufacturers and engineers are pushing the boundaries of monitoring...

April 07, 2014, by Gary Parks


Reliable monitoring is essential to performers on stage, allowing them to blend their musical contributions with the other players – keeping them in time, on pitch, and able to creatively interact.

Traditionally, this function was performed by low-profile loudspeakers aimed generally toward the areas where the performers were active, with level control, sufficient coverage, bleed into open microphones, and feedback all issues that needed to be overcome. Another issue, especially with acts performing at high levels, was/is a contribution to hearing loss.

I first became aware of in-ear monitors, and wireless delivery of the mix, more than 20 years ago when I was asked to check out a prototype from a company called Garwood, based in the UK. The system consisted of a transmitter and a commercial stereo receiver unit (as I recall it was from Sony) operating in the FM band, with a pair of ear buds for monitoring.

In talking with some sound engineers for corroboration, I heard that a handful of singers were trying the system but rarely the other players, and that not hearing other musicians and the audience “live” was a common objection. (It should also be noted that Future Sonics was another pioneer of this approach at the time.)

Fast-forward a couple of decades, and in-ears and other personal monitoring solutions see wide usage. Let’s explore how manufacturers and engineers are pushing the boundaries of monitoring.

The Advantages
Monitoring a performance and what the rest of the band is doing while wearing in-ear monitors has a number of advantages over monitor loudspeakers. Typically, the performer has personal control the level of the mix via a wireless beltpack receiver or other interface, and unless the level controls and limiters are overridden, that level will be safer than the uncontrolled output of stage monitors and additional sound sources.

So there’s less potential for hearing damage as well as listening fatigue, but still enough level to stay present with the performance. And no matter where the artist moves on stage, the mix will remain consistent and much cleaner.

That mix can be even more highly controlled, either by the monitor engineer or by personal monitor-mix stations where the performer can select exactly what they want to hear at which relative levels, and make adjustments on the fly. With the mix going straight from the board into the ears, personalization of a mix is much more refined, and can make achieving a satisfactory mix faster and easier.

For the engineer and audience, having fewer or no monitor wedges lowers the level coming off the stage into the house, so that the house loudspeaker system isn’t competing with the stage for attention. This can be further enhanced with isolation boxes on instrument amplifiers, along with side/rear-firing them, and similar methods. Also, either having no wedges on stage or having them at lower levels to supplement in-ear monitors will help with gain-before-feedback as well as mic isolation.

A major part of performing is making the connection with the audience, and that energy is part of the “live” feeling that can be compromised by wearing isolating in-ears delivering a clean personal mix. An early and ongoing solution to this problem is adding side-stage audience mics to feed applause and other ambient sounds into the monitor mix. Pulling out one ear bud or loosening them to hear what’s going on can defeat the benefits of hearing protection and a more consistent mix.

Engineer Sean Quackenbush (O.A.R., Robert Randolph) with part of the Sensaphonics 3D Active Ambient IEM system.

Performers also need to interact on stage, and this includes being able to talk with each other during or between tunes. Artists also want to communicate with techs and the monitor mixer during a show. With in-ear monitors sealing the ear canal and attenuating ambient sounds by 20 dB or more, that communication can be much more difficult.

A solution from Sensaphonics addressing these challenges is the 3D Active Ambient IEM system. Each custom earpiece contains a microphone, and what it “hears” can be added to a monitor mix at any desired level.

The beltpack has a toggle switch that goes between a performance mix with your preferred ambient level mixed in, and a communications mode that brings up the level of the mic and dials down the monitor mix for those necessary conversations. Another approach is found in the JH Audio Ambient FR earpiece, which has an “ambient bore” to let in an attenuated version of outside sounds.

At The Ear
The elements for personal monitoring include the method of mixing the sources – the monitor console or individual mixers for the musicians, the delivery system for those signals, and the transducers themselves.

Though headphones are occasionally used, ear pieces or “buds” as they’re commonly called are much less obtrusive. Some of the differences among these in-ear devices involve custom-molded versus standard foam tips, the number of individual transducers used to reproduce full-bandwidth audio, the types of drivers used and how they are crossed over, and how they are constructed.

Some companies, such as Ultimate Ears, Future Sonics, JH Audio and Sensaphonics, only offer custom-molded in-ears that fit the exact contours of a particular musician’s ear canals. This precision leads to a tighter seal to attenuate the ambient sound, potentially greater comfort, and a more controlled audio environment. The process begins with a visit to an audiologist who takes molds of both ears.

Some even provide guidance to find a qualified audiologist, with precise instructions of how deep into the canal the mold should go and that the person’s mouth should be open during the process “to ensure a more secure fit while the artist is singing, playing and instrument, or talking.”

Having a tight seal within the ear canal also enhances bass performance. Jack Kontney of Sensaphonics notes that “the soft silicone flexes with the ear canal when singing and changing facial expressions” so that a complete seal is maintained. An incomplete seal can lead to a loss of low frequencies, especially below 100 Hz – and is especially important when using balanced-armature drivers.

A tight seal also prevents the loud ambient sounds from entering, so that effective monitoring can be attained at lower levels. Further, according to Sensaphonics, medical-grade silicone provides several dB better attenuation than acrylic, reducing outside sounds by greater than 30 dB.

Inside an Ultimate Ears 18 Pro Custom earpiece.

Ear buds use either dynamic or balanced-armature drivers, or a combination of both, to reproduce the audio signal. Dynamic drivers function similarly to loudspeaker cones, only are miniaturized. They can be more efficient at reproducing bass frequencies, with potentially less detailed highs.

Balanced armatures suspend a rod surrounded by a coil within a magnetic field, and the motion of the rod is coupled with a diaphragm.  Their response tends to be highly detailed. As an example, the AF140 uses a dynamic and a balanced-armature driver in tandem for the lows, crossed over to a balanced armature for the highs.

JH Audio JH16 and Future Sonics mg6pro multi-driver ear buds.

With some buds, the frequency spectrum is divided between a pair of drivers; others use multiple drivers with several crossover points, and offer models with three, four, or more. Ultimate Ears 18 Pro Custom IEMs have six balanced-armature drivers – two LF, one each low and high mid, and two HF – while the Audiofly AF180 offers four balanced armatures and the JH Audio JH16 is a 3-way design with eight drivers per ear (double dual LF, dual mid, and dual high).

Recently introduced mg6pro ear buds from Future Sonics incorporate multiple 13 mm proprietary miniature dynamic transducers, crossover-free, and with proprietary +/-20 dB Ambient Noise Rejection (A.N.R.).

Universal-fit in-ear monitors are available from a variety of companies, such as Shure, Audiofly, Avlex MIPRO, Westone, Etymotic, and others. These units couple the earpiece with replaceable foam tips that conform to the contours of the ear canal.

While they don’t offer the fit and seal of a customized system, they are high-performance audio devices, like studio headphones. Listening recently to a CD through a pair of Audiofly AF140s, I had a “what’s that?” reaction and realized that I was hearing the detail of the flute player’s breathing on the recording.

Making It Personal
Going beyond a handful of different mixes provided by the monitor engineer, compact monitor mixers can be positioned by the individual musicians who can then customize their own mixes.

Professional personal mixers allow musicians to select and custom-mix 16 channels or more (discrete channels or sub-mixes) of digital audio from all available channels, adjust levels, pan, EQ and effects for each channel, plus save and recall presets of previous mixes.

Aviom is a pioneer in personal mixing, and recently introduced the A360, offering 16 mono or stereo channels that can be selected from a 64-channel A-Net or Dante digital audio network, plus an additional dual profile channel that gives the musician instant access to a most important channel of their choice. The system also has an onboard mic that can be enabled for one-touch ambience, or a stereo ambience feed from the console can be tied to this control.

The Roland Systems Group M-48 provides access to either 16 or 40 channels of digital audio when the appropriate Roland digital snake is connected to a Roland V-Mixer console. The setup of connected M-48s can be controlled locally or via software on a control computer. The personal mixer offers multiple outputs to feed a pair of floor wedges as well as headphones or IEMs.

The Allen & Heath ME-1 personal mixer works seamlessly with the company’s iLive and GLD digital mixers, complemented by the ME-U hub that opens it up to use with other consoles via Dante, EtherSound or MADI. ME-1 also has an Aviom compatibility mode.

The dbx professional PMC16 personal monitor controller can be used with the dbx TR1616 converter or any other Harman BLU link compatible device, and multiple PMC16s can be daisy chained using Cat-5e, allowing each user to receive 16 channels. It also is outfitted with onboard Lexicon reverb. The Movek myMix system has a powerful yet simple interface that includes a large backlit screen, rotary controller, and four function push buttons, allowing the user to select and control a 16-channel mix.

myMix myMix-Mixer and Allen & Heath ME-1, both personal mixers.

And another step farther, Pivitec and PreSonus combine hardware with configuration and control software running on tablet PCs and smart phones. The Pivitec system is based on AVB Ethernet protocols, using compatible network routers and switches plus 16-channel rack-mountable input modules.

PreSonus offers an app called QMix to provide up to 10 musicians with individual wireless mixes on their iPhone or iPod Touch, when used in conjunction with the company’s StudioLive console. The iOS device will detect all StudioLive mixers on the network, and can create a mix that includes all mixer channels. Aviom has also announced that iOS support for the A360 is coming this year.

Going Wireless
Today’s performer may be wearing at least two wireless packs – one to transmit voice or instrument to the console, and one to receive a personalized stereo mix.  Being wireless provides freedom of movement while retaining a clean, consistent monitor mix.  Several wireless microphone manufacturers also offer wireless IEM systems, including Shure, Sennheiser, Audio-Technica, Lectrosonics and others.

Shure offers the PSM900 single-channel and PSM1000 dual-channel wireless personal monitoring systems, which operate in the UHF band. They are analog systems with a frequency response of 35 Hz to 15 kHz, with a stereo separation of 60 dB. The PSM900 covers 36 MHz of spectrum, and up to 20 compatible frequencies can be used together.  Transmitter power is selectable at three levels – 10, 50, and 100 mW.  The slim bodypack is ruggedly constructed with a metal chassis, and has a detachable whip antenna, stereo mini jack, and a rotary level control. 

Audio-Technica M2 (above) and Shure PSM 900 single-channel wireless monitoring systems.

Audio-Technica offers the M2 single-channel wireless monitoring system operating in the UHF band over 33 MHz of spectrum, with multiple bands available. Up to 10 systems can operate together per band. In addition to L/R inputs, an additional input for a click track or ambient mic is provided.

Meanwhile, Sennheiser SR 2000 single-channel and SR 2500 dual-channel wireless IEMs also operate in the UHF band, with the system spanning a 75 MHz band. The transmitter has a 5-band graphic equalizer that can be accessed via the menu.

Note that as the term “wireless” makes clear, these systems use RF spectrum, so these systems need to be coordinated along with wireless mic, instrument, and intercom systems at every show.

Quality in-ear monitors are available at many price points, ranging from a couple hundred to a couple thousand dollars. Hearing a consistent mix is certainly easier when using them, and at less damaging levels. There are benefits to be had in isolation, comfort, and sound quality with some of the custom units. For performers who want to instantly adjust their mix during the performance, the technology is available.

With all the movement on stage, many choices of reliable wireless delivery are available, and to my ears sound as good as wired. In the end, it all boils down to meeting the needs and preferences of the musicians for quality monitoring.

Gary Parks is a pro audio writer who has worked in the industry for more than 25 years, including serving as marketing manager and wireless product manager for Clear-Com, handling RF planning software sales with EDX Wireless, and managing loudspeaker and wireless product management at Electro-Voice.

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Zen On Stage: The Latest On IEM & Personal Monitoring