An Alternate Look at the Sensaphonics 3D Active Ambient PM System
In the December 2007 issue of FOH magazine, Bill Evans presented a review of the Sensaphonics 3D Active Ambient Personal Monitor System (www.sensaphonics.com). For the complete nuts and bolts of the system you can refer to that review, but this month in On the Digital Edge we’re going to revisit Sensaphonics’ technology from a slightly different perspective.
The Concept
The feature that sets this Sensaphonics system apart from other personal monitor systems is the implementation of the Active Ambient concept. In addition to the drivers used to produce sound, 3DAA ear molds feature built-in miniature condenser microphones. There are two basic modes when using the 3DAA system: Perform and Full Ambient. In Perform mode, audio from these microphones is mixed in with the feed from the monitor desk, freeing the performer from the feeling of isolation one gets while using PMs.
This is a significant development in ear monitor mixing because monitor engineers battle to avoid that feeling of isolation. Some monitor engineers use a pair of mics placed on the stage to capture ambient sound, while others use audience microphones to do the same. If those ambient mics are panned in the performer’s monitor mix (which they should be, to provide a pan perspective of the stage), when the performer turns their back on the audience, the panning becomes reversed relative to the stationary microphones.
Having the microphones in one’s earpieces solves this issue. In Full Ambient mode, input from the monitor desk is attenuated, and sound from the “earmics” is brought up to unity gain — i.e. to a level such that one would experience if one were not wearing any ear molds at all. This makes it easy for performers to communicate in between songs.
The Belt Pack
The belt pack for the 3DAA system is different from the typical PM pack. Inside, there’s a 9-volt battery compartment, two switches and a rotary trimmer pot. One switch calibrates the pack for single-or dual-driver earpieces. (My review system employed single-driver earpieces. The dual-driver earpieces can output a few dB higher.) The other switch enables a hearing-protection limiter that kicks in at 105 dB. The rotary pot adjusts level from the embedded mics, ranging from “off” to “full” (ambience at unity gain) in 4 dB steps. On the exterior of the pack are an on/off switch, the mode switch (Full Ambient or Perform), LED indicators for power, and monitor and ambient signal levels, plus a level knob for monitor input. There are also connectors for the ear molds — these are non-standard dual 1/8-inch TRRS because they carry the microphone signal— and my unit has a LEMO connector for the audio input (more on this later). One minor gripe about the 3DAA system is that turning the system on and off produces an audible click in the earpieces, so turn it on before you put in the molds.
The ambient signal is always available at the earpieces. In Perform mode, the ambient feed is attenuated and the user dials in as much (or as little) ambient sound as they like. When one is wearing a properly fitted set of ear molds and the system is off, the outside world is attenuated somewhere in the vicinity of 30 dB (Editor’s note: Sensaphonics graciously coordinated my visit to Dr. Craig Kaspar, an excellent New York-based audiologist who totally gets the concept behind personal monitors, and skillfully fitted me for the molds).
An Epiphany
My first experiences with the 3DAA system were an epiphany: I wore them while tracking drums in the studio. I could hear the cue mix and the natural ambient sound of the drums at a volume level significantly reduced from what I would hear without ear molds. Having consistently played drums with hearing protection for the past 30 years, I rarely hear the fidelity of my cymbals and hi hat, so it was wonderful to be able to do so. In fact it’s wonderful to simply play drums with the volume turned down and no loss of high frequency content.
That experience led me down an unconventional path with the 3DAA system: I use them the turn down the volume level of my live sound world. It works like this: the ear molds provide approximately 30 dB of attenuation, so I use them to “plug” my ears. Then I switch the system to Perform, and use the attenuation control inside the 3DAA belt pack to dial in the amount of ambient sound that I wish to hear. Usually one or two clicks from “off” are enough — which I believe translates to around 24 dB down from unity. In case you’re not clear on this: I am mixing my shows while wearing the 3DAA system. I hear my PA system through the mics embedded in the ear molds, which means that my ears are experiencing an SPL reduced from what is actually happening in the room. So if my PA is producing a SPL in the vicinity of 105 dB, I’m hearing the PA at a SPL more like the low 80s — a very manageable level for safe listening.
The Same, but Quieter
When I was experimenting with this, I’d place one earpiece in and mix for 10 or 15 minutes, and then remove that earpiece and put the other in, trying to rest my ears while also ensuring that the mix was OK. After a while I trusted the system enough to put in both earpieces and mix. Lo and behold, when I pulled out the two earpieces, my mix sounded pretty much the same — just louder. Using the 3DAA System is not exactly the same as not wearing plugs, but it’s close enough to mix with confidence that what you are hearing through the earpieces is consistent with what your audience is hearing, except not as loud. Of course you have to remain aware of the fact that the audience is experiencing audio at a level louder than you are, so don’t get fooled into thinking the PA is lower than it really is.
About that LEMO input connector: That’s intended for a feed from the monitor desk, but no one says you can’t connect your FOH console’s headphone output to it. That allows you to use the solo function through the 3DAA system as if you were wearing cans, with the rotary knob on the belt pack controlling the level of the solo’d channel(s) relative to the ambient sound.
Mixing in Peace
I’ve been mixing live sound for many years and throughout that time, I’ve played all sorts of games in an effort to conserve my hearing: mix a song or two with “open” ears, mix a few songs with a plug in one ear, and then switch ears for a few songs, then back. I’ve used custom molds fitted with attenuators, but when I’d remove them to check my mix, it always sounded different. The Sensaphonics 3D Active Ambient In Ear Monitor System removes these issues, allowing me to mix in peace. In the conclusion of Bill Evans’ FOH “Road Test,” he noted that PMs are self-defense against loud stage volumes. Well, the Sensaphonics 3DAA System is self-defense for front-of-house engineers. I’m able to mix at reduced levels without second-guessing the mix. I don’t have ear fatigue at the end of the day, and I’m convinced that I’m sleeping better on show nights. This is an excellent product that can change the way you mix, and help conserve your hearing. Highly recommended.
