Your browser is out-of-date!

Update your browser to view this website correctly. Update my browser now


Ultimate Ears (UE) In-Ear Reference Monitors – A Real-World Review

Capitol Records’ engineering team collaborates with UE on IEMs specifically built for audio production.

Our increasingly mobile world has allowed audio production to escape the tethered confines of cozy studios (for better or for worse, many may argue). Thus the “on-the-go audio pro” is indeed the new normal, well captured in print on Pro Audio Review’s January 2011 cover: our senior contributor Russ Long editing vocals via AVID Pro Tools 9 with only a Mac Book Pro, headphones, and an iLok at a Nashville-area coffee shop.

Meanwhile, over the past six months, I have been living with a set of Ultimate Ears In-Ear Reference Monitors, using them for audio production, live work and performance, as well as leisure listening. And, while I’ve worn molded earplugs for nearly 20 years now — Westone Labs custom earplugs with Etymotic Research ER-15 and ER-25 attenuator inserts, much like those Rob Tavaglione reviews in this very issue of PAR — I have hesitated to rely on either headphones or IEMs for judgment calls when it comes to recording projects I’ve been intimately involved in. That has all changed.


In developing an audio production reference-worthy IEM, the folks at Ultimate Ears enlisted the expertise of Hollywood’s Capitol Studios engineering staff for a long and intense three-stage beta testing process. The idea was to build an IEM that would serve as the primary reference point for the most discriminating professional users from tracking to mixing in any environment. If successful, it would allow for truly critical listening in acoustically undesirable and/or loud environments such as airplanes, tour buses, family reunions, etc. — you get the point.

UE Reference Monitors feature an internal three-speaker configuration — woofer, middriver and tweeter — in an acrylic housing that offers noise isolation specifications of up to -26 dB. Input sensitivity is 98 dB SPL at 1 kHz; efficiency is 112 dB SPL at 1 kHz, 1mW; frequency response is 5 Hz to 20 kHz; and impedance is 35 ohms at 1 kHz.

The black and clear Reference Monitors come with a 48- or 64-inch cable, (a choice of clear or black), terminated with an eighth-inch, gold-plated TRS connector, in an incredibly rugged yet lightweight 6 x 4 x 2-inch aluminum case with the user’s name etched directly under the UE logo. Included in the package is an eighth-inch to quarter-inch TRS adaptor and special IEM cleaning tool. The Reference Monitors offer a one-year limited hardware warranty.

A trip to your local audiologist for your ear impressions is a requirement for these (or any) custom IEMs. [For more on the experience of getting an ear impression, read Rob Tavaglione’s aforementioned Etymotic Research ER Series Earplugs review. — Ed.]

In Use

Despite the specs supplied above, I must admit that the idea of reference-level performance that rivals our industry’s best studio monitors with using such tiny drivers seems voodoo to me, but it’s hard to argue with real results in real-world performances. I used the Reference Monitors in all of the following applications: critical listening for hours on airplanes, in noisy public places (adjusting EQ and compression, editing and mixing); A/B-ing between source material in my own comfortable audio workspace alongside speakers I’ve know well and have used now for years; mixing FOH and monitors in both indoor and outdoor environments; as musician (drummer) IEMs in both studio and live applications; and recreational listening too (ranging from iPod audio to full resolution audio via high-quality D/A converter/headphone amplifier). As I mentioned above, I have literally lived much of my past six months — as a self-recordist, mixer, studio/live musician, and music lover — with these IEMs in my ears.

In application, the Reference Monitor’s acrylic body is comfortable in the ear canal, yet completely inflexible; for comparison/reference, most custom earplugs are softer. For that reason, what you can hear may dramatically change based on how the shape of your ear canal changes (if you open your mouth, for example), though it can be argued that can happen when you listen via traditional studio monitors, too. The channels that extend down into the user’s ear are deep, but not uncomfortable. Compared to using headphones in similar applications, headphones are far more conducive to being taken on/off (or in/out, as IEMs must be); for that reason, if only minimal isolation is needed along with regular/frequent verbal communication via “live air,” a high-quality circum-aural headphone would still be preferable in such an application.


I’m incredibly impressed with these IEMs. With them, I feel there is an aural quality resembling a virtual acoustic space between my ears and a set of studio monitors, much like when I sit in front of my own reference speakers in my own audio workspace. Something like “real air,” the feeling is closer to monitoring in an environment, rather than the less-than-three dimensional feeling I’ve nearly universally had when using either headphones or other IEMs during attempted critical listening applications.

Further, I would describe their overall sound as uncharacteristically gentle in that manner, almost as if the sound lilts through air measured in feet rather than in millimeters. Depth and the sharp preciseness of its imaging is remarkable, and ultimately translatable, to the rest of the listening world (i.e., with the UE Reference Monitors, you can be sure about where you place a sound source in a mix). According to UE, that final point was a most important goal in the collaboration with Capitol Studios so, mission accomplished, I must say. Adding to that quality, the Reference Monitors’ midrange is so well defined that those crucial mix elements such as vocals sit precisely and accurately, allowing these personal monitors to create — most likely due to their portability and isolating qualities — the most translatable monitoring experience I’ve ever had. The experience is something closer to listening to studio monitor pairs far more costly than these $999 in-ear monitors — even though nearly $1k for what many just call “ear buds” seems like a lot of money. But these aren’t ear buds; they are in-ear control rooms — and superb, never-fatiguing-to-hear ones at that, though I wouldn’t be honest if I didn’t admit that I always eventually tire of having something stuck into my ear.

That last point — the physical downside of having something that isolates you from the natural acoustics of the outside world — is the only reservation I have regarding reference-grade IEMs (or headphones, for that matter) as a primary/only monitoring source; real-time collaboration, discussion of mixes, etc., are the necessary tasks that only traditional studio monitors will allow.

Though the future of studio monitors isn’t necessarily under siege by IEMs for this very reason, I can certainly envision a time where every audio pro has a reference monitor and a reference IEM of choice, evenly switching between the two depending on where in the world he or she may be working. For that reason, Ultimate Ears Reference Monitors are already ahead of the curve.

Price: $999 direct (plus ear impression fees at your local audiologist)
Contact: Ultimate Ears |

Strother Bullins is the reviews and features editor for Pro Audio Review.