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Review: Logitech’s Ultimate Ears Personal Reference Monitors

The fitting and subsequent use of UE’s latest in-ears prompts this PAR Contributor to call it “the ultimate IEM experience” for live sound performance, and much more.

As the world’s first personally tuned custom in-ear monitors (IEMs), Ultimate Ears’ (UE) Personal Reference Monitors are truly unique. Engineered to fit, look and sound exactly how the user desires them, these Personal Reference Monitors were designed to deliver a very personal listening experience, bringing the custom IEM market to a whole new level.

My Own Personal Reference

First, let me fill you in on my background. In 2005, I was living in Cancun, Mexico and playing in the house band at Jimmy Buffett’s Margaritaville. At the time, this was kind of a dream gig, with me living across the street on a beachfront property in paradise. Yet every night I went on at 9pm to relive my own personal nightmare: the temperamental stage monitor. Don’t get me wrong — the management wasn’t cheap, and neither was the band, and we had sends on the house board for more monitor mixes, but this monitor never seemed to work very well (and sometimes didn’t at all) and floor space onstage for more/better monitoring was extremely limited. It was then I decided to take matters into my own hands: I saved up my first month’s worth of gig money and bought my very first IEM system, a Sennheiser ew 300 rig. Soon after, as I sought after more clarity and volume/isolation, I upgraded from the stock earbuds to Ultimate Ears Super Fi Pros. I went on to use those UE’s four nights a week for six straight years. And I have never used a monitor wedge since. 

Fast forward to Spring 2012 and, now fully appreciative of the quality of Ultimate Ears products, I got a call from my editor to visit the Ultimate Ears factory in Irvine, CA for a tour and to review their latest product that was going to “change the game” for custom IEMs as we know it. Of course, I jumped at the chance.


Every pair of UE Personal Reference Monitors start with a proprietary five-armature design, a three-way crossover circuit, triple bore sound channels and custom moldings to fit your ears that provide -26db of isolation and passive noise cancellation. Each set of monitors are touted to offer what I’ve personally learned to expect from a UE IEM; notably clear vocals and midrange instruments, “open” high frequency detail along with a rich, powerful low end for (what seems to me) a purer and truer monitoring experience. Specifications include a 20 Hz to 18 kHz frequency response; input sensitivity of 110.6 dB @ 1 kHz, 50mV; efficiency of 115.6 dB @ 1mW; and impedance of 21 ohms @ 1 kHz. Input is via an eighth-inch (3.5 mm) gold-plated TRS connector. 

Up until this point, the custom IEM market has strictly been custom fit moldings, custom colors, cosmetics and graphics. With its Personal Reference Monitor, Ultimate Ears now offers even more customization — arguably the first “fully customized” IEM, by tuning each customer’s IEM to the sound signature they themselves determine. UE’s Personal Reference Tuning Box, made available to the customer during the fitting stage of their purchase, is the key to this customization. It allows each customer to “dial in” their preferences, which dictates their personal sound signature based on what sounds good to them. Playing the role of a mastering-grade stereo parametric equalizer, the Tuning Box allows the customer to adjust the high, mid and low frequencies on both left and right channels. Then, using the frequency curve that the customer creates with the Tuning Box, Ultimate Ears creates a pair of fitted earphones to the customer’s precise frequency-based preferences; as such, it can be a sound that is as personal as one’s own fingerprint.

Another notable feature of this product is UE’s RewardTag system. In the unfortunate event that you lose these IEMs, the finder (who obviously would be unable to fit them into their own ear canals) would find details within its case about RewardTag and would be encouraged to return them directly to Ultimate Ears, which would send a reward for its safe return. 

I had more than a few questions about the concept, and after receiving an incredible tutorial and tour of UE’s factory, my questions were answered, and my skepticism turned into genuine excitement. 

In Use: The Process

As I arrived at UE, the Vice President and General Manager of Ultimate Ears by Logitech, Philippe Depallens, greeted me. Within five minutes, I could see how passionate he was about his products. He gave me a detailed overview the new Personal Reference Monitor system; UE calls this a “system” due to the IEM design process, which begins by the customer traveling to one of UE’s select locations — currently New York City, Nashville, Los Angeles, or Irvine, with more locations expected in the near future — to sit down with their Personal Reference Tuning Box. The streamlined box features the aforementioned knob-based frequency controls and a bypass button per side for immediate comparisons to “flat” EQ. “There are some people out there — we’ve met many of them over the years — that knowexactlywhat they need and want in terms of their IEM sound signature,” said Philippe. “Our new, handcrafted Ultimate Ears Personal Reference Monitors are designed with these people in mind.” 

For my Tuning Box session, I was provided with a set of UE18 IEMs and the choice of listening to many different styles of music through an iPod; of course, via Tuning Box, customers may reference any sound source: iPods/portable digital players, guitar rigs, favorite microphones/signal chains, etc. I selected a wide variety of very familiar performances by Al Green, U2, Santana, Rage Against the Machine, among others, and also auditioned some preset frequencies/tones requested by recording engineers and audiophiles involved in the R&D process. I closed my eyes and listened, fine-tuning the left and right channels based on what I wanted to hear, then occasionally pressed the bypass buttons to reference my adjustments back to the “flat” source. The process was enjoyable enough that I could have sat there for hours, but was wisely reminded by Philippe and Product Manager Vincent Liu, that for the most ideal results, to avoid ear fatigue; UE suggests approximately 20 minutes of listening to create your ultimate frequency response. 

Just a few months previously at the 2012 Winter NAMM show, I had visited the Ultimate Ears by Logitech booth for their free ear molds offer by a certified audiologist; thus, I did not need a fitting during my UE factory visit. While I continued talking with Philippe, Vincent documented my specifications for the factory to begin the process of crafting my own UE Personal Reference Monitors. 

In Use: The Product

UE policy dictates that once a customer places an order, it will be processed, crafted and shipped within one week. Sure enough, I was at UE HQ on a Thursday afternoon and by the following Thursday, I received an email saying my custom IEMs were on the way. I also received an email with a video link to a tutorial on how to wear, clean and maintain my new IEMs.

Upon opening its tour-grade flat black aluminum “flight case” featuring my name engraved on top, I proceeded to read the Personal Reference Monitors manual, which began with a simple “Thank You.” The following pages explained the use and care of my IEMs in a straightforward and intuitive manner, as well as the limited-yet-gracious two-year warranty that covers just about any necessary repair. 

As I popped in these IEMs for the first time, then plugged in my normal IEM rig, I literally could not believe my ears. I have used a lot of earbuds with my Sennheiser ew 300 over the past seven years, but I had never heard anything like this before. Then came rehearsals with the band. The clarity of my vocals and the tones of my guitar were ideal. I even told my drummer (at the displeasure of the rest of the band) to hit harder; I really wanted to test my IEMs’ isolation. As he banged away on the drums (and the other guys look at me like they were ready to kill me), everything was clear, clean, and detailed. 

I also noticed that I was using half the gain on my beltpack than before — half! Also compared to before, my IEM monitoring experience included low end that was kicked up a notch to truly full-bodied and engulfing; the mids were boosted intensely, increasing overall warmth and presence; and the highs were up just a tad: all of which was just like I heard it in the UE offices earlier. I have a high to mid-ranging tonality to my voice — at times perhaps slightly nasally, a la Rush’s Geddy Lee or REO Speedwagon’s Kevin Cronin — so I boosted what I needed on the Personal Reference Tuning Box to get what I wanted from my IEMs. For that reason, Ultimate Ears hit a grand slam in my book. And with each rehearsal and performance, it just keeps getting better, more comfortable. 


The Ultimate Ears Personal Reference Monitors are the “ultimate experience” in the upper echelon of IEM. But the question is, at nearly $2k, do you get your money’s worth? Absolutely. One hundred percent and then some. From getting a custom ear fitting included; to sitting down with the Tuning Box to shape your own frequency response; to choosing one of four special wood veneer finishes (specifically and only for the UE Personal Reference Monitors) or any color or graphic you want; I find that the Personal Reference Monitors are the Gibson Les Paul Customs of the IEM world. 

This entire experience, albeit brief, was amazing to me. I was thoroughly impressed by the extreme detail in which UE will create these products for discriminating artists. It’s obvious that Philippe and the entire UE staff are incredibly customer-centric.

If you are reading this review and are considering custom IEMs, then you surely already know that it is an investment. Speaking of investments, custom-fit IEMs are an investment in the continued good health of your ears and, especially for audio professionals, your hearing truly is priceless. 

Joshua Garber is a Minneapolis/St. Paul-based musician, engineer, and DJ/KJ with pro stints in the Cancun MX and Charlotte live music markets.

Price: $1,999.99

Contact: Ultimate Ears by Logitech |

At The Factory: Building UE’s Personal Reference Monitors

View the videos below for a comprehensive look inside Joshua’s experience at Logitech’s Ultimate Ears factory in Southern California.