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Ultimate Ears Universal Fit In-Ear Monitors IE 150, 250, and 350 – the Synth and Software Review



Less expensive than custom molded IEMs, great for studio and live monitoring

Ultimate Ears earned a reputation for making outstanding custom-molded earphones – meaning in-ear monitors (IEMs), as opposed to over- or on-the-ear headphones. Now they’ve added three universal fit models that aren’t custom-molded, the obvious advantage being that they’re able to lower the prices.

We checked out the UE 150 ($199), UE 250 ($299), and UE 350 ($399).

People may think of stage monitors when they hear “IEM,” but these are great for studio use as well. And in fact that’s how we used them over the course of this review, driving them with a CEntrance DACport Pro Portable Reference. The DACport Pro has an excellent headphone amp. For stage use, normally you’d be using a wireless receiver instead.

Before listening to them, the salient difference between the three models is their drivers. The UE 150 has a single dynamic driver, which is a miniature full-range speaker – the familiar moving-coil electromagnetic design we all know.

Both the other two models use Knowles Balanced Armature Drivers. These drivers also work by electromagnetism, but they’re unique and we’ll let the company explain the technology. Suffice it to say that you can hear the difference in clarity right away. The UE 250 has two Knowles drivers, the UE 350 has three, much like 2-way and 3-way speakers.

First impressions

These earphones are packaged beautifully, which really does have an effect on one’s first impression. It says that the company cares.

The packages and everything else about the three models is the same, in fact the only way you can tell them apart (other than by looking inside their clear enclosures) is that their faceplates are subtly different.

Graphic from the Ultimate Ears Pro website showing the relative frequency responses of the three models. In reality, you’re more likely to notice other differences before this, as outlined in the review.

All three come with a hard protective case. Its lid is held on by friction, and it takes a lot of strength to take it off (although it may well loosen up over time).

The cables have a loop near the earphones, and you run it behind your ears. That keeps them out of the way. Like the earphones themselves, the cables are clear, which makes them as minimally visible as possible.

Because these are universal earphones, they come with several color-coded sizes of earpieces to accommodate different sizes of ear canals. And that leads to the biggest issue with this type of in-ear monitor.

Fit – a warning

All the UE monitors rely on a tight seal to sound right. Without that, they sound like a telephone – the bass escapes; with it, they sound excellent. And that’s the whole point to custom-molded IEMs.

With the universal IEM models, you try different earpieces until you find the ones that fit your ears. They just snap on, and once you find the right ones they do provide the requisite tight seal.

Then in an act of extreme idiocy, I pushed one of the earphones into my ear a little too tightly… and when I removed it, the *!@*$% earpiece came off and got stuck deep inside my ear canal. My wife couldn’t even see it, it was in so far.

Fortunately I was able to get it out with tweezers (please don’t try that at home – you could damage your ears!) and avoid a trip to the emergency room. But I’d already grabbed my jacket, and frankly it was quite scary.

When told about this adventure, UE suggested starting with the biggest earpiece and working down until you find the right ones. They also pointed out that all manufacturer’s earpieces work the same way, not just theirs.

Well, then all manufacturers desperately need to thread their earpieces to prevent this from happening. In the meantime, if you’re able to spring for equivalent custom-molded IEMs – UE makes a whole line of them – I recommend it highly. If not, please do be careful!


Once you find the right size of earpiece, all three models sound excellent, and the seal lowers the level of outside noise about as well as most active noise-canceling headphones.

For a popular comparison, if you’re accustomed to listening to Apple AirPods when you’re using earphones, you’ll be struck by how natural the UE models sound. Their bass is at a more natural (lower) level, their frequency response is even, hi-hats don’t disappear, and in general they give you a much more credible sense of what’s been recorded.

Now, that’s not an insult to the AirPods, which are the equivalent of living room speakers rather than studio monitors intended for production. They’re almost fashion accessories, designed for convenience and to enhance the sound, and of course their wireless Bluetooth connection would introduce far too much delay for live performance.

The other point of comparison is that all three UE IEMs have an overall harder sound than AirPods. That’s not to say they’re unpleasant, they just sound dryer – which once again reflects the different applications.

The UE 150s, with their traditional driver, do sound different from the other two models. Probably the most notable difference is that its midrange – vocals, etc. – isn’t quite as smooth. This is a major exaggeration, but imagine listening to music through a keyboard amp rather than studio monitors.

The 150’s low end is slightly rounder, however, and there seems to be a little more of it than in the 250s. Still, the 36Hz boom in the beginning of April Lavigne’s “Skater Boi” (a great reference for checking transducers) comes through more prominently on the 150s than the 250s.

As you’d expect when you move up the line, the 250s and 350s do sound smoother and their midrange is fuller. The difference between the two models is smaller than between the 150s and 250s, but subjectively the 350s just sound less strained overall, and perhaps more detailed. They also have more low end, and what’s there is defined better.

Bear in mind that saying one model sounds, say, rounder, doesn’t mean that the other models are harsh, it’s just a subjective comparison.


Once you’ve chosen the right earpieces that provide a tight seal, all three Ultimate Ears IEMs are very nice to listen to, and they have the frequency response extension and flattened curve necessary for studio use. They also get loud without straining, a requirement for stage use, and they block outside noise as well as any active noise-canceling headphones.

Recommended, but I do urge all manufacturers to thread their removable earpieces!

Prices: UE 150, $199; UE 250, $299; UE 350, $399.

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