Review – Etymotic ER4SR & ER4XR Hi-Fidelity Earphones

Etymotic is a company whose name holds a revered position in audio circles. The reason is that founder Mead Killion and his team pioneered the Hi-Fidelity earphone, with a unique balanced single armature design. Their flagship model for the past 25 years was the ER-4, essentially unchanged since 1991. So, when they announced the ER4SR and ER4XR revisions to the legendary ER4 model, audiophiles around the world perked up their ears.

Etymotic, in response to a question about their history, wrote "We began life with the ER-1 earphone in 1985, and the next major product was the Musicians Earplugs in 1988 (brought to the market after meetings with the Chicago Sympony Orchestra), followed by the ER-20 HiFI earplugs in 1990. Combined sales, including private label versions, total just short of 5 million pairs. While it is true that Mead Killion pioneered the ER-1 high fidelity "tubephone" earphone in 1984 it is also true that it was a team effort.

The ER-4, which came seven years later, was actually a bootleg project by two Etymotic engineers who agreed that the frequency response of the ER-1 was essentially transparent but felt there would be a market for a smaller in-the-ear version with the same basic response and noise isolation but without 10 inches of plastic tubing leading to each ear. Similarly, the ER4SR and ER4XR were a team effort led by another audiophile engineer, who argued that there were enough legitimate improvements available to justify a new model series. Perhaps the freedom to disagree with management is why Etymotic still has its first seven engineers, who were hired 25-33 years ago."

Thus, it shouldn't come as a surprise that a member of the original ER-4 team wrote "We try to preserve hearing, not destroy it!" When I first met Mead years ago it seemed that as much as he was in love with high-fidelity, as both an audiologist and musician, hearing protection was his primary impetus. In an earlier interview his concern was that by not sealing the ear canal, products like earbuds which don't block out ambient noise, force the listener to really crank up the volume, with predictable hearing loss, a concern backed by scientific studies that explored the impact of the iPod and other portable music players. That 2006 interview can be heard at

One design feature that set Etymotic apart from other manufacturers is the use of a single armature, in contrast to earphones with as many as 12 drivers in them. One of the issues of multiple drivers in any context, earphone or speaker, is phase coherence, in short which is the ability for all the audio signals to reach the user at the same time. The argument against multiple drivers is that it’s just too difficult a set of variables to control, along with issues of complicated crossovers, linearity, and even use of the electric signal so that no driver is louder than another driver, to list just a few issues.

The argument for multiple drivers is simple, which is the belief that no single driver can properly reproduce all frequencies, so one solution is to use multiple drivers with crossovers that are matched to specific frequencies, so a tweeter for the high end, a bass driver, mid-tone drivers, etc. is the end result. Also, multiple driver earphones are typically dynamic in nature, so tiny little pistons. Some listeners prefer the dynamic design since it is typically believed to have a bit more “punch” in the bottom end, but this isn’t always true if properly designed. Etymotic argues (and demonstrates) that their single balanced armature model does in fact reproduce all frequencies, with an accurate and repeatable frequency response, and without the compromises of multiple dynamic drivers and their inherent complexities.

I should add that when I was young one of the first hi-fidelity speakers I heard was the famed Ohm Acoustics "Ohm A" designed by Lincoln Walsh and featured a single driver. Walsh's design stemmed from research from Bell Labs that suggested that the ideal driver would be a perfectly round sphere, without seams, that could reproduce all necessary frequencies, with 360 degree coverage. Obviously theory isn't always possible, but Walsh took that to mean that a single driver was the ideal design. Etymotic's single driver proves the point, and probably would have made Walsh proud.

And Etymotic does make a lower cost dynamic driver model, the mc5 Earphones, and a lower cost armature model, the hf5 Earphones, and both are at the top of their price class. But Etymotic’s flagship is their ER-4 series, all based on the single balanced-armature design, and no matter the argument for multiple drivers, Etymotic’s single armature models are consistently ranked among the top earphones on the market, so obviously, the design works, and does so in an exemplary fashion. What changes did they make to the ER-4, which was already one of the best regarded earphones on the market?

The most obvious changes are cosmetic. The new models feature a new sleek, anodized and laser-etched aluminum body, with reinforced, user-replaceable detachable cables. So, if you want to tweak your cables, now you can. From an audio standpoint, according to Etymotic “Like its predecessor, the ER 4SR channels are matched within an industry-leading 1dB across frequencies from 100Hz to 10 kHz.” And as in the past, “Included with every pair of ER•4 earphones are an industry-exclusive channel-matching compliance graph, signed by the Etymotic engineer who precision matched and custom tuned the balanced-armature drivers.”

So, if you loved the sound of your ER 4’s, then you will love the sound of the new models. The difference between the old models and new units is subtle. I found a bit more depth, a better, less finicky fit, and the new design is more ergonomically friendly in terms of inserting and removing them from your ears. One thing to keep in mind, is that in a world of ever changing product introductions and designs, the continued popularity and positive critical reviews are proof of a design utilizing the single balanced armature that has stood the test of time.

There are two versions of the new models, The ER 4SR and ER4 XR. The SR model is the flat, studio reference design, and the XR features some extended bass response. In practice unless I switched earphones at the same time, you grow accustomed to either model, the difference being pretty subtle. I did find myself preferring the slightly enhanced bass of the XR models, especially in noisy situations like airplane, trains, or auto travel. Both models are more sensitive than their predecessors, and every device I tried them with was able to drive them without any issues whatsoever. If on a desert island, I think I’d go for the XR models. The bass enhancement is subtle and comes off as a richer sound, not a bass boost sound. So, for me they felt a tiny bit more musical and inviting, but we are talking small shades of gray.

They are supplied with a little black case, different size foam EarTips, 3-Flange EarTips, a Filter Removal Tool, and the performance chart. They have a stated 98% noise isolation which Etymotic states is the “highest of any earphones or headset on the market” and come with a 2-year warranty.

If you want a flat reference response curve then the ER 4SR is for you, if you like a bit more warmth, a subtly enhanced bottom end, then go for the ER 4XR. Using products like the Oppo HA-2 portable DAC/Headphone Amp, which has a lovely bass boost option, I found that both were wonderful to listen to. Using the splendid new Astell&Kern AK Jr. Portable High-Resolution Audio Player with tracks from HD Tracks and the Society of Sound, both revealed every nuance, along with plenty of punch. Listening to the newly released David Bowie “Who Can I Be Now? 1974-1976” Box Set from HD Tracks with sparkling new remasters of some of Bowie’s finest albums, shines with the ER 4s and demonstrate their versatility. The bottom end bass response from “Diamond Dogs” has just the amount of kick in the gut sound, while Bowie’s impassioned vocals on “Wild in the Wind” from “Station to Station” are clear, believable, and surrounded by air. The Etymotic ER 4SR and Etymotic ER 4XR are amongst the best earphones we’ve ever heard. Highly recommended.

Harris Fogel and Nancy Burlan, Posted 10/15/2016


For more information on the Etymotic ER4SR and ERXR Earphones visit:

For more information on the Oppo HA-2 Portable Headphone Amplifier/DAC visit:

For more information on the Astell&Kern AK Jr. Portable High-Resolution Audio Player visit:

For more information on HD Tracks visit:

For more information on the Society of Sound visit: