Etymotic ER4SR Review


Hi everyone, this is part 1 of a 3-part review series on the legendary Etymotic ER4SR and the Sony MDR-EX1000. This part will focus on the ER4SR before moving on to part 2 on the EX1000 and concluding with a detailed comparison between the two in part 3.

The Etymotic ER4SR is a modern recreation of Etymotic's ER4B, which was first released in 1991. The ER4SR is comparatively new, being released in 2016. Despite a 25-year difference, the ER4SR has undergone minimal changes to its design. The biggest change is the movement of the 40 Ohm resistor to the inside of the shell in the ER4SR rather than having it in the cable for as in the ER4B. This allowed for an easier cable swap especially as the ER4SR now utilizes the common MMCX standard. The ER4SR additionally has a brother, the ER4XR, which provides more presence in the low end of the frequency range.

The Etymotic ER4 line gained quite the reputation throughout the years. For those who are newer to the IEM scene, here's a short list of them with some of my thoughts on the matter:
  • Diffuse-field (DF) target tuned. Etymotic developed the DF target for IEMs which serve as a proto-precursor to the popular Harman target. The ER4 line was built to fit the DF target as closely as possible. To date, Etymotic remains steadfast in their commitment to the DF target while very few other IEM models emulate what Etymotic has done.
  • Single balanced armature. The ER4 line pioneered the single BA concept, pushing it's chosen BA to the absolute limit. Despite the market calling for more and more BAs crammed into a single shell, the ER4 is still the most lauded single BA unit in the IEM scene. That said, it does have the common downsides that accompany BA IEMs.
  • Isolation and comfort. Enter the infamous triple flange tips. These tips provide an upwards of 42 dB of noise reduction. The cost is a deeply inserted tip into your ear that (personally) feels rather invasive. It's comfortable enough if you don't move your jaw too much but there is an itchy feeling that comes with a centimeter of silicon blocking your ear canals. The foam tips are just about as good at providing isolation while being a lot more comfortable. Unfortunately, the glue to binds the foam to inner silicon tube becomes unbonded easily and requires replacing sooner than later.
  • Cable. The top half of the ER4SR/XR cable is a nightmare. It is a 2-core braid that's stiff, prone to tangle, and produces a horrendous amount of cable noise when brushed against. For all the external isolation the flange tips provide, it won't stop the internal cable noise. While the ER4SR/XR does use an MMCX cable system, there is a small notch in the shell to prevent the cable rotation. This means that not every aftermarket cable may fit exactly into it.


Overall Sound Thoughts

I first listened to the Etymotic ER4SR at an audio meet-up, coming from the Tin Audio T2. It was stunning. Even among other IEMs such as the Campfire Andromeda I tried that day, the ER4SR had left the greatest impression on me. A couple years later, I own a set myself and the ER4SR still retains a bit of that "wow" factor. To date, no other IEM has managed to immediately impress me as directly as the ER4SR has.

The ER4SR exudes clarity and coherency. Etymotic's uncompromising commitment to the DF target is displayed in full force. The ER4SR is laser focused; it is very mid/upper-mid heavy while lean in the lower frequencies and tame in the upper. There isn't an ounce of fat in here. This tuning couple with the single BA's lack of crossover messiness gives the ER4SR a superb sense of transparency.

Sound Review


The bass is unquestionably lean and very tight. It's all punch without a hint of muddiness or boominess. The frequency response does go down 20 Hz with only a slight roll-off. Rumble is present if subdued. While I have no complaints over the quantity of the bass, the quality of it leaves a bit to be desired. The bass sounds "dry" without the meatiness you'd expect from heavy-hitting instruments like the floor tom or bass drum. This characteristic is likely due to the quick decay of the BA in the ER4SR and is a common complaint in standard BA sets. On the upside, it is fast. Bass guitar lines cut through cleanly without and notes are very well defined. For some, this level of sterility may be off-putting especially in genres that demand a more energetic bass response.


The ER4SR is essentially all upper-mids. Etymotic's DF target demands a 2.7 kHz peak with about 12 dB of gain. Despite the significant emphasis on upper mids, due to the relatively large spread of the peak it's more of a large hump from 1-5 kHz rather than a sharp mountain peak. This prevents the ER4SR from sounding shouty or peaky; rather, it sounds quite smooth. Some instruments such as the flute or chimes take full advantage of this upper mids emphasis and sound phenomenal. Other instruments such as the acoustic guitar feel a little thin at times and lack the body that typically accompanies it.

Vocals in particular sound just right on the ER4SR in terms of forwardness and transparency. Tonality is very good, if a little lean. A minor nitpick is that it sounds smoothed over to the point of being unnatural. In certain tracks which have a touch of natural sibilance or sharpness to the voice (as per the recording) the ER4SR seems to overly dampen it down. While the ER4SR never sounds sibilant, it does lose out on some of the zing that makes a track especially magical.


Treble is tightly reigned in. There are no notable peaks past the mids and extends to about 18 kHz before falling off completely.There isn't much to say for the treble other than it's inoffensive. It passes the hats/cymbals test as the ER4SR doesn't suffer from common pitfalls such as being too harsh or splashy. It's clean albeit subdued. Like the bass however, the treble also sounds "dry". There is a lack of shimmer and brilliance that keeps the treble from feeling alive. The ER4SR isn't particularly airy as well but avoids sounding congested. Overall, it accomplishes what it's meant to do: take a backseat to the upper mids.


Etymotic is infamous for their small soundstage and the ER4SR is a prime example. It's horizontally narrow with no height and little depth. It seems as if Etymotic decided that soundstage on IEMs are a wasted effort and chose to sacrifice it completely. On the other hand, imaging is relatively good. It's nuanced and decently precise given how small of a space it has to play within the soundstage. The ER4SR ends up sounding extremely centered and in-your-head, especially when it comes to vocals. Part of this may be due to the deep fit, the precise channel matching of its drivers, and upper-mid forward frequency response. If clarity and coherency were the first things I noticed, the second was just how centered the overall feel of the ER4SR was. It's truly an experience like no other.

The third thing that wow'd me the first time I listened to them was its resolution. Even by today's standards, the ER4SR holds up well. Resolution is very good and that perception is enhanced by the intimate soundstage, superb isolation, and outstanding clarity and coherency. It feels as if the ER4SR shoves detail right in your face.

A downfall of the ER4SR is it's relative lack of dynamics. It does have a somewhat compressed feeling overall. Nothing deal-breaking of course but compared to a traditional dynamic driver IEMs there is a lack of slam. A single-BA does have it's limitations.


The Etymotic ER4SR is a legendary reference class IEM that anyone serious about portable audio should make an effort to try. You might just end up owning a set permanently. It's hard to convey in words how the ER4SRs sound like beyond it's DF nature. There really is a "wow" factor when you listen to them for the first time. Everything Etymotic set out to accomplish with the ER4SR works well together as an overall package. Despite the market having evolved significantly over the past 30 years, the ER4 line remains rightfully relevant to this day. Even with the wave of ChiFi IEMs attempting to push the price/performance envelope further and further, the $300 MSRP for the ER4SR is still completely justifiable for experience you get. For those with a lighter wallet, the newer ER2 line at $160 is a very compelling option.

That said, for me personally, the ER4SR is more of a technical wonder and a reference IEM than for musical enjoyment. I find that I appreciate music more with the ER4SR than actually being engaged or enjoying it. Admittedly, part of that has to do with the discomfort from the deep insert that sits in the back of my mind. But I think that between the small stage, "dryness" of the treble and bass, and overall sterility of the tuning, the ER4SR ends up being a little too surgical for my tastes.

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