Let me begin this review with a rather unusual introduction:
Truth to be told, I have not much in mind what to exactly write here. I don’t even have a strict plan on what to write overall other than “it sounds flat, neutral and uncoloured” at the moment. This is a challenging review, a very challenging one actually.
Usually for any headphone, in-ear or earbud, I have a clear structure in my mind of what to write. With the models that I own for a few years, it is quite easy and other than performing sine sweeps and directly comparing the in-ear with some competitors, the whole review usually already exists in my head. And also with samples that come in, I usually have a clear order on what I do prior to starting the review and the rest is then quite easy to finish, as I then already know what to write in the “Sound” section.
With one in-ear that I can confidentially say I love the most among all other models and that I own for round about three years now, which is a pity as I should have “discovered” it way earlier, which unfortunately didn’t happen as it didn’t get any mention at all in the German online audio communities, it was quite different: from the first word written to completing my review, it took me almost a
whole year although I already owned it for more than a year at this time. There was just emptiness in my head concerning what to write.
The thing is that it is fairly easy to review a headphone that deviates from purely neutral sound (which certainly isn’t meant in any negative way here), as there is plenty of what to write about. Even in-ears that tend to go into a very neutral direction but aren’t 100% flat are rather easy to describe. Writing the review for that particular in-ear in German however was not easy, as it sounded about as neutral as it could get and didn’t even add the slightest bit of its own character to the sound – it was just flat and lifeless (both meant in a good way here), however the problem with this is to properly put it into words. But eventually I had finished that review and was happy with the result and what I’ve written (however, I have never translated it into English, although I had thought about it not just once).
Now history seems to repeat itself – at least this review right here features the successor of that particular in-ear, and the in-ear monitor that is reviewed here is supposed to be even a wee bit more flat and neutral than its predecessor based on the diffuse-field target.
You will of course know by the title that I am talking about the Etymotic ER•4SR and that that German review was about the ER•4S, but without reading the title and just the preamble, you might have probably guessed the models as well if you are at least remotely familiar with Etymotic Research that was founded in 1983 in the USA by Mead Killion (http://www.etymotic.com/about-us/interview-with-mead), a man that I highly respect.
In the early 1990s, the “grand daddy” of neutrality, as I like to call it, was born, the Etymotic ER•4 series, a series of in-ear that was manufactured for more than 20 years with just quite minor cosmetic changes, mainly concerning the cables.
When I read on the CES exhibitor page in late 2015 that Etymotic Research would be there as an exhibitor and also present an updated line of their ER•4 series, you can believe me that I was quite excited.
And so it came that the ER•4SR and ER•4XR were released as the successors of the ER•4S and ER•4P, with the first being just a small facelift on the sound side, whereas the second turned out to be more than just a facelift of the ER•4P, delivering what many customers were craving for – an Etymotic that still sounds balanced and neutral but carries just a bit more bass and warmth than the ER•4S.
And while the sound signature of the ER•4SR (SR by the way stands for “Studio Reference”) is greatly identical to the ER•4S’s (which is not much surprising, as bringing something that is already very close to a perfect diffuse-field flat target response even closer to it is not easy), it is internally and externally different and doesn’t only feature a different Balanced Armature driver inside along with a higher sensitivity and lower impedance, but is also equipped with a new cable that is now using MMCX connectors on the in-ears’ side instead of the 2-pin connectors that were also used for Sennheiser’s HD 6X0 series.
While the “old” ER•4 series used the same drivers in the whole product range and only differed in terms of cable impedance (with the exception of the ER•4B that also had capacitors inside) which allowed the ER•4P to be turned into the ER•4S by just adding an impedance adapter, the new ER•4XR (XR stands for “Extended Response”) is using different BA drivers than the ER•4SR and is a separate in-ear that cannot be turned into the SR version like that.
After this quite long introduction, all I want to say is that I’d like to invite you to read the rest of my review in that I will try to elaborate how the ER•4SR sounds and what makes it so great in my opinion.
Before I continue, I want to give out a huge “thank you” to Etymotic Research who agreed to send samples of the ER•4SR and ER•4XR to me free of charge to write these honest reviews that represent nothing less than my honest and unfiltered opinion on the products.
PS: If you can see bricks, steps and other artefacts in the very dark sections of my photos that aren't on the original files - congratulations, you have just discovered what online photo compression looks like.
Frequency Response: 20 Hz - 16 kHz
Transducers: high performance, Balanced Armature micro-drivers
Noise Isolation: 35-42 dB
Impedance (@1kHz): 4XR (45 Ohms) 4SR (45 Ohms)
Sensitivity (@1 kHz) SPL at 0.1 V: 4XR (98 dB) 4SR (98 dB)
Maximum Output (SPL): 122 dB
Cable: 5 ft, detachable
User Replaceable ACCU-Filters: Yes
Warranty: 2 Years
Custom-Fit Option: Yes
The in-ears arrive in a nicely designed packaging that contains a large zippered storage case that has got enough space for the in-ears as well as an audio player/DAC/amplifier inside, and has even got pockets to store the included accessories which are a 6.3 to 3.5 mm adapter, a shirt clip, spare ACCU filters with a removal tool, two pairs of small/medium triple-flange silicone tips, two pairs of medium/large silicone tips and two pairs of grey foam tips. What I find really nice is that a “certificate of performance” that shows the frequency response, channel matching, serial numbers, sensitivity and total harmonic distortion of both ear pieces, is included as well.
While I wouldn’t mind if a smaller storage pouch like the one that came with the ER•4S was included, too, the one included isn’t much larger than a Pelican 1010 case which is still quite reasonable in size.
Looks, Feels, Build Quality:
Compared to the previous generation where they were made of plastic, the new ER•4 series’ housings are made of metal and gain a more premium appearance due to this. The unique serial number is still engraved into each individual housing, but now there also is the model-specific labelling that tells you which in-ear you have.
The old 2-pin connector known from Sennheiser’s HD 6X0 series has been dropped and now there are rotation-locked MMCX connectors instead. They seem quite reliable, however only time will show how reliable they really are (in a scenario where I don’t remove the cable unless I have to).
The cable is an improvement over the older one, as it is more flexible and softer while it is still sturdy and looks overall quite similar. What I really like about it is that a chin-slider has finally been incorporated, compared to the ER•4S where it was unfortunately missing.
Although the y-splitter doesn’t contain any resistors anymore, it has still got that cylindrical shape as an homage to the previous generation where the bulky shape was necessary to carry the resistors (and in case of the ER•4B also the capacitors).
I’d personally like coloured side markers on the cable, because apart from the small black letters on each side, there are none. Knowing that the old ER•4 generation underwent some cosmetic changes, I wouldn’t be surprised though if the side-markers were changed some time in the future.
The ER•4 series in-ears need to be inserted really deep, passing the ear canals’ second bend, else the sound is likely incorrect. This might be irritating or even slightly painful at first if you aren’t used to in-ears that are inserted as deep, however I have no problem with this and don’t experience any pain at all.
Best insertion works with the cables down, so you automatically know when you have reached the correct insertion depth. Right afterwards, the cable can be guided around the ears, which is also how I do it, which will also audibly reduce cable noise (microphonics) to a tolerable level (less microphonics are barely possible because of the deep insertion, however with the over-the ear wearing style and using the chin-slider, they can be reduced well).
I have got quite large ear canals wherefore I had to modify my ER•4S’s tips in order to get a consistent seal with it.
The new ER•4 series in-ears however come with ear tips that have got the same dimensions but are made of a different material. To my surprise, I get the large ear tips to seal in my large ear canals with them, as they are more stable and also stickier. Nonetheless, I still need to adjust the fit from time to time, wherefore I modified the tips the same way I did with the old ones (I cut the smallest flange off, put it on the nozzle first and then attached the now double-flange tip to it – with this, I get a very good seal in my large ear canals but the length of the ear tips remains identical to prior to the modification).
If properly inserted and sealed, noise isolation is very high.
Neutral = Neutral?
Before I head over to the “Sound” section of my review, I will take a short look at the theory and research of neutrality with headphones and in-ears and give a very brief introduction to this topic.
With loudspeakers in a room, it is quite easy to define what a measurably neutral frequency response should look like, as it is supposed to be a flat line. The case is different in the headphone realm: A headphone or in-ear that would measure exactly like a flat speaker in a raw measurement would sound different directly at the eardrum – this is because our ears, ear canals and upper body amplify certain areas of the frequency range, which is a totally natural thing. With headphones and in-ears, these natural reflections and amplification disappear as the source of sound is directly at the ear, respectively inserted into the ear, wherefore the ear canal is closed on both sides and the “Open Ear Gain” disappears.
To imitate the natural amplification of the lack of this Open Ear Gain, a headphone should ideally show a boost in this area of the frequency response when an uncompensated frequency response chart is viewed (roughly speaking, the boost should be seen between ca. 200 and 15000 Hz, with the climax around 2.7 kHz with an elevation of around 15 dB here). Measured directly at the ear drum, this would result in a perceived flat and neutral frequency response (important and related key words on this topic are “HRTF” and “Open Ear Gain”).
Of course the ear anatomy will slightly differ among individuals, wherefore the perception of the averaged diffuse-field target might not be perceived equally by everybody, especially when it comes to the perception of the upper midrange and presence area, wherefore some people perceive an in-ear that measures flat in the presence area and lower treble after subtracting the Open Ear Gain from the raw measurement as exhausting or even shrill whereas many other individuals hear the same frequency response as acoustically flat and neutral.
Most frequency responses of headphones one can see in magazines and large online sites are therefore usually shown with the diffuse-field compensation already subtracted from the raw measurement and show the frequency response that is perceived directly at the ear drum instead of the raw measurement that can be confusing at first if one is used to loudspeaker measurements.
Apart from the existence of the Open Ear Gain, there is one thing that has caused some inconsistency among researchers about what the ideal neutrally perceived frequency response for headphones should be: Listening to music, we don’t only hear the sound waves that reach our ear drums, but also feel the mechanical vibration/body-borne noise with our whole body, especially at higher volume levels. With headphones however, there is no mechanical vibration/body-borne noise anymore, wherefore some people might find a diffuse-field neutral headphone to sound too thin although a neutrally measuring loudspeaker in a highly treated might not perceived this way by the same person. Some people and researchers are therefore convinced that the lack of mechanical vibration/body-borne noise when listening through headphones should be compensated by adding a slight (!) emphasis to lower notes in order to get a headphone to be subjectively perceived to sound equally neutral as a neutrally measuring loudspeaker.
As one can see, the perceived neutrality with headphones is a topic where there is no 100% unity even among famous researchers upon what the ideal frequency response should look like, and of course the individual ear and body anatomy might as well contribute to individual variance although major researches have come to the same conclusion of what the averaged HRTF looks like.
Sources I used for listening were mainly my iBasso DX90, the Cowon Plenue M2, and my Chord Mojo plus Leckerton UHA-6S.MKII stack with the Shinrico SHD5 as source device.
To get the correct sound, the correct eartip length and correct insertion depth are important. That the end of the sound outlet should be inserted very deep in one’s ear canals, past the second bend, should be clear after he “Comfort, Isolation” section.
The correct length of the ear tips however is at least just as important. As described further above, I am using the ER•4SR with the largest included triple-flange tips that I have modified to seal well in my large ear canals while maintaining the same length as before. With other tips (single-flange or Shure Olive Foamies that are shorter than the Etymotic ear tips), the sound was not as accurate in my ears and deviated from the correct sound that I am only getting with the correct insertion depth and ear tip length (solely Etymotic’s cylindrical foam tips generate pretty much the same sound as the stock triple-flange tips in my ears).
The ER•4SR is so neutral and flat over the whole audible spectrum that many other in-ears sound audibly more coloured in direct comparison when listening to music and sine sweeps and that some other in-ears that are described and advertised as neutral don’t sound as neutral in comparison (however, see the “Neutral = Neutral?” paragraph further above; it is (usually) not the case that other manufacturers don’t know what they are doing when creating the sound of an in-ear, however they might have a different view on (subjectively perceived) neutrality with headphones, or have different target responses in mind when tuning an in-ear, or don’t go for a 100% flat response to make the sound a bit more pleasant for a greater target group).
But first things first: Etymotic’s ER•4SR is both measurably and audibly extremely neutral and flat and seems to harmonise very well with my ears’ HRTF.
The mild lift in the presence range is just barely there in my ears when listening to music or sine sweeps, and definitely not as fatiguing as some people perceive it. The midrange appears a little more direct though and also slightly more exhausting over time compared to an in-ear that is on the more laid-back side here.
Listening to sine sweeps, noise and music, this single-BA in-ear is the most even, flat and coherent sounding in-ear in my ears. From the sub-bass to the upper treble, there is no waviness at all, and there are no narrow or wide dips or peaks either except from a minor lift in the presence range around 2-3 kHz and a slight recession around 7 kHz that is however hard to make out. Due to this, the timbre is extremely natural and all instruments as well as vocals sound ideally neutral and straight to the point uncoloured to my ears.
Even without (nerdy) sine sweeps but just music, the Etymotic in-ear demonstrates how uncoloured and flat sound can be from an in-ear. I would also consider it as being lifeless (in a good way as in that it doesn’t add its own character to the sound but just plays back what is on the recording without adding any extra flavours). Due to its extremely high flatness, it will also easily show when a bit too little or too much of a certain frequency was added in the master of a recording, which also makes it to a great professional tool (that it actually mainly is).
Of course, the seal along with the insertion depth and ear tip length need to be correct for this, and the sound also has to match one’s personal HRTF that might vary a bit among individuals. Lucky for me, it seems like the ER•4SR’s frequency response, just like my beloved ER•4S’s that sounds widely similar, matches my ears’ HRTF very well.
I would bet money on that the ER•4SR will sound too boring, sterile and flat for a high number of people compared to the majority of in-ears on the market (including those that are tuned to go into a more balanced direction).
This extremely high accuracy is what makes the ER•4SR so great and also a worthy successor of the legendary ER•4S that sounds most widely similar.
That it doesn’t necessarily need a multi-BA setup to get great sound quality in the price range around $500 is what Etymotic has showed once again with their new in-ears. The sound is very nimble, fast, coherent and very resolving as well, something that one probably wouldn’t expect from a single-driver setup.
Especially commendable is the ER•4SR’s excellent transient response over the whole frequency range – everything sounds in place and doesn’t lose direction at any frequency band.
It is remarkable what the ER•4SR puts out in terms of tonal range/extension, bass quality, resolution and authenticity – just like its predecessor, it shows that a well-implemented and -tuned single Balanced Armature driver doesn’t lack behind its similarly priced competitors.
In some categories, there are multi-driver in-ears that can somewhat beat the Ety in terms of partial resolution or bass speed, however there are very few in-ears at this price point that deliver such an excellent overall package where nothing lacks behind – there is hardly any flaw in terms of resolution.
Besides the excellent coherency and authenticity, the ER•4SR puts out a very detailed and well-separated treble along with a highly transparent midrange. Its bass response is really fast as well, and it outperforms some other single-BA in-ears as well in terms of speed and tightness. Compared to some of the higher-priced multi-BA in-ears though, while the bass speed might be comparable, the ER•4SR’s bottom-end will appear a bit softer but nonetheless highly controlled and therefore a bit more visceral.
The soundstage surely isn’t the largest in all directions, however just as with the ER•4S, I have never perceived it as small or congested at all but averagely large with an excellent width-to-depth-ratio and a perfect spherical and three-dimensional illusion.
Instruments are very precisely placed in the imaginary space and layering is precise as well, without any fogginess. Separation is really good as well and instruments don’t blend into each other but are separated with even some empty space between and around them. In this regard, it has even slightly improved over the ER•4S in my ears, as with more complex and faster recordings, the ER•4SR sounds a bit better separated and caves in less but remains very controlled.
Personally, I really love the ER•4SR’s spatial presentation, as it manages to convince me in terms of authenticity and three-dimensionality while not being extra wide or deep. Therefore, the Etymotic also counts to my personal favourites when it comes to soundstage.
In Comparison with other In-Ears:
Ultimate Ears Reference Monitors:
Compared to the Etymotic, the UE is a bit less of a reference when it comes to absolute flatness, even though it still sounds very neutral (Ultimate Ears also said that the UERM was tuned for subjective neutrality, so things like the compensation for the lack of mechanical vibrations might have been important in the tuning process as well).
In comparison, which can also be heard when listening to sine sweeps alone with it, the UERM has got around 3 dB more bass than the Ety and the more forward lower fundamental range wherefore it is a little warmer there. Except for the presence range that is a little forward on the ER•4SR, both sound comparable to me in the midrange. Going up with the sine sweeps, I can hear a dip in the UERMs’ middle treble along with a narrow peak around 10 kHz that can sound a bit harsh if a single note hits it exactly.
So especially in the treble, the ER•4SR is more linear and even in comparison, wherefore it also sounds more authentic and realistic here.
In terms of bass speed and control, as well as detail retrieval and instrument separation, the UERM is ahead, however the difference in terms of instrument separation has become smaller than compared to the ER•4S.
The ER•4SR’s cable is softer and more flexible. It has also finally got a chin-slider above the y-splitter wherefore microphonics can be lowered, too. And while the new silicone tips have got the same diameter as the older grey ones, they seal easier in my ears and I probably wouldn’t even necessarily have to modify them.
The ER•4SR’s sensitivity is higher wherefore it needs less voltage to reach the same listening level as the ER•4S.
In terms of sound, you will only find small changes. Both have got the same flat, diffuse-field neutral bass response. The ER•4SR has got the slightly less forward presence range wherefore it will appear to be slightly less fatiguing over time. The ER•4SR has also got slightly less level around 10 kHz. My ER•4S has got somewhat more quantity above 10 kHz, wherefore it will be perceived as a tiny bit brighter and further extending (it has got a bit more subtle glare above 10 kHz). Parts of that could of course also be due to slight manufacturing tolerances instead of actual tuning differences.
When it comes to detail retrieval, both are pretty much on the same high level to my ears. The only real difference is that the ER•4SR’s bass appears to be slightly softer in comparison but also a little more visceral as a result.
In terms of soundstage, ER•4SR’s appears to be a touch wider than the ER•4S’s in comparison. I’ve always perceived the ER•4S as authentic and three-dimensional when it came to spatiality, and the same goes for its successor that I hear as having the somewhat cleaner instrument separation between the two which becomes the most obvious with faster and more complex recordings.
Noble Audio SAVANNA:
The Etymotic’s bass is flatter (around 3.5 dB less) in the midbass, upper bass and lower root in comparison, however both have got about the same sub-bass quantity. The Noble’s mids are just slightly darker in comparison. To my ears, the SAVANNA’s treble is just slightly less present than the ER•4SR’s but almost identically even and coherent, which brings it extremely close to the Ety’s evenness and naturalness in the treble (in fact, the SAVANNA would even be identically even in the treble to my ears if cymbal crashes decayed slightly less quickly).
The SAVANNA has got the somewhat larger soundstage in all directions and the slightly cleaner instrument separation.
Overall, it is about as even, realistic and coherent sounding as the Etymotic but with a bit more bass kick.
Being used to speakers, in-ears and headphones that head into the flat/neutral direction, I never found my ER•4S or the ER•4SR to lack bass or sub-bass at all, it just wasn’t emphasised and spot-on flat to the diffuse-field target response. Some people however, who really liked the ER•4 series’ midrange and treble, wanted a little more bass impact at times. And this is exactly what the ER•4XR gives: basically the same sound signature as the ER•4SR, however with a bit more bass.
Beginning in the lower root, the ER•4XR’s bottom-end evenly rises towards the sub-bass where its climax is at. Nonetheless it is no bassy in-ear at all and just adds a bit more level to make those who want a bit more compensation for the lack of mechanical vibrations happier.
According to what I am hearing (equalized comparisons to determine the exact level difference at a certain point) and measuring, the slight boost isn’t more than 3 dB at 100 Hz, 4 dB at 50 Hz and a bit less than 5 dB at 30 Hz and below compared to the ER•4SR, which is not much but enough to give the ER•4XR a bit more sub-bass and midbass quantity along with a little more warmth in the lower root without affecting the midrange balance. Speaking of the midrange: both my ears and my measurements as well as those on the included certificates tell me that the ER•4XR has got a little less of a presence range lift compared to the ER•4SR wherefore it will be perceived as being a little less fatiguing over time. It has also got slightly more level than the ER•4SR I have on hand around 10 kHz and between 10 and 20 kHz, wherefore it is a little brighter than the ER•4SR to my ears but not to the extent of where we could really speak about an emphasis (there might also be some small production tolerance in place), as the difference is quite small actually and both mainly differ in the bass.
Both in-ears sound equal to me when it comes to detail retrieval and bass quality.
The ER•4XR has got an almost identical soundstage to my ears that is just ever so slightly less deep and the minimally less precise separation.
The Shure is somewhat more on the mid-centric side of neutrality.
The SE425 is comparable to the ER•4SR in the bass department but has got slightly more upper bass and lower root. To my ears, the Shure’s midrange is somewhat more emphasised. The SE425 has got somewhat less level in the highs, however just slightly. Though, it starts rolling off audibly earlier wherefore treble extension is limited on the Shure – the Ety has got the better treble extension above 10 kHz.
The ER•4SR is the in-ear with the higher detail retrieval and better transient response out of the two in-ears.
The Shure’s soundstage is quite small and congested in comparison, and the Ety also features the better instrument separation.
The king is dead, long live the king!
The Etymotic ER•4SR is a worthy successor of the legendary ER•4S with a most widely similar sound signature with just minor tweaks on the sound side and a better cable as well as a better ear tip material.
If you already own an ER•4S, I don’t see the absolute necessity to get the ER•4SR, as while there are some differences on the sound side, they are anything but major. However if you don’t already own a measurably really flat in-ear but need or want one, the ER•4SR should be your model of choice as it has got what is probably still the flattest and most uncoloured sound ever found in an in-ear, based on research that still remains true.
I have always considered the ER•4S as a reference and legend since the first day I had it (correctly) in my ears, and the same goes for its successor.
The only thing that I could wish for are coloured side-markers on the cable connectors, however given that the old ER•4 line also underwent some cosmetic changes over the years, I wouldn’t be too surprised to see the ER•4SR and ER•4XR with colour-coded side-markers in the future as well.