Etymotic ER2SE - A Reference Headphone for your Ears and Your Couplers
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earfonia

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Are those couplers made out of silicone eartips with heat shrink tubing over top? It’s not totally clear from the photo, and I’d love more details!
Since this thread is more about Etymotic ER2SE measurement and tour, we can discuss further here:
https://www.head-fi.org/threads/audio-measurements-on-a-headfi-budget.893084/page-5#post-15305173

I can post a few more close up pictures if you're interested.
I happen to have Monster Gel ear tips that have gel filled the gap in the silicone ear tip that I use as the mold for the heat shrink tube. I use steel rod like chopstick (metal chopstick) or drill bit as the mold for the tube. I will show more pics on the budget thread.
 
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csglinux

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A slightly belated happy 2020 to all my fellow headfi measurement enthusiasts!

Sorry for the long radio silence - work just got in the way of all the important stuff. Anyway, a quick update... The headphone package is, I believe, now with @hakuzen. He has a very nice setup, so I'm looking forward to his seeing his distortion measurements with eager anticipation :) After that, the plan was @castleofargh, then possibly @crinacle, @oratory1990, maybe with a detour via @earfonia(?). I will leave all that in @castleofargh's capable hands.

Two thoughts/suggestions/requests going forward:

1) At least for me, this has been a great learning exercise and I think there are a number of useful points to be made regarding all our measurements. At some point when we're finished with the tour, I think it would be worthwhile writing up a small summary post with figures showing comparisons between some of our measurements. If people preferred, we could make that post without indicating who's measurements belonged to whom. (Would anybody object to having their measurements posted on a common set graphs, labeled with everybody's respective headfi handle?) I just think there are valuable lessons for all of us that I'd like to document.

2) Where do we go from here? One other headfi member had suggested trying to pool a set of measurements for various IEMs. I've no desire to compete with the excellent job @crinacle's already doing, but maybe we can help fill in certain measurement gaps in a collective measurement database. One thought would be a thread with somebody (other than me, please!) maintaining an indexed list of IEMs from contributed posts, each of which could contain individual IEM measurements, graphs, REW .mdat files, measurement rig descriptions, etc. Any interest in pursuing this?
 
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earfonia

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A slightly belated happy 2020 to all my fellow headfi measurement enthusiasts!

Sorry for the long radio silence - work just got in the way of all the important stuff. Anyway, a quick update... The headphone package is, I believe, now with @hakuzen. He has a very nice setup, so I'm looking forward to his seeing his distortion measurements with eager anticipation :) After that, the plan was @castleofargh, then possibly @crinacle, @oratory1990, maybe with a detour via @earfonia(?). I will leave all that in @castleofargh's capable hands.
I'm ok with any arrangement. Thanks!

Another useful effort is probably to estimate our own 'Balanced Target FR curve' estimated for our own ears based on our measurement equipment. So we can estimate tonality deviation from our FR target.
Just My 2 cents.

This is my FR target 2019 for my AliExpress IEC60318-4 compliant coupler + mic:
Earfonia FR Target 2019.png


The 2 curves are upper target and lower target. Basically my balance tonality tolerance.
 
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castleofargh

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A slightly belated happy 2020 to all my fellow headfi measurement enthusiasts!

Sorry for the long radio silence - work just got in the way of all the important stuff. Anyway, a quick update... The headphone package is, I believe, now with @hakuzen. He has a very nice setup, so I'm looking forward to his seeing his distortion measurements with eager anticipation :) After that, the plan was @castleofargh, then possibly @crinacle, @oratory1990, maybe with a detour via @earfonia(?). I will leave all that in @castleofargh's capable hands.

Two thoughts/suggestions/requests going forward:

1) At least for me, this has been a great learning exercise and I think there are a number of useful points to be made regarding all our measurements. At some point when we're finished with the tour, I think it would be worthwhile writing up a small summary post with figures showing comparisons between some of our measurements. If people preferred, we could make that post without indicating who's measurements belonged to whom. (Would anybody object to having their measurements posted on a common set graphs, labeled with everybody's respective headfi handle?) I just think there are valuable lessons for all of us that I'd like to document.

2) Where do we go from here? One other headfi member had suggested trying to pool a set of measurements for various IEMs. I've no desire to compete with the excellent job @crinacle's already doing, but maybe we can help fill in certain measurement gaps in a collective measurement database. One thought would be a thread with somebody (other than me, please!) maintaining an indexed list of IEMs from contributed posts, each of which could contain individual IEM measurements, graphs, REW .mdat files, measurement rig descriptions, etc. Any interest in pursuing this?
1) I'm fine with everything, you can even use this marvel I made years ago to display my photoshop skillzz and my already deep dedication to FR graphs:
lcd-x.gif



2) Don't look at me, I'm not even here.
 
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csglinux

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I'm ok with any arrangement. Thanks!

Another useful effort is probably to estimate our own 'Balanced Target FR curve' estimated for our own ears based on our measurement equipment. So we can estimate tonality deviation from our FR target.
Just My 2 cents.

This is my FR target 2019 for my AliExpress IEC60318-4 compliant coupler + mic:


The 2 curves are upper target and lower target. Basically my balance tonality tolerance.
Two burning questions here... :)

1) I've never seen 711 couplers for sale on AliExpress. Can you share the link? Also, can you join the tour?!? Because if this is a coupler brand we're not familiar with, it would be really useful to see what your coupler does with the ER2SE in the ~1 kHz region.
2) I think my tuning preferences would be quite similar to yours. Apart from one thing. Do you really prefer the sub-bass to roll off like that? I always prefer sub-bass > mid-bass.
 
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earfonia

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Two burning questions here... :)

1) I've never seen 711 couplers for sale on AliExpress. Can you share the link? Also, can you join the tour?!? Because if this is a coupler brand we're not familiar with, it would be really useful to see what your coupler does with the ER2SE in the ~1 kHz region.
2) I think my tuning preferences would be quite similar to yours. Apart from one thing. Do you really prefer the sub-bass to roll off like that? I always prefer sub-bass > mid-bass.
1. AliExpress 711 coupler link:
https://www.aliexpress.com/item/4000073069259.html?spm=a2g0s.9042311.0.0.27424c4di1SuPh

Choose type 1 from the option, that's the one that I bought. So far measurement result has been consistent, meaning, it is not difficult to get 0.5 dB consistency from multiple measurement.

2. Yes I can join the tour. I'm in Singapore, same country (city) as Crinacle.

3. My FR target was the result of a mix of measurements from several IEMs that sound balanced to my ears. And the sub bass usually a little bit rolled off, or flat relative to mid-bass. But I'm perfectly ok with sub-bass = mid-bass or sub-bass > mid-bass
 
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csglinux

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1. AliExpress 711 coupler link:
https://www.aliexpress.com/item/4000073069259.html?spm=a2g0s.9042311.0.0.27424c4di1SuPh

Choose type 1 from the option, that's the one that I bought. So far measurement result has been consistent, meaning, it is not difficult to get 0.5 dB consistency from multiple measurement.

2. Yes I can join the tour. I'm in Singapore, same country (city) as Crinacle.

3. My FR target was the result of a mix of measurements from several IEMs that sound balanced to my ears. And the sub bass usually a little bit rolled off, or flat relative to mid-bass. But I'm perfectly ok with sub-bass = mid-bass or sub-bass > mid-bass
Great post! Thanks for that link to AliExpress. It appears to be the same seller (Lilliang Hong - reputable seller, BTW) that's selling these couplers on Taobao.com. AliExpress is a whole lot easier to buy from if you're outside China, so this is useful info - thank you.

That's an interesting idea to take an SPL bound over all your favorite headphones. I'll try doing the same when I get time (and I suspect I'll get quite similar-looking bounds). One comment though - those little roll-offs that you see at both ends... I think they're just there as a feature (a weakness) of all your headphones. I doubt it's something that most people would want, given that the equal loudness curves continue to rise all the way to the extremes (low and high frequencies) of our hearing. IMHO, those roll-offs are there only because it's very difficult (currently impossible?) to create a headphone that rolls up at the extremes. As of 2020, I'm not aware of any headphone that does that.
 
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benji18tat

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hello everbody , bought er2se, they are great but after hf5 i found highs are lacking a bit, and female vocals and strings not as clear as hf5 as well, but oh boy, tried these parametric eq settings from this review https://zhuanlan.zhihu.com/p/64157774 and i was just shocked how good they could sound, equal if not better than er4b, author says that after proper eqing its the best sounding etys, what do you think?
 
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benji18tat

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25hz minus 2
31hz minus 2.5
40hz minus 3
50hz minus 3,3
63hz minus 3,5
80hz minus 3,3
100hz minus 3.3
125hz minus 3
160hz minus 2.9
200hz minus 2,7
250hz minus 2,7
315hz minus 2.7
400hz minus 2,37
500hz minus 2
630hz minus 1,7
800hz minus 2.15
1000hz minus 3.35
1250hz minus 4.81
1600hz minus 5.15
2000hz minus 4.36
2500hz minus 4.54
3150hz minus 3.49
4000hz minus 2.47
5000hz minus 2.09
6200hz minus 1.5
8000hz minus 3.0
1000hz minus 1.5
dont know exact values of some parameters approximated them from the graph in that review, but it sounds so good
 
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hakuzen

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Hello everybody.

First of all, my apologies for the tour IEMs being stuck here for so long. I started to work in a very demanding job when I received the pack, although this can't be an excuse of the huge delay. Thank you all for being so patient and comprehensive.


1. Sensitivity, SPL calibration.

I first tried with the tips which came plugged on the IEM, stock frosted tri-flange small ER38-15SM. In order to get a proper seal, had to insert the tip so deep that it was touching and bending the fabric mesh inside the coupler.
So changed to stock frosted tri-flange large ER38-15L (ER38-15SM temporal measurement is included though), and tried to restore the mesh shape.

I don't know which method you use to set 94dB SPL at 500Hz; I'm going to tell mine, because found some differences relative to official sensitivity, and you might find defects in my method.
To calibrate SPL, I use a coupler attached to the SPL meter, because I guess it's the most accurate way to measure SPL with IEM. The mic included in the SPL meter is a free-field one, but it shouldn't show significant differences compared to a pressure-field mic at 1kHz or 500Hz.
PCE-322A_coupler_ER2SE.JPG

Sensitivity:

Official: 96dB SPL @ 100mV, 1kHz.

Mine:
Audacity to generate sine signals (100%, 0dBFS). SPL meter: PCE 322-A, calibrated with PCE-SC41 calibrator, class 2. Tip: ER38-15L.
Left/Right: 94.7/94.65 dB SPL @ 100mV, 1kHz (114.7/114.65 dB/V, 96.46/96.41 dB/mW).

As you can see, there is more than 1dB discrepancy with official data (which uses to be very accurate from etymotic).
The difference between various insertion depths is around 0.3dB (@ 100mV).
I also own a different calibrator, Chinese ND9A, also class 2, but I always thought it was worse accurate, based in previous measurements. It gives around 0.8dB difference. Using this as reference, measured sensitivity would be much near to official specification. So I might was wrong, and this Chinese calibrator is better calibrated than my more expensive one (also made in China, probably). Anyways, these class 2 calibrators have a tolerance of +-0.5dB (or even +-0.8dB). So guess that using etymotic official sensitivity specification to calibrate SPL by voltage shouldn't be a worse approach.


2. Impedance and phase

Left:
ER2SE L Z.png

Right:
ER2SE R Z.png

These are drivers impedances, discounting stock cable resistance (besides of the resistance of the leads used when measuring). Add ~630mΩ offset to get impedance of drivers + stock cable.
There is near 0.1Ω difference between left and right. Measured imbalance was around 0.05dB between sides (@94dB,1kHz, as seen above, in sensitivity measurements).


3. Frequency response

94dB SPL @ 500Hz. 24bits, 192kHz. 2*4M sine sweeps.
Using my SPL calibration gear and method, average insertion depth, set 106dB SPL @ 500Hz (REW sine level was -12dBFS), 439mV (right driver).

Tip: ER38-15L. Right.
ER2SE ER38-15L R FR.png

The difference (highs resonances) when using different tips is huge, as expected.
Next measurements are temporal, not calibrated to 94dB @ 500Hz (I'll explain in next post why I haven't got calibrated measurements using different tips yet). Added to get an idea of tips incidence.

Tip: ER38-15L. Left (not calibrated)
ER2SE ER38-15L L FR temp.png

Tip: ER38-15SM. Right. The tip was touching -and bending- the mesh of the coupler, so result is weird. Not calibrated.
ER2SE ER38-15SM R FR temp.png

Tip: Chinese foam T100. Right. Not calibrated.
ER2SE foamChT100 R FR temp.png


3. Impulse response

Tip: ER38-15L. Right.
ER2SE ER38-15L R IR.png
 
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hakuzen

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4. Distortion (THD)

94dB SPL @ 500Hz. 24bits, 192kHz. 2*4M sine sweeps.
Using my SPL calibration gear and method, average insertion depth, set 106dB SPL @ 500Hz (REW sine level was -12dBFS), 439mV (right driver).

Tip: ER38-15L. Right.
ER2SE ER38-15L R THD.png

Temporal measurements, not calibrated:

Tip: ER38-15L. Left.
ER2SE ER38-15L L THD temp.png

Tip: ER38-15SM. Right. The tip was touching -and bending- the mesh of the coupler.
ER2SE ER38-15SM R THD temp.png

Tip: Chinese Foam T-100. Right.
ER2SE foamChT100 R THD temp.png


Compared to @csglinux measurements (using GRAS RA0045 and RME Babyface Pro), I got very similar distortion curve, but around 0.06% higher at 500Hz (for example).
Wondered why my measurements had higher overall distortion.
Checked distortion of my sources (EMU-0404 lineout + JDS Labs C5D phones output) and my inputs (EMU-0404 preamplifier). Of course, they are worse than RME Babyface Pro ones, but the difference shouldn't explain such discrepancy.
Then I checked and changed the cable which goes from the mic preamplifier (BNC) to the soundcard input (XLR). But I didn't take care, and left phantom power (48V) activated while plugging and unplugging the cables. Result: I've fried the mic preamplifier, and couldn't go on measuring. Take this in account: never plug/unplug the XLR cable with 48V phantom power activated!
Now I understand why the stock cable (BNC to XLR) has got a resistance of ~3kΩ between pins 2 (negative signal here, inverted) and pin 1 (ground) of the XLR plug.
The preamp was probably fried when plugging the other cable.
AWA14604C_01_xlr.JPG AWA14604C_02_xlr.JPG

I still don't know the source of the THD level discrepancy. Guess 2 main reasons: quality of the condenser mic, and/or different SPL calibration when measuring.

I've ordered a new mic preamplifier and it would arrive here in around 12 days.
I'll do a full battery of measurements, well calibrated, and using several tips I have around suitable for ER2SE. And the other IEMs.
But I can't ask you for waiting longer. My bad, once again.
So if you prefer I send the tour IEMs to next stage, they could come back here after last one, to make all the measurements.
I think that @castleofargh is next. So please tell me what to do.
 
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earfonia

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Are those couplers made out of silicone eartips with heat shrink tubing over top? It’s not totally clear from the photo, and I’d love more details!
Yes, it is. Several things to form the mold for the heat shrink tubing including 'filled' silicone eartip on top. I don't have the time now, but once I have the time, I will post some pics during the DIY process.

Ooopss I forgot I've replied this earlier. You can ignore this reply.
 
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earfonia

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Mine:
Audacity to generate sine signals (100%, 0dBFS). SPL meter: PCE 322-A, calibrated with PCE-SC41 calibrator, class 2. Tip: ER38-15L.
Left/Right: 94.7/94.65 dB SPL @ 100mV, 1kHz (114.7/114.65 dB/V, 96.46/96.41 dB/mW).

As you can see, there is more than 1dB discrepancy with official data (which uses to be very accurate from etymotic).
The difference between various insertion depths is around 0.3dB (@ 100mV).
Could it be caused by the seal of microphone capsule of the SPL meter PCE 322-A, that the mic capsule is not properly sealed to the nozzle of the meter?

I have 2x UMIK-1, when new both mic capsule were not sealed properly and causing bass response to drop when using for IEM measurement with coupler. I have to open the tip of the UMIK-1, applied some glue to properly seal the mic capsule, only after that it can be used for IEM measurement with coupler.


3. Frequency response

94dB SPL @ 500Hz. 24bits, 192kHz. 2*4M sine sweeps.
Using my SPL calibration gear and method, average insertion depth, set 106dB SPL @ 500Hz (REW sine level was -12dBFS), 439mV (right driver).
When you mentioned 439mV measured at the right driver, is that means at this voltage across the right driver, and you plugged the IEM to the coupler, your SPL meter + IEC coupler will measure 106 dB SPL @ 500 Hz?

Did you measure the voltage when it was measured 94dB SPL @ 500 Hz?

Thanks!
 
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castleofargh

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@hakuzen I can't help for your variations. I cry every time I look at Head-fi's measurements of an ER4S and then look at my measurement of my pair on my cheap rig. And I'm confident you will cry too once this IEM reaches Jude. Or maybe if we ruin the IEM with violent shocks and overly loud signals, he'll end up measuring worst THD? See there's hope already. ^_^ from your usual experience, wouldn't this tiny amount of THD variation be found when you measure an IEM a little quieter or louder? Perhaps your suspicion of issue on output calibration could indeed explain both your problems. But that's only one guess, there are just too many things that could affect THD measurements.


About waiting, I not in a hurry but what about those still waiting? While we're at it, who's waiting for the tour right now?
I'm sure that a few guys would want in if they only knew about this. @CoiL still not interested? As I've seen you super active in anything concerning IEMs and/or measurements, perhaps you have some ideas for members who have their own rig and might find this interesting? I've been somewhat out of touch with new IEMs and people who now provide graphs of them. For a while I still followed the discovery thread everyday, but I'm just too tempted to react to some phantasmagorical statements, and it never ends well when I do:japanese_ogre:. So I just stay away now

@james444 I know Ety is not your favorite brand, but now that you have something to measure all your IEM mods, don't you want to try joining in this tour and get yet another attempt at a random reference target?(I would make a killing as a salesperson^_^).
 
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csglinux

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Awesome work, @hakuzen!

I don't see there's any rush for you to send the package on (unless somebody else out there is absolute dire need to receive it very quickly?). Right now, most of the world is either in lockdown or about to be, so as far as I'm concerned, I'd say spend your quarantine time doing something more interesting and less stressful than reading the news :wink:
I'm sorry to hear about your mic pre-amp. Hope you get up and running with a new one soon.

These results look very good. Most of us are seeing fairly broad agreement with these generic 711 couplers, which is really encouraging. On each individual measurement issue...

Calibration: I know Etymotic used to be famed for their high precision, but I think the idea of the ER2 line was to outsource the manufacturing, make them more cheaply, and one of the costs cut was the (previously, i.e., ER4 series) careful calibration and pairing. We may have been lucky that this particular set was quite well balanced. We both saw ~0.1dB difference in L and R channels 94 dB @ 1 kHz. (Left channel being ever so slightly louder than the right). That's a really, really good tolerance. I recently auditioned a $3000 IEM whose channels were off by more than 2dB under the same conditions. Even my ER4XR's official graph/certificate specifies a 0.4 dB difference between L and R at 1 kHz @ 200 mV. I didn't actually try to measure the ER2SE's SPL at 100 mV, but I've no reason to assume your measurements are off. I'd bet there's some leeway in Etymotic's officially-quoted product specs.

Could it be caused by the seal of microphone capsule of the SPL meter PCE 322-A, that the mic capsule is not properly sealed to the nozzle of the meter?

I have 2x UMIK-1, when new both mic capsule were not sealed properly and causing bass response to drop when using for IEM measurement with coupler. I have to open the tip of the UMIK-1, applied some glue to properly seal the mic capsule, only after that it can be used for IEM measurement with coupler.
That's a good thought. I guess it's possible. A significant bass roll-off would be easy to see when you're measuring the whole spectrum, but not so obvious if you were only looking at one number. Still, I suspect Etymotic's tolerances aren't all that close. Maybe the next person in the tour can double check this? But regardless, I think within one decibel is actually pretty good and almost certainly enough for our purposes.

Impedance: Looks identical to my measurements :)

Frequency response: Looks very close to those from a GRAS coupler, even around the 1 kHz region. Nice job :) As for the eartip hitting the coupler mesh/grill, I've experienced the same problem. It's probably easy to do this and not even realize it's happened. I went for a slightly shallower insertion (dropping the primary canal-resonance peak to around 10.5 kHz) to avoid this, but I was still able to get a seal. Other brands of coupler might, perhaps, have shorter canal extenders? The main differences in FR appear to be the secondary peaks around 15-16 kHz. In my experience, these are the most sensitive to the eartip type and size. I believe certain eartips (small frost triple flange being one) won't necessarily seal in the coupler canal properly at the first flange, but only at the second (or third?). This might result in a small Helmoltz cavity in the gap(s). It's likely this happens in certain people's ears too. I've seen huge differences in the ER4XR measurements in the 13 kHz+ region just by switching from small to large flange tips. There's an audible difference there also - unfortunately, none of these triple flange tips are much use to me on a long-term basis, because I just find them too uncomfortable. One way or another, I think we have to keep the eartip from touching the coupler grill.

Impulse response: Looks identical to that from a GRAS coupler. Nice :)

Distortion: There may be differences in quoted THD specs for various input/output soundcards or ADCs/DACs, but these are all still likely to be an order of magnitude better than the distortion in most IEMs. I'm almost sure the differences here are in the couplers' microphones. I've recently spent more time and money than any sane person would looking into this. While condenser mics generally seem to have way lower distortion than the cheaper 3.5 mm dynamic/electret mics, there's still a bit of spread. The two mics I've found with the lowest distortion are the GRAS 40AO (plus 26CA pre-amp) and the Earthworks M23. But these are both pricey. Even the M23 is ~$500 and still needs to be carefully fixed to a coupler. (In my experience, although they have very low distortion, Earthworks' mics aren't quite as flat as their specs claim.) The coupler response will also have a small effect, because if certain resonance peaks are more pronounced in one coupler than another, that will also give rise to higher THD at the lower frequencies that would look like the fundamental to some higher-order harmonic. For example, the GRAS hi-res couplers (RA0401 and RA0402) will report artificially low values of THD across the board, because they intentionally miss the ear canal resonances. I recently made some measurements of the Beyerdynamic Xelentos and the Final Audio A8000. Both seem to have the same total distortion characteristics at 80 dB. Is that likely? I doubt it. I suspect I've just hit a floor which is the THD of the coupler mics:
thd.png


Although it's still fun to look at, does THD really matter? Really? (A lot of folks are going to plug their headphones into a tube amp anyway.) I have a feeling FR is way more important than THD. Like 100% more important :wink:

Stay safe everybody. Social distancing. You have a great excuse right now to stay at home and listen to some music :)
 
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