How to measure IEMs cheap for use with AutoEQ?

[MayaTlab]

This is looking to be a bit more straightforward than anticipated, though that doesn't mean easy answers, lol. The coupler seems to be performing well.

After correcting for this:
View attachment 364481

Genuine GRAS couplers may not always be aligned with the centre line between the standard's limits :

https://www.grasacoustics.com/files/m/a/man_60318-4_ear%20simulators.pdf

For the few select IEMs which I own that I think are appropriate to perform this first line of checks, the average delta that I obtain vs Oratory and CSGlinux's databases is not exactly consistent with correcting the transfer impedance plot that was provided so that it aligns with the centre line, but I think that as far as I'm concerned the sample size is still too small to begin with.

I get a good, consistent matches with oratory1990 (of results that more or less have the 8kHz resonance line up and which seem to be more recent).
View attachment 364482

Looking good so far ! If you have a deeper insertion IEM (ER2SE for example), it could be interesting to see how it compares as well - but in the case of the ER2SE seatings can occasionally be quite inconsistent when using the older-style tri-flange tips and sample variation isn't perfect either. Don't over-sweat the details, even comparing Oratory and CSGLinux's databases does not result in a perfectly flat transfer function.

I've been quite happy with the sample variation of the Moondrop Chu (1st gen) so perhaps add this one to your roster of test IEMs :

(this is each earbud compared to the dB average of all six.)

You may have noticed that the resonance may be slightly less dampened in your coupler out of the box. I would try to experiment with damping material (which you can place for now right behind the reference plane, above the protective grid). I would not try to compensate with a static compensation for damping issues.

It seems from comparing 3 different IEMs (and multiple copies of each) that the only important difference between these RA0045-based results and Amir's results (outside of the resonances, obviously) is this, roughly a 1.5 dB bump between 800-5kHz.

That's the general trend I observed as well, with differences above as well in terms of damping / length modes and some additional factors.

Again, I am shocked by the consistency I am seeing. I thought the coupler was going to be a piece of crap, honestly.

Some are for the most part quite fine in terms of acoustic impedance indeed. The problem has never been that they're always sh*t, it's that they vary .

Ironically, this seems like the opposite of what one of the graphs in the thread described.
View attachment 364486

That's just RA0045 vs RA0402, the pinna is not involved here.

I have always had the suspicion that IEMs were brighter than what many results show.

I am not certain what you mean by "brighter", but 711 couplers are a bit less accurate than newer type 4.3/4.4 ones in terms of representing the average acoustic impedance. The transfer function between 711 couplers and the 5128 tends to tilt the midrange brighter (here four different sources doing the same test, that is to say compare a bunch of IEMs on a 5128 fixture and a 711 coupler, and plotting the difference) :

Your own ear's acoustic impedance may not necessarily align with the average however.

 

[USER]

Preliminary investigation could show that the 1.5dB bump between 800-5kHz may help bring the results to ASR/Sean Olive territory. Obviously the resolution of Sean Olive's graph is too low. We'd need Amir to measure one to have a better understanding.

Here are the results of Sean Olive's EQ on my JBL Endurance Run 2 measurements. First is without "ASR correction," second is with it.
Ignore the resonances above 8kHz in mine and the dip at around 200Hz in Olive's. Normalized at 450Hz.

Regular results. Normalized at 500Hz. Again, ignore the Olive dip right before 200Hz.

Again, this is preliminary work. But it is interesting (to me, anyways). I want to measure everything again with my E1DA Cosmos next week.

 

[USER]

Looking good so far ! If you have a deeper insertion IEM (ER2SE for example), it could be interesting to see how it compares as well - but in the case of the ER2SE seatings can occasionally be quite inconsistent when using the older-style tri-flange tips and sample variation isn't perfect either. Don't over-sweat the details, even comparing Oratory and CSGLinux's databases does not result in a perfectly flat transfer function.

Thanks for all the good info! In fact, I do have an ER2SE. I plan on measuring it once I am more confident as it is a rather intimidating IEM, lol.

Cheers.

 

[USER]

I think I know what I am going to do. As an important Old El Paso commercial once asked, "¿Por qué no los dos?"

 

[MayaTlab]

I want to measure everything again with my E1DA Cosmos next week.

I'm quite curious to see how your Apple dongle and the E1DA will compare in terms of FR. Looking forward to it !

Thanks for all the good info! In fact, I do have an ER2SE. I plan on measuring it once I am more confident as it is a rather intimidating IEM, lol.

CSGlinux measured his with the older-style tri-flange eartip that is no longer provided in the newer packages (but you can get it by chopping off the tube of the tips provided with one of their noise protection plugs). I don't know how Oratory measured them.

This eartip can occasionally lead to odd results depending on exactly how the flanges mate with the ear canal extension (same volume level, same earbud, same eartip, somewhat similar resonance, just different seatings where I deliberately tried to introduce "accidents") :

Also, sample variation for four earbuds (I had some difficulty with hitting the exact same resonance though) :

 

[USER]

I'm loving how easy it is to measure Bluetooth IEMs with REW.

These are so comfy and the little protrusion helps keep it on your ears. Typical "sports" FR with bass boost. Not crazy but the JBL app makes it super easy to correct and they sound terrific afterward. They clearly have the measurements so I don't know why they don't publish them. Maybe they figure it doesn't matter if people will use the app.

These are not my official distortion measurements as they are very simple captures and I will put-together a more appropriate set-up, but I figured that the peak distortion results are maybe sort of reliable and they are what really matters anyways. (Please correct me if I am wrong.) Seems rightish? JBL wireless IEMs were never meant to be played loud and these have clearly hit their limit. Here the measurements were taken at ~94 dB at 450Hz.

 

[markanini]

've been quite happy with the sample variation of the Moondrop Chu (1st gen) so perhaps add this one to your roster of test IEMs :

(this is each earbud compared to the dB average of all six.)

I would recommended getting Chu for learning how damping works in the front vent and nozzles, even more when you have a coupler and can measure the effects.

 

[USER]

I would recommended getting Chu for learning how damping works in the front vent and nozzles, even more when you have a coupler and can measure the effects.

Yup. I agree. I already have a vent plug mod measurement posted for the 7Hz Salnotes Zeros. (It's of my "hot rod" version with the vent covered and spring tips to boost the bass and smoothen the highs--ie. use them without EQ.) I posted some tip comparisons as well. I have some mesh filters that I will measure with the Zeros. It's nice to see videos about mods but so much more fun to test it on your own IEMS. That's why I got the coupler to begin with.

 

[Gershy13]

I also want to say that one significant benefit of buying a coupler and playing around with it is that you really do get a good "feel" of who is good at producing measurements and can learn to intuit issues with the results and know what to ignore and sort of correct some things by eye. I am finding that I am able to be more consistent than I thought I would be early on in the process--though I have to be super patient and willing to measure 20+ times to get things as good as possible! In my case it is about being as precise with the 8kHz resonance as I can. (My posts are mainly for people thinking of buying a coupler if that wasn't clear.) It's easy to see that many on squig.link give up, though of course I myself have met fitting limits and have had to settle.

Here are two measurements from 2 different days. That is pretty decent considering I was not thinking of comparing the results when I made them.

View attachment 364350

I believe the slight differences are in some part due to the resonances not aligning perfectly. You can see it close-up in REW. But even this is pretty good. I certainly respect the better measurers more than I did before. I am excited to send Amir some IEMs that I have measured myself as that will help a lot.

Obviously this doesn't relate to getting perfect matches out of a conversion EQ between two measurement systems, but who expects that? Things are going to be different given all the variables but a good measurer provides a lot of details and and develops a good reputation. (Plus I can now see issues in some of Amir's graphs that I can ignore or differentiate them from general IEM performance differences.) Getting a good conversion EQ is the result of a mixture of careful analysis and common sense (the latter bettered by measuring a lot of IEMs oneself). I've already gotten a consistent conversion EQ between ASR and one of the better squig.link measurers so I am comfortable with the process and know what I want out of it. Right now I am testing many hardware and software set-up variables so that I can learn about the causes of anomalies and what they look like. I'm looking forward to comparing my Apple Dongle set-up to a high quality E1DA Cosmos one this weekend.
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In the end I hope that people are not afraid to try this. The specter of technological limitations and unknown or uncontrolled variables certainly hovers, but unless one has an authentic coupler/set-up this is simply a hobby for amateurs. Certainly many youtube reviewers forget this when they take their own measurements too seriously and make really silly assumptions, especially concerning the higher frequencies. But I also find a strong link between poor analysis and "review" quality and people that very clearly did not ever compare their results to a more legitimate source.

Edit: I've said this before but maybe it bears repeating: I have no intention of reviewing IEMS, lol. I purchased the coupler to help me get the best performance out of my IEMs be it through tip changes or EQ. If this helps me post measurements on here that I am more comfortable presenting than I would otherwise, all the better. The $110 investment is a no-brainer to me.

I have worked on a phono cartridge measurement thread that I take very seriously and am proud of, however. So I am no stranger to imperfect measurements, lol.

Introducing the Phono Cartridge Measurement Library

After years of development we are finally launching our phono cartridge measurement library. These measurements were created using the brilliant cartridge response python script written by @scott wurcer and @JP. Information about its origins can be found in the following threads...

www.audiosciencereview.com

I'm considering getting one just to help me make decisions about EQ and tips too. Are the measurements reliable up to 20khz? I see places say that they aren't accurate above around 10k, but for relative measurements would this be okay? Say if I have two items and I want to compare their performance even in the upper treble. Or check the difference between silicone and foam tips on a planar iem that I find too bright etc.

 

[USER]

I'm considering getting one just to help me make decisions about EQ and tips too. Are the measurements reliable up to 20khz? I see places say that they aren't accurate above around 10k, but for relative measurements would this be okay? Say if I have two items and I want to compare their performance even in the upper treble. Or check the difference between silicone and foam tips on a planar iem that I find too bright etc.

If I remember correctly these measurements are not to be taken seriously after 10kHz. (All GRAS measurements??) But even below that is not necessarily what you are going to get because things like ear canal shape and tip insertion depth change the results. Here, with the coupler, insertion depth shifts the resonances around and the areas around them. The best we can do is adjust insertion depth so that the main resonance is as close to 8kHz as possible. You can kind of understand now how this is a troubling scenario as we may not even insert our own IEMS the same way the same day. Sometimes it is not possible to hit 8kHz (it is easier to do this with the coupler sideways) because of the tip and/or IEM design so you do the best you can but a good rule to follow is that you should ignore measurements that don't hit 8kHz resonance as they don't make apples to apples comparisons so to speak. More, cheaper couplers like these show stronger and more disruptive resonances that show more "negative space" around them than is actually there. Certainly ignore a measurer that is not consistent because it shows laziness as it can take many, many tries to get results right. Nonetheless I think these are great for those type of decisions you mention because you can compare your results to each other to see the effects in a contained system. I think my coupler is the best IEM-related purchase I have made. I've learned a lot about IEMs and also now better read and understand measurements.

 

[USER]

Forgot to mention perhaps the best reason to get a coupler: to find issues you may not have confidence in determining are there otherwise.

In all honestly, I had no idea one channel was off with this set. Part of this is that I took what I was hearing for granted after years of use and also the fact that I only use wireless IEMs sporadically in specific situations. As you can see, I couldn't hit the 8kHz resonance with these.

When I ordered these through Amazon and from Linsoul I received a set that was clearly used. These companies are well-known for trying to sneak out used items when they can. I immediately set-up a return but held on to them for a few days in order to test them. I don't know if it is a coincidence or not, but the previously returned set has a slight channel imbalance. The brand new set is pretty much perfect. Is it a big deal? Probably not. But I always want to know how far off my IEMs are.

This is a cheap set that I purchased to practice measurements with. I am now better equipped to hear this issue.

If you are the type of person that spend hundreds on or continually purchases IEMs I think it is unwise to not to buy a measurement rig for about $120. Seeing as there are so many small boutique brands, I personally want some extra reassurance regarding my respective purchases. Same goes with refurbished items and used goods. You have to be able to rely on yourself to make sure what you buy is of good quality.

 

[Gershy13]

If I remember correctly these measurements are not to be taken seriously after 10kHz. (All GRAS measurements??) But even below that is not necessarily what you are going to get because things like ear canal shape and tip insertion depth change the results. Here, with the coupler, insertion depth shifts the resonances around and the areas around them. The best we can do is adjust insertion depth so that the main resonance is as close to 8kHz as possible. You can kind of understand now how this is a troubling scenario as we may not even insert our own IEMS the same way the same day. Sometimes it is not possible to hit 8kHz (it is easier to do this with the coupler sideways) because of the tip and/or IEM design so you do the best you can but a good rule to follow is that you should ignore measurements that don't hit 8kHz resonance as they don't make apples to apples comparisons so to speak. More, cheaper couplers like these show stronger and more disruptive resonances that show more "negative space" around them than is actually there. Certainly ignore a measurer that is not consistent because it shows laziness as it can take many, many tries to get results right. Nonetheless I think these are great for those type of decisions you mention because you can compare your results to each other to see the effects in a contained system. I think my coupler is the best IEM-related purchase I have made. I've learned a lot about IEMs and also now better read and understand measurements.

Thanks, yeah i know that after 10k it gets a bit eh. But i was wondering if that was only when comparing to other measurements/your ears. Basically my question is will it be accurate for 10khz+ for relative measurements? If i matched the 8k resonance on both? Or say i dont even move the iem for both measurements, i just change something at the source (EQ, impedance adapter, etc) Would these results show up on the graph even for above 10k? For relative measurements could it be compared?

 

[USER]

Thanks, yeah i know that after 10k it gets a bit eh. But i was wondering if that was only when comparing to other measurements/your ears. Basically my question is will it be accurate for 10khz+ for relative measurements? If i matched the 8k resonance on both? Or say i dont even move the iem for both measurements, i just change something at the source (EQ, impedance adapter, etc) Would these results show up on the graph even for above 10k? For relative measurements could it be compared?

I would think that it would be good enough for comparisons and that differences would be easy to see, especially for our use case, but I will be the first to admit that we are getting into a realm that is past my limited knowledge of the subject matter. I just don't know too much about performance past 10kHz. Hopefully someone can shed more light onto the question.