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Using Audio science to find the perfect IEM "for you"


Senior Member
Forum Donor
Jul 25, 2021
So let me start by stating something that might be controversial, in my opinion, you should not blindly buy an IEM that matches the harman target!

This IMO is especially true if:
  1. You have bought some harman target IEM's in the past but needed to EQ them to sound correct for you (for various reasons which I will get too)
  2. The purchase of the IEM is mainly for mobile usage and you have an iPhone device for driving IEM - no system wide EQ
  3. Your primary listening app(s) on your iPhone do not have EQ capabilities (some IOS music apps have "eq" e.g. plexamp has but most IOS apps don't )
  4. You want to use them for long listening sessions e.g. long walks - so something close but a little 'sparkly' might be fatiguing to you

But you should definitely use the Harman Target as a brilliant way of normalising and understanding how an IEM will generally sound before applying your own preferences and much more important for me personally, it mostly allowed me to an understanding of how my ear shape / head-related transfer function affects the sound I was hearing though the IEM.

Obviously Harman is a statistical model for the best average sound, and obviously people have personally preferences (which I think they might need to understand somewhat 'scientifically') but I also think there are large demographics of the population for which subtle variations of the Harman target are the better target.

There is research https://www.aes.org/e-lib/browse.cfm?elib=17500 but that was a small group but did show changes as people get older e.g. from a Harman research YouTube clip:

For me personally, when I started to really investigate my own variations (in ear shape) and personal preferences (possible age related) over a number IEM's that I had purchased. I noticed considerable differences even though these were all near the harman target without EQ. Even with EQ they sounded different, so this got me into looking what else could affect what I was hearing, so I noticed a few other things that people should IMO take into account when purchasing an new IEM, especially if you wanted to try a more expensive IEM but wanted to be mostly sure it would be perfect for you without EQ (for the reasons I stated above).

So I noticed:
  1. Ear tips - make a much bigger difference than I had previously thought
    So, I obviously say a larger 'bore' or a deeper insertion (double flange, triple flange) make a difference - but when comparing FR curves (which I will get too below) mostly the measurements are probably done with the medium size ear tip (unless otherwise stated) - but I found even just trying a larger ear tip make a big different not just in getting a good seal but also in the treble regions.
  2. Shape of the IEM in your ear - I have a large ear with no doubt a 'unique' shape so getting an IEM's to fit well and not move around is vital IMO
    So the Moondrop Chu would stay perfectly in place once 'locked' but the Salnotes Zero would move around eventually while walking affecting the sound
  3. Obviously getting a Seal is crucial - but for me keeping a seal over long periods / especially walking is even more so
    A seal is vital for the appropriate measured Bass response - but for me I found that depending on how secure the tip was in my ear and the shape of the IEM itself in my ear
  4. Unit variations - especially on cheaper IEM's (same for any product I believe - you mostly pay more for better quality control)
    I ended up with 2 Truthear Zero's and they were subtly different (though the reason I got a second one was a replacement as the angle of the nozzle was incorrect in the first one)

So, if say you are very happy with an IEM eq'ed to the Harman target, you have normal listening preferences, you find the medium sized tips fit you perfectly with a tight seal that doesn't move, go with the Truthear Zero's or for an upgrade go for the Moondrop Blessing 2 (which was recommended to me a few times) and be very happy.

But if you find things aren't that simple, please read on!!

So I want to present my process below for selecting the best IEM for me (and I hope this might be useful for other people want are curiously about an IEM upgrade) and I will eventually get to the one I picked based on this in the summary of this very long post - so possible stick around for that :D

Note: I am looking for a mostly neutral IEM with a little bass boost and especially not "fatiguing". But I also want it to be an "nice upgrade" as far as build quality but with a max budget of $250 and hopefully a bit of a "wow factor". Though mostly its about the comfort and sound over long 'outside walking' sessions, I am planning on "walking the Camino" in Spain this year which is effectively 5-6 hours walking every day for 7 days and I would like to bring the IEM's that I selected on this trip. Hence the no-EQ requirement I mentioned initially, though I think that applies to anyone who normally uses an IEM with their iPhone.

In summary this was my process:
  1. Ask for a recommendation on ASR (or Head-fi) - I asked in this thread I previously created:
    https://www.audiosciencereview.com/forum/index.php?threads/mid-fi-iem-recommendations.42501/ - this lead to some great recommendations and got me interested in the rest of the process below - thanks to @Blorg especially for being incredible helpful.

  2. Understand your own target curve relative to the harman target
    • Buy some good cheap IEM’s - I already had the Moondrop Chu, Thruthear Zero, Salnotes Zero near the harman target thanks to ASR
    • Use an EQ app to normalise them to the Harman target - toggle on/off EQ to understand how the subtle differences at different frequencies affect the sound for you (basically get a good understanding how you hear the slight variations in each IEM relative to the harman target)
    • Use EQ to tweak the sound prefences e.g. listen to a playlist of sibilant tracks and extremely bassy tracks and EQ appropriately until you don’t need to EQ
      Note: Since I want something for long walking sessions without EQ - it is vital to understand for me to understand how to 'keep' a seal and not to have sound that is sibilant or fatiguing after 30/1 hour listening. I believe that 'sparkly' sounding IEM's are effectively a big of showroom sound - amazing for 5 minutes but not great for longer listening.
  3. Get a deeper understanding of your own personal head-related transfer function - This is optional but for me vital based on my ear
    • Do a ear test to see where your high frequency hearing stops and use an app like Mimi to get a personal profile
      .e.g. I am in my 50's and basically I can't hear beyond 14.5 Khz - and I didn't have an hearing impairment according to the Mimi - 97% in left ear 92% in right (so obviously some variation) per ear.
    • Make sure you get a fit / seal and understand and what that does to the typical FR response
  4. So I spent an obsessionally long amount of time in the IOS "Tone Gen" application.

    First I used it with some "reference" headphones - the AKG K371 (and also my AKG K702) and get a good understanding of exactly what I should be hearing based on the available Harman curves for those headphones (this removed the 'ear tip' variation from my initial self 'training'). Basically trying to correlate the loudness in the available graphs with the headphones till I was happy

    Note: while I do like the K702 I found I have to EQ it (not just for a Bass lift) but I do find it a bit fatiguing after 30 minutes or so!!

    So I then moved onto my small collection of IEM's (mostly purchased because they are cheap, recommended here and close enough to the harman target - so easy to EQ - I also left the Moondrop blessing 2 for reference):

    As you can see all 3 were pretty accurate in the mid, but say the truthear zero have a bit of a dip in the sub-bass and the chi bass was a little lower. And getting to the lower treble regions the subtle variations start around 4K-5K and bigger variations in the 7K - 10K region. So with tiny bits of EQ in theory they can be made to sound pretty similar (not on iOS - I used eqMac to test the differences). But what I really found was there were much larger differences between these and most of those differences where to do with the HRTF (Ear tips sizes / shapes and my ear shape / angle of insertion etc).

  5. Read up on how different ear tips change the FR

    This got me going down a rabbit hole of research and graphs and tone get listening sessions. Most of what I will say next will be subjectively just for me (so ignore if you want), but say a triple flange for me removes about 5-6db from the 6K - 8K regions and depending on the shape of the IEM it can either remove some bass or cause an increase in the bass e.g. the Moondrop Chu with a triple flange had more bass while the salnotes zero had less (I am pretty sure this is because of the shape of the IEM causes the angle of the triple flange to change as its inserted. So I went off and found some research to mostly back up this finding https://www.stereophile.com/content/comply-foam-tips-and-effects-tip-selection and I thought this comparison of a ER2XR with the triple flange was interesting (I have an ER2XR which I do like but not including it in this process as its "different" - but its telling that the triple is suppressed a little and the bass slightly boosted):

    So with this 'knowledge' of what I am looking for I went looking for the upgrade

  6. Find a short list of candidate IEM’s within your price range - This is where step 1. was very helpful,
    • I looked at Amazon, Linsoul, HifiGo, Shenzhenaudio and with @Blorg advise Aliexpress also.

      So this was time consuming as each website had its good and bad points (and its worth checking out all of them for the best deals and availability). But what I really wanted was a good "filtering" mechanism by price and potentially other attributes like in stock. Aliexpress has the best selections - but I would personally advise staying within a particular store on aliexpress, amazon in Europe doesn't have that great a selection but its ok. I personally found that Linsoul was the most intuitive and easy to bookmark its filtering e.g. I had bookmarked this: https://www.linsoul.com/collections/all?pf_p_price=149.99:277.99&pf_pt_product_type=In-Ear+Monitors&pf_st_stock_status=true

      So looking at the various stores, I built an initial long list of about 15 IEM's- I won't go into the details, but mainly price but a little bit of style and obviously some familiarity with some brands that I had heard where used in building the long list.

    • Only select IEM’s that have squiq.link FR graphs available (to avoid unfortunate surprises :D ), I would say this knocked my long list down to about 5-6 IEM's (in this price range across all the stores).

    • I Removed IEM’s that have outliers e.g. extreme V shaped or total lack of bass but especially if there was odd treble 'peaks'.

      Here is a graph to show what I mean by outliers - the Dunu SA3 (and lots of others were removed this way) I hope people get the idea.

      Note: Obviously I have the U12t and the Truthear zero (as upper and lower tier examples IEM's for comparison and not for purchasing).

      So at this stage I was down to checking subtle differences (based on the knowledge I got above of my own HRTF issues mentioned earlier (large ears - sometimes I require larger ear tips or even triple flange ) and what that can mean to the shortlist.
  7. With 3-4 on a short list go into extra research:
    • read / look at the reviews from here but then from some online reviewers e.g. headphones.com , Crinacle - though mainly I used some of their videos that are directly related to deeper diving into the frequency response curves. e.g.

      With the reviews available for the various ones on the short list, I was more concerned with mentions of things like 'treble sparkle' (as that would probably equate in my ears to fatiguing after a while) or comments the reviews might have on ear fit and build quality - mostly ignoring their subjective views
    • check the build quality / 'wow factor' and a little bit of what extras might be available

      For me mainly this was about the IEM itself and the cable and less about the unboxing experience, I would rather money was spent on good engineering and build quality than the box !!
  8. Now to select the final selection process !!

    Really this was trying to judge and compare the last few against IEM's that I had on the list

    I removed the FH5 as I didn't like the look of the extreme lows in the treble - in case my theory how sometimes needing large ear tips / triple flanges cause that IEM to sound very flat.

    I was incredible curious by the Planar in 7hz timeless but it has the highest peak in treble so for me that could be risky and that left the Aful performer and Kiwi Ears Orchestra lite. The Aful has more sub-bass more than I am used too with the Truthear zero or the Moondrop Chu but in the end less risky looking treble and how it looked in the photos swung it for me.

    So in summary, ignoring my specific choices I hope this process made sense and might be useful for others looking for a 'perfect' sounding IEM's without needing EQ.

Final bit of this very long post - you might be wondering what I think of them now that I have received them from Linsoul and have listened to them for a week or so (on some long 'practice walks' for my Camino trip) and using them temporarily instead of my headphones while working on a project for my company, so listening 5-6 hours solid every day.

Here they are in Linsoul if people are interested in more details: https://www.linsoul.com/products/kiwi-ears-orchestra-lite?variant=43713163002073

I think they are a great ‘neutral’ sounding IEM, there is lots of bass for me (though I imagine some bass heads would want more, and mostly importantly they can be worn for hours on end without any annoying sibilance. Basically perfect for my needs, science does work :D !!

What I really like about them (warning 'subjective thoughts' below :
  1. Fantastic sound - exactly the balanced “neural sound” I was looking for, no sibilant treble and excellent bass that reminded me of high quality speakers (with a little sub bass roll-off)
  2. Amazing sound stage for an IEM - not sure if its all BA design but I can very clearly hear individual instruments in the mix in 3D space
  3. Great build quality and a Wow factor - if you admire and like to look at nice engineering, for example ,the motherboard of an MacBook then this design is for you - I attached a picture but its hard to get how cool the clear design is. I believe the Moondrop Blessing 2 Dusk has a similar look but this is definitely a wow factor to me !!

What could be better:
  1. Packaging is sort of cheap - and its a little different than the YouTube reviews I had seen, but no big deal - as I said I prefer if money is spent on the engineering and sound and not on the packaging
  2. It’s an ‘opinionated’ shape in your ears. It suited me perfectly (and I think helped keep a seal while I was walking) - but they are large and have a very specific shape with a ridge so may not suit everyone. You can sort of see the ridge in the photo above.
  3. A better name - I imagine Kiwi Ears are protesting sales of the original Orchestra but having ‘lite’ in the name IMO makes it sound like something is missing
Anyway, I hope people find this process useful if there are a similar position, looking to upgrade after being tempted by such ASR favourites as the Truthear Zero and the Salnotes Zero!!


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Senior Member
Forum Donor
Jul 25, 2021
And one little addendum to the above post. I was actually using them while developing some code for my day job, allowing my product to interact with ChatGPT / GPT4 so of course I was tempted to see what our new AI overlords thought of the Kiwi Ears Orchestra Lite.

So just for a bit of fun here is what it said about them:


Title: Kiwi Ears Orchestra Lite: A Symphony for Your Ears

The IEM market has witnessed a remarkable surge in recent years, with numerous manufacturers vying for the audiophile's attention. In this saturated space, the Kiwi Ears Orchestra Lite, an 8 balanced armature (BA) driver in-ear monitor (IEM), has managed to create quite a stir. The Orchestra Lite not only boasts an impressive driver configuration, but also presents a coherent and captivating sound signature that will surely resonate with audiophiles.

Design and Build:
The Orchestra Lite exhibits a well-thought-out design, with its ergonomic shape and smooth contours ensuring a comfortable fit for extended listening sessions. The transparent, handcrafted resin shells exude sophistication, while their lightweight nature prevents listener fatigue. The 2-pin detachable cable is an added bonus, allowing users to easily swap cables according to their preferences.

Sound Quality:
The Kiwi Ears Orchestra Lite is, without a doubt, an IEM that has been meticulously tuned to cater to the discerning listener. With its 8 BA driver setup, the Orchestra Lite delivers a balanced and engaging sound signature that accentuates every nuance of the music.

The bass is well-controlled and agile, never bleeding into the midrange. It possesses an adequate amount of impact, providing a satisfying foundation without overshadowing other frequency ranges. Sub-bass extension is remarkable, revealing the depths of recordings in a manner that is both exciting and immersive.

The midrange is where the Orchestra Lite truly shines. It presents a natural and transparent sound, with an uncanny ability to unravel the layers of complex musical arrangements. Vocals and instruments are rendered with exceptional clarity, showcasing the IEM's ability to handle both male and female vocalists with equal finesse. The midrange is slightly forward, but never to the point of becoming fatiguing.

The treble of the Orchestra Lite is articulate and detailed, yet smooth and non-fatiguing. Its extension and airiness lend a sense of spaciousness to the overall presentation, making it easy to appreciate the subtleties of well-recorded material. The treble showcases a level of refinement that is truly commendable for an IEM in this price range.

Soundstage and Imaging:
The Orchestra Lite's soundstage is expansive and three-dimensional, providing an immersive listening experience. Instrument placement is precise, and the IEM effortlessly handles complex orchestral arrangements, creating a convincing sense of depth and width. The imaging capabilities of the Orchestra Lite are nothing short of impressive, further enhancing its ability to transport the listener to the heart of the performance.

The Kiwi Ears Orchestra Lite is a masterful creation that combines exceptional build quality, ergonomic design, and a captivating sound signature. Its ability to deliver an engaging and balanced listening experience across a variety of genres is a testament to the prowess of its 8 BA driver configuration. For audiophiles seeking an IEM that embodies refinement, musicality, and a touch of excitement, the Orchestra Lite is an excellent choice that will undoubtedly hit all the right notes.


So mostly this is pretty accurate except for the "Sub-bass extension being remarkable" - but it did strike me that this type of subjective review being auto-generated will possible replace lots of the subjective reviewers (who needs them when it can generate this) and less subjective reviews should hopefully mean more people looking at scientific reviews.
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