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Tuesday, November 2, 2010

CUSTOM•FIT ear sleeves for ER-4

Dr. Mead C. Killion, the founder of Etymotic Research, used to say: "Adding custom earmoulds to high-fidelity earphones could compromise fidelity." But recently he seems to have changed his mind on custom moulds: "but we found a partner in ACS that allows us to maintain the Etymotic sound signature while providing an extra level of customisation."

I trust Dr. Killion, so I've gotten my self a pair of CUSTOM•FIT ear sleeves, exclusively made for my ER-4B. ACS Ltd. (Or more precisely, DST Swiss) took care of the entire process. The cost was $100, which was quite affordable, but 2.5 months of waiting period was just little too long, IMO.

This is the result, and I AM VERY DISAPPOINTED with the quality of this CUSTOM•FIT ear sleeves. Yes, I am. Here's why:

As you can see, the insertion depth of CUSTOM•FIT is extremely shallow, causing a linear distortion mentioned previously.(insertion up to the reference plane, 13mm away from the eardrum, is a must) Due to the distortion caused by the insertion depth, ER-4B sounds like a hollow tin-can and does not work along with binaural recordings or any other HRTF synthesis.

Furthermore, the lengths of an acoustic tube on both channels are not matched, resulting in λ/4 resonance of the tubes at different frequencies. This skews the frequency response of ER-4B even further.

If someone is willing to pay $100 only for the sake of comfort of ER-4, CUSTOM•FIT is the way to go for. However, if you're serious about the fidelity of what you hear, stay away from it.

Of course, I've requested a re-make of my ear sleeves to the DST SWISS with detailed instruction, but I've yet to received an answer(price quote) from the DST SWISS. :(

Update on 11/09/2010: DST SWISS neither answers my phone, nor calls back though I left a message. Are they intentionally avoiding me? Dr. Kasper, from Etymotic Research, just called in and promised me to fix everything that went wrong. Even though I can't trust DST Swiss anymore, I can certainly believe in Etymotic Research. He said he will call back in couple of days, so I will wait for his call.

Update on 12/21/2010: On Dec. 9th, 2010, DST SWISS sent me another pair, by charging me $85 without my authorization. And the result was more or less the same to the first pair! So I contacted Dr. Kasper again on the same day to address the issue. On his email, he said DST SWISS is not affiliated with ACS USA anymore, and I can get the refund of $85 charge. (which I got on Dec. 15th) Dr. Kasper promised to send me another pair, this time made by the lab which is now 100% owned by ACS. THANK GOD I don't have to deal with those DST SWISS anymore..!

Update on 01/17/2011: Dr. Kasper forwarded my inqueries to Mr. Matthew Sinisi, Customer & Provider Relations Representative of the new ACS USA. Mr. Sinisi told me the UK lab got my ear canal scans, and they'll make the sleeves ASAP. After initial 2.5 months + later 3 months, I will finally be able to get the sleeves with quality that I originally expected from ACS.

Update on 02/18/2011: I finally got new sleeves, and they fit perfectly. Their physical built quality is top-notch; Yet, acoustically, they are more or less the same to the ones made by DST SWISS. Below is the analysis.
Currently, with a quick calculation, the right sleeve is 19mm away from the eardrum, while the left one is 22mm away. Considering the adequate residual distance of 13mm, new sleeves are way too far away from the eardrum. I contacted Dr. Kasper, and he said he will discuss the issue with the lab technician who manufactured my sleeves. I'll see how it goes. (I surely am a man of patience)

Update on 02/19/2011: Dr. Kasper informed me that new sleeves are in production now with above issues taken care of. Hopefully ACS get it right this time, so that ACS and I do not have to go through this kind of ordeal ever again.

Update on 03/14/2011: The 4th pair is here. Below is the analysis.


  1. So, any news on whether they were able to get it right?

  2. I would like to see this story updated...

    With a Happy Ending, and a direction that we who hold the Etymotic so highly, could go and get a proper custom mold.

    Thanks for the excellent info, Jim

    1. It is neither Etymotic's, nor ACS' fault. With current technology, there is no practical way to properly figure out exactly at how much depth the 0.5cc is obtained, unless a 3D MRI scanning is utilized. So no further attempt will be made with conventional custom-IEM manufacturers.

      Still, I am preparing for the second attempt of making custom sleeves, so stay tuned for any updates LOL

  3. Regarding internal tube resonance, I got this responce from Don Wilson: "You can remove the filter from the ER-4 and place it 3mm from the end of the earmold and the response will be good. As long as the hole from the end of the driver to the end of the earmold is 2mm the filter should fit good. Part of the purpose of the filter is to terminate the tube removing any resonances."

  4. My custom process was an epic fail as well. I'm on my fourth pair from microsonics. They've tweaked them each time, and although the sound improved, it is still far from acceptable. I'd rather use something like the earpods than my custom er4s tips. I've been sticking with the triple flange despite the comfort issues and am playing with some pfe small silicone tips that work surprisingly well, but have a similar discomfort simply due to the depth. I do not recommend custom tips for the er4 series. Try every other tip on the planet. It will cost less and you might find one that works just as good.