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.