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acrylic vs silicon housing for custom iem?

post #1 of 66
Thread Starter 

Hi everyone, I am considering the 1964q iems but they offer two kinds of housing the (normal) acrylic housing and a silicon one which I think is also offered by acs. I thought this warranted a new thread since I have HEARD that silicon housings are more comfortable and do isolate a bit more but I have no certainty. I am wondering if anyone has tried both kinds of housings and could tell a bit more about it? Thanks in advance, Greetings, Anouk,

post #2 of 66

I am also interested in this as well...unfortunately don't think it has been documented that thoroughly.

post #3 of 66

I have only had acrylic, but from what I know, silicon offers more comfort when someone is moving their mouth a lot, such as singing.  I do have to say that my full sized hard shell customs do get slightly uncomfortable after several hours, but I am sure I could get used to it.  Shigzeo is probably the resident expert.

post #4 of 66

From my experience both acrylic and silicon have their strenghts and weaknesses. As far as I am concerned I prefer silicon vs acrylic. The isolation and comfort provided by silicon is greater to my ears. It's hard to tell about the sound as I have never compared the same driver configuration in both kinds of shells and anyway I believe these need to be tuned differently as the acoustic environment is different in both cases, but to my tastes I do like my silicon IEM more than acrylic one regarding the sound. I think for some people it is easier to put on acrylic shells as they are hard and not that flexible. However, once in ears they disappear and you can tell their supperior isolation which in the world of BA IEM's is tantamount to overall sound quality. I think it is important to note that acrylic shells are hollow inside, as far as I know, whereas silicon ones are entirely filled with silicon as a whole. I guess it also highly depends on ones ears, their shape and sensitivity as it's a very personal thing. I have also heard that making silicon monitors vs acrylic ones is much more complicated and time consuming. Probably the reason why there is such a small number of companies offering full silicon products.


post #5 of 66

Thanks for the info keynote.  To my knowledge, it is difficult/not possible to use detachable cables with silicon.  The EM3 Pro uses a solid acrylic housing, not a shell; no breaking it (or reshelling it?)!  ACS and Spiral Ears both use silicon, and Kozee Sound Solutions does also, although there is an acrylic option (along with detachable cables & better drivers) for $50 extra.

post #6 of 66

I just want to point out that if you do go for silicone, I wouldn't advise getting them in clear/white because of future discoloration.
It will tint yellow =_= looks kinda gross and doesn't wash off because it leeches and seeps in (it isn't a surface discoloration but the whole thing changes color)

EDIT: I have not previously owned neither types for housing, but is based on my experiences with silicone-material and general observation. I'm not entirely sure for housing though =_=

post #7 of 66

A topic that definitely deserves more attention. Bravo!


The only major suppliers of silicone shell earphones are Sensaphonics (US) and ACS (UK). I'm not experienced with 1964 so can't comment on those except to say their site seems to be all about acrylic shells, except for sleeves made for universals. I probably missed a key link...


I've experienced both, and silicone is superior in every meaningful way. Keynote's summary is pretty good.


Comfort? No contest. Would you rather sleep on a brick or a pillow? Even if the brick has smooth, rounded corners, I'll take the pillow every time.


Isolation? Again, no contest. According to Dr. Brian Fligor, ScD (Children's Hospital Boston, Harvard Medical School), the expected difference in broadband isolation between acrylic shells and silicone earpieces is about 12 dB -- a significant advantage for silicone, and one that is especially pertinent to proper IEM design. YMMV.


Slight digression: From my perspective, the whole idea of "tuning" IEMs to the "acoustical environment" is kind of ridiculous. The entire idea behind BA IEM design is to approximate direct injection, essentially taking acoustics out of the equation. The driver is connected to a tube, which is inserted into the ear canal.  The entire "room" that is being filled with sound (the space between the end of the earphone and the eardrum) is about one cubic centimeter (1cc).


Hollow acrylic shells are (relatively) easy to manufacture but IMHO mechanically weak. First, the drivers are physically mounted to the shell, opening up the possibility of unwanted vibration. Second, they are much more susceptible to harm, as hard shells can crack when, say, stepped on. Third, they are hard, which means they are (a) less comfortable (ever seen hard plastic earplugs or hearing aids?) and (b) that the seal can be broken, compromising bass response.


In terms of manufacturing, silicone is indeed much more problematic to work with; nothing sticks to it! Acrylic shells can be basically machine-made, requiring a human only for component assembly and polishing. Medical-grade silicone doesn't lend itself to automated processing, so every step is done by hand. Sensaphonics has a team of experienced artisans armed with Dremel tools to craft all earphones in their in-house lab. This increased labor cost is significant, making Sensaphonics are real bargain compared with the manufacturing cost of acrylic shells. (ACS uses a similar process afaik, but obviously I don't speak for them.)

post #8 of 66
Originally Posted by average_joe View Post

To my knowledge, it is difficult/not possible to use detachable cables with silicon. 

Again, I speak only for Sensaphonics, but all their models come with a field-replaceable cable as standard.


Also, FYI: It's "silicone," not "silicon."


-Silicon is a natural chemical element found in great abundance on Earth, primarily as a major component of common sand. Silicon is generally found in a crystalline form and is often used in semiconductors.

-Silicone is a manmade substance derived from silicon and other chemicals, and it may be a liquid or a rubber-like plastic polymer. There are many different formulations of silicone. Sensaphonics uses a cold-cure, medical grade silicone that is very flexible, non-stick, moisture-resistant and transparent.

post #9 of 66

Hey Jack

I was just wondering are there any known issues of transparent silicone discoloring after extended use? (Particularly clear/white)
I use semi-transparent white/clear silicone tips and they tinted yellow slightly. I tried to wash it off but it seeped into the material itself so I did some quick googling and found that this was prominent in scuba diving gear as well.

Does silicone have characteristics which may lead to discoloration?

Thanks etysmile.gif

post #10 of 66

I knew there were others with silicone shells but couldn't think of them at the time, and I thought I saw a replaceable cable on one of the silicone shells I saw at one point in time.  I am still learning, so thanks for the FYI Jack, I guess I had my ICs mixed up with my custom shells (as did everyone else in this thread up to your post)!  


And since you are on this thread Jack, is TheGomdoRi correct about the discoloration of clear silicone?  And are there different grades of silicone?  Are they prone to tearing over time (ACS warns about pulling the custom out by the cable)?  How about cleaning of a silicone shell vs. an acrylic shell?  Thanks!

post #11 of 66



I am wondering if you could comment on some people saying that silicone loses shape over time and if this would actually be significant.

post #12 of 66

I can only speak authoritatively on Sensaphonics products, as the specific silicone formulation used by other manufacturers is proprietary information that I'm not privy to. And I am neither a chemist nor an engineer, so the knowledge I share deserves a grain of salt. That said, I'm fairly confident that Sensaphonics and ACS use the same basic silicone.


I guess I just answered one of the questions: Yes, there are many formulations of silicone. Sensaphonics founder Dr. Michael Santucci did a lot of basic research to determine which form of medical grade silicone is most appropriate for custom earphones. He made the world's first custom-fit silicone IEM earphones, the ProPhonic 2X-S, in 2000. It is still in production today.


-Sensaphonics silicone does not shrink, tear, harden or otherwise degrade in normal use. We too caution against pulling them out of the ear by the cable. That's just common sense -- the same warning you find regarding pulling an electrical plug from a wall socket. These are professional audio products, made for the rigors of life on the road.

-I've had mine for 4 years now and they have not yellowed. If anything, they are a little pinkish but still basically clear. They aren't as "shiny" as when new. (The lacquer coating eventually wears off.) I suspect that there are possible interactions with individual body chemistry that may produce minor discoloration, or perhaps it's a question of the specific silicone formulation used, or both.

-Cleaning silicone earpieces has never been an issue. I just wipe them down with an alcohol-free wipe (same ones I use on my laptop screen), primarily for reasons of hygiene, as nothing really sticks to them. And of course, use the wire loop tool to keep earwax out of the ports.

post #13 of 66
Originally Posted by monoglycer View Post



I am wondering if you could comment on some people saying that silicone loses shape over time and if this would actually be significant.

Not Sensaphonics products.


When fit issues develop, it is far more likely that the user's ear canal shape has changed. This is true for all professional-grade IEMs.

post #14 of 66
Thread Starter 

Hi everyone, wow this thread has grown. Thanks for the information, i hope more people will check in. Oh the information about the 1964ears silicone shells is in their faq. They can do the shells for 100 dollar above the price of their acrylic customs. Greetings, Anouk,

post #15 of 66
Thread Starter 
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