[Coasterjeffry]

Hi all,
 
I'd appreciate your advice.  Just received custom sleeves for my Etymotic ER4s.    I wonder if I need new impressions and thought your experience with customs might be helpful.
 
Main issue - Seal breaking!
 
I am used to using Shure Olives with a deep insertion.  There NO way I can do anything like breaking a seal on those...   After fooling around with insertion on these sleeves I have found how to get the proper seal (I think) with the full sound, tone, bass, etc. It does not feel "tight" like a deeply inserted foam tip but sounds perfect.  Now....as SOON as I open my jaw the seal is broken and the tone/bass is completely lost.   Close jaw again...BAM...it's sealed and perfect.   If I slightly extend my jaw forward, same thing.
 
RE: Impressions.  I did not (out of ignorance) have a bite block in and have an "open-mouth" impression taken.   I now see places like 1964EARS demand this style of impression.   Is that my issue?   Or, am I expecting something wrong when I think the seal should remain no matter what I do with my jaw/mouth within reason.  
 
Your experience and advice is very much appreciated!

 

[albertnam]

I don't have sleeves, but I believe customs should be a similar experience. 
 
Regardless of how far I open my mouth, my seal does not break. In my opinion, your best bet is to have impressions taken open-mouth.