Bret Halford
500+ Head-Fier
I am aware of this. FiR's is what I would call a competing implementation. It has its own drawbacks, but contact dependency is substantially reduced.The BCD technology in the kinetic bass from FiR is different to UM and EE though. There isn’t a literal “bone conduction driver” inside these IEMs like how you can see the silver disc like driver in the Evo, Odyssey, Mentor, etc.
Like @Deezel177 said , I think a lot of the issues with custom bcd from EE actually stems more from their dual DD configurations, even the Legend X is quite a roomy CIEM, throw in some EST and BCD drivers and it requires even more space that just won’t work for a large majority of ears.
As you note (?) UM's BCD is relatively similar to EE's. They offer custom quadbrids and have for sometime. I frequently see impressions that note the BCD is more effective in the CIEM version.