Oh absolutely. That's exactly what put me on the path to custom iem's. I have some universal fit Westone UM Pro30s (that I love by the way) that come with a variety of tips. The little rubber cup tips never work for me, I like the roll up, insert and let them expand tips. On those, my ears required the largest size that came with them. But I noticed if I turned my head just right or opened my mouth too far I'd loose the seal, and the bottom end as well. Their largest foam tip was 15mm on the large end of the tapered tip (toward the outside) Apparently I have large ear canals that are just about the same size at the tips. I found that if I installed the tips on the monitors backwards with the wide end pointing inward I could get a nice seal that wouldn't break. However the foam tips for the Westone have a little plastic tube glued in them that fits the monitor stem. To put them in backwards, I had to carefully scrape the foam tips off the plastic tubes and then put the tube back in the wrong end of the foam with some RTV sealant. It worked fine, just a major pain. I'd have to buy a set of 5 pairs of tips and modify the set, and of course they wear out. So that wasn't a sustainable option.
I searched the web for foam tips larger than 15mm and came up dry. I ran across Earplug superstore who can make custom tips that fit my UM Pro30s and my ear canal, and started down that path with their ear impression kit with green impression material, but before I got as far as ordering, I found this thread. I'm very much a DIY kind of guy, tools anywhere from small clock repair tools to engine lifts and hydraulic presses, and a career in commercial audio with years on my tools and now in design, so here I am, up to my ears in a new adventure that's taking far longer than I anticipated....all for the loss of low frequency lol And I'm a bass player, soooo... gots to have my low end in my ears.
When I started diving off into this, I thought 'this will be a piece of cake', and I have to say, I've found every step of the process has tiny hidden things you don't think about, or that require time, research, unusual material to secure etc. And I haven't even scratched the surface on individual drivers and crossovers etc. Other than wanting to build ONE custom set right now with the Knowles quad driver, I have a couple of other UM Pro30s that I plan to carefully open and surgically transfer components to custom shells with new MMCX connectors.
On a side note, this thread has been WONDERFUL for learning before doing by reading what others have tried and why it did or didn't work. I'm really trying for the first build to be something useful instead of an 'oh crap' and end up having to crack it open for modifications or start over.
