Quote:
Originally Posted by
JonRGM 
I only have experience with my B2s (which I think have dual Knowles, unsure the model) but you've given me things to google at the very least.
The B2 have a TWFK-30017, which is the only publicly-available TWFK model from Knowles. 1964 uses a company-only version (you gotta get it wholesale, as a client of Knowles), which is electrically very different --- likely completely different DC resistance, (and hence) coil impedance, damping scheme, etc. The TWFK family tends to have a distinctive "sound", though, as its armature design and housing dictates its mechanical resonances --- which is why I recommended the V6 to you out of all the different 1964 models. Though the tonal balance will be different, the V6 will share more timbre qualities with the B2 than any other 1964 product.
Google won't give you too much, and honestly, knowing the driver setup doesn't really tell the whole story to BA-based IEMs. There's the crossover and the tubing selection/length/diameter, which are actually more important and integral to the final sound signature of the entire design. 1964 spent a good amount of time experimenting with that stuff, I'm sure.
I have a resource thread on here that gives people a look at a lot of the driver setups of BA-based IEMs, but that's more for DIYers to have a reference to play around with and emulate their favorite earphones, etc., and for quizzical audio geeks like me.