while researching the adaptation for music nib,
original feed seemed to lack the feeding capability.
through research, the following has been discovered.
by adding addtional top rib structure, the flow of feed increased by 2~3x easily.
*the round grooves are for dual heart hole of music nib.
from now on all eureka custom fountain pens will get this adaptation.
for the owners of previous gen eureka ebonite feeds,
you can cut the rib structure manually, with a rozor blade.
***Do not cut the round grooves! this is for music nib (dual heart hole) only!
similar effect can be achieved, although the asthetics depends on your hand skills.