Raul indicates "bobbin" is synonymous with "armature", just different terms for the "thing" they wind the coil-wire around. Is "core" another synonym?
I ask because there is also the "air core" design, where the coil-wire is wound around — nothing. Thus there is no interaction between the different materials, hysteresis, or "magnetization" of an iron core.
As it was explained to me, the "air core" is wound around something of course, it must be. They use — Ice. The wire is wound around a sliver of ice of the right shape, which then melts away, leaving no core/bobbin/armature at all. Hence "air core". This must be done in a deep-freezer, of the walk-in kind.Fidelity Research used this method in some of their models, as it was explained to me by a FR aficionado I knew many years ago. Maybe he was wrong, maybe nuts — but my FR MC-201 advertises its air-core as a feature that offers lighter moving mass and lack of the interactions mentioned above.
Do any of you know more about this?
I’d like to think he wasn’t crazy. I bought several FR cartridges from him, because of their sound of course, not the ice-theory.