Reluctance here is the resistance to a magnetic field offered by an air gap. One pole piece of a magnet is split through a pair of coils to twin faces, in proximity to which is a ferrous moving member linked to the stylus and connected to the other pole. Movement varies the air gap between the member and one face, hence also the magnetic flux through the circuit and coil.
"From reading the information on your web page it’s clear you did a thorough job of trying to anticipate every possible question and concern of your customers, and that you have thought carefully about how to run your business. I picked you to do the audio transfer of two very old “voice of your man in service” 78’s, both of which had ..."