towards perfection.
Moving mass
Magnetic cartridges have three elements necessary to generate a voltage; a magnet, coil
assemblies, and an “iron” or ferrous component of some shape. The performance of any
magnetic cartridge is largely dependent on how little “moving mass” it has; this is both the
mass of the stylus at the end of the cantilever, as well as the total mass of the voltage
generating parts that the stylus must move. While there are some advantages to specific
designs, both moving magnet and moving coil cartridges are at a distinct disadvantage in
regard to moving mass as they are required to move either a relatively large magnet, or a
“coil assembly”. The coil assembly is in reality is a series of wire windings often on a metal
core, more properly labeled as an “armature”.
In a moving iron design, one has the potential to reduce the moving mass to a very small
value by virtue of the having the required two relatively massive elements (coils and
magnet) held in fixed position.
It is important to understand that while it is true that all designs have trade-offs, a designer
must arrange the order of trade-offs carefully. Reducing moving mass is at the top of the
list for Soundsmith; less inertia in the generating elements means faster starts and faster
stops. It also means a much easier job of damping the unwanted “ringing” of the moving
system, a system that must make sudden, accurate and controlled directional changes to
follow the grooves of a record.
In order to obtain accurate vinyl reproduction, the stylus must remain in near constant
contact with the groove walls. The larger the moving mass, the greater the jittering of the
stylus, meaning that it is in reality taking “samples” of the groove walls from moment to
moment, and averaging or guessing at what is taking place in between those samples. A
“digital” sort of rendering, if you will. Lower mass? Less jitter. Less jitter means more time
in contact with the groove, which means detail and micro detail. If a cartridge can’t stay in
contact with the groove walls, you can’t hear everything that is on the record. In a very real
sense, it’s that simple.
The obvious question, “Why doesn’t everyone make cartridges this way, if reducing the
moving mass is an absolute requirement for accuracy?” the answer to that is simple as well.
It’s very hard to do so. A properly designed Moving Iron cartridge requires an ultra-high
level of precision in manufacturing, and potentially low product yield. It is not the best path
for profitability, only sonic ability.
Another advantage of this design is the inherent high level of channel separation. Unlike
MC cartridges, a rotation of the generating element in The Zephyr MIMC Star (moving
iron) due to manufacturing tolerances or aging does not affect the separation at all.
Furthermore, unlike moving coil cartridges, our Moving Iron designs CANNOT rotate out
of position, maintaining the critical azimuth position for the life of the cartridge.
