MM or MI Cartridge?

The big difference between MC/MI/and MM cartridges boils down to a very few factors, most notably stylus profile, of which much ink has been spilled, and inductance, which is rarely mentioned. Moving coil carts have the lowest, then Moving Iron, and then Moving Magnet. why does this matter? Inductance directly relates to a property called hysteresis, the delay between a change in input and a change in output. Google 'hysteresis curve' and you'll see the characteristic 'S' shaped hysteresis curve, and its return, the hysteresis loop. Ultra low output MCs sound fast and detailed in large because they have low inductance, thus low hysteresis. MI carts like Grado and Soundsmith  have greater inductance, roughly in the 50mH range, but the difference is incremental. Most Moving Magnet carts have 10X more inductance around 450-550 mH and accordingly 10X more hysteresis, more delay between changes in input (stylus motion) and a change in output voltage. They simply cannot respond without 'smearing'. The tradeoff in general is output voltage, where MM carts win by a mile, thus making preamp design easier and more forgiving. This is why most MC carts require an additional level of gain, and usually worse S/N ratios. There are other factors, to be sure, vibration control, compliance, tracking ability, and several more but all of those can be controlled independently of the electromagnetic performance of the generator which is determined in large by the cartridge designers choice of MC, MI, or MM. I haven't gone into cartridge loading which is important, but cannot compensate for the hysteresis inherent in the design.

@terry9 I pretty clearly stated there were a lot of other factors " There are other factors, to be sure, vibration control, compliance, tracking ability, and several more but all of those can be controlled independently of the electromagnetic performance of the generator which is determined in large by the cartridge designers choice of MC, MI, or MM. I haven’t gone into cartridge loading which is important, but cannot compensate for the hysteresis inherent in the design." Viewed as a Venn Diagram, there’s a lot over potential overlaps. I have been a big Grado Fan for 50 years, but unfortunately Grados hum on my JMW Memorial 10.5 3D, and no amount of grounding magic could fix it.

@wolfie62 There are many forms of hysteresis, defined as the delay between input and output. What you describe is a single type, and seem to go further to claim that an aircore inductor has no time constant associated with its inductance. I do not claim any reduction in speed, but rather a delay in propagation. Faraday’s Law put it this way: "The electromotive force around a closed path is equal to the negative of the time rate of change of the magnetic flux enclosed by the path" Please note the ’time rate of change’. A magnet may also have more than one possible magnetic moment in a given magnetic field, depending on how the field changed in the past. Plots of a single component of the moment often form a loop or hysteresis curve, where there are different values of one variable depending on the direction of change of another variable.

In the elastic hysteresis of rubber, the area in the canter of a hysteresis loop is the energy dissipated due to material internal friction. Cartridge suspension materials such as rubber and some polyurethanes exhibit a high degree of elastic hysteresis, as do cantilever geometries and materials.

@lewm notes: "the three types do group well apart from each other if you base it on inductance. LOMCs are always much less than 100uH (micro-Henries). Many are actually down in the 10uH and below range. Whereas MI types typically measure in the low mH range, and a classic MM will measure 400mH and higher. The difference between 10uH (for a LOMC with low internal R) and 500mH (for a classic MM) is 50,000X!"

Although I do believe that the general ’flavor’ of MM, MC ,and MI tend to group along those lines, It is certainly NOT the only or deciding factor. However, I don’t think any serious listener would confuse, say, an Ortofon MM, with any number of MC carts, or would deny that Grados have a unique family character.