We have a whole thread on measurements that sprouted from this one.
A few things stand out in MM vs MC:
1. Capacitive loading matters for many (most?) MMs, whereas most MCs not only ignore cap loading, but also are not too sensitive to resistive loading, other than output levels
2. Rising top octaves are common for both types
3. EQ can do a lot to normalize MM vs MC sound differences
A couple of things....
Capacitive loading is related to the inductance of the cartridge generator - most MM's (not ALL) are high inductance, some (FEW) were mid inductance, and very few were low inductance (ie: similar to MC's).
Low inductance MM designs exhibit the same behaviour to loading as MC's do.
The reason most MM's are high inductance, is that a high inductance set of coils is required to provide a high level output - which then minimises the requirements of the phono stage, and also potentially reduces noise and sensitivity to EM... it is more complicated and expensive to engineer a good phono stage for a low output, than it is for a high output cartridge.
The rising top end, which is mostly common to all cartridges is a consequence of the cantilever resonance and the available effective mass of typical cantilevers today.
At the height of cantilever technology in the late 1980's, the lowest effective mass designs, the high end SOTA designs, managed to get the effective mass sufficiently low to push that resonance out to 100kHz (for the very very best, from technics), with a range of very slightly lower end cartridges achieving between 30kHz and 75kHz resonance frequencies.
The famous Shure V15VMR with the berillium tube cantilever, managed to push resonance out to 32kHz... that was still sufficiently close to the audio zone, that a very slight rise could still be detected at 20Khz.
It achieved its exemplary neutrality (ie: flat frequency respons) by using a relatively lowish inductance body (if I had to categorise it, it is in the low end of the high inductance designs), with light cartridge loading to control that final rise.
The Dynavector Karat (
https://www.dynavector.com/audio/17dx.php ) is one of the only surviving low effective mass designs - with the resonance out at 50Khz.... it achieves this by having a very very short cantilever - which results in very low effective mass.
Yes it is low output MC, and is probably the most neutral cartridge currently on the market (before applying EQ, custom loading, etc... etc...)
The Karat does not suffer from a rising top end (at least not at 20Khz....)
Fundamentally, in an age when digital EQ is readily available, and easily/economically available, we no longer have to rely on cartridge loading to achieve the flat frequency response / Neutrality we seek. (or whatever target profile you as an individual prefer !!)
The core, native frequency response of a stylus/cantilever is driven by its effective mass, and how far out (preferably outside the audio range!) the resonance of the combo ends up.
Most of today's styli, end up with a resonance WITHIN the audio zone... for the better designs, with exotic cantilevers, typically between 16kHz and 19kHz - Hence the common rising top end (along with rising distortion at the resonant frequency).
There is NO difference between MM and MC in this area of performance.
Yeah there are so many variables, that any two designs, will show differences.... you can cherry pick MM's and MC's to your hearts content to demonstrate the superiority of one or the other generator system.... but it is not meaningful.
More than that - due to the hand made nature of cartridges, you can pretty much choose any 2 exemplars of the exact same cartridge model, and they will exhibit differences.... I have 2 Jico SAS styli, of the same model, one with a resonance at 14kHz and the other at 16kHz.... the same exact model.
And usually the stylus isn't removeable/replaceable.
