Mono Reissues and the Conical Stylus

My parents own.ed a major number of mono recordings from their times living in the states in the 50's. A part is musically so-so, but there are treasures like eg. the Mozart sonata recordings with Walter Gieseking. I always liked the magical sound of these recordings "even" played with my stereo cartridges like Koetsu Black, Monster Genesis 2000 and others. (Turntable were at some time Merrill Heirloom, then WTT Signature and lately a modified Technics SL1210, I used the ET2 arm, where possible). I BTW used these mono recordings to tweak lateral azimuth by minimizimng the"null" mono signal via electrically mono-ed- out-of-phase channels.
After reading several enthusiastic UK reviews of the Miyajima Mono cartridges I started to get intrigued and asked friends, and finally bought a Miyajima Zero and mounted it on a friends Lenco "monster" with Adanalog air bearing arm, where we could "directly" compare a modded (and very good sounding) Denon DL103 vs. the Miyajima on mono recordings.
I was quite smashed by the difference. "Stereo illusions" excepted, I rarely heard as lifelike true timbres and dynamics, and as much colours, and the bass was in a class by itself - in a never heard of way. The "virtual mono" coming from the stereo cartridge somehow simply sounded broken and fluttering, somehow instable.
I truly recommend trying to hear - no, experience this difference for yourself, if you are interested in mono recordings.After listening, some observations and thinking trickled in: Stereo cartridges have to track and electromechanically decode vertical information, mono cartridges do not. For stereo cartridges there is a certain design freedom regarding lateral and vertical compliance, eg. resonance frequency, but in the end vertical resonance will practically never be above 20Hz. The stiffer the suspension, the less the cantilever moves vertically - and that's where almost all extra-musical LF "rubbish" lays.The Miyajimas suspension is much stiffer vertically than laterally, and stiffer than any cartridge I ever saw. And IMO / IME this reduces flutter / Doppler distortion from excess cantilever movement by (almost) an order of magnitude.It reduces this on both a mechanical level and by not decoding it electromagnetically. Which means the coils. cores, and magnetic circuits are much less modulated / saturated by LF, where saturation is at its worst.Internally or externally mono-ing will simply not do the same distortion elimination trick. (It might simply be a marketing decision to sit on a me-mono-too-bandwaggon :-).
Yes, probably cartridge tips will make a difference too...

Dave, interesting comparisons! And they align well with what I wrote. The mechanical aspect ie. stiffer vertical suspension seems to me still a very important factor.
Recently Shibata tips resurrected, interestingly at the top of the ladder. I principally assumed tha a vdH / Gyger Type I stylus or a MR stylus were "better than Shibata", that's the way they were introduced in the eighties. Maybe... it was already good vdH marketing - or the re-inroduction of Shibata is? However, from what I read about the new top AT MM cartridges, I somehow trust that the Shibata excel in optimizing the musical detail vs. amusical artefacts ratio.
The resurgence of conical styli, with the original SPU or DL 103 "cult" contains some arguments pro conical styli. Ie. a suggested geometrically much more complex pinching effect / movement of the "sharper" modern styli, including MR or Shibata. This would lead to spurious vertical movement as artefacts (more with these sharper styli than with conical styli), and is a claimed reason for the more relaxed "pro-music" way of musical tracing of these very traditional (and superb) cartridges.
Extending this line of thoughts... could mean that the "real" advantage of these sharper styli would stand out considerably more with a "real" mono cartridge like a Miyajima Zero, because the spurious vertical movements would not be decoded, or far less. And the lack of out-of-phase, vertical stereo signals would eliminate a source of intermodulation on top of these spurious movements.

My main point is: The difference I heard was as clearly audible as any I ever heard. Between a very good stereo and a "real mono" cartridge. It’s the kind of difference every non-audiophile hears, because it’s the difference between kind of fake and real life, it’s about musicality and direct connection to the musicians. I agree with you mijostyn that there is too much talk about micro-differences that are only relevant for audiophiles, which are not really relevant for the musical experience.
The rest of my post might be over the top of (your? others?) head, and / or you don’t like the difference to exist? I could understand that. I did so for quite a long time.
Regarding the conical stylus: The stereo cartridge had a very good line contact stylus, the Miyajima a 1um conical. The line contact to our ears didn’t swamp the electromechanical advantage of the "real mono" cartridge. Although it most probably would improve the latter, as Dave observed.
The review (Hifi News) of the 1um vs. the 0.7um version of the Miyajima hinted at even better sound with the bigger radius on "original" mono recordings. But the 0.7um is probably the safer bet, because it wan't harm any of the newer microgroove cut mono LPs (or mono reissues). I decided for the 1um because of the big stock of old monos in my family.