jjss49, I’ll share a few thoughts in the hope some of it might be helpful.
Stereo LPs were introduced in late 1957, early 1958. For about a decade afterward most labels released both mono and stereo versions of given recordings. Among some jazz lovers the mono LPs are preferred for sonic reasons. They lacked the artificial "hole in the center of the soundstage" of many early stereo recordings (which exaggerated the stereo separation with hard left and right mixing) and they often had better bass impact. Some of those LPs command more $ today used than their stereo siblings. Non-jazz mono LPs are generally less sought after and so can be cheaper on the used market, particularly classical.
There is much debate about the best way to play back mono LPs. At the very least you should have a mono switch on your receiver or preamp. There are ways around that you can do a search for if you don’t have one. Many listeners prefer mono cartridges too, but there can be a question of what constitutes a "true" mono cartridge. The importance here is that mono LPs are cut with information only in the lateral plane while stereo LPs utilize both lateral and vertical motion to pick up information from the V groove. Mono cartridges can be quieter for background since they don’t read vertical information from the groove.
With the resurgence of interest in vinyl over the past 10+ years there has been significant reissuing of classic and popular recordings. Some of those will be mono. However few if any mono cutter heads remain so these new monos are actually cut with stereo cutter heads. I believe this is why you will find newly produced mono cartridges with various elliptical styli, rather than conical which was common with older mono cartridges.
So if you are buying and playing mainly reissued mono LPs, a modern mono cartridge should be fine. Depending on how many mono LPs you have and how particular you are, your regular stereo cartridge with the suggested mono switch may be all you need.
But if you already have a collection of earlier mono LPs (1948 through the late ’60s), or you want to search out and collect originals, then you may want to set up a mono cartridge. ’48 to about ’57 LPs are best played with a 1.0 mil conical stylus. ’58 to late ’60s era monos are best with a 0.7 mil conical stylus. That reflects a change in cutter heads at the time.
With all this I’ve not touched on EQ. Many folks assume once the RIAA curve was approved around 1955 every label adopted it. Not true, some continued with their own chosen EQ into the ’60s.
All this just depends on how many mono records you own, when they were produced, and how particular you may be about accurate playback. Have fun!
