If I use a 'true' mono catridge (e.g. EMT TMD, Miyajima Zero etc) on reissued mono records (not the originals from the 50s-60s) will it damage them? (Due to the fact that some of them where cut using a stereo lathe)
There are people out there that believe that. I am not expert, so I won't say if it will cause damage or not. Jonathan Carr of Lyra believes that "true Mono" cart with no vertical compliance will cause damage.
On another note. The EMT TMD has vertical compliance. It is the OFD series that do not, which means they have a single coil of a true mono cart.
I have a EMT OFD 15i and I have yet to use it a lot. I have heard it briefly in a friends and my setup and I am waiting to find time to set up my EMT 997 arm. I have a friend with a Miyajima BE mono and uses it with the modern reissues and I think it sounds fabulous and when compared to his big rig for stereo it more than holds it own for a fraction of the cost.
I do know one thing that you can play and enjoy records that would be basically unlistenable because of noise. I need to educate myself more about the mono world too.
I think it's a hit or miss proposition with regard to damaging a new reissue cut on a stereo lathe. The latter means that the groove will not have constant depth as would a record cut on a mono lathe. If you use a mono cart with no vertical compliance you run the risk of at least distortion on heavy modulation or at worse literally slicing off the peaks of the vertically modulated mono groove. I used to own a Miyajima Premium Mono BE and on several reissues there was very noticeable breakup on plucked bass notes, which did not occur when I played the same passages with my stereo cart. Although otherwise the Miyajima was a really fine sounding cart, especially on original 50s monos, I eventually replaced it with an Ortofon Cadenza Mono which had no problem with any mono reissues since it has vertical compliance and sounded very nice on the original monos as well.