Mono questions

Odd. I wonder why I have original Capitol issues of "Something Cool" with June Christy, both the mono and stereo versions.  It takes 5 minutes of listening to know that these are two entirely different recording sessions.  She doesn't even attempt to sing the tunes exactly the same on the two versions (at least in most cases).  These are circa 1960 recordings.  Granted, I don't know how common this was, because I don't own enough mono and stereo pairs to judge.  But it certainly must have been done with some regularity, because June Christy was a very successful artist but no Sarah or Ella. Perhaps, as you say, these are admixtures of "different takes from the same session".  That would also explain what I hear, but why choose one take for the mono version and another for the stereo?  Does that not imply that in one case they set up the mikes for mono, etc?  I am not claiming to know the answers to those questions.

Folkfreak is correct in noting that back in the early 60s, studios frequently staged two sessions, in one of which they recorded in mono and in the other, in stereo. In those cases, the two recordings can never sound exactly the same. But I don’t think that this is your question. I think you are asking about whether or not you "need" either a mono cartridge or a mono mode on your linestage to get the most out of your mono recordings. In that case, the answer is a resounding yes.

On mono LPs, audio information is recorded only in the lateral plane, whereas in stereo, both horizontal and vertical motion of the stylus are sensed by the stereo cartridge and converted into two channels of information. If you play a mono LP into a stereo circuit, the cartridge will reproduce vertical modulation of the stylus velocity as noise. If you then depress your mono mode button, there will be phase cancellation of the noise thus produced. This really does work to improve the listening experience, in many ways. If you likewise use a mono cartridge, there will be a similar positive effect.

One can of worms is that SOME mono cartridges are merely stereo cartridges in which the two channels are internally bridged to produce a mono output. In theory, this is identical to engaging the mono mode button on your preamp. Some other mono cartridges are "true mono", built such that there can be no voltage output in response to vertical movement of the stylus assembly. Whether using such a cartridge is audibly superior to using either a mono mode switch or a "bridged stereo" cartridge with mono output is open to debate. And believe me, it’s been debated to death. Finding out which mono cartridges are true mono vs bridged stereo types is also tricky. You have to read between the lines of ad copy to deduce what’s up. There is also a vociferous group who believe that a mono mode switch is all anyone ever needs to get the most out of mono LPs.

One more thing, as regards the comment on Miyajima mono cartridges.  The hum from some Miyajima cartridges in some set-ups is not endemic to ALL mono cartridges. It actually arises BECAUSE the Miyajima cartridges are among those few on the market that are truly mono in build. When there is some potential difference (voltage) between the grounds of a stereo preamplifier receiving the ground leg of the signal from the Miyajima, that small voltage can be converted to hum.  This is curable.  I don't think (but I am not sure) that this would happen with the more common "bridged stereo" type of mono cartridge. Hum is not an inevitable consequence of mono reproduction.