How are you playing your precious MONO Vinyl?

@lewm 

I think the stereo/mono equivalence for a comparison between my two cartridges is quite valid. They are both Lyra Atlas, i.e. the same design. It’s just that one has stereo coils and the other has mono coils, and if you look at the design diagram on the box of each they are exactly the same. Only the coils differ between them. Otherwise they are the same cartridge (i.e. design and build). I can only tell the difference between them visually by looking at the serial number.

With the Lyra Mono one can also connect the two mono channels in series for additional output when used in a pure mono system.

See here what Lyra (i.e. @jcarr) has to say about it: https://lyraanalog.com/atlas.php (you’ll need to select the Mono link on that page)

I had Steve Leung of VAS convert an older BM Ruby 3 stereo cartridge by rotating the former holding the coils 45° and connecting the horizontally sensitive coil to both outputs. He removed the disconnected coil and put a new stylus on it. This was a lot cheaper than buying a new mono cartridge. But back to the original question:

Is EQ-100 or something similar, absolute necessary from a purist perspective or should I take the pragmatic path and use the ‘Mono’ switch on my Integrated with a built in phono?

If you have a true mono cartridge there is no need to use the mono switch on your integrated amp: each channel is receiving exactly the same signal, so it should make no difference. As to whether there is an advantage to using a mono phono stage, that is a matter of the relative quality of the phono stage you use now versus the proposed mono stage, but I don't think there is a reason to say that a mono phono stage is always better than a stereo stage used with a mono cartridge. If a purist approach is to be taken, with a mono amplifier and a single speaker, it would conform, but that involves a whole separate system and I don't think that's your intention.

@dogberry 

Thank you for your astute summation of both the logic and the limits of the purist mono path. You have given the clarification I was hoping for, ahead of my implementation. Nope, the playback will still be from L/R speakers. 

With a true mono cartridge, the signal coming from both channel pins is already identical (since it derives from lateral movement only), correct? 

If above is true then engaging the mono switch on my preamp would be redundant. I don’t have much information to go by here, if my Integrated mono switch performs any phase manipulation or summing after gain, if it does; that might add some noise or coloration, so it’s often best left off with a true mono cart. Something I intend to play around after installation. 

Since my post, I did bit more research and found out EQ-100 would be beneficial for early mono records that used non-RIAA EQ curves. Here are the mastering notes from Beatles Mono Vinyl set, 

“These albums were cut for vinyl from the original master tapes using a completely analog signal path and with constant reference to first generation pressings of the original albums. They were made using a Studer A80 master recorder with analog preview & program paths, and a Neumann VMS70 cutting lathe originally installed in Capitol Studios in 1971. This specific all-analog cutting technique allows faithful representation of the full musical range and dynamics present on the original tapes”

My wonderful journey into analog playback continues….

What is "EQ-100"?

If you think you have a true mono cartridge, do try with vs without the mono switch engaged and let us know what you hear. At least some of the Beatles LPs originally came out on Parlophone in the UK and were mono to begin with.  However, since the works are from the 60s, it is quite likely that modern RIAA equalization was used. I have never read otherwise.

’Since my post, I did bit more research and found out EQ-100 would be beneficial for early mono records that used non-RIAA EQ curves’

I agree with above statement regarding non-RIAA EQ curves. My phon preamp is a Graham Slee Revelation C (similar functionality as the Aurorasound EQ-100. Cartridge used: Ortofon MC Cadenza Mono).

I do favour this setup to any other setup using other phono preamps and stereo cartridges because of sound quality. I have a lot of old mono records with pre RIAA EQ curves. As per advice of Graham Slee, I am using only Input Right, bridging Input Left with an ’inactive’ plug.

https://www.hifisystemcomponents.com/phono-preamps/revelation-mm-revelation-mc-archival-phono-preamps.html

The Revelation C was designed for archivists with a preference for low-output moving coil cartridges, and is based on the Reflex C hi-fi RIAA stage moving coil phono preamp.

As well as being a stereo RIAA preamp there are settings for other types of record, so rather than guessing the tonal balance, the Revelations have all the EQ settings you should need arranged on a three switch front-panel matrix.