I learned about listening to Mono LP’s here.
1. Get thee a true Mono Cartridge. It makes a little, some, a lot of difference depending on the LP.
Mono picks up horizontal movement only. It will not pick up anything from the inadvertent vertical movement: slight warps, up and down from dust in the grooves, surface dust, scuffs that are small but make some vertical happen.
I sell LPs, and I advise mono lp buyers: slight scuffs are not too apparent using Mono Cartridge, retains an involving musical experience. Play same LP with Stereo cartridge, the noise from the slight scuffs is essentially doubled, hard to enjoy the music.
I have a vintage Mono LP, Chicago Jazz, late 28’s, early1930’s, includes some early Louis Armstrong and many others. Play with Stereo, it was like a history lesson, where’s Louis? I would never play it again.
Got mono cartridge, what a difference. Not imaging, but clear distinction of the various instruments, that’s a trombone, that’s a trumpet. There’s Louis. I play it for my friends, they get it right away.
2. MONO MODE if your preamp/amp has a choice. You still want to start with a Mono Cartridge.
3. Speakers ’Perfectly’ Balanced, Frequencies matched L to R. IF your ’speakers output’ are not perfectly balanced, or speakers perfect but the actual received frequencies ’in the space’ are not perfectly balanced a random slight stereo effect will occur, left speaker or side of the space emphasizing part of the frequencies of some instruments, right speaker likewise. Just unbalanced enough to give some imaging.
I have 2 L-Pads: ’presence’ to adjust the volume of the mid horn to the woofer and ’brilliance’ to adjust the tweeter to the mid horn. OMG is it hard to get it right. I use a SPL meter on a tripod, a test CD with 29 frequency bands, do some, take a break, do some more, sleep on it, finish in the morning. Get each balanced individually, then both playing revise things, then L to R balance.
Casandra Wilson’s (others) voice cannot move slightly off center in either direction as frequencies change.
4. Listen to only one speaker. This is how the early music was listened to. Eliminates item 3 above, and you can listen anywhere in the room, space, out on the porch, ... you get the idea. It is hard to turn off our search for imaging, listening from somewhere else takes that habit away.
5. Some Mono LPs are curiously partly stereo, some imaging does occur. Miles Davis, Sketches of Spain is an example of: Is this Mono or did they take Stereo and mix Mono? Those Castanets are definitely from over there! Part of the aural confusion:
"Some percussion instruments are tuned and can sound different notes, like the xylophone, timpani or piano, and some are untuned with no definite pitch, like the bass drum, cymbals or castanets."
I bought a new Sketches of Spain LP, random effects same as my old one.
The better your system ’images’ in Stereo, the more it will reveal, some stereo effects, if Mono: when it reaches your ears, is not perfectly balanced
Essentially: get a mono cartridge, and if some stereo is distractingly apparent, turn one speaker off.