mono cartridge vs stereo

Artmat, the cheap and dirty upgrade is to switch your preamplifier to "mono" mode. You will thereby gain most of the benefits associated with using a mono cartridge. If your preamp does not have a mono switch, mono can be derived from the stereo output using a Y-adapter. I keep meaning to buy a mono cartridge, but in the meantime I find that my mono LPs sound much better with my Klyne 6LX preamp in mono mode. (The trick is that older products like the Klyne tended to have a mono switch. Some time in the late 90s, mono switches seem to have all but disappeared.) It goes without saying that you need not be concerned about using a stereo cartridge with recently issued mono LPs, as regards damage to the LP.

Gondo, A mono phono stage adds yet another layer of complication, in terms of decision making. First, why use a mono phono stage if your "mono" cartridge is naught but a stereo cartridge that is internally strapped to produce a mono signal? In that case, one's "stereo" phono stage is merely processing the very same signal to produce two mono output signals, to drive two speakers in mono. I actually like that, because it produces a bigger more room-filling sound than I can achieve driving only one speaker of a stereo pair. Now, what might be the advantage of a mono phono stage? I guess it would be that the two stereo channels in your stereo phono stage are not exactly matched, thus producing subtly variant signals that end up as two slightly different signals on your two speakers, maybe robbing some ultimate fidelity. But if you worry about that, then why couldn't one simply abrogate the output of one channel of a stereo phono stage and thereby use only one half of it, to drive one speaker?
Do OMA suggest driving two speakers with the mono output of their mono phono stage, or just one? Probably the latter.

One could write several more paragraphs on the other things to consider, like for true vintage mono LPs not equalized for RIAA standards. In that case, if the OMA product has selectable equalization curves, therein would lie an added value. But it's a sticky wicket.

If our modern day audio press were interested in education, a la the dear departed Audio Magazine, they would run an article explaining "mono" cartridges and the technical differences between vintage mono and modern mono recordings. But they're in business to sell stuff, whether buying makes sense or not.

I suspect there is no difference between using a modern mono cartridge that is really an internally bridged stereo cartridge with modern mono LPs vs a mono switch on your preamp with those same recordings. With vintage mono the groove width is different and the idel stylus shape is different, and to get that optimal geometry you have to have a mono cartridge built to do the job. At least that's the state of my understanding.

Peter, The way I see it, you would have to use two Y-adapters back to back, as you suggest, to use a stereo preamp to play a mono LP in mono with a stereo cartridge. Such a set-up would put you in about the same place as a "mono" switch on your preamplifier, except you would have the signal-robbing effects of all those connectors in the unamplified phono signal path. That set-up is akin to using a mono cartridge that in reality is a stereo cartridge with the two channels combined to give mono output. This option was discussed at the top of this thread, but I have never encountered any one who tried it. As for me, I learned a lot from Syntax's two long posts. It is his opinion that a true mono cartridge is superior to either of the options I mention here. I cannot argue that, because I have no mono cartridge, but I intend to buy one. I may even buy a Lyra Delos Mono, since Syntax praised it highly. For me, I can only say that flipping the mono switch on my preamp, when playing a mono LP with a stereo cartridge is a very big improvement over listening in stereo to the same LP.

Actually, I was wrong in my post above this one. The two Y-adapters would feed the 2-channel output of the stereo cartridge to the phono stage in parallel. This would alter the impedance relationship between the cartridge and the phono stage that may or may not have negative consequences. When you use the mono switch on your preamplifier, you are combining the channels AFTER RIAA correction and phono stage amplification, which has got to be less harmful. Sorry if I misled anyone.

If you have separate phono and linestages, you could install the Y-adapters between the two components, which would work exactly like a mono switch, more or less.

Hi-fi_er is correct.  I have never understood how it is that the advice to connect the two stereo channel outputs externally before the signal gets to the phono stage is so often given out by persons who claim to have done the same.  It really should not work well for reasons given by Hifi; each channel "sees" the input of the phono stage AND the output of the other channel in parallel with each other. This makes for a difficult load with respect to the job of each channel as a mono source and ought to cause distortion.

In a preamplifier with a mono button, the bridging of the stereo input is done usually after the gain stage and before a buffered output stage.  Thus the cartridge is shielded, coming and going, from the potential negative effects of combining channels.