mono cartridge vs stereo

I should understand this subject better than I do, but here goes. The problem with using a stereo cartridge on a mono record is that the stereo cartridge has both vertical and horizontal compliance, which on a mono record having music only in the horizontal plane opens up the possibility for picking up a significant amount of surface noise. On new reissues of mono LPs this is really not a problem, or at least it shouldn't be. For old and well used mono LPs, though, the noise difference is frequently quite pronounced. If the wiring in the cartridge is set up to ignore the vertical information, the net effect is identical to using the mono button on preamps so equipped, and is also identical to using Y cables as already discussed. I have a mono cartridge and can attest that it sounds significantly better on old mono records than using a stereo cartridge, but on new re-issues, the advantage is less pronounced. One of my stereo cartridges is an Ortofon 2M Black, which has a shibata stylus. The shibata shape is not easy to set up for quiet tracking with the vertical tracking angle being particularly critical. For that reason, I prefer the much more forgiving conical stylus geometry for mono. I hope that helps.

Thanks Bill. I don't have the flexibility to set up a mono cartridge on my turntable. Too much effort readjusting the VTA every time I would change. So I guess I'm stuck with using Y adapters, or on advice from VAC, I could strap together the positive pins of one of my inputs on the preamp to essentially create a mono input. I'm considering that approach, because I have extra RCA inputs.

Peter_s.
Yes, the difference between a stereo and true mono cart is if there is output from vertical cantilever motion. Noise with old mono records is dramatically reduced with a true mono cart, but virtually all records since the around 1950 are V cut microgroove, invented in '48.
http://ortofon.com/hifi/products/mono-series

"If you play a mono record with a stereo cartridge you will not achieve the same signal in the two channels due to imperfections such as crosstalk, noise, phase errors, tracking error, antiskating and distortion. This difference between the channels will result in an unstable and partially fuzzy image. A mono switch, to some extent, can improve this."

If you combine channels in your line stage it should have the same impedance implications as combining cart output - cut it in half. There's source impedance and input impedance. If channels are combined wouldn't both be halved?
Regards,

Interesting topic. Just to put in my $s worth, I would not be comfortable & would never suggest combing stereo cartridge outputs as you will then be loading each channel with the other.  This would then mean that each channel is "looking into the other" & creating a serious loading problem.

Even when combing channels (Y cord etc), you have to make sure of this loading problem as well. Outputs from the various stages have a very low source impedance  whereas inputs are high impedance -10K or so. Hence when you combine outputs you need build-out resistors to prevent undue loading from one channel "looking into the other". Shorting or combining inputs is OK though. So be careful with Y adapters.

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.