mono cartridge vs stereo

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.

I just did a pseudo mono setup in the past week that involved strapping a stereo cartridge (a modified Denon 103R potted in an aluminum body and retipped by Soundsmith with a ruby cantilever and line contact stylus). 

The whole setup flies in the face of conventional wisdom on this (strapped cartridge, line contact stylus etc.) but generally sounds fabulous both on vintage (late 50's and very early 60's) monos as well as reissues. 

There is no question that in terms of overall presentation I am getting grossly superior results to playing these records with a stereo cartridge (which I've been doing for years). The soundstage is now huge on the monos and overall tonality and information retrieval is grossly improved. There's no question in my mind that distortion levels have been reduced as well. 

The one area in which I'm not totally convinced that a "true mono" cartridge would not be vastly superior is that of noise. Most of my records, including the monos are in great shape and noise free but I do have some monos that are VG to VG+ and those still exhibit a fair bit of noise, although it does seem to be less obtrusive than when I was playing them with a stereo cartridge. This is one area in which I think I might get grossly better performance with a true mono cartridge, although I'm not absolutely convinced that a spherical/conical styus is absolutely the way to go, even with vintage mono vinyl. The best mono I've heard (limited I admit) was with a Koetsu Rosewood that had been modified/rebuilt for mono (not exactly sure how) by Andy Chong at phonocartridgeretipping.com and it utilized the same boron cantilever and microridge stylus that I have on my stereo cartridge here. 

All systems are different and mine utilizes a somewhat unique phono stage, an Aqvox 2 CI, which is a current mode stage and is fully balanced (both inputs and outputs) and also does not have adjustable loading but essentially presents a short, or at least a very low impedance, to moving coil cartridges at the input. As a result, it is generally thought that it tends to work with moving coils with a fairly low internal impedance. My stereo cartridge has a 5 ohm internal impedance and by strapping the 103R I supposedly halved the impedance from 14 to 7 which would, in theory, at least, be a positive with my phono stage. 

So the results I'm getting may be a result of a number of different/unique circumstances, but I am getting excellent results strapping the 103R for mono playback. In the end I was able to accomplish it for next to nothing as I literally had everything laying around in storage here (arm, cartridge, armboard and phono leads). At this stage I am really having trouble trying to justify the purchase of a true mono cartridge but I may end up going that way at some point.