[Ted Kendall]

There is indeed a lot of claptrap in some quarters (although not on this forum) about mono and stereo records and cartridges. So here's a summary of the main points:

Mono records are only modulated laterally, that is the groove wiggles from side to side. There is some consequent vertical movement of the stylus, but this is ignored by a mono pickup or, indeed, a stereo pickup wired for mono.

Stereo records, on the other hand, are modulated both vertically and laterally, the vertical wiggles containing the difference between the two channels. A little algebra shows that the left and right signals are therefore recorded "on the slant" on their respective groove walls, hence references to the "45/45" system.

Historically, therefore, mono cartridges did not need to be designed with much in the way of vertical compliance, as there was no intended mod. in the vertical direction. Some of the more enlightened designs had some vertical compliance, because the vertical wiggles caused by pinch effect from the lateral mod would otherwise be ploughed through, causing distortion in the lateral wiggles. Thus the Ortofon C had a fair degree of vertical compliance and was kind to records, whereas the Tannoy Variluctance, notoriously, had virtually none, and was considerably less kind. Either used to play a stereo disc would damage it to some extent, not least because of the smaller tip required for a stereo disc, but a Variluctance would chew up the groove and spit out the bits.

Initially, both mono and stereo versions of a given release were sold, but the industry soon tired of the expense of "double inventory", as it was called, and resolved to make all future releases stereo only - this was around 1968, and I remember Woolworths clearing out mono discs dirt cheap - still have some of 'em! This necessitated the design of mono pickups with enough vertical compliance not to damage a stereo record, to allow the hordes of Dansette customers still to buy new releases. Also, as mentioned above, the groove radius of stereo discs was such that a tip of the order of 0.0007" was required, rather than 0.001".

I think the first of these pickups was the Walton M1, a distant relation of the Acos Hi-Light and Decca Deram. This failed commercially, but was soon superseded by compatible designs from Acos and BSR, among others. As a guide, you can reasonably assume that any pickup which first appeared post 1965-ish is compatible with a stereo disc, even if it is itself mono.

So, a stereo pickup will happily play both stereo and mono discs, the only proviso being that the outputs should be paralleled for mono operation and that older discs may play better with a .001" tip rather than a .0007".

A mono pickup prior to 1965 should not under any circumstances be used to play a stereo disc. Immediate and permanent damage will ensue. A later, compatible, pickup may be used without problems.

Incidentally, the modern drive towards mono pickups for mono records is basically audiophool poltroonery. If a stereo cartridge is any good in the first place, its paralleled outputs will match that of a mono pickup on a mono disc too closely to be worth worrying about. If you want to play 'fifties mono discs on your Ortofon C, there is no harm in it, but it is by no means essential.

And yes, Stanton 500s are good workhorses for old arms - tough as old boots and not bad sounding.