John, the r45 or r57 cartridges are the whole moving capsule part AS WELL AS the part right below, that screws onto the body.
Yes. I've done surgery on many. any, many of them, of all vintages except possibly the very newest, if there have been changes in the last 10 or so years.
Starting in 1967, how many have you taken apart, right down to the bare magnetic structure with voice coil, over how may years of development?
These days I'm inclined to suspect that I might remember more about the physical evolution of the Unidyne III cartridge than anybody still left at Shure, based on claims they've made recently that I KNOW from my own experience not to be true - unless their CS reps are lying to support the company line. But I prefer to believe that they simply don't have anybody remaining who knows or remembers.
Even the top part of the cartridge is physically different - from the label, to the design of the perforated metal at the bottom, and the coil material itself.
Ah, the sticky label, yes. As to the rest of it, it didn't used to be different at all - they sold the same R45 capsule as a replacement for both. And they're still physically interchanceable. There have been incremental changes in the R57 over the years, with many of those changes being in the mid-80s when they changed the design of the lead-out wires to PC material tabs after I showed a couple of Shure reps how I serviced broken cartridges with "rotating head disease". It was about trhe same time that they changed the internal design of the head grille to make it easier and cheaper to produce. Switch to an aluminum Vt was also definitrely a cost cutting measure. It might have been in the late '90s/early '00s, when the cost of copper started going through the roof, or it might have started when they found themselves stuck with a surplus of 47 and 77 cartridges when those mics flopped.
It seems really dubious that there would be a one part fits all solution between those different models, unless someone was just ordering one part and fitting them onto everything because they didn't know any better.
It used to be the same part. I have been out of the Shure mic fixing game for some time, but would really like to get my hands on a pair of cartridges as see just how far they have diverged, both from each other and from the original. I just don't have a couple hundered extra bucks to waste. Too bad this isn't two years ago when I had the extra money.