Any thoughts about the Super OM 40, my understanding: 10=Red, 20=Blue, 30=Bronze, 40=Black
Your reasoning is *about* correct. I have not compared them under the microscope, I actually NEVER listened to any 2M under anything like known system conditions. I did not measure any 2M either - yet.
That *about* is based on THE VERY SOUND reason - mechanical integrity and freedom from resonances in cartridge/stylus combination. OM series evolved from the LM series - and got the "Super" with the introduction of the Ortofon's patented slit pole pieces.
Being lazy, I will use pics from AK to explain the mechanical difference between the LM and OM ( either normal or super, same body in physical dimensions save internal pole pins ) : http://mail.audiokarma.net/forums/showthread.php?t=234658 Contrary to some claims in the thread, OM is NOT mechanically superiour to LM - the "pillar" between the actual cartridge and mounting plate is much shorter on LM, with both being about the same thickness, that means it flexes less under the load imposed by the stylus.
It is kind of acceptable to use so flimpsy mechanical structure in a high compliance cartridge - it does not result in directly objectionable degradation of sound to a casual listener. Trouble is, Ortofon did use the very same OM form for one of their best ever carts - MC 200, specifically MC200U normal 1/2" mount version. And that is a VERY LOW compliance cartridge ( besides being very low output, 0.09 mV - which I use to put MC stages trough their paces; only a less than handful of carts ever available produce even lower output ). You can have the toughest of "poles" for tonearm, MC200U will still not sound dynamic, with good bass control, good spatial reproduction, without treble going slightly fuzzy, etc. In this case, the mechanical integrity of that pillar is just plain insufficient.
I bought my MC200U in 1984 - and "had to endure" it mounted to Kuzma Stogi 20 g effective mass version arm for a year or two, until its Fine Line stylus no longer was so fine due to wear. With Ortofon prices for replacement of stylus with MC cartridges ( 2/3rd of the cost of the new cartridge ) and not being exactly over the moon with MC200U performance in the first place, I had an idea. What IF some mechanical strenghtening member was added to the OM style body in order to prevent it being modulated by the stylus movement ? After about a couple of attempts and couple of hours of precise filing a piece of fiberglass epoxy printed circuit material board, I came up with the solution that finally did the trick. It has to be made so tight/snug fit that it mounts WITHOUT any glue - just snapping into place. You can trust me, it is not something for the faint at heart, particularly as I at the time did not possess any OM body to practice with, all of that was actually being done on the MC200U itself. And MC carts do not have replaceable stylus - multiple trial and error attempts ( angles etc are ANYTHING BUT right/square/parallel/regular ) .
Result ? Probably the first MC200U that did sound correctly. After that, I had it retipped at Benz Switzerland, not some Fine Line, but VdH 1S - the sharpest VdH rarely seen
and by now I think ( to think is to know nothing...) out of production. Firm non resonant body and superiour stylus tip profile propelled an otherwise potentially superiour design to an actually superiour sounding cartridge.
Remember, accelerations in the record groove can and do reach 2000 G. As F = m x a still stands, that means with a 0.5 mg stylus tip effective mass, that poor "pillar" is exerted to about 10 "kilogram" of wiggling in the worst case scenario ( 5-10 kHz range, where recording velocity can reach and exceed 100 cm/s velocity ) - YES, your cartridge AND arm has to work that hard. And is the reason why spaghetti thin arm tube Infinity Black Widow had to give way to designs with large arm tube diameter spearheaded by Linn Ittok and culminating in Continuum Cobra.
I will post pics of the real McCoy ( which got unfortunately decantileverized by a friend ...) in a couple of days - and you will see that 2M is a practical answer by the Ortofon to this in the past overlooked problem.
So, in view of this, 10<Red, 20<Blue, 30<Bronze, 40<Black.
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