Raul, it was perfectly illustrated above with my pictures to show the difference in the stylus tip mounting method and the cantilever materials of the AT-ML150 and the AT-ML170 models. The frequency response is 5Hz - 40Khz vs. 10Hz - 30Khz. The 150 is no way identical to the 170 in terms of sound and the price difference between those two models is huge on the used market today. The AT-ML170 is much closer to the AT-ML180 than to lower AT-ML150.
I will remind to other about this old TAS review:
http://www.regonaudio.com/Stanton881AudioTechnicaATML70.html"
Kavi Alexander, auteur of the remarkable Water Lily Acoustics series of analogue vinyl discs, is monitoring disc production by comparing test pressings to the master tape. What cartridge is he using? Another moving magnet, this time the Technics EPC 100, Mark IV, unfortunately no longer available in the US. But he describes the Audio Technica ATML-170 as very similar, and very close to the actual sound of the tape. In this comparison, he says, virtually no moving coil does so well; most have seriously apparent colorations. "
The difference in inductance between AL-ML180 and all others is 310 ohm vs 730 ohm. It’s more than a double. And the angle of the tip/cantilever is 23 degree vs. 20 degree. The mass of the 180 cartridge is a bit higher too (7,5 vs. 7g).
As for your review of the AT20SLa with ATN20SS (instead of ATN20SL or ATN20SLa) stylus then we’re speaking about the difference ONLY in the cantilever material, there is no difference in generator at all! But you’re sayin’ 20SS is superior, so the same conclusion must be applied to the defference between AT-ML models especially if the difference is not only the cantilever, but inductance, stylus tip mass and more in case with AT-ML180 versus all others.