Dear Raul, While I yield to your generally superior experience to mine, I must say that all the information at my disposal would indicate that the 300 series of Acutex cartridges were induced magnet types. However, the 400 series are conventional MMs. I do see that on the Bluz Bros website, they say that BOTH series are MM, which we both know for sure is incorrect with respect to the 300 series, which makes me all the more ready to disregard anything they have to say on Acutex, especially since they have none to sell. On the other hand, I will grant you that the 400 series LOOK a lot like the 300 series in terms of shape, which would fit the idea that the 400s are also IM types. However, I also found this quote from a website much like this one, and surely not the last word any more than this one is the last word. Nevertheless, "while the 420 (full name 420 STR) is a very good cartridge, it's not in
the same league as the 320 (full name M320III STR). The STR refers to
the "Special Tri-Radial" stylus tip, a line contact type developed by
Toshiba, so the 320 and 420 have that in common but that's about it.The
420STR and M320III STR were the top of the line in their respective
series but the 300 Series had things going for it that were dispensed
with when the 400 Series came along. Whereas the 300 Series were an
induced magnet design, the 400 Series were of the more typical moving
magnet type. They also abandoned the tri-pole design which is where the
magic is in these cartridges and also in the boxy "Brick" types. The
stereo chain responsible for the Acutex brand of cartridges, speakers
and headphones (interestingly, all transducers) was Atlantis Sound in
Falls Church, VA in suburban DC."
