Stylus diameter for 78 rpm was larger. I think that all 33 rpm, mono and stereo, call for the smaller diameter.
Ortofon mono cartridges
There are two different versions of the venerable Ortofon SPU "G" mono cartridge: SPU mono GM/25 and SPU mono GM/65. The 25 and 65 refer to stylus diameter. Can someone help explain the different applications to me? I believe the type 65 is for vintage records, while the 25 is intended for more contemporary mono records. Am I correct?