That's the jist of the original comment as far as I understand - the suggestion was that the 301 has more 'rumble/noise/vibration' (delete as applicable) in the vertical plane than the 401, which was fine for playing mono as the pickup recognises only left/right movement.... therefore the theory was that the 301 is less useful at stereo (which uses up/down movement too) than the 401, where whatever caused this 'rumble/noise/vibration' was apparently addressed.
clivem2 said:Re rumble/noise etc on the 301, whilst I'm having "fun" getting the plinth right for my 301, rumble/noise are not problems I have. I suspect the overall condition on any 301/401 is more important than whether it's a 301 or 401.