Richardkrebs,
With all due respect the sonic signature of the different materials you outline are meaningless unless the rest of the system is described at the time of testing. For example it might well have been that the system was slow and the concrete, whilst sounding hard, may have been showing up coloration elsewhere. I see very little science and no concrete evidence to support your observations.
Furthermore, it is well known that the geometry of the original Hadcock 228 was in fact incorrect and if you had built an arm to that geometry then I'm surprised you could not hear the high tracking error and distortion. Specifically the offset angle was incorrect and this was remedied with the release of the 242 in recent years.
With all due respect the sonic signature of the different materials you outline are meaningless unless the rest of the system is described at the time of testing. For example it might well have been that the system was slow and the concrete, whilst sounding hard, may have been showing up coloration elsewhere. I see very little science and no concrete evidence to support your observations.
Furthermore, it is well known that the geometry of the original Hadcock 228 was in fact incorrect and if you had built an arm to that geometry then I'm surprised you could not hear the high tracking error and distortion. Specifically the offset angle was incorrect and this was remedied with the release of the 242 in recent years.