ALUMINIUM DIAPHRAGMS.

[Marco Gilardetti]

The flat surfaces on that tonearm are the "Plano-Reflex" feature of Columbia's "Viva-Tonal" system. They were deployed on the assumption that higher frequency sound waves would be reflected by them just as mirrors reflect light, and would reach the horn's mouth travelling directly on a rectilinear path.

Under today's knowledge and perspective, I am quite persuaded that Plano-Reflex surfaces were mostly just pretending. Even in case some waves would really travel that "direct" way, they would reach the mouth of the horn so feeble compared to the impendance-adapted wave fronts, that they would berely be audible. However, this feature that possibly delivers no advantage aside, the Viva-Tonal system was so well engineered overall that the gramophones belonging to that line are by all means comparable to (if not better than) HMV's Othophonics in terms of sound quality. It's really a head-to-head race.

[anchorman]

So nobody has copies of the pictures of the overstall tooling that was posted years ago and is now no longer visible?

[emgcr]

I had those items for a short while many years ago but, sadly, had no time to try them. From memory, I think they ended up with Chunny who probably posted the photos. There should be no problem making more---male/female lathe press tools of relevant sizes. Those particular ones were not spun---again from memory. I have just checked my emails and in conversation with Chunny he told me that he had tried them and they were not very satisfasctory and that replacements needed to be made anyway.

[anchorman]

Thanks Graham!

I was just curious to see what the tools looked like to possibly inform me while making my own. I'll try to get ahold of Chunny and see if he still has the pictures.