UK Vintage Radio Repair and Restoration Discussion Forum - View Single Post - Why were the RPM speeds of records chosen

Radio Wrangler · 26th Nov 2014, 12:18 pm

3600 and 1800 rpm are the speeds of 2-pole and 4-pole synchronous motors running from 60Hz

Here in the 50Hz world the speeds are 1500 and 3000 rpm.

I wonder if 78rpm happens to have realisable gear ratios to both?

David

26th Nov 2014, 12:18 pm	#8
Radio Wrangler Moderator Join Date: Mar 2012 Location: Fife, Scotland, UK. Posts: 22,876	Re: Why were the rpm speeds of records chosen 3600 and 1800 rpm are the speeds of 2-pole and 4-pole synchronous motors running from 60Hz Here in the 50Hz world the speeds are 1500 and 3000 rpm. I wonder if 78rpm happens to have realisable gear ratios to both? David __________________ Can't afford the volcanic island yet, but the plans for my monorail and the goons' uniforms are done