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Old 8th Mar 2018, 3:34 pm   #60
barrymagrec
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Join Date: Dec 2017
Location: Morden, Surrey, UK.
Posts: 566
Default Re: Electric clocks running slow warning

Quote:
Originally Posted by Goldie99 View Post
Am I right in assuming these frequency variations, at this order of magnitude, are also sufficient to noticeably(*) impact the speed of AC synchronous drive turntables, e.g., a Linn LP-12 (pre-Valhalla) ?

(*) By noticeably, I mean audibly.
I`d be very surprised, prior to circa 1970 most broadcast tape machines used mains synchronous capstan motors and I don`t remember anyone suggesting a problem - the broadcast spec for speed stability was +/- 0.2% or about 3.6 seconds an hour, this was measured assuming correct mains frequency but even so much more speed error would have played havoc with programme timings, crashing the pips and so on.

Any variation in mains frequency is likely to be quite slow so not easily heard.

Also bear in mind that TV runs 24 fps feature films at 25 fps so more than 4% fast yet no one seems to notice.
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