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How sensitive is the ear to pitch and flutter variations produced by some turntables ?Is a turntable platter spun by an AC synchronous motor accurate enough for HiFi.
What are the tolerances for the frequency stability of mains voltage and are they within the limits for good HiFi reproduction ?
Sorry for the dull and technical questions but I'm intersted as it wil help me to understand what's important with regard to turntable performance as opposed to being seduced by a whole load of pseudo science and technobaffle.
Also; what was the standard for frequency stability for the cutting lathes that were used to master the LPs that we love. Or indeed, the master tape recorders ?
Are we wasting our time chasing technical specification or is there a level below which HiFi cannot truly exist ?
Follow Ups:
Henry
actually, a lot of it IS deliberately baffling...a good term, methinks!
"The Blues ain't about makin' yourself feel better; it's about makin' other people feel worse!" -- Bleedin' Gums Murphy
1. Very sensitive. Hard to put a figure on it as the degree of sensitivity is also dependent on the time scale of the change - you may not notice a 600 ppm change (one cent of pitch) over the duration of a record unless you have perfect pitch. You will notice it if it fluctuates over a time scale of a second or less.2. The motor itself, yes, see answer to next question. There are other problem which are greater than the motor, the worst is belt creep. One post recently measured belt creep at a figure very close to the 750 ppm level I derived from theory.
3. According to data presented at leapsecond.com the short term Allan deviation of 60 Hz mains is better than 100 ppm. This is about equal to a standard quartz oscillator circuit. I personally think better stability improves sound BUT I'm biased as I have spent a lot of time and money on these improvements.
4. Early cutting lathes ran at mains synchronous speed so see 3 above. Later ones used quartz controlled direct drive which gave improved speed stability.
It's possible to do even better - I have been talking to a local guy about getting some frequency test records cut, once we work out the details I am hoping to build a new PS for his Neumann lathe so I can get better than 1 ppm accuracy.
Is this a waste of time? I guess I'll only know after I've wasted it.
Thank you for the informed reply.I ask as I have had to sell my beloved sp10 which I thought was excellent technically and sonically and wondered on which specs I could compromise yet still have a great sound.
I appreciate your advice.
Yes.
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