Turntable speed measurements for speed accuracy?

The quartz units always had a rating since the units design was stable. Belts driven is always if'y, in that the variables, belt age, motor accuracy due to line volt fluctuations etc. were not in the manufacturers control after the units were manufactured.

The reason is that most manufacturers, including those who publish measurements, do not measure at the platter and probably do not know how. What is widely done and extremely misleading, is to report the accuracy of the chip used. This information is provided by the manufacturer of the chip and really has no correlation with the turntable's actual speed accuracy.

It would be nice if review rags would perform speed accuracy tests with every turntable they review. It seems like this is a fundamental specification of performance to actually measure.

If a turntable cannot spin a record at a consistent speed, then what good is it?

Especially the high end manufacturers, if you put a high end turntable on the market, shouldn't you back up your high end design with a standard or reproducible speed accuracy measurement?

I only bring this up, because my last 'high end' turntable costing over $6500 (and this is on the low end for 'high end' turntables) could not play a record and keep a consistent speed. It sure had exotic features on it like vacuum pull down platter, exotic wood finish and '25 years of experience' of manufacturing turntables.

A vintage $300 turntable is able to keep a more consistent speed than a current design $6500 turntable. The turntable drive implementations are different, the vintage table uses a Quartz Direct Drive where as the 'modern high end' table uses a belt drive. The difference was noticeable right from the first song cued up.

I'm sure there is more to a good sounding turntable than just speed accuracy, but I would think this is priority number one? Yes?

Hello,

The problem with speed accuracy in many turntables, as I see it, is that far too many of them depend upon mains current as their sole power source. If a turntable has a precision power supply, then speed control is addressed by default. In my opinion, a turntable's primary tasks are to spin a record accurately, and spin it quietly. Do that, and you are halfway home.

Regards,
Win

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What is widely done and extremely misleading, is to report the accuracy of the chip used. This information is provided by the manufacturer of the chip and really has no correlation with the turntable's actual speed accuracy.

Agreed. There's some correlation but it's hardly conclusive or adequate information.

It's just as inaccurate to report on the speed accuracy of the motor itself. Speed accuracy at the platter is the goal, and it's easily affected by stylus drag. Measuring or quoting specs anywhere but at the platter with the stylus in a modulated groove has little meaning.

If a turntable has a precision power supply, then speed control is addressed by default.

I disagree. A precise source of power is certainly essential, but it isn't sufficient. Power must be converted from electrical to mechanical energy by the motor, wherein many opportunities for inaccuracy reside. Even if the motor does that job perfectly (and no motor does) that mechanical energy must be transmitted to the platter without loss or inaccuracy, another opportunity for errors. Finally, the entire system must be able to overcome the variable load of stylus drag whilst playing real records, an extremely difficult engineering problem.

I agree it's vital, but maintaining constant and accurate platter speed under variable load is a terribly complex problem, and no set of wow and flutter measurements will come anywhere close to identifying how good a particular rig really is in this respect.