I'd say that was a little high; certainly compared to 2 Lyras, Shiraz, Karma, Benz Ebony, Trandfig.Proteus and 2 x Koetsus (I may have missed one or two
). The Lyras are about 1.75g, whereas the others varied between that and 2g (max recommended).
I stand corrected. What I should have made very clear (in hindsight) is that I use new production, but very much ancient design "transcription" cartridges. VTF of >3 grams is not a rarity there.
There will be subtle ebbs and flows relating to drag and the various counter-forces (motor torque, belt compliance, rotational mass etc). This is unavoidable, just the nature of any drive system on anything (e.g. applies to cars, lathes, food mixers, anything). Everything will react to load to a varying degree.
That is more than certainly true,
at least in my case, as shown here (
a polar plot of speed fluctuations for 40 full rotations, a total of 160 measured data points, for each nominal speed):
I have a lot of flexibility to experiment easily. With the arrangement, I can vary belt tension and idler pressure just by moving components around - difficult to do in a closed system. That saves me a lot of hassle, but it also shows how difficult it is to maintain precision and stability in a production line without excessive complications which inevitably either (1) cost exponentialy, (2) degrade the sound or (3) both.
The Korf Audio blog has a series of recent posts on turntable drives (belt drive, idler, direct drive).
Korf make a lot of very good points,
and are very generous with sharing their knowledge. I am a bit wary lately with
their interpretation of their results as it plays into what I feel is a very subtle sales pitch. It inevitably leads to a product that fixes the issues determined by their interpretation. I may be mistaken, but it seems to have happened three times in a row, so there is that. Of course, one cannot forget the raw information they willingly share, so most certainly a win for the hobby.
Like OMA, Onkk's designer (Paul Beckett) was talking about how tracking speed continuously at the platter was the key to his turntable's performance.
I stand by that approach. It is very sound logic to me. Measuring speed at the motor (via encoders) is certainly easier to implement, but in my head is never correct unless a rigid coupling exists between motor and platter. And it almost never does - some slip and/or misplacement is inevitable. Even NAB standards (the paper from 1964) clearly specify measuring speed on the platter to determine compliance within specified tolerances. They do, however, allow for a tolerance of 0.3% on the playback side, so there is that too.
Measuring speed 5,000 times a second, meaning 9,000 times per revolution at 33.(3) seems a bit ludicrous though - but it may have been crucial to the designs of 70s DDs.