Record clamp/weight and turntable speed

@chakster , speed fluctuations can happen just as easily with a poorly designed DD table as with a poorly designed belt drive. Well designed tables of either type do not have this problem at all. The only thing you can say about the DD turntable is it will start up almost instantaneously and sound universally horrible:-)
It is not at all a matter or torque. It might take a little longer for a low torque table to get to speed but that is all. Once the platter is in motion it takes very little torque to keep it going. Even the lowly AR XA runs just fine with a record clamp.

@mijostyn  The “sound” of a turntable drive is BS, you hear the sound of cartridge/tonearm mainly. The rest is speculations. Speed must be stable, period.
Even very cheap direct drive can’t be affected by the weight of a record clamp.
Not every Direct Drive have a high torque and immediate start at constant speed. Not every DD have a high mass platter. My luxman pd-444 or Victor TT-101 are not high torque turntables.
Technics is a high torque turntable, even if you put 3kg on the platter the rotation will be stable with immediate start!
Belt drive can be affected by many factors and the speed is the main issue, read tons of comments on audiogon from BD turntable owners, those type of drive is notorius for not stable rotation. Most of BD turntables on the market is junk and people love it!

@mijostyn  I did indeed download the RPM app and discovered my main VPI HW-19 tt runs around 33.64, while my Craigslist marketplace let-the-kids-use-a-turntable TT runs around 33.17.

Without a dedicated clocking device, do all tt's vary in their speeds like this?
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Heavy clamps increase the wear on the bearing.
There is no reason for them to be heavy if they have correct mechanical design.  Screwing onto a threaded centre pin is a much better approach than using mass to hold the record down.

@simao   It's really quite difficult to get a TT to run at 33.333333 rpm.
And a cogging computer controlled direct drive is not the way to do it.

@chakster     3kg???   Many TTs have platters weighing 25kg, some much more.
Over-engineered glitzy TTs with extra bling are one of my pet hates.

Simao, there are many things that can push the speed a little one way or the other such as temperature and AC line drift. Very few turntables are right on unless you can adjust the speed. Some modern turntables actually have a computer monitoring the speed and making the adjustments for you in unnoticeable increments.
@chakster , you are right. It is the tonearm and cartridge that produce the sound and DD turntables make them sound lousy which I can easily demonstrate to you in person. The last thing you want in close proximity to a cartridge is a pulsating magnetic device. Not to mention that I know of no DD turntable that is adequately isolated making matters even worse. But everyone knows by now how the two of us feel and neither is going to change the others mind without a demonstration that can not be performed. So it is a moot point.
Clearthinker Theoretically I agree. The more weight you place on a bearing, the shorter will be it's life span. (except for magnetic and air bearings). Threaded reflex clamps are the way to go for sure unless you have vacuum. However the bearings of most good turntables are very over-engineered and unless subjected to trauma you could measure their lifespan in centuries. My Sota Sapphire was as quiet when I sold it as the day I bought it 40 years previously. That is listening to the sub chassis with a stethoscope. I also agree on your bling thing. Turntables are meant to be heard, not looked at. They only need to be tidy and well built/finished, just one of the reasons I like Sota's and Dohmann's. Tricking one out to make it look like Star Wars is a waste of money, money that could be better spent elsewhere.