Direct drive vs belt vs rim vs idler arm

Hi Dover, one thing to quickly recalculate is that the record spins 0.5556 revolutions per second. (Inverse of 1.8) So the speed error would be 0.008% if it takes 7200 seconds to lose/gain one rotation.
What I believe is that we will hear a difference in PRAT if speed is off before we hear sour notes (tonal pitch); at least most of us. If speed is off by 0.1%, then concert A would be off by 0.44Hz. I do not think that I could tell the difference even if I had a tuning fork to my ear. But I now know that I can sense the pace of the music by small changes in speed. An orchestra, for example, tunes to the oboe. If the oboe is off a Hertz or two, it doesn't matter because the whole orchestra will be matched to it; but the tempo of the music doesn't change- can't do that with a recording.

Your tt platter is a flywheel. Like any good flywheel design, the bulk of the mass is on the outer edge (Think 2001 A Space Odyssey). The moment of inertial equations illustrate the effectiveness of having the bulk of the mass at the outer edge. A uniform mass flywheel is I=1/2mr^2, but when the mass is concentrated at the outer edge it is I=mr^2. The moment of inertia is doubled. Therefore, a "hollow" flywheel half the mass of a solid flywheel has the same moment of inertia. And the moment of inertia is directly related to the amount of torque it takes to accelerate the platter- double "I" and torque must double to get the same amount of acceleration. Conversely, double "I" and the impact of stylus drag change on platter speed drops by half.

Here is another thought to feed on our neurosis. (I hate to suffer alone :) Like I have said before, the tolerance on the center hole of records is such that the record Wow&Flutter is going to be around 0.5%. My favorite iPhone app will show you that too. It will show you the raw W&F as well as the filtered W&F of your tt. Last Winter, I filed out the center hole of my test record a bit so I could center it on the tt platter. It worked and I was able to reduce/change the record W&F. It is not easy to do. The outside diameter of records is not that round either. I had to try to center it relative to the grooves. But now, think about this. Your turntable has W&F in the 0.03% range and a typical record, say 0.5%. The two values are additive, so depending on the position of the record relative to the platter the total W&F could be 0.53% or 0.47% or somewhere in-between. (Min and max values worse case). So it is very likely that you could play a particular record one day and it seems to sound really great- pace is on and the music flows and the next time it sound kind of dead- all based on the randomness of the record position to the platter. Other than my test record, I have never experimented with this concept. I try not to think about it.

Hi Mosin – regarding your Merry Go Round.

As a manufacturer, I find you have left out a very important detail for us to consider.

Please tell us what type of BEARING your merry go round uses. Is it something nice and smooth and slippery or does it float ?

You see IMO - this is a total resonance vibration hobby. An imperfect sharp rock of various designs and angles that goes into an imperfect groove of an imperfect piece of plastic..... to make vibrations ........

In the last three years I have found as an amateur that the Achilles Heel for turntables I have owned - seems to be the BEARING.

It also seems to be the elephant in the room. Pretty boring. You can’t even see the damn thing. I think it’s still there. But the platter is too heavy for me to think about lifting it out right now. Will look later later.... Some squirt some oil in, others squirt in grease. Still others have found some secret product? Maybe it came from the moon?

IMO - it contains the family jewels and is the DNA as far as how any of the turntables I have owned actually sounded. It is the ROOT.

Put a TT motor right up to the Bearing or close to it – the result is usually a turntable designed like a fortress (spaceship?) to protect against all those vibration / resonance nasties. Not that there is anything wrong with this - many ways to skins a cat here.

How many people on this thread other than actual designers and manufacturers, know what type of bearing is contained in their turntable? How many know what the replacement cost is, and its percentage relation to the cost of your whole TT?

Well here is maybe a little silver bullet for you – in my humble opinion.

Find this out and you may find out if your table was built for:

1)Performance
2)Profit
3)To win the beauty contest.
4)All of the above.

IMO - 4 is the correct answer - Hey we do have to listen and look at it every day, and you want your manufacturer to stay in business right - for support ?

For those looking to buy a turntable – challenge your seller to give this information to you.

Look.. I am done – I think – my vinyl journey. After what I have learned however as an Amateur, I would never ever again buy an expensive turntable without this information.

So

What if you find out that the $5000 table you are eyeing has a bearing that costs 68 dollars to replace? Would you still buy it ? This is just thought...

So the BEARING imo is one, but not the only BIG Rock in this hobby.

No more coffee for me this morning...sorry if any of this comes off as cynical....

Actually, high precision bearings are not that expensive. Balls with sub micron tolerances can be purchased for pennies- even in ceramic and ruby. Shafts can be had very cheaply that are ground to high precision tolerances. That is the product of an industrial base that today produces robust machinery that lasts 10s of million to 100s of million cycles. The markup that an individual may pay for a bearing at retail is 10-100 times the price that a high volume manufacturer would pay. A good example are the ball bearings in my mower deck. The autoparts store wanted $55 each for these things and I needed 6 of them. I bought the exact same bearings at an online auction site- a pack of 12 for $22. A large volume manufacturer can probably get them for less than a dollar a piece. Think I got junk for $22? That was several years ago and these bearings have lasted just as long as the factory originals.
My tt has a hardened steel ball turning on a flat sapphire disc. It is not only very quiet, but would likely last for a billion cycles. At 33 1/3 rpm that is 57 years continuous running. My great great grandkids will be playing records on it.