Direct drive vs belt vs rim vs idler arm

Yes, and the closer the dot on the wall or paper is to the Timeline pointof origin, the harder it will be to for the eye to detect any drift. So if it looks fine at 18" it may be apparent at 10 feet over time that the speed is off.

I agree with Jazdoc's observation that as long as one is very close to accurate speed other issues are very important. IE, How the turntable deals with vibrational energy generated from the motor, the bearing, airborn, floorborn, the stylus/groove interface, the armboard etc. It is not clear to me that absolutely perfect speed accuracy and consistency is the most important characteristic of a turntable.

My thoughts on my direct rim drive is that it's torque is of a magnitude greater than comparable belt drives which rely on platter mass and momentum to maintain speed.
The Salvation's high torque smooths out the speed inconsistency I became more and more aware of with my belt Orbe. This enables the Salvation to deal with groove modulation effects much better than my Orbe.
It's been a total revelation to hear piano notes solid as a rock when struck and as the note decays. My Orbe never quite managed this trick.
I'm convinced eliminating groove modulation timing variability eliminates a whole series of artificial warmth artifacts, and allows a real cognitive ease when listening to vinyl.
But Pete, I'm sure you're correct other factors eg isolation etc. contribute to the overall sound. However my paradigm shift moving from belt drive has convinced me that high torque average speed stability and instantaneous resistance to groove modulation is critical.

Spirit of music

Where are the specifications that suggest the Transfi has high torque.
On the contrary, from their website -

"Note1: The 9kg platter has immense inertia & will take a few seconds to respond to the control knob. Only very slight tweaks are needed.

Note2: You will find speed drift may require frequent minor adjustments until the bearing, motor & electronics are burned in.

Typically, starting from cold the system will run slightly fast. As operating temperature is reached it will slow. A suggested method of operation is to let the system warm up then set the speed. Play several records & fine tune until the speed remains constant.....then leave the control alone.
When you switch the system off, the motor does not need to be disengaged from the traction belt. The next time you start the system from cold, it will run fast. If you try to adjust the speed at this stage it will slow as the system warms, so best to let it run fast until it settles to the correct speed.

IMPORTANT

The whole system of speed control is finely tuned, & any variation in consistency may require adjustment, from VTF of the cartridge to the weight of record clamp used. Sophisticated motor speed control methods have been ditched in the case of Salvation as these all proved detrimental to the sound using this direct rim drive method. In practice, speed drift on Salvation is not an issue providing you are not varying the way you play your records from record to record or are a stickler for speed accuracy! Please consider this before ordering."

If you have a temperature controlled room, the angle of your dangle is stable, and you are not a stickler for speed accuracy, then this is the turntable for you - this is their own words.

The Michell Gyrodeck is not a paragon of TT speed accuracy that should be used as a standard either - tiny motor, stretchy flimsy elastic belt, floppy suspension and all.

Dover, your post leaves me with a lot of questions, but I won't go there. However, there is a need to explore torque and inertia. They can be confusing terms. Explained in the very most simplistic way possible, torque is what you need to get the platter spinning, and inertia is what you need to keep it going smoothly.

So, it is possible to get very good results with a very low torque motor because you can still have good inertia. The downside is that the turntable will reach its speed much more slowly, assuming the platter is a heavy one.

You can have both high torque and high inertia, but there is usually a price to pay. That price is motor size and lots of heat generated by it. Ashland was noted for making such motors, and quiet ones at that. The one used in a Fairchild 750 studio machine is the size of a clothes dryer motor, and it runs very, very warm. So does the more common one found on some Rek-O-Kut turntables and the Canadian made McCurdy. I would be happy with either motor in the Saskia, but they are no longer available.

By comparison, we are stuck with lower torque motors, if we want great precision, but we can still have lots of inertia. This is where system design comes into play, and done right a design can greatly benefit speed accuracy.

I suppose the point here is that most turntables, if not all, are compromised to some degree, however small. The trick is in making certain that any of those compromises do not negatively affect the end result. Hopefully, reliability and looks aren't affected, either. It isn't as easy to accomplish as you might think. Such an undertaking requires a lot of thought.

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...unlike my clunky grammar which required zero thought. :D