Upgrade from TW Acustic Raven AC-3 to what?

Dear Aoliviero, the Studer capstans I worked and work with are all AC. In this model it is all about constant speed of the motor spindle/pulley/flywheel.
I see your point. A motor trying to compensate slippage by altering speed is of course a contradiction for the slippage concept.
In general - this concept is kind of tricky to set up and works only with certain TT's (platter mass...). It works with thread/string NOT with belt. It works best (as all drive principle in TTs) when the horizontal plane of the bearing is force free. The actual "embracement" of the thread around the platters diameter must have a pretty large angle - 210 degrees and more.
It not easy to fine tune, but once done it works smooth and reliable and gives extreme constant speed with ease. What I always liked particular about this model was the "natural touch" - letting inertia doing its work undisturbed.
Nice. Quite the opposite of the "control" approach.

The recent threads suggest that maybe the way to segment this better might be in the following camps:

1) Strong coupling to platter and strong control of plater speed

The direct drives would fall into this camp. As would most belt drives that have strong connection to the platter.

I would think that either low or high mass platters can fall into this category with high mass being better.

Either low or high torque with higher torque being better when trying to control a high mass platter with belt.

Either DC or AC with speed stability playing the more important parameter independent of motor type.

I would also think platters with purpisely hgiher friction bearings or eddy-brakes would have to fall into this category.

2) Loose-coupling to platter, use of platter inertia to maintain stability

This would need to be a string-based drive with enough slippage. Obviosuly, direct drives would not be present since there is direct motor coupling to platter.

I would think you would need to use an AC motor or the like since it is a constant speed device and would not change spindel speed if there is slippage.

I'm not sure if torque would matter for an AC motor.

I think one would defintely need the high platter mass in this case to maximize platter inertia.

I would think that a more freely spinning, "friction-less" platter would be better than something that is helb back by a large bearing friction or eddy-brake. But then maybe a certain amount would be okay?

Anyway, would seem that the number of turntables in camp two is smaller. Forsell? Acoustic Signature? Platine? Custom units?

Andrew

Yes, the "camp two" is considerably smaller. You may add to that short list the big Micro Seikis, Final Audio, Epic and Melcos of decades past. Than the german Apolyt from the 90ies with so far 15 units built and featuring the most extreme and most expensive approach of this principle. The classic Platine Verdier however does feature eddy-current brake (side effect of its vertical magnetic supported bearing) and is used today by various owners with all kinds of DIY-drives (I have seen idler-wheel driving PVs as well as tape, belt, thread and even transmission belts).
Cheers,
D.

D.
So you prefer belt/string over any other method, so.

With anyone here the sound you get or strive for serves your own sonic interest and adjectives.
I use one belt drive table and one refurbished direct drive table. I prefer the dd, silly cheap compared to the belt drive.

lastly a question for Dover, what do you think of someone dumping a Walker Black Diamond for a refurbished Technics SP10 MKII ?????

The original topic was, "Upgrade from TW Acustic Raven AC-3 to what?"

That is the proverbial can of worms, isn't it? We can sit here ad infinitum, and discuss the merits of this or that implementation, but at the end of the day the user wants to improve upon the turntable that he currently owns. That turntable happens to be a very well-respected one, so his choice is likely to be another that is built with equal passion, but its builder will be acting with a different vision of how it should sound. The bottomline is that the implementation of the vision should be in keeping with the buyer's expectations. He wants a different sound that more closely meets what he feels is right for his particular system.

It isn't about technical merits at this point. Rather, it is more about choices that meet personal criteria because he already has a top-flight turntable.