New Teres Direct Drive Motor Available as Option

Gee, the opening statement in the advertisement for this new take on the idler wheel/rim-drive could have been torn out of my earliest - and current - writings on the subject...except for the inclusion of idler-wheel drive as a victim of speed instabilities. Ironic, in a way, since it is the controversy I started a few years back about the speed instabilities of belt-drives - which Teres built their name on - which started the whole debate about which system was superior, sorry if this is boring you, Viridian, I realize that belt-drivers are feeling severely put-upon these days.

Long ago and still now, the bedrock of my insistence the idler-wheel system was superior to the other two systems (DD and BD) was based in simple and actual verification, simple (the lesson in science I kept/keep talking about): comparison in the system of your choice. A theory stands or falls by the experiment, which either proves or disproves it. If experiment/comparison/verification proves a theory wrong (i.e. that belt-drives are not adequate to combating the VERY important and nefarious Stylus Force Drag, which idlers were actually and specifically designed to combat), then it is time to abandon theory. Apparently, by the release of this variant on the rim-drive, Teres now admits I was right, implicitly.

But is this new system superior to the venerable idler-wheel system in terms of speed stability, as advertised, which I have insisted from day one was THE Prime consideration in designing turntables (and only idler-wheel drives designed to provide adequately)? Only verification/experiment/comparison will tell. As with the growing list of megabuck belt-drives falling before the Lenco and other fine and properly set up idler-wheel drives in front of witnesses, this new Teres system will have to face the music, and eventually be compared to a properly set-up idler-wheel drive.

The Teres system is designed in such a way that the motor CANNOT provide the torque of idler-wheel drives, which with their massive 1800 rpm motors can actually lift an 80-pound plinth when engaged at high speed (i.e. 78 rpm), since such a powerful motor directly applied would guarantee rumble (which is non-existent in a properly rebuilt idler-wheel drive, due to its separate and spring-loaded wheel). Not only is it about SPEED STABILITY, it is also about TORQUE.

That said, it is music to my eyes/ears to see the speed stability of belt-drives questioned in a advertisement of a spin-off of the rim-drive technology (sorry again if this is boring you Viridian ;-), and to Teres I say Bravo. I also wish you luck in the coming comparison :-).

Well, John- who would have thought that that humility would be your most endearing character trait? ;~) I'm not a mechanical engineer or a physicist, but wouldn't torque mostly be an issue in terms of coming to speed from a stop? Once turning at relatively constant 33 or 45 or 78 rpms, wouldn't there be very little torque necessary to overcome stylus drag. I ask this as a serious question, based on my perception of torque as an attribute of a motor that contributes to its ability to accelerate from a stop or at least from low rpms, as in a drag racer from a starting line, where torque at low rpms is just as important as total horsepower at high rpms.

Swampwalker, I don't want to wade into an argument about belt drive vs idler drive vs etc, but "torque" is defined as angular force. So, torque is the product of mass multiplied by acceleration, like any other force. Then, if stylus drag could be thought of as the equivalent of a force that delivers "negative acceleration" to the platter, a high torque motor might be of benefit in overcoming it. The question you raise is however a good one which I have not seen addressed; just what in fact is the magnitude of the force we describe as "stylus drag"? I dunno myself. I think it's key that stylus drag is constantly varying during different musical passages. That's where idlers may have a real advantage, by offering relative immunity to minute changes in platter speed that might other wise result from stylus drag.

Jean,

I think I understand your comparison of idler drive to belt drive, but I'm lost in your comparison of idler to Verus rim drive.

I would think the comparison of rim drive to idler drive boils down to the relative compliance of the interface between motor and platter. With rim drive there will be speed instability if the rubber ring around the transmission wheel has excessive compliance. Is idler drive really much better in this regard?

There is also the matter of transmission of motor rumble. But as with your replinthed Lenco, noise problem can sometimes be engineered.

The torque necessary to meet the changing force of stylus drag is far less than what is necessary to lift an 80 lb. plinth. But it is nice to know that a Lenco motor could be used to drive an electric bicycle.

Don't forget there is also the benefit of high platter mass to counteract the negative acceleration. It is the weight of that spinning flywheel that stores energy and helps get the car off the line. Too heavy, the car is slower to build rpms. Too light, and the car doesn't leave as quickly. The whole system should be analyzed, not just the individual parts. Relative to those light-weight cast or stamped metal tables of the earlier idler/rim drive 'tables the Teres platters are 3 or four times the weight. As Swampwalker said, the high torque may be great for getting the platter spinning from stop but once the platter is at speed, how much torque is needed to maintain constant speed? Which is a state of near zero acceleration. The energy stored in a 30 to 40 lbs platter is helping a lot. The connection of the LP to the platter must also be considered. It does no good if the platter is marching along but the LP is slipping on the surface.

"by offering relative immunity to minute changes in platter speed that might other wise result from stylus drag"

I would agree with that. IMO, this is also why the mylar belts are superior to all other belts I've heard. They don't stretch at all. However, they can slip ever so slightly and that is where the door is open for the possibility of rim drive. Obviously, the next step up should be direct drive, and it goes without saying that every drive systems needs to be well implemented.