If your tracking force is 2g, then the torque required to turn the record just by stylus drag at the outer edge of the record would be about 0.62N-mm or 0.0055 lbf-in. (That's assuming a coefficient of friction of 0.2) If you want to figure additional drag due to groove modulation (pushing the stylus back and forth) then figure a torque as high as 0.027 lbf-in. That would be a sideways groove which would pop the stylus out of the track. Additional torque is needed, of course for bearing friction and windage. Let's figure windage is negligible since the platter is spinning at just 0.56 rev/s. You can calculate the bearing friction torque if you have a way to measure speed change over time and know the moment of inertia of your platter or with a force gage.
My point is that the extra torque isn't needed; but I wonder if the added motor/belt provides additional sinking of vibrations away from the platter to improve the sound. If that is the case, then idler pulleys with extra belts might have the same advantages. Haven't I seen VPI TNT tables with extra belts and idlers? Maybe some one that has that type of set up can weigh in on if it helps or not with the sound.
