Good idea, let's do some calculations. Im considering a turntable where a motor drives a platter through a belt.
I've used parameters which are sort-of garrard'ish -- but belt driven.
I did a spreadsheet to compute 4 different things:
1. The resonance frequency of the belt-platter system. Thick rubber band => 3Hz, Guitar string => 13 Hz.
2. The platter rotational energy. = 0.41 J [Nm]
3. The torque of the motor. = 27 Nm
4. The rotational energy of the motor. = 0.5 J [Nm]
Unfortunately I cant upload the spreadsheet but I'd be happy to mail it to anyone interested.
Im unsure about the parameters used to compute 4 but it cant be magnitudes off.
What is clear is that the (electric) torque of the motor is a way bigger reservoir of resistance to speed change
and stylus drag than the platter or the moving inner bits of the motor. In fact, to match numbers the platter would
need to be approximately 200 kg placed in a 15 cm radius.
Hence, the drive system (the belt) matters. The point here is that any non-constant stylus drag will trigger a cyclic movement
in the platter relative to the motor (wow) at a resonance frequency that is determined by the mass of the platter and the
spring constant of the belt. If the belt is a thick rubber band you get a resonance frequency of 3 Hz and if its a guitar string
you get 13 Hz resonance frequency. Take your pick. This resonance will be dampened by the damping of the band only.
Crucially, this resonance is correlated to the music.
BTW2: The LP12 wobbles in all dimension, including spring suspension between motor and platter. The only clear beat
Ive heard with the Sondek was the sales guy stamping his foot behind me
Jesper
Ps! I would like to see the paper if you have it.