maxon: ideal choice for TT motors
Jam,
Speed stability of maxons is fair-to-good (together with the commutator noise their only drawback); i do not know whether it is the motor or the lab supply which is drifting.
But it is a very slow drift and in no way affecting the music.
However, it has to be checked regularly. Unless you buy a Teres motor /controller kit which uses a maxon and has a µcontroller checking the slow speed drift and correcting the motor supply voltage.
Klaus,
nice of you to defend me, but i do not sense a language barreer

with native speakers here and sometimes i am a bit blunt in my choice of terms; "***" was meant to be a sharp-minded pun. ***** produce some ... hmmh .. not-continuous noise signal shapes. Unpleasant noises (except to the own ears

) ... but whereas human ***** do so now and then, the maxon's *** does it all the time when running. And while my *** cannot really be kept airtight ( must have to do with exchange of not-neglectable amounts of gasses, would discomfort me considerably

), the maxon's *** can be sealed up and ---whoosh--- the unpleasant noise is gone.
I looked for the thread meanwhile, it is the "TT motor slightly bent".
All (particularly lurkers),
the maxon commutator noise is rather silent, but is is noticable within a distance of , say, 1 meter. But as many lesser TT motors (synchonous motors, split-pole asynchronoous motors, electronically commutated motors) are usually dead silent, the motors from maxon and their direct competitors Faulhaber are criticized frequently for their commutator noise which is rather silent but not dead-silent.
But these maxon motors with bell-type iron-less rotors having up to 11 overlapping windings excel for TT application. They are unbeatable as far torque ripple, low rotor inertia, high dynamic stability is concerned and they are precision-made for precision applications: the shaft has excentricity/wobble close to zero (less than 5µm). And they do not ask much for that: a clean DC voltage. Angular speed and supply voltage are linearly related, can be it be easier? 16rpm is no problem, 78 rpm neither.
Exactly what we need for a TT motor, provided we can tackle or tolerate minor flaws.
Ooops. forgot, retail they cost between 60 and 200 US$ each, depending on quantity and supplier.