Vintage DD turntables. Are we living dangerously?


I have just acquired a 32 year old JVC/Victor TT-101 DD turntable after having its lesser brother, the TT-81 for the last year.
TT-101
This is one of the great DD designs made at a time when the giant Japanese electronics companies like Technics, Denon, JVC/Victor and Pioneer could pour millions of dollars into 'flagship' models to 'enhance' their lower range models which often sold in the millions.
Because of their complexity however.......if they malfunction.....parts are 'unobtanium'....and they often cannot be repaired.
128x128halcro
Aaarrrggghhh. You’ve done it again, DDrive. Stop already with the "motor vibrations going up into the spindle". This is not really a problem with a direct-drive turntable. As I mentioned on the other thread, DDs are subject to bearing noise, just like any other type of turntable, and to EMI because the motor is close to the platter surface and thus relatively close to the transducer itself, compared to a belt-drive and some (not all) idlers. But DD's are not much subject to mechanical vibrations due to the motor, unless via a circuitous route via the chassis transmission of vibrations that in turn might reach the bearing.  The motor when producing torque also exerts a force on the chassis, opposite in direction to the force on the platter, which is why, maybe, DD's sound best with rather massive chassis'.

I also took a look at the Arche website; in my opinion, that platter mat is designed for belt-drive turntables, wherein motor vibration CAN in fact be transmitted into the platter via the belt making contact with the rim. The most it can do for a DD turntable is to improve isolation of the LP from bearing noise or vibration, if that is a problem. I guess also that by the mere fact of elevating the LP further away from the motor, it might also diminish any EMI effects from the motor. Perhaps this has something to do with why it sounds very good on your turntable. However, I do not detect that EMI is a problem with my SP10 Mk3, although I have never measured the field strength at the platter surface. As you know, the Mk3 platter is quite thick and constructed of alu, stainless, and what I think is brass or bronze, all of which make for a pretty good EMI shielding effect.

I can’t resist correcting Dover, because the opportunity to do so is rare. The force that keeps a body in orbit is by convention referred to as a "centripetal force", because it is literally "center-seeking". Think about a biblical type of sling shot. When you spin it around over your head, you are applying a force that keeps the projectile in the sling from flying off in a straight line tangent to the orbit. That force has a vector direction toward the center of rotation, your hand. I actually do not know where we got the term "centrifugal", but it is clearly a misnomer. What we think of as centrifugal force is really inertia, the tendency of a body in motion to continue in motion in a straight line, unless acted upon by an outside force. Inertia is observed as the result of the absence of a force.  Centripetal force is applied via the sling to counter-act the inertia of the stone or other projectile in the pocket of the sling. 
Centrifugal force (Latin for "center fleeing") describes the tendency of an object following a curved path to fly outwards, away from the center of the curve. It's not really a force; it results from inertia — the tendency of an object to resist any change in its state of rest or motion. Centripetal force is a real force that counteracts the centrifugal force and prevents the object from "flying out," keeping it moving instead with a uniform speed along a circular path.

Centrifugal = imaginary
Centripetal = real
ddriveman: I tried the mu metal shield and ERS paper on my Yamaha GT2000 between the original platter and the copper platter mat. I found the ERS paper to give more refined highs, but that could have been due to its damping effect as a slightly soft layer between two metal layers. The mu metal didn't seem to have a beneficial effect and may have had a slight negative one. Anyone else with experiences?
Yes.....I wrapped Mu metal around the power supply of the Victor TT101 and the results mirror that of sampsa.
No effect or better without.
The metal screen/cover to the motor unit (when properly grounded) does the job it's supposed to do....


halcro OP
1,983 posts
09-15-2016 6:47am
Yes.....I wrapped Mu metal around the power supply of the Victor TT101 and the results mirror that of sampsa.
No effect or better without.
The metal screen/cover to the motor unit (when properly grounded) does the job it’s supposed to do....

It should probably be mentioned that the grounded screen/cover and the mu metal wrap have entirely functions, the screen function is RFI/EMI absorption whereas the mu metal function is low frequency magnetic field absorption. I’ve had good results wrapping large toroidal transformers and medium size rectangular transformers with low frequency high permeability mu metal; I actually wrap them twice leaving a small gap between the two layers. Better safe than sorry.

cheers