Vintage DD turntables. Are we living dangerously?

fleib
06-29-2016 7:24am
**Thus it is a force vector that has a direction described by an arc opposite to the direction of the arc of turntable rotation.**

What force vector is that? If the platter/motor moves it would be in the direction of rotation. There is no force vector opposite to direction of rotation. It’s the motor unit coupling to the mass of the pod that resists movement. The mass of the motor is heavy enough to resist, otherwise Raul wouldn’t have been able to listen to the table.

Interesting point. Assuming the motor is still coupled with three rubber pads, it's not only the mass of the pod which resists motion, it's also the integrity of the coupling and mass of the motor unit insuring that resistance. I wonder if performance would improve if the motor unit was bolted onto the pod.

Dover,

Modern physics says centrifugal force is a misnomer.  It's called
centripetal force.

The Victor motor units are relatively heavy containing the transformer and all the electronics.  One can spin the platter under power and it doesn't go anywhere.  I haven't listened to the table (TT81) under these conditions.

Regards,

Halcro,

I wonder if you would hear a difference if the motor unit was bolted on. I'm sure you're aware of the three bolt holes underneath the edge of the platter. This is how the motors were bolted to the CL-P2D plinth. 

It might be better with the rubber acting as a damper.  Of course you could always use rubber washers in-between.  If the washers were compressed there should be no movement?

With a wooden plinth it's easy to install threaded inserts, but with a stone pod you'd probably have to drill a big enough hole and fill around the insert with epoxy? 

Regards,

Hi Halcro,

I should begin by saying, “nice job on the granite plinth”, which I neglected to mention on my earlier post. The black granite matches the armpods beautifully.

Thank you for the in-depth explanation to my inquiries.  The reason for my curiosity is because I’ve recently joined an exclusive” Are we living dangerously?” club. My JVC/Victor TT-101 was sold to me with a CL-P2 plinth and acrylic dust cover.  The Victor CL-P2 plinth is made from particle board with a veneer clad, faux Rosewood, as with most plinths made from this era. The plinth itself is quite heavy and comes with four large plastic footers.  The TT motor is evenly secured with hardware to the wood plinth.  I’m looking for ways to improve on this plinth; whether it is a custom plinth as you have done or tweak the existing CL-P2.  An Elgar 6000A line conditioner is used to feed 100VAC to the TT-101. I’ve dialed down the Elgar to the lowest possible voltage of 105VAC to best meet TT-101 requirements. I need to shuffle my equipment around to accommodate the TT-101 before spinning any vinyl on this TT.

Since my inquiry on how your custom granite plinth is coupled to the TT-101 motor, several posters have commented to your approach.  To me, it seems intuitive to mechanically fasten the motor to the plinth for best sonic results. What was the rationale to have the motor “sit” on the rubber points rather than have it bolted in place? I noticed the metal skeleton plinth also used rubber supports.  Did you experiment both ways before concluding that this was sonically the best approach? It seems intrinsic that the plinth material selected has a lesser degree of importance when the motor just “sit” on the plinth as opposed to mechanically coupling the motor to the plinth.    

Furthermore, is it possible the granite plinth sounds better than the open metal skeleton design because the granite design encases the TT and is able to shield air borne vibrations reaching the motor?

Regards,

Norm