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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
norm's avatar
norm
52 posts
 

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 



totem395
390 posts
 
halcro
it would be better to mechanically connect it but at this stage, I don't know how?
🤔
Pretty much as fleib mentioned, the way to go and its not that difficult
would be to start by getting 3 threaded inserts, 1 diamond bit [hollow core] that is slightly larger than the insert od drill at low speed with water lubrication. Partially fill the hole with an epoxy, tape over the bottom of the insert to prevent epoxy filling the insert. Place the 3 fasteners
in the rim of of the TT, lower the table and start the fasteners into the threaded inserts while the epoxy is still setting up there by centering
the inserts to the fasteners.
Use a slow setting epoxy to give yourself more time, and have an extra set of hands, one to lower the TT into position but not all the way down, and another to start the aligning threading operation.
dover
2,262 posts
 
Fleib,
Centripetal comes from the latin words "centrum" - centre and "petere" which means to seek. I can assure you that when using centrifuges the contents do indeed fly away from the centre, not towards.
If you have any doubt, at the next carnival you can attend, take a ride on a horizontal spinning wheel and leave your seatbelt off.  Then you can report back to us whether you flew back towards the centre or indeed away from the centre.


fleib
1,124 posts
 

Dover,

Although I don't attend carnivals I have no argument with that. The question here is, does the rotation of the platter have enough force to overcome the mass coupling of the motor unit?

Evidence suggests, the weight of the motor unit is enough to resist movement depending on the coupling to the pod, but is there micro movement which might not be readily obvious?

That brings up another question. If the motor unit is bolted to the pod, would it be better to damp the coupling with rubber washers?  A compressed thin rubber washer might not allow movement and provide a degree of damping which Halcro now has? 

Regards,

halcro's avatar
halcro OP
2,664 posts
 
Welcome to the TT-101 club Norm 👏
It seems to be growing at a great rate....
What table did you have before?
I've listened extensively to a TT-71 mounted in a JVC wood plinth and whilst sounding good, it does not quite have the solidity of focus nor the reach into the lower sonic regions that the heavy granite plinth endows.
The crystalline shimmers of the upper frequency harmonics are also clearer and more delicate with the granite.
And Fleib is right.....the rubber dampening between the aluminium motor unit and the granite base is essential, as listening with the motor unit in direct contact with the granite was a drain on the emotional content.
Direct contact to wood is a different kettle of fish...🐠🐟
I think you're correct in the assumption that with the rubber supports, the actual 'material' of the base assumes lesser importance than its 'mass'. And that was the motivating force in directing my design to 'stone'. Other than brass, bronze or steel....stone was the densest material for that form of plinth.
I don't however agree with your thoughts on air-borne vibrations affecting the motor unit.
What tonearm are you intending to use with your turntable?...or did it come with one already mounted?
And have you checked that all the functions work correctly on the notoriously complex TT-101?
Regards

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