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Direct drive/rim drive/idler drive vs. belt drive?

O.K. here is one for all the physics majors and engineers.

Does a high mass platter being belt driven offer the same steady inertia/speed as a direct drive or idler drive?
Is the lack of torque in the belt drive motor compensated for by the high mass platter. Object in motion stays in motion etc. Or are there other factors to take into consideration?
I am considering building up a Garrard 301 or Technics SP10, but is it all nonsense about the advantage of torque.
I am aware that the plinths on these tables can make a huge difference, I've got that covered.
My other options would be SME20 or Basis 2500 of Kuzma Stogi Reference etc.
If I have misstated some technical word, please avert your eyes. I don't want a lecture on semantics, I think everyone knows what I mean.
Thanks in advance.
mrmatt
atmasphere's avatar
atmasphere
11,794 posts
 
Lew, 5/8" is a pretty big hole. The stomp switches are usually set up for 1/2".

We found that the plinth had a lot of effect too- again, it is a resonant signature, and one unique to each 'table. The more you can reduce this issue (along with tighter coupling between the platter bearing and the tonearm) the less signature the individual machine will display: bass will have more impact, overall greater dynamic impact (more lively, without added brightness), blacker backgrounds... again a lot of the same effects that deadening the platter has.
lewm
13,030 posts
 
Ralph, I agree completely with what you say re the effect of plinth-ing. I was surprised that the slate plinth had such a profound effect on the "sound" of my Denon DP80. I would have thought that a direct-drive system would be rather a closed one in which colorations introduced by the drive were directly "injected" (for want of a better term) into the audio signal via the coupling of motor to spindle. Thus, except for better controlling the inertia of the motor itself, I thought that the positive effect of the slate would be limited. I was quite wrong.
"bass will have more impact, overall greater dynamic impact (more lively, without added brightness), blacker backgrounds..." That's what I hear too. Win's turntable (the Saskia) must be quite awesome.
quiddity
119 posts
 

Lewm

The easiest solution I can see to your problem is to have the switch control a relay. If you have lowish DC voltages available (preferably either 5V or 12V) this is easy to do.

You'll need some logic to convert the momentary action to a latching action but it's not hard to do. Since I have B+ delay on all my valve gear I use mains switching by relay as a matter of course anyway and I like the safety aspects.

Mark Kelly
lewm
13,030 posts
 
Thanks for the help, Mark. I actually found a plain old push-push switch that will likely do the job, but the relay is my next option. This is just to switch a Lenco motor on and off, so sophistication is not a priority.
jloveys
226 posts
 
Ralph: brilliant description of the reduced resonance signature of the turntable parts. BRILLIANT.
My experiments with plinths and platters show that you are right on spot !
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