Rerurn to Romy the Cat's Site
In the Forum: Analog Playback
In the Thread: Ultimate Turntable
Post Subject: The ideas that work?Posted by Paul S on: 2/26/2008
The "best" TT I ever heard - by a mile - was the old Versa Dynamics, but the performance quickly deteriorated, apparently from water vapor messing up the "straight-line" arm function. Oh, well.
Mass is definitely part of the answer. Maybe use an idler to get the platter moving and then switch it off to a belt drive. This might allow the use of a more friendly belt material than whatever it would take to get a heavy platter off rest.
Lead and/or or various sintered materials seem to work best for platters, and it is better, or just as well, IMO, to keep the mass +/- constant than to layer it.
If the magnetic fields could be reasonably contained then this might be a better platter lifting/decoupling strategy than air, which is likely to contain some water. Lateral constraint is another issue I have not thought through yet, but perhaps magnets could also be used to keep the platter centered enough to use minimal mechanical restraint. Big platters dragging can make BIG rumble, and wobble of any sort will out.
Good drive motors are expensive, but I see no good reason to go over the top with it. DD with a big heavy platter seems like asking for trouble.
Experiments have convinced me that there are better and worse ways to deal with extraneous energy from the stylus/disc interface. Platter material/composition sure seems to play a big part (see above), along with disc/platter interface.
Perhaps it's a sop, but in the real world I happen to love vacuum holddown; just enough to effectively couple the disc consistently to the platter. Here again, no reason to get exotic. The small inexpensive pump on my rig has been silent and trouble free for 20 years. OK, it is faintly audible as it first sucks the disc down. But it shuts down to inaudibility once the vacuum level is achieved. No doubt it could be done better; but this is proof it can be done simply, inexpensively and reliably. And I can and perhaps should say that, at least with the minimal vacumm, there has been no harm to my LPs over a 20 years of using the vacuum holddown.
As for suspension/isolation, there might be situations where LP playback does not need it, but I have not seen these situations.
It looks/sounds like many TTs spring from rampant imaginations that put "design ideas" and or pre-conceived notions about appearance ahead of actually dealing with obvious issues as simply as possible. In fact, turntable "manufacturers" seem to be more likely than most to invent/focus on problems so they can "solve" them in fantastical ways. The results are too complex by half, and many of their "features" are just nonsensical, while the overall designs yet ignore or fail to deal with significant performance issues.
Best regards,
Paul SRerurn to Romy the Cat's Site