A Copernican View of the Turntable System

Dear Chris,
The stainless steel pricing looks better than the brass. The only down side is it is harder to mill yourself so you might need a professional machine shop?
I'd go for 316 grade rather 304 as it does not tarnish and is definitely non-magnetic.
I can't quite follow the 'air' reference to the top-plate? I personally would want the top-plate connected to the mass of the armpod as securely as possible. In fact the only reason for a top-plate IMO is to allow clamping of the tonearm and connection of the Din cable, otherwise I'd happily screw or clamp the tonearm directly to the armpod.
Cheers
Henry

Dear Chris, I present to you my reservations about the possibility of ringing. The 7mm Brass is a lengthy piece and the porpotions are not quite ideal for doing this "air" mounting. Furthermore I believe that the 3 tiny bolts are not so absolute idea in terms of controlling the resonances, even if they can provide the convenience of alignment, the threaded holes together with the asymetrical body of the tiny bolts , are not comparable with some pretty harder & perfectly round bearing balls in order to detune the armboard resonance & above that, in terms of rigidity are more secure.
I'm with Halcro at this. You better try the massive & solid approach -as the more secure way- that is also more tolerant to some crafting inaccuracies. Also keeping the project simple is always the better way. I agree with your choise of Al plate / Brass pod / Steel spikes for your next project. (Although I prefer the Symposium Rollerblock JR instead of spikes)

Geoch/Chris,

I'd be careful about using Rollerblocks beneath an arm tower. The ball bearings are not secure enough and movement when lifting and placing the arm would almost certainly create ongoing alignment problems. In fact, the only place that I find the rollerblocks ideal is beneath my CDP, where mechanical movement is minute enough to never create a problem and yet the benefits can be easily heard.

Here in Greece it is common place the Rollerblock JR under really heavy mass loaded free standing arm pillars when we are using parrallel tracking arms.

Dear Geoch – I am trying to understand the benefit or reason for using the Rollerblock Jr.

Based on what Dgob is saying and the fact the Rollerblock use bearings how much weight are we really talking about when you say “really heavy loaded”.

I ask because I have two 2 ET tonearms. If there is one thing I have learned about that air bearing - is that it is very sensitive. It is set at 19 psi and it needs to be totally rigid and parallel once set and not move or it will introduce coloration, and distortion that is audible.

But I also think that this would apply to other "pivot" arms as well - any movement at all is not good ?