A Copernican View of the Turntable System

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 ?

The "JR" has some advantages over the more expensive std Rollerblocks :
They have 1.86" disc plates on both! levels that are both! threaded at the outer side and are also both! curved inward. So, we can permanently fix them in the desired place at the upper level (armpod) and at the lower level (shelf). The disc plates are shelf centered with great precision by gravity as long as the shelf is allready dead leveled on horizontal plane. The 1.86" threaded disc plates can provide further leveling adjustment and their contribution is admirable in contrast to spikes/thin discs. The movements by accident are terrifying indeed, but in normal careful use, the great mass of the armpod impedes any disposition and restrains it to a soft activity. The remaining faint movement is progressively die out very quickly before the cartridge touch the LP. Of course it is a matter of the end user to value the pros & cons of this option, but the disadvantage of the careful operation & handling is an accustomed practice anyway to the parallel tracker's user. If you have a friend by which can borrow a set of 3 Rollerblock JR and see if you can manage to handle their lateral movement, it is definitely worth a try.

..."in normal careful use, the great mass of the armpod impedes any disposition and restrains it to a soft activity." Geoch, that is beautiful English, worthy of an erudite 19th century scientific journal entry. But what is "soft activity"? Any activity, if activity means movement or motion, is a bad thing if the platter does not move precisely in concert.