Micro SX-8000 II or SZ-1

T-bone

The problem with that idea (besides complexity) is that you lose most of the advantage of running an external flywheel because your gearing ratio is much reduced. Using the effective mass analogy as given above, a 5 kg flywheel of 150mm diameter coupled "outside to outside" would add about 3 kg of effective mass to the platter.

As a contrast, the motor arrangement in the "Saskia" table adds an effective mass of about 85 kg.

In any case there are other ways of addressing the limitations of belt drives regarding creep (which is what I assume you mean by "the belt tension issue". There will be a completely new take on the issue exhibited at RMAF come October if everything goes to plan.


Mark Kelly

The required figures are in the link provided above.

The motor / flywheel has an inertia of 5.1 x 10^-3 kg.m^2.

It turns at 750 rpm, so the inertia referred to the platter is multiplied by the square of the gearing ratio.

22.5^2 = 506.25 so the total moment of inertia = 506.25 x 5.1 x 10^-3 kg.m^2 which is 2.58 kg.m^2.

In the perfectly ridiculous unit of tonnes.cm^2 this is indeed nearly 26.

Thuchan

Assuming that question was directed at me;

I think it's an interesting contrast with the Micro Seiki approach. The MS product shows a level of design sophistication and engineering input which is well beyond that achieved by VPI.

This is reflected in pricing too.

The system seems to have eaten the post on equivalent mass, so I'll do another.

The idea is analogous to the method of calculating equivalent mass for tonearms and the calculation is the same: divide the moment of inertia by the square of the radius of action, the result being an equivalent mass.

Using a standard radius of action of 150mm, the equivalent mass of the flywheel arrangement for the Micro Seiki is 2.58 kg.m^2 / (0.15m)^2 giving 115 kg.

Note that due to distribution of mass, a TT platter would have to be about 200 kg to achieve this equivalent mass.


Mark Kelly

T Bone

The equivalent mass given by OMA is calculated according to the method I used.

It's not the mass of a platter equivalent to the total inertia of the system, this would be even higher (around 400 lbs). IIRC Win decided to use the more conservative figure - he's a big believer in understating and over-achieving.

Mark Kelly

Let's not turn this into a discussion of Saskia, it's meant to be about the Micro Seikis. I used it as an example only.

I'd like to confirm T-Bone's opinion.

Two sx8000s chained together would be about 1/10th as effective as the high inertia motor assembly of the SZ-1, from the point of view of inertia alone.

The two platter solution would however result in far less belt creep. There is no solution for this dilemma within the compliant belt drive paradigm.

Mark Kelly