Direct drive vs belt vs rim vs idler arm

01-24-13: Richardkrebs
Halcro
The reason for my question was that it is popular to add significant inertia via metal aftermarket mats. The thought is that this can screw with the servo, which if excessive, it should.

Krebs Upgrade

Hi RichardKrebs
As part of coming up with the Krebs upgrade were you able to determine what the weight threshold is for an SP10MKII platter before it starts to ^%*% with the servo. Very much interested in your opinion as I have a couple mats. Thanks.

Ct0517
The Krebs upgrade causes no material change to the platters inertia and I have not done any tests on the effect, if any, of extra mass via heavy matts or clamps. This was part of my line of questions to Halcro on any changes to the 101's platter's inertia.

So the quick answer is that I don't know where the threshold is, but would very much like to find out.

Just a little plug here. Customers of both MK2 and MK3 upgrades have universally noted a marked improvement in percieved speed stability. Some of these customers are using heavy aftermarket metal mats and clamps/weights, which appear to have no negative effect on the servo.
Ken McCarty's review of the MK3 upgrade on Albert Porter's system thread covers the speed topic nicely.

Thanks for the response Richard. Was curious.
My copper mat does not cause a problem to the servo from what I can tell but longer term I haven’t a clue. My “gut” says don’t use it based on the difference in weight with the original mat. A clean SP10MKII is worth $$$$ in working condition. One with a %#@* up servo is worth a quarter of the amount to me personally.
Cheers Chris

Has anyone on this thread used an SP10MKII with a copper mat for 5 years or longer - any issues ?

Richard,
I did try a Micro Seiki Cu180 copper platter mat as a replacement to the original rubber mat on the Victor TT-101 DD deck.....and heard a definite improvement.
The trouble was not audibly discernible with the servo correction mechanism....as you and Chris allude to.....but the 'brake' mechanism of the TT-101 was not able to handle the added mass of the platter when the 'stop' button was pressed.
This certainly worried me as, like Chris......I did not wish to stuff my perfectly working TT-101 for a slight improvement in performance?
After much experimentation......I found that the Victor pigskin mat laid directly on the aluminium platter......sounded as close as damn-it to the 1.8Kg copper mat without affecting the 'brake' mechanism one iota?

Go figure......?

One thing all this testing has shown IMHO......is that the performance of belt-drive turntables in general.....and the Raven AC in particular.....can be surprisingly good?
Just study all the test data in comparison to the TT-101 (which is demonstratively as good as it gets from an 'objective' point of view)....and those who bemoan the inability of their Ravens to 'hold' correct speed, should re-assess their set-ups?

I suspect that the big Micros and Dover's Final belt drives can be even better than the Raven in this aspect....which would push them even closer to the speed-accuracy performance the best DD turntables?