Hi Pojuojuo:
The VTF and antiskating that you chose are well within our recommendations, so it doesn't sound like you have problems. One thing to keep in mind is that as temperatures drop with the onset of winter, the optimal VTF is very likely to increase a bit.
Regarding screw lengths, the Skala has a somewhat unusual construction in that the white polymer horizontal "base" section is comparatively soft and designed to compress when the mounting screws are tightened, thereby tensioning the phosphor-bronze vertical "blade" section firmly against the headshell. To make this concept work, only the final 2.5mm part of the white base section is tapped. That is, the base section is 6.5mm thick, but only the lower 2.5mm (the side closest to the LP) are threaded. You want the mounting screws to fully engage the 2.5mm threaded section, and the screw length should be at least headshell thickness + 6.5mm. Note that, due to the reduced contact patch between the phosphor bronze "blade" section and the headshell, you do not need to tighten the mounting screws with as much force as you would with many other cartridges. Indeed, you shouldn't use excess force, since you may run the risk of damaging the polymer base.
Regarding screw materials, I agree with Syntax that aluminum doesn't sound very good, but I am not that fond of copper either, besides, 2.6mm copper screws are not easy to find. It is possible to obtain 2.6mm JIS-standard brass screws, and there is nothing wrong with using them - other than the sound (which is admittedly personal preference). The screws that are supplied with all of the Lyra cartridges are a special grade of stainless steel alloyed with copper, and this is a robust material that I find sounds better than most stainless steels.
I prefer phosphor bronze over copper or brass, but I have not seen anyone producing 2.6mm JIS-pitch phosphor bronze screws. Another good-sounding screw material is titanium, but it should be machined, not cast or forged. I have listened to cast titanium (bad-sounding) and forged titanium (not quite as bad-sounding), and neither approaches the sound quality of a machined-from billet titanium screw. But again, I don't know of anyone producing machined 2.6mm JIS-pitch titanium screws, and I suspect that the price will not be cheap.
One more comment regarding screws - the mounting screwthreads on the Skala (and all other Lyra cartridges) are 2.6mm and made to JIS standards. They are not 2.5mm, and they are not made to DIN or other standards. 2.5mm screws or DIN-spec screws will not sound as good as 2.6mm JIS screws (due to improper fit), and they may end up damaging the Skala body.
Regarding Marakanetz's suggestion to sandwich washers between the cartridge and headshell, while I acknowledge that there are some tonearms that will sound less problematic if the mechanical vibrations from the cartridge are not fed directly into the tonearm structure, a tonearm with good bearings and a good mechanical structure will not require such filtering, and the sound will be better as a result. FWIW, I have installed a Skala on a RB-1000 without any mechanical isolation between cartridge and headshell, and got quite pleasing results.
Regarding phono cable choice, please be aware that the total amount of shunt capacitance between the Skala and the input of the phono stage has a strong effect on the optimal value for the input resistor of the phono stage, and the bulk of this capacitance will be comprised by the phono cable. Therefore I recommend that you use a phono cable with as little capacitance as possible. Having less capacitance will allow you to use a higher-value resistance at the phono stage, and this will allow the Skala to produce more of the dynamics and resolution that it is capable of. Conversely, if the capacitance (combined value of phono stage, phono cable, and wiring inside tonearm) is higher, you will need to use lower-value resistance at the phono stage, and this will curtail the ultimate level of performance that the Skala is able to deliver in your system.
Regarding platter mats, I concur with Syntax's recommendation of the Boston Audio Mat 1 (good) or Mat 2 (better). ART in Italy used to make a nice-sounding carbon graphite mat, but they are out of business (you may be able to find one second-hand).
Regarding clamps, ideally you should have a clamp with adjustable force, because there is such a thing as optimal weight / force, neither too little, nor too much, and the optimal weight changes depending on the LP thickness and vinyl formulation.
kind regards, jonathan carr
