Will SME-V, etc benefit with non-stock alignment?

Mike, it sounds like the base of your Skala has been pushed backward relative to the pillar, probably during a mounting/unmounting operation. Unlike any of our other cartridge models (which are all monolithic structures), the Skala employs a two-section structure which is comprised of a small-footprint vertical metal pillar (which the cantilever assembly is mounted to, and a larger-footprint horizontal polymer base which carries the mounting screw bosses. A slide-and-rail system friction-fits the two sections to each other, thereby providing a relatively lossy interface (and therefore greater mechanical damping), but the downside of such a system is that under certain circumstances the sections can move slightly relative to each other.

Once the mounting screws are torqued down, they cause the polymer base to compress and bend, which then pulls the footprint of the vertical pillar firmly against the headshell surface so that everything is locked in position and cannot move. But if the polymer base is pulled or pushed before the mounting screws are in place and properly torqued down, it is possible for it to slide fore and aft. There is a built-in stopper to prevent excess base movement, but the base can slide a little before it hits the stopper. Mike, if you have measured 10.5mm from mounting screwhole center to stylus, it means that the polymer base has been pushed back relative to the metal pillar and should be pulled forward a little.

It is possible to pull the polymer base back forward, but you need to be very sure and very careful when doing this - otherwise there is a good chance that you will break the cantilever. If you want to try to nudge the base back to where it belongs and feel that you are up to the task, send me an email and I will think of a suitable way to describe the procedures that you need to take, with as little hazard to the cantilever as possible.

I am not going to post this information publically, because someone is going to follow the instructions, make a mistake and trash the cantilever.

FWIW, the exact location of the polymer base means absolutely nothing for the sound and performance (the Skala can play happily without any base at all), but for easier setup with arc protractors, it is better that the base is in the right position.

regards, jonathan carr

PS. Is anyone familiar with the Max Townshend gauge (US patent 166,447)? The actual gauge is a little different from the patent, primarily in how the error lines are defined. The patent shows straight error lines which indicate the error amount in degrees, while the actual gauge has curved error lines which indicate the error amount in distortion percentages. I find this tool to be quite useful, and extremely versatile (even when the hole for the arm pillar has been drilled in the wrong location, or the geometry data for the tonearm is missing).

Jonathan,

Thanks for your PS reference. I think you are referring to US Patent #4,351,045 - I tried a search on the number you gave and it spit out a result from 1875 - a bit before Max's time.

This sounds like quite the fascinating tool/idea; I've never actually seen the device, but I'm always on the lookout for new and different ways to skin the proverbial cat. Cheers,

-Richard

Hi all,
seems that thread got exhausted quite quickly. And what I take from it:
There is NO benefit with non-stock alignment.

Jolly good to know, it will save me some bucks spending on any of these aftermarket protractors.

Thank you for sharing,
Axel

Axel,
My answer is YES. The MINT Tractor was a big improvement over my stock SME protractor. Once I supplied Yip with my exact cartridge specs (stylus tip to mounting hole distance) he made a protactor for my specific cartridge/arm combination. I found that my overhang was off by about 1.5mm and zenith or offset angle was off by a couple of degrees. There is no way to accurately confirm offset angle with the SME tools, but it is very easy to align the cantilever with the parallel lines on the MINT tractor and rotate the cartridge until everything is correct at the null points. The sound of my system improved considerably, and I assume that it is because the cartridge is better aligned and now I hear less distortion. The cost of $110.00 was easily worth it for me.

Raul: Yes, I think that to insist on 9.52 would be a severe limitation on cartridge designers. I can easily envision configurations which would tend to be shorter than 9.52, and I can envision configurations which would tend to be longer, too. Of course, if cartridge designers all avoided architectural diversity and only used configurations which fit into the 9~10mm range, 9.52mm would be OK (grin).

One other major variable is the rubber damper systems used in most cartridges. In the small sizes used in cartridges, rubber is not a very consistent material. The characteristic that you are looking for primarily from a damper is consistent damping behavior, but due to the variable nature of the material, consistent damping behavior is not the same thing as consistent thickness, or even consistent pressure. When I was just starting out in cartridge design and still inexperienced, I thought that a consistent pressure system would be perfect for adjusting the dampers and suspension, and would make a major step towards consistent dimensions. So I designed a calibrated adjustable weight system to apply consistent pressure to the dampers and suspension during the building process, and instructed a batch of cartridges to be built like this. The dimensions were fairly consistent (albeit not absolutely so). However, the performance measurements were all over the place, really bad, and that batch of cartridges needed to be built again.

I learned the hard way that each damper is unique, it is better to let a trained and experienced cartridge craftsman adjust the dampers individually, and accept whatever dimensions that arise from this.

You can, of course, prioritize consistent dimensions (like I did decades ago), but most likely you will find that the cure leads to worse diseases in other areas.

One thing that I haven't seen yet in these threads is an effort to _quantify_ the change in distortion that will occur if a cartridge is not precisely 9.52mm, what happens to the distortion if the base is shifted backwards (assuming an SME), how much the headshell offset angle needs to be changed to compensate, and how much slack you need between the headshell screwholes and mounting screws to accomplish the requisite change in offset angle. Cartridge alignment is never going to be perfect - for example a Baerwald alignment only results in zero tracking distortion at two tiny places over a span of 100mm or so. If we are going to talk about distortion, at least let us try to first quantify it, and then we can decide for ourselves if the level of distortion is acceptable or not.

FWIW, also note that some other tonearms with fixed screwhole headshells, like the Naim Aro, appear to have been designed with a much shorter cartridge in mind, From what I can tell, these were designed for cartridges of 7.5mm or 7mm pitch. The same applies to the Linn arms, if you use the third hole.

cheers!