Cartridge alignment, WallyTractor, SmartTractor, oscilloscope and Analogmaigk.

With the Walltractor, you first measure the pivot to spindle distance with the supplied tool to find the closest matching curve that establishes the overhang.  There are a fixed number of curves for the pivot to spindle distances measured, so your actual distance might not be a precise match.  That is a potential source of error, the overhang may not be a precise match.  Once you have that distance, you tighten one screw of the two that hold the cartridge so that the cartridge is free to pivot around the fixed screw for you to change the angle of the cartridge to assure that the cantilever is correctly aligned.  When the cantilever is correctly aligned at the two null points, you have a quite precise alignment, even if the overhang started out as a somewhat rough approximation.

The potential source of error with the Smartractor has to do with precisely aligning the whole gauge to the pivot point--if the pointer is not precisely over the center of the pivot, the lines on the gauge will be slightly off.  Again, the amount of error should be pretty low if you get the needle quite close to the pivot point. 

Both protractors are more than good enough, particularly when you consider that the ideal alignment involves angling the cartridge to make sure that the zenith is correct, and none of these tools do that.  Wallytools has a service for that which also analyzes the cartridge for other parameters, including the dynamic SRA (the actual angle of the stylus when it is playing a moving record).  The analysis requires extremely expensive microscopes and know how, so no consumer can do this for themselves.  

Honestly, seriously high quality cartridge alignment can be done with a free download found on-line printed on a piece of paper. The only thing you will then be missing is the paper is thinner than a record. So you tape the paper on a record. 

I am not kidding. This is exactly what the MoFi Geo-Disk is, only the MoFi is the right thickness and includes all the sight lines and directions printed right on it. I have used mine several times on 3 different arms, three different tables, and 5 different cartridges, always resulting in beautiful imaging, which is the key benefit of quality alignment.

Unfortunately no one who has spent a thousand dollars is ever going to admit the paper is just as good. Also no audiophile worth his salt is ever going to let on that turntable setup is really not that hard. So I know this will fall on deaf ears. Especially your guru. She will give you the most withering look, I just know it. 

So since I know you will disregard this sage advice here is what I recommend, if you are up to it. Print the alignment paper and hide it away somewhere. Then when you are done fiddling and twiddling and agonizing over the scope and test records, everything at last is perfect, pull out the piece of paper.

Place it on the platter. Set the stylus down on the mark. Notice how it falls exactly where it should. Because no matter how complicated you make it, if done right it will always be just like this.

We now return you to our regularly scheduled program.

@millercarbon I do not dismiss advice... I will not use paper because we own already the 2 protractors, and my printer does not print very thin lines which I know I need, but not because I want to ignore advice :)  

At home we like to keep things simple, specially on our hobbies. What is the point to stress about something it is supposed to bring pleasure.  

Thank you for the advise on the isolation very much, to be completely frank I keep forgetting that my house in the US is built out of wood sticks and plaster. The first time I tried to hang a picture, the nail disappeared 🙄! and now that my audio rack is about 350Kg,  when I walk the subwoofer cone wants to go for a walk and leave the enclosure behind so I am hoping your suggestions help. 

I also will have put some bars between the soil and the floor for support, like lifting a car, with the hope that will help. 

@larryi  I am glad you confirmed my theory and the effective lengths.

I do not believe the dynamic SRA is that difficult to do, a decent microscope with a good camera/depth of filed, take 10 pictures and average the angles. the big trick is to have the microscope/camera plane perfectly at 90 degrees from the horizontal plane, which it is not that difficult to do either.

Where I see more of the Wally service value is in analyzing how well aligned is the stone, is this called cantilever, with the stylus(?)