How critical is the exact placement of the tonearm

That's correct, Dsa. The proprietor, Yip, makes the protractor for the tonearm parameters you specify. I had given him the numbers for the protractor I need without the name of the tonearm and table. I guess he is building a database as he asked for these before accepting my order. Another thing that came out in the thread on Thom's forum is that you will also need to specify the spindle hole diameter. Yip does cut to high tolerances so keep that in mind with the spindle hole. Oh, I also like the way he personalizes them.

Yip also asked if I wanted a lupe he recommends for seeing what is going on while adjusting with his protractor. I ordered one since I liked the look of it and feel I can never have too many tools for seeing what I'm doing.

What I like about the arc-style protractor is that you have a single tool that allows you to get the pivot to spindle right at the same time you get the cartridge alignment right. It is possible to get things right with most any 2 point protractor, but you would still need a tool and method to measure the pivot to spindle to get it really, really close. So if you are getting accurate results with a 2 pointer, that's all you need. In my case, I didn't realize how off I was until I tried the arc-style. I was clearly off the arc. Once I got things adjusted closer and re-checked using my 2 pointer, I found I was off by less than .5 mm with pivot to spindle. But the difference in the sound of reproduced music was noticeable, especially in the articulation of consonances. Well, that's what I noticed first. I suppose the benefit is to all micro-dynamics. Getting this adjustment closer to theoretical perfection provides for just that much more of an "in the room" presence from practically every LP I played since. There is probably still a small error in my setup but I'd say it is limited to the width of the printed arc. Once Yip's protractor arrives I'll adjust things again.

Swampwalker pointed out the importance of Eyeball-to-Stylus distance, which is critical but often, umm, overlooked! Like him, I wear progressive lenses. Unlike him, I am quite nearsighted. Being able to see even the smallest styli from an E2S of 5" or less is helpful. Of course I need a hand finding the turntable...

I've never used an arc protractor and don't feel a particular need for one. All my tonearms have allowed for overhang adjustment in the headshell and I've never had a problem visualizing which direction to adjust overhang when using a two-point protractor.

To match overhang (and thus eff. length) to whatever pivot-to-spindle distance the arm is mounted at, just check the cantilever angle at each null point. If your eff. length is wrong the cantilever will be swinging through too many degrees or arc or too few (think of it as splay-footed or pigeon-toed, respectively). If the cantilever is swinging through:
- too many degrees of arc (splay-footed), make your eff. length longer
- too few degrees of arc (pigeon-toed), make your eff. length shorter

I know this isn't intuitive for everyone so an arc protractor could be a good solution. My guess is that it would take me longer. I can tweak the position of a tiny cartridge more finely than I can tweak the position of my armboard, so + or - 0.5mm for the arm mounting position works fine for me.

Different strokes...

Re: SME - I know more than one IV/V owner who's drilled out the cartridge mounting holes slightly. Not much, just enough to allow for a degree or two of adjustment to cantilever angle. Seems like a reasonable idea, especially since few cartridges are perfectly made.

In the above arc protractor thread, Richard posts a link to a set of 3 loupes sold at Edumnd Scientific Supply ... for about $5.00.

Cheers,
Thom

I agree, Doug. It's not that one protractor is superior to another. All should work very well if they are used properly. But one could work better for someone versus another style protractor, depending simply on which may seem to be more user friendly. However, getting back to original question, the placement of the tonearm is still very critical to get right no matter what protractor one uses.

I guess I don't in either Swampwalker's or Doug's "eyesight camp". My eyes have gotten bad in both near and far sight over the years. Good thing there are also great optical tools available as well as great protractors! It really is an excellent point. I think it is easier for me to see of the stylus is on or off the arc. Once I have that, squaring up to a single point is simple. As long as I don't move the cartridge screws too much forward or back, things are good. But re-checking the alignment with the arc after squaring the cantilever up is still a good idea. Just as with the two point protractor, it is an iterative process.

After using various other types of alignment tools my Wally universal is a set and forget item. I did not have any idea how far off my adjustments were till using the Wally tool. You cant miss following the arc curve for your arm type.

It would be great if a group of vinyl users got together getting one for joint use as most arm arcs or inscribed on it. It took a little time with Wally but well worth the trouble.