Set Overhang on arm w/adjustable tracking angle

GP,

Sorry to hear of your mishap... ouch!

FWIW, the protractor Clearaudio supplied pretty much guarantees imprecise results. It's very difficult to ascertain whether you're sighting along the correct axes when centering the armwand or when squaring the cantilever. Move your head even a tiny amount and everything changes. Additionally, with just one null point you can't even double check your alignment at another point on the record. They probably chose it for its apparent simplicity to avoid intimidating customers, but better tools are available if you're fussed about such things.

You'd probably hear audible improvements with a better protractor, but whether you do or not... enjoy the music!

Thanks for all your responses. They have confirmed my suspicions of how to align the cartridge. Here's why I was confused: The arm and turntable I have included the Clearaudio protractor, but there were no instructions for using it. I was confused because it only has a single null point printed on it.

Recently, I learned that I was missing the instructions for the protractor. There is no mention of its use in the instructions for setting up the arm. I found a manual online for the Unify arm which described the way to set up the protractor. Essentially, there are two lines within which you align the wand. Then you set up the cartridge at the single null point as you do with any arm. Why there's only one null point, I can't say.

Set up was finicky, for sure, but I got everything lined up properly and proceeded to trash the tip of the cartridge. First time that's happened in 40 years! So, one cartridge to Soundsmith and a spare installed.

All's good. Thanks again for all your help.

GP

Doug,
I know there was a large variation in that cartridge dimension in the "good old days" but I was under the impression this had more or less standardised on 9.5mm. So aligning the pivot to that dimension on the assumption it will be within a mm or two must introduce less error by almost a factor of 10 when rotating the cartridge than if the pivot is 9.5mm away.

A facility for an adjustable pivot to stylus distance together with a cartridge mount that only rotates is another way to do it to avoid the two settings interacting. But then an arc protractor couldn't be used. It would have to be one based on the Dennesen principle or a standard two point.
John

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Peter,

Good thought. If one is lucky enough to have a cartridge whose stylus falls directly beneath the axis of rotation of the tonearm's mounting plate, rotating the cartridge would not affect overhang/eff. length. Unfortunately (as I'm sure you know), there's no standard for cantilever length, so having this happen is a matter of luck.

Fully agree on the advantages of the Mint for zenith alignment. No protractor I've used comes close in this regard (a Wally might, but I've not used that one).

John,

Sadly, a tonearm designer has no way to predict where a stylus will fall relative to the mounting hole(s). Cantilever lengths vary from one cartridge to another.

Garibaldi,
Doug has has given an excellent summary. The only point I would make is that your arm should have 17.31mm overhang not 14mm.

Peter,
It is interesting that few of the current arms with the facility to rotate and slide the cartridge choose to do as you suggest. It seems an obvious design advantage, particularly if the two movements are kept separate. It is, of course, simpler and cheaper to combine the two functions on a bar between the cartridge mounting holes.

John

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Doug, if the screw holding the cartridge mounting plate is directly above the stylus, would rotating the cartridge change the overhang? I follow your post and it makes sense to me in every case except the one I mention.

It seems to me that if the cartridge is being rotated along a zenith axis which corresponds precisely with where the stylus tip meets the LP, overhang becomes determined only by the position of the arm pivot point.

I find cartridge zenith alignment to be one of the key advantages of the Mint LP protractor. It is very easy to align the cantilever with the tangent lines at the null points.

Garibaldi,

You may not have set up many cartridges but you came to a good place. There are many experienced vinyl-philes here. I've set up several arms with single-point mounting schemes like your Satisfy. It's actually easier than a two-slot headshell once you get the hang of it, but it does need some practice.

I don't think I can set the overhang unless the Lofgren alignment is achieved, but I can't set the Lofgren alignment until the overhang is measured... Is this a case where I just have to adjust both alignment and overhang until I measure 14mm overhang and the correct Lofgren alignment?

That's exactly right. Overhang and zenith angle (what you're calling "tracking angle") are interdependent. Changing one alters the other and vice-versa, so we adjust them iteratively:

1. Adjust one parameter
2. Check both parameters after each adjustment
3. Adjust whichever one is more out of whack
4. Repeat steps 2-3 as many times as necessary; you'll find yourself making progressively smaller adjustments as you zero in toward ideal alignment

(Yes, it's possible to tweak one parameter while simultaneously counter-tweaking the other to compensate... this may come with practice.)

IMPORTANT - what tools are you using? Trying to align a cartridge without a suitable alignment protractor is nearly impossible.

The easiest-to-use and most accurate protractors are called "arc protractors". They include a printed or scribed arc that the stylus should follow as the arm swings across the record. They also include several alignment grids spaced along the arc. Once overhang is right (i.e., the stylus is accurately tracing the arc), set the stylus on the grid, view from the front and twist until the cantilever is square to the grid. Voila!

Free downloadable/printable arc protractors for many tonearms are posted at vinylengine.com. For a higher quality result, you can purchase a first class protractor from MintLP.com. Many here (including me) use Mint protractors with excellent results on a wide variety of tonearms. If you had a good arc protractor, all your questions would be answered. :-)

Hope this was helpful...