Best protractor for aligning to cantilever

The protractor from www.turntablebasics.com is the poor man's version of a Wallytractor. Just $20 and usually instant shipping.

It doesn't have the finely scribed lines of a Wally, but it is built on a mirror, which just as important. No non-mirrored protractor is as accurate as a mirrored one. A mirror lets you use parallax to ensure you're sighting exactly down the intended line. Not possible on a non-mirrored device.

Dougdeacon,

Is there a mirrored protractor for Stevenson geometry? I have a vintage Yamaha YP-D8 table and if I understand correctly Yamaha used Stevenson for their arm/table alignment. I have a turntablebasics mirrored protractor that I used with my old table, but haven't used it since I got the Yammie table. I have Stevenson printed on a sheet of paper, compliments of vinylengine, but find it hard to use, since it lacks rigidity and the mirror surface. Thanks,
Rich

Here are my issues with the Turntable Basics protractor:

1) The Turntable Basics protractor is made from a 3mm thick piece of Plexiglas with the mirrored surface on the underside. The silk-screening is on the top of the Plexiglas. This 3mm gap between the mirrored surface and the silk-screening creates a series of reflections that (IMHO) detracts more from the process than it helps. I feel like I'm looking at one of those '60's spinning swirls that is sucking me back in time.

2) The Turntable Basics protractor is (again, IMHO) another example of an alignment tool that "tells you the answer" without giving you a logical process to arrive at that answer. Think about it...what you are trying to do is create a triangle of *very* precise dimensions. The Turntable Basics protractor (among others) facilitates this by defining one fixed point (the spindle), guessing at a second fixed point (the pivot) and fiddling with a 3rd point (the overhang) until you arrive at "the answer". This is insane by itself, and then throw in a table that has an adjustable pivot-to-spindle distance. It will almost make you run screaming back to digital. Almost.

And here's why I like a paper protractor:

I have a Teres turntable, and due to the arm board configuration, my pivot-to-spindle distance is adjustable. My first challenge is to make sure my pivot-to-spindle distance is precisely 222.76mm. I print out my protractor, use a couple of pieces of clear adhesive tape to reinforce the 7mm spindle hole, and use an Exacto knife to cut out the spindle hole.

Since I'm using a OL Silver arm, the mounting hole in my arm board is 25mm. It just so happens that the outer diameter of a piece of copper water pipe is 25mm. I stick this small piece of pipe in the mounting hole to bring the 25mm mounting hole "reference" on the same plane as the platter (and spindle).

Again, I use a couple of pieces of clear adhesive tape to reinforce the 25mm mounting hole (the center of which is 222.76mm from the center of the spindle), and use an Exacto knife to cut out the mounting hole. I can now use my template to ensure an accurate pivot-to-spindle distance (no guessing or approximating) and I now have 2 fixed points on my triangle.

Next, I use some painter's tape to tape the paper protractor to the platter, and the platter to the turntable plinth / base. Since I only paid $0.02 for my protractor, I don't mind cutting away the part that extends to the arm board so I can remove the pipe and mount my arm. With the arm mounted, it takes a minute or so to set the effective length and the offset angle.

At this point, a Turntable Basics protractor does come in handy to verify the offset angle...and maybe that's the whole point of this thread. But unless the rest of your planar geometry is spot-on, it is really worth obsessing over offset angle?

Now, if someone could help me print my protractor on some sort of paper-thin mirrored piece of plastic, I think we'd be on to something.

Rich,

I don't know of a mirrored protractor for Stevenson. I imagine Wally could make one...

Nrenter,

1. The dual reflections that trouble you are what gives the TTB the advantage I described above. They are its best feature. You just have to practice using them. Whiskey helps. ;-)

If you're trying to sight down the centerline of an alignment grid, having two images makes it possible to get precisely lined up. The printed line and its reflection are either directly on top of each other or they're not. This degree of precision is impossible without dual images.

2. No need to guess at the second fixed point (the pivot). A length of thread makes aiming the TTB (or any universal protractor) simple and highly accurate.

A. Tape a length of thread to the beginning of the protractor's sight line. Make the thread long enough to reach across the protractor and over the top of the tonearm pivot.

B. Aim the protractor roughly and pull the thread gently taut, with the free end crossing directly over the pivot.

C. View the thread from directly above. Move your head back and forth to align the thread and its reflection from the mirror. This guarantees you're sighting exactly vertical.

D. Pivot the protractor until the sight line, the thread and the thread's reflection all line up. Voila! A perfectly aimed protractor. Simple, repeatable and exact.

(Thanks to Frank Schroeder for this tip.)

I don't see how an adjustable armboard affects the use of a cartridge alignment protractor. I have a Teres too. The function of the swivelling armboard is to set tonearm pivot-to-spindle distance. Once that's locked in you don't move the armboard again unless you change tonearms. By the time you're ready for cartridge mounting, the armboard is fixed.

If using a universal protractor, absolute precision in pivot-to-spindle distance is unnecessary. That's the whole point of an aimable protractor and headshells with slots. Pivot-to-spindle is a hair off? No problem. The protractor will automatically produce a pivot-to-stylus dimension to compensate. If the stylus is square at both null points your triangle is correct, by definition.

BTW, if you're using a Baerwald protractor with an OL arm, you may have better luck mounting the arm at ~220mm than the stock distance of 222.76. Regas weren't designed for Baerwald and some cartridges aren't long enough to reach the Baerwald null points with the arm mounted at the stock distance.

Now, if someone could help me print my protractor on some sort of paper-thin mirrored piece of plastic, I think we'd be on to something.

That would defeat the major advantage of the mirror. See #1. :-)

Nrenter, I think the Dennesen addresses the concerns in your Issue #2. It adjusts for the triangulation between the table spindle, the arm pivot point, and the overhang. It includes an indentation for the stylus tip which falls on the proper overhang arc. While not a mirrored finish (as stated earlier, both metal and plastic versions were produced) there is a reference line etched on the surface that passes through the stylus tip point. I find this line easy to use in aligning the cantilever for offset.

My recommendation for the Dennesen is based on it's accuracy and ease of use. I've owned and used multiple protractors, including the DB, and the Dennesen is the hands down winner for me.

Unfortunately I believe both Dennesen models have been out of production for some time, but may appear on the used market from time to time. A new device, the Frickert, appears to be very similar in design although I have no experience with it.