I wasn’t very impressed with the VPI protractor - too many potential error points. My current table came with a similar protractor. It has the same problem, most notably the poor choice of grid lines and somewhat loose fit of the jig. Most of the available Dennison style protractors don’t fare much better. They typically don’t match the thickness of an LP, the pivot locating rods leave room for error, and the spindle holes are too large.
If you want utmost accuracy, believe it or not, the best protractors are free. They are printable arc protractors that avoid all of these problems. The best of these is available from Conrad Hoffman’s software. You can download it here:
http://conradhoffman.com/chsw.htm
Click on "custom arc template generator..."
You only need to know the distance between the tonearm pivot and platter spindle. This is often published in tonearm specs or you might find it on the Vinyl Engine site.
You’ll want to use the "Lofgren A" (Baerwald) and "DIN" choices.
If you carefully cut the spindle hole (I use a razor blade), it will fit very snug. You adjust your stylus overhang so that it follows the whole arc, then adjust the zenith so it aligns with at least one of the grids, though I can usually get mine to align to both. You repeat this cycle until everything is perfect.The real beauty of this protractor is the grid lines for the cantilever. It has thin lines that will be perfectly parallel to either side of the cantilever when you get it right. This really helps to avoid problems with parallax error that are common with most protractor designs. It also allows for alignment at the exact height of the playing surface (you just tape the protractor to the top of an old LP).
I’ve used dozens of protractor variations, some that were quite expensive, and none yielded results as good as this free arc protractor.
If you want utmost accuracy, believe it or not, the best protractors are free. They are printable arc protractors that avoid all of these problems. The best of these is available from Conrad Hoffman’s software. You can download it here:
http://conradhoffman.com/chsw.htm
Click on "custom arc template generator..."
You only need to know the distance between the tonearm pivot and platter spindle. This is often published in tonearm specs or you might find it on the Vinyl Engine site.
You’ll want to use the "Lofgren A" (Baerwald) and "DIN" choices.
If you carefully cut the spindle hole (I use a razor blade), it will fit very snug. You adjust your stylus overhang so that it follows the whole arc, then adjust the zenith so it aligns with at least one of the grids, though I can usually get mine to align to both. You repeat this cycle until everything is perfect.The real beauty of this protractor is the grid lines for the cantilever. It has thin lines that will be perfectly parallel to either side of the cantilever when you get it right. This really helps to avoid problems with parallax error that are common with most protractor designs. It also allows for alignment at the exact height of the playing surface (you just tape the protractor to the top of an old LP).
I’ve used dozens of protractor variations, some that were quite expensive, and none yielded results as good as this free arc protractor.
