MintLP arc protractor

Greetings,

The problem here is that the turntable in question has already had its tonearm mounted, and save some potential play in the mounting hole, its pivot-spindle distance is fixed.

Normally, you establish a pivot-spindle distance from the effective length before mounting the tonearm, but using (for example) the Ellison spreadsheet, you can work this backwards.

So, assuming it's an accurate Rega Stevenson mount, you have a 222mm pivot to spindle distance which resolves to ~ 237mm eff. len. for Stevenson and ~239.3mm for Baerwaald.

This 2.3mm (approx.) difference is what Doug was referring to when he said you might run into problems with a "short" cantilever - meaning a cartridge whose stylus is positioned considerably closer to the mounting bolts than the 9.0mm statistical norm.

There's a potential for your not being able to slide the cartridge forward enough in the headshell slots to achieve the 239.3mm effective length. This is why Yip is being so persnickety.

As Johnbrown wisely suggests, you can do a proof of concept by printing out a Hoffman protractor. This will set your mind at ease.

Cheers,
Thom @ Galibier

Johnbrown's suggestion is perfect and exactly what I did with my setup when ordering from Yip to insure everything was going to work with the parameters I provided him.

Got my Mint protractor yesterday and checked my alignment then and again today.... It is "spot on" across the arc. Seems that I either did a damn good job using my various tools or just "got lucky."

Don't know whether to feel gyped or proud. :-}

Doak

Just think if it this way, Doak. Now you have a tool that can provide repeatability. :-)

Oh, and don't stop at just getting the arc correct. There could well be more improvements waiting for you.

Doak,
I found that I was close to being on the arc of the Mint with my SME protractor but cartridge zenith (rotation) was way off. Dan ed is correct to suggest to also check cantilever alignment at the null points using the Mint.