Alignment Snafu? Or?


Hello all, I am about to order another Protractor, this one an Arc Type from Ken Willis over at the Asylum.

Ken has asked if my arm was at 210mm, or 211mm Spindle-Pivot Distance, and taking an actual measurement this evening, I actually find out my arm is mounted at 212mm. So, may I ask what should he make this Protractor for, 212mm? Or no? Will 1mm make a critical difference in accuracy, and sound? I will forward this info to him as well, and see what he says. More input, and advice is of course better. Thanks, Mark
markd51
Hello

I just purchased a wally tractor universal. On it is an arc for rega arms with an effective length of 239 mm. I have an origin live arm, the OL specs are spindle to pivot distance 223 mm and overhang 17.24 mm, effective length 240 mm. Being a newby do I then shoot for a spindle to pivot distance of 222 mm and use the 239 mm arc or aim for 223 mm P-S and use the 239 mm or another (241mm) arc?

Thanks
Ted,

You're more likely to be able to align a cartridge at the Baerwald points on an OL arm if you mount the arm somewhat closer than the specified 223mm. The problem with 223mm is that, (i) Rega/OL arms were not designed for Baerwald and, (ii) at OL's specified 223mm mounting distance most cartridges will be very near the ends of the headshell slots and some won't align properly even when slid all the way forward.

Here's what I'd do:

1. Mount the arm at 222 (the Rega-specified distance, which is presumably what Wally scribed his Rega arc for);

2. Mount the cartridge and see if you can get the stylus to hit the arc at all points by moving the cartridge forward or back in the headshell;

3. If you can trace the arc, bingo. Square it up on the alignment grids and your're done.

4. If you can't trace the arc, even with the cartridge all the way forward, you'll need to choose another arc and another mounting distance.

G'luck,
Doug
Ted,

Forgot to mention. With an OL at 222m, aligning a cartridge at the Baerwald points will leave it slightly angled (inward) in the headshell. That's okay - as long as the stylus is tracing the arc and aligned on the grids.
Thanks . I'm assuming the general principle is to have the stylus track the (in this case 239mm ) arc somewhat irrespective of the exact manufacturers specified distances. This would imply that other arcs are equally acceptable if possible, limited only by the design of the arm/headshell/cartridge.
Part Deux,I went on today to check my mint Denon DP-2550, with Grace DA-307 Arm, S-P distance supposed to be 230mm, and evidently, the previous numb nuts mounted the Arm at 221mm Way off.

The furthest I can mount the Arm is at 228mm, so I have contacted ken, and see if a Protractor at 228mm, with nullpoints at 57.9mm/114.6mm is doable?

Not Baerwald, or Stevenson, but hopefully this will be the ticket to good sound from this very nice Table.
This is my "Quad Baby", set up with new AT-15S, and a NOS in box AT-20SLa on ice.

Just bought a spare AT20SS Stylus from LP Gear for the AT-20SLa, and understand it will fit the AT-15S as well. Ultra "skinny" Beryllium Cantilever! Looks beautiful!

Also grabbed one of those Black Nitrile "Tranquility" Belts for my VPI 19 Table, will put it on tonight, and give a listen with the ZYX Airy 3X. I'll probably be in the police logs tomorrow! Mark