"Heybrook Universal Protractor"

[Tom Henshaw]

Dear Folks,
If the Heybrook Universal Protractor is a turntable or tonearm specific protractor, why is it referred to as "Universal"? I ask because I've made my own protractor using the Heybrook null points (63.5mm--120mm). The neatness of those two measurements appeals to me. My turntable is a Trio KD-1033 with an "S" shaped tonearm. I've made the protractor from card. I've got the measurements spot-on, including the spindle hole (which I had to cut out by hand). But, should I use it--or make another using Baerwald null points?
Regards, Tom Henshaw

[JaS]

The Heybrook protractor has grids for both null points allowing adjustment of both overhang and offset angle. This is what makes it universal.

However, unlike the more usual Baerwald type which is optimised for the lowest peak distortion for IEC groove radii, Heybrook chose slightly different null points. These result in an alignment somewhere between Stevenson and Baerwald.

The orange trace in this graph shows a comparison between the alignments.



http://www.vinylengine.com/tonearm_alig ... =calculate

Regards,
JaS

[Tom Henshaw]

Dear JaS,
Thanks. On the basis of the graph you've kindly provided I reckon The protractor I've made should be good enough for the job.
Regards, Tom

[Whitneyville]

I own a Heybrook TT2 with a Grace 707 arm, and the Heybrook alignment has some "real-world LP" advantages between US and DIN spec'd pressings (if slight). I wouldn't sit up nights worrying about the difference in the Heybrook and Baerwald, though. The Lofgen B would be nearly perfect if the inner grove radius was 65mm, but you can't get there with many stock Japanese "S" arms.