Questions about the Chpratz protractor

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p_m
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Questions about the Chpratz protractor

Post by p_m » 13 Jul 2019 03:07

Can this protractor be used for any pivot-spindle distance and effective length ?
And can it be used regardless of any standard alignment (Baerwald, Loefgren, Stevenson) that your turntable is setup for ?

JoeE SP9
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Re: Questions about the Chpratz protractor

Post by JoeE SP9 » 14 Jul 2019 21:17

Two point protractors are made to follow one of the three alignment schemes. They are universal.

georgesgiralt
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Re: Questions about the Chpratz protractor

Post by georgesgiralt » 14 Jul 2019 21:25

Hello
If I'm not mistaken, the Chpratz protractor is devised to measure the distortion of your setup.
You set your arm up using your favorite method and manufacturer values (spindle to arm pivot distance, overhang, etc...) and after that, you use the Chpratz protractor to measure the distortion you will get at various point of a record.
It is not, per se, a device to set your cart and arm up.

JaS
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Re: Questions about the Chpratz protractor

Post by JaS » 15 Jul 2019 09:00

p_m wrote:
13 Jul 2019 03:07
Can this protractor be used for any pivot-spindle distance and effective length ?
And can it be used regardless of any standard alignment (Baerwald, Loefgren, Stevenson) that your turntable is setup for ?
(a) Yes

(b) Yes and no. The protractor has null points between 60 and 150mm, but headshells only have limited adjustment for accommodating different cartridges using the standard alignment. If you try to align to null points that require radically different offset/overhang then you may run out of adjustment.

p_m
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Re: Questions about the Chpratz protractor

Post by p_m » 15 Jul 2019 17:11

Thank you all for your responses.
So this protractor basically shows the tangent to the groove distance marks. And the +/- error in degrees if the stylus was not perfectly tangent to the groove at the point.
Correct me if I am wrong - technically this protractor can be used to align a cartridge but with practically some amount of trial and error. You aim for the least amount of error at the end points as well as throughout the stylus arc.
If so it would be particularly useful to owners who struggle getting their stylus aligned to any standard alignment. I have seen several posts of users having a difficult time aligning even to Stevenson alignment (which requires the shortest arm length).

georgesgiralt
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Re: Questions about the Chpratz protractor

Post by georgesgiralt » 15 Jul 2019 17:40

It is useful to check that the protractor you used is good for your setup.
Example set your device with Stevenson and use the Chpratz to measure the minimum and maximum error. Change setup by using another protractor and re-check. Choose the system which gives you the least error throughout the record.

JaS
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Re: Questions about the Chpratz protractor

Post by JaS » 15 Jul 2019 18:16

It's used the same way as other 2-point protractors, except that you can choose the null points (to the nearest 1mm). For example you may want to align to known original null points, or to custom null points optimised for 7 or 10" records. The angular error lines help visualise how far out of alignment the cartridge is at the null points during the alignment process.

Once aligned you could also use the tool to measure the amount of tracking error at other points on the record, but to be honest it's easier to plot the tracking error/distortion first using software, then use known good points eg Baerwald null points for the lowest peak distortion.

For example: https://www.vinylengine.com/tonearm_ali ... =calculate

p_m
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Re: Questions about the Chpratz protractor

Post by p_m » 16 Jul 2019 06:46

I do have one feedback i’d like to give to the creator of this protractor.
To improve readability the major groove distance lines could be longer and color coded. Also, horizontal straight lines across the length would useful too for checking the front of the cartridge because sometimes it’s very difficult or impossible to check the sides of the cartridge.
Again these should be color coded to improve readability. Please see attached pics to see what I am trying to suggest. I know, not a clean job but thats why I am asking the creator so that its all in pdf accurately.
Thanks!
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