JMW10 3D setup.

Re: JMW10 3D setup.

Postby Ghost rider » Mon Feb 22, 2021 7:10 pm

Brf wrote:
Ghost rider wrote:Well the arc between the two are close or I got lucky or I have a tractor made for a Prime with a JMW9 arc.

A broke clock is right twice a day, sort of thing.


Arc protractors are designed for a specific spindle to pivot distance. Your null points and alignment will be off. Did you order a MintLP protractor with a 258mm S2P distance?

I just looked closely at the two closely and they are different. I just got lucky I used the VPI to set the overhang and made the null areas look eq/eq on the JMW9 tractor.

So today using a good forehead light I looked with my bare eyes and it looked good. I know if I get a loop and look again it will be off a tiny bit and I'll try to change it and it will take me hours to get it perfect or possibly as good as it is now. Sometime I need to leave well enough alone.
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Re: JMW10 3D setup.

Postby Brf » Mon Feb 22, 2021 7:43 pm

Are you saying that when you aligned the cartridge using the MintLP designed for the JMW 9, and then switched to the MintLP JMW 10-3D, your stylus tip traced the arc with the cantilever aligned at both null points the same for both protractors. Is that correct?
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Re: JMW10 3D setup.

Postby Ghost rider » Mon Feb 22, 2021 7:49 pm

jonathanb wrote:I believe each complete turn of the VTA dial equals .79mm (1/32 in.)
I have been able to confirm .79mm looks correct. Today I back to not using a mat. My Herbie's mat is 4mm you can see how I'm able to use one of my shims to maintain correct heights.

The mark just below "with mat" is where I determined to be my main height with the mat. I set that on the lower level of the arm base and the pencil mark is the bottom of the adjustable stage supporting the arm. I made a 4mm line below the original line, lowered the tower down to the line it was 5 complete turns, No guessing about it. I'd say your .79mm is spot on. Thank you for posting it.

My shim serves double duty. If I flip I can check the level of my platter. A laser line splits the top of the shim with no mat and the line with 4mm down is with a mat. Just by chance I set the laser on a record shelf.
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Re: JMW10 3D setup.

Postby Johnny » Mon Feb 22, 2021 8:52 pm

Ghost rider wrote:
Brf wrote:
Ghost rider wrote:Well the arc between the two are close or I got lucky or I have a tractor made for a Prime with a JMW9 arc.

A broke clock is right twice a day, sort of thing.


Arc protractors are designed for a specific spindle to pivot distance. Your null points and alignment will be off. Did you order a MintLP protractor with a 258mm S2P distance?

I just looked closely at the two closely and they are different. I just got lucky I used the VPI to set the overhang and made the null areas look eq/eq on the JMW9 tractor.

So today using a good forehead light I looked with my bare eyes and it looked good. I know if I get a loop and look again it will be off a tiny bit and I'll try to change it and it will take me hours to get it perfect or possibly as good as it is now. Sometime I need to leave well enough alone.


Sorry, it’s impossible that two arc protractors with different spindle to distance measurements produce the same results for a single tonearm cartridge combo. Think about it as a circle. One drawn with a 9 inch radius and the other with a 10 inch radius. How can a single tonearm with a fixed length track both circles?
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Re: JMW10 3D setup.

Postby Ghost rider » Mon Feb 22, 2021 9:45 pm

Johnny wrote:
Ghost rider wrote:
Brf wrote:
Arc protractors are designed for a specific spindle to pivot distance. Your null points and alignment will be off. Did you order a MintLP protractor with a 258mm S2P distance?

I just looked closely at the two closely and they are different. I just got lucky I used the VPI to set the overhang and made the null areas look eq/eq on the JMW9 tractor.

So today using a good forehead light I looked with my bare eyes and it looked good. I know if I get a loop and look again it will be off a tiny bit and I'll try to change it and it will take me hours to get it perfect or possibly as good as it is now. Sometime I need to leave well enough alone.


Sorry, it’s impossible that two arc protractors with different spindle to distance measurements produce the same results for a single tonearm cartridge combo. Think about it as a circle. One drawn with a 9 inch radius and the other with a 10 inch radius. How can a single tonearm with a fixed length track both circles?


I'm not saying I set the alignment perfect while using the JMW9 tractor. I set the overhang using the VPI tractor ( as good as I could using it!) Then I looked at the Best Tracktor for JMW9 and I stayed eq/eq/eq/eq off the arc line and just a little to the inside of both null points. That turns out to be damn near perfect and I could do it again if I had to. Now that I have the JMW10 tractor I'm all good.
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Re: JMW10 3D setup.

Postby edw » Tue Feb 23, 2021 10:55 am

With MintLP, once set up, the stylus will track every part of the arc perfectly (not just the null points). The stylus should not deviate off the arc.
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Re: JMW10 3D setup.

Postby Ghost rider » Thu Feb 25, 2021 12:41 pm

I looked at the alignment today and it follows the arc perfectly so that much I know is correct. I got a picture of the one null point that doesn't look perfect and like I said I think this is close enough. It's nice to know it's right and like I said I could duplicate this alignment all day long with my JMW9 tractor.
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Re: JMW10 3D setup.

Postby Brf » Thu Feb 25, 2021 12:54 pm

Ghost rider wrote:I looked at the alignment today and it follows the arc perfectly so that much I know is correct. I got a picture of the one null point that doesn't look perfect and like I said I think this is close enough. It's nice to know it's right and like I said I could duplicate this alignment all day long with my JMW9 tractor.


Looks better than good enough to me.
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Re: JMW10 3D setup.

Postby Stringreen » Thu Feb 25, 2021 4:30 pm

I used the Mint for setup on my VPI 10 inch (used to be called 10.5) plastic arm.....matches the VPI alignment gauge.
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