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  MintLP Protractor for the JMW-9T tonearm
I was just about finished with my order of a MintLP protractor for my Scout's JMW-9T tonearm when an issue with the geometry of this particular tonearm arose. Yip from MintLP at first assumed the tonearm was the regular JMW-9, which has the same effective length as the Signature version. When I sent him a link to the description of the 9T from the VPI website to make sure he knew it was the upgraded version, he said he had made a mistake as the description stated that the 9T had the same geometry as the Rega RB-300 and could be dropped onto any Rega armboard. He suggested I contact VPI to get a definitive answer about the 9T.

So I did contact VPI and they responded that the 9T indeed has the same geometry as the Signature and the same as the Rega. So I'm now a little confused why Yip seemed to think the Rega RB-300 and the JMW-9 have different effective lengths? Is anybody familiar with the above mentioned tonearms and can confirm either way to settle this? I'd hate to waste over $100 on a custom made protractor if it's made on a wrong assumption.

Thank you.
Actusreus  (Threads | Answers | This Thread)

  Responses (1-15 of 15)
Click title to read one, or click date to read all below it.

03-30-10   I have never owned a vpi but i have read many threads concer ...   2002ss335

03-30-10   My take is kip wants to give you a good tool that will serve ...   Dan_ed

03-30-10   Oh boy, my head is spinning after reading this article. so b ...   Actusreus

03-31-10   The clear answer with regard to vpi tonearm geometry is that ...   Dougdeacon

03-31-10   Actusreus... if you are still interested in pursuing this ve ...   Istanbulu

03-31-10   I forgot where i read it, but i seem to remember reading som ...   Stringreen

04-02-10   I am more than happy to report back so that we're closer to ...   Actusreus

04-03-10   Actusreus... i'm not sure of or completely clear on the impl ...   Istanbulu

04-03-10: Actusreus

The Mint protractor for the JMW-9 tonearms is made based on the mounting distance of 223mm and effective length of 240mm based on the Baerwald algorithm, which Yip uses for his protractors. The mounting distance of 223mm is what VPI used to officially state on their website before removing it. That's why Mint has been making their protractors based on these numbers. However, the vinyl engine article linked in the first response reports that the actual mounting distance on the JMW-9 is 222mm, not 223. I measured mine and it indeed appears that it is 222mm. This would also comport with what VPI told me in response to my email, i.e., that the JMW-9 has the same geometry as the Rega RB-300, which has the mounting distance of 222mm. If so, the protractor for the JMW-9 tonearm should be made based on the mounting distance of 222mm and the effective length of 239.5mm under the Baerwald algorithm, and NOT 223mm and 240mm, respectively.

That is why I wonder if the JMW-9 protractors are actually correct. Because VPI refuses to reveal the actual measurements, it is difficult to determine exactly what numbers the protractors for VPI tonearms should be made based on. That's why I wanted to try a set-up with both to compare.

Hope this clarifies my previous post.

Actusreus  (Threads | Answers | This Thread)

04-03-10   Actusreus... thank you, and i was afraid you might actually ...   Istanbulu

04-03-10   First off, yip has been extremely professional and helpful. ...   Actusreus

04-04-10   Hi actursreus... i agree about yip and his professionalism a ...   Istanbulu

04-08-10   Istanbulu, to provide you with an update: -i contacted vpi ...   Actusreus

04-08-10   Yes, yip is one of the good guys in this business. let me kn ...   Istanbulu

05-10-10   I thought i'd provide an update as i received my mint tracto ...   Actusreus

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