Santa Baby! re. 2nd pivot Mod Tweek

Re: Santa Baby! re. 2nd pivot Mod Tweek

Postby gene9p » Wed Mar 22, 2017 10:37 am

I would try setting it up with out peeling off the cover of the adhesive tape. This way you could move it around until you find the correct placing. A little blu tac on the bottom will hold it where you want it b4 making it permanent. Of course for everyone who gets it right, there will be a bunch who get it wrong...LOL.
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Re: Santa Baby! re. 2nd pivot Mod Tweek

Postby Mat » Wed Mar 22, 2017 10:48 am

Hi everyone, sorry to hear about how much we aren't liking the instructions. Just to give you an idea on where it came from... we sent out a few with no instructions to see how controlled situations would handle it on its on. We made and tweaked the instructions based on the feedback and then the end result was reported to work fine for setting up the Dual Pivot. Just wanted to share so that everyone knows that were was effort, a base line, and application for the instructions made. That being said, BRF strikes again. I love what he added and how he added it so the instructions have been improved identifying that the first part is for mounting and the second part (BRF's wording) is for instruction. The comment about the super glue is because the dual pivot doesn't really mount too great on the bases without the VTA on the fly base but using super glue locks the double surface down. We are always happy to take feedback and improve and I also added gene's comment because you can do exactly that. Position it first, then take off the double sided tape when ready. I promise it is not as intimidating as it sounds when you have it in person. :)
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Re: Santa Baby! re. 2nd pivot Mod Tweek

Postby WntrMute » Wed Mar 22, 2017 11:02 am

Dorian wrote:I have to say that for me, this would need to be a DRAMATIC upgrade to justify the apparent installation effort and associated potential screw-ups (by me).

I suprised at the difference in interpreting the ease/difficulty in installation. From my perspective this looks like a easy 30 min at most job. Nothing to break or damage. Even if you were to overtighten the pivot - the only damage would be cosmetic. Nothing is permenent. Cart is not disturbed. I'm looking forward to trying this mod as it seems like it removes a lot tonearm wobble and changes in azimuth over warps.
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Re: Santa Baby! re. 2nd pivot Mod Tweek

Postby Johnny » Wed Mar 22, 2017 11:51 am

Mat wrote:Hi everyone, sorry to hear about how much we aren't liking the instructions. Just to give you an idea on where it came from... we sent out a few with no instructions to see how controlled situations would handle it on its on. We made and tweaked the instructions based on the feedback and then the end result was reported to work fine for setting up the Dual Pivot. Just wanted to share so that everyone knows that were was effort, a base line, and application for the instructions made. That being said, BRF strikes again. I love what he added and how he added it so the instructions have been improved identifying that the first part is for mounting and the second part (BRF's wording) is for instruction. The comment about the super glue is because the dual pivot doesn't really mount too great on the bases without the VTA on the fly base but using super glue locks the double surface down. We are always happy to take feedback and improve and I also added gene's comment because you can do exactly that. Position it first, then take off the double sided tape when ready. I promise it is not as intimidating as it sounds when you have it in person. :)


Why don't you have BRF write your manuals :D

All kidding aside, VPI manuals have come a long way from where they use to be.
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Re: Santa Baby! re. 2nd pivot Mod Tweek

Postby Ducky » Wed Mar 22, 2017 1:04 pm

I don't have a fancy engineering degree, but I did take physics and geometry in high school. From my limited understanding, if the 2nd pivot point is not at the same offset angle from perpendicular to the arm wand as the cartridge, the azimuth will change as the arm pivots up and down i.e. on a warped record. Perhaps there should be a way to determine where this is on the counter weight ring?

I would also think there is a desired amount of weight (and therefore drag) apportioned to the 2nd pivot that would be optimum or at least a desired range. Is there some way to determine this or approximate it by empirical set up procedures?
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Re: Santa Baby! re. 2nd pivot Mod Tweek

Postby Brf » Wed Mar 22, 2017 2:27 pm

Ducky wrote:I don't have a fancy engineering degree, but I did take physics and geometry in high school. From my limited understanding, if the 2nd pivot point is not at the same offset angle from perpendicular to the arm wand as the cartridge, the azimuth will change as the arm pivots up and down i.e. on a warped record. Perhaps there should be a way to determine where this is on the counter weight ring?


Ducky, you must have been one of those who paid attention in high school. Your are correct in you observation about the location of the second pivot. The good news is that if you extend the head shell offset angle towards the direction of the bearing pivot and then draw a line 90 degrees from the offset line through the center of the bearing bell, it will result in the location suggested by VPI (just behind the side azimuth weight).

For those looking for a less technical description, the rationale is the same as for fixed bearing tonearms having their bearing's offset. Take a look at a Rega's bearing offset.

IMHO, if you position the dual pivot just behind the azimuth side weight, it will be close enough to the optimal position to mitigate a change in azimuth as a result of a change in the vertical plane.

Ducky wrote:I would also think there is a desired amount of weight (and therefore drag) apportioned to the 2nd pivot that would be optimum or at least a desired range. Is there some way to determine this or approximate it by empirical set up procedures?


Other than the fact that the load must be constant and consistent, I do not have an exact answer, but the mechanics would suggest that the force must be enough to resist the energy produced by the cartridge that would impart movement in the tonearm (which is the whole basis of the mod)
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Re: Santa Baby! re. 2nd pivot Mod Tweek

Postby Dorian » Wed Mar 22, 2017 4:49 pm

WntrMute wrote:
Dorian wrote:I have to say that for me, this would need to be a DRAMATIC upgrade to justify the apparent installation effort and associated potential screw-ups (by me).

I suprised at the difference in interpreting the ease/difficulty in installation. From my perspective this looks like a easy 30 min at most job. Nothing to break or damage. Even if you were to overtighten the pivot - the only damage would be cosmetic. Nothing is permenent. Cart is not disturbed. I'm looking forward to trying this mod as it seems like it removes a lot tonearm wobble and changes in azimuth over warps.

Hopefully you're right. I am going to let a few other early adopters see how it goes for them first before taking the plunge.
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Re: Santa Baby! re. 2nd pivot Mod Tweek

Postby Okwute » Wed Mar 22, 2017 9:54 pm

Brf wrote:
Ducky wrote:I don't have a fancy engineering degree, but I did take physics and geometry in high school. From my limited understanding, if the 2nd pivot point is not at the same offset angle from perpendicular to the arm wand as the cartridge, the azimuth will change as the arm pivots up and down i.e. on a warped record. Perhaps there should be a way to determine where this is on the counter weight ring?


Ducky, you must have been one of those who paid attention in high school. Your are correct in you observation about the location of the second pivot. The good news is that if you extend the head shell offset angle towards the direction of the bearing pivot and then draw a line 90 degrees from the offset line through the center of the bearing bell, it will result in the location suggested by VPI (just behind the side azimuth weight).

For those looking for a less technical description, the rationale is the same as for fixed bearing tonearms having their bearing's offset. Take a look at a Rega's bearing offset.

IMHO, if you position the dual pivot just behind the azimuth side weight, it will be close enough to the optimal position to mitigate a change in azimuth as a result of a change in the vertical plane.

Ducky wrote:I would also think there is a desired amount of weight (and therefore drag) apportioned to the 2nd pivot that would be optimum or at least a desired range. Is there some way to determine this or approximate it by empirical set up procedures?


Other than the fact that the load must be consistent and contact, I do not have an exact answer, but the mechanics would suggest that the force must be enough to resist the energy produced by the cartridge that would impart movement in the tonearm (which is the whole basis of the mod)



BRF, I do not have an engineering degree as well but dang it I just enjoy reading your detailed write-up and instructions :D . Shaking my head and thankful that this forum exists and we have you and other fine folks on here that take the time to share your knowledge and make things a little less intimidating. I salute you!
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Re: Santa Baby! re. 2nd pivot Mod Tweek

Postby MOON » Sat Mar 25, 2017 7:29 am

Mat,
Could you make a little video of the installation process and have it on this site under VPI video's. That would make it much easier for us and you would probably have increased sales as well which would include me.
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Re: Santa Baby! re. 2nd pivot Mod Tweek

Postby adeep42 » Sat Mar 25, 2017 11:27 am

+1 for Moon
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