VPI 3D Dual Pivot Conversion Kit

[MylesBAstor]

[Analog21]

Myles, are you doing a review on it or just for your own personal use? Would love to hear your thoughts, if possible.

[MylesBAstor]

Both.

[Analog21]

Excellent!

[EdAInWestOC]

BTW...the VPI part number for the Dual Pivot Assembly kit is R0009

[MylesBAstor]

[jonathanb]

Ok, fine…I'll admit it:

I'm jealous.

[Rob]

if a picture is worth a 1000 words then its also worth at least a few questions so, the apparatus attached to the balance weight collar (attached pic) is the "2nd bearing" that rides on a 'thrust pad' of sorts. Is the azimuth now adjusted via the grub screw I see protruding topside and did the addition of the "apparatus" and its attendant weight require re-adjustment of the static side to side balance? I'm still struggling with the idea of a 2nd bearing and how it would improve the sound of the JMW 'arm based on it being a true unipivot.

[Joe Pittman]

I'm still struggling with the idea of a 2nd bearing and how it would improve the sound of the JMW 'arm based on it being a true unipivot.

As I mentioned in a previous thread, the dual pivot design is similar to the Spotheim SpJ tonearm, where a unipivot is supplemented by a secondary pivot point which slides on a thrust plate. The secondary pivot point prevents any side-to-side teeter-totter motion, the achilles heel of uni-pivots. In addition, the secondary pivot also allows precise azimuth adjustment. The SpJ arm was different in that the secondary pivot was fixed at the arm and the thrust plate had adjustable height which allowed azimuth adjustment on the fly.

The new dual pivot mechanism is very clever in its simplicity, ability to be retrofitted to existing arms, user installation and exceptionally low cost of $150 retail.

[MylesBAstor]

if a picture is worth a 1000 words then its also worth at least a few questions so, the apparatus attached to the balance weight collar (attached pic) is the "2nd bearing" that rides on a 'thrust pad' of sorts. Is the azimuth now adjusted via the grub screw I see protruding topside and did the addition of the "apparatus"

Yes. There's a small tiptoes shaped cone underneath that makes contact with a Teflon covered plate that glues onto the arm mounting by the unipivot.

and its attendant weight require re-adjustment of the static side to side balance?

Good question. Nothing in instructions and not sure given the arrangement would make any difference. But I will ask.

I'm still struggling with the idea of a 2nd bearing and how it would improve the sound of the JMW 'arm based on it being a true unipivot.

Idea is stability. Of course Judy Spotheim used this idea of a dual pivot though implemented a little differently a way back. Graham gets stability IIRC through magnets. Some others use damping right? Graham used to damp his arm and didn't at least the older centroid use damping? Not up on the Vector arm that Andre has but doesn't it also use damping?

I'm just did a rough setup tonight and will fine tune tomorrow. But so far definitely crazy huge soundstage, more solid imaging and bass. Also seems to have better resolution.Will need to redial in to make any sort of judgement.

But it once I play with it I'll get more info. I don't like to have the technical clouding the listening experience. Sometimes it's good to see if what hear correlates with the technical side of things.

[Rob]

the vector uses a 2nd radial bearing on its axis, it's an unusual approach that works very well. The Centroid is different than the RPM-2, which I have owned and that arm is very similar to the vector (it actually pre-dates the vector) in that the pivot base sits in a recessed well that can be run dry (no damping) or filled with fluid, Allen recommends Mobil 1, 5W instead of silicone fluids.

[MylesBAstor]

Ok I see upon further reflection what you are getting at. I just visualized needed to extend screw until just contacted the thrust plate. But I will check on that.

[MylesBAstor]

I see upon further research that Basis and Continuum both use dual pivot designs.

[Rob]

As I mentioned in a previous thread, the dual pivot design is similar to the Spotheim SpJ tonearm, where a unipivot is supplemented by a secondary pivot point which slides on a thrust plate. The secondary pivot point prevents any side-to-side teeter-totter motion, the achilles heel of uni-pivots. In addition, the secondary pivot also allows precise azimuth adjustment. The SpJ arm was different in that the secondary pivot was fixed at the arm and the thrust plate had adjustable height which allowed azimuth adjustment on the fly.

The new dual pivot mechanism is very clever in its simplicity, ability to be retrofitted to existing arms, user installation and exceptionally low cost of $150 retail.

Joe, I get that. I've owned the earlier JMW with the adjustable steel collar instead of the balance weights. I've also owned both flavors of Bob's arms the 2.2 and Phantom. As you know, the 2.2 used opposing threaded tungsten weights that could be adjusted individually to fine tune azimuth - again, very straight ahead approach. frankly, the slight wobbling never bothered me in the least It was only a minor 'issue' when cuing up a record.

What I really would like to see up close is Judy's solution that you described, I have a feeling its more elegant than VPI's approach.

[MylesBAstor]

As I mentioned in a previous thread, the dual pivot design is similar to the Spotheim SpJ tonearm, where a unipivot is supplemented by a secondary pivot point which slides on a thrust plate. The secondary pivot point prevents any side-to-side teeter-totter motion, the achilles heel of uni-pivots. In addition, the secondary pivot also allows precise azimuth adjustment. The SpJ arm was different in that the secondary pivot was fixed at the arm and the thrust plate had adjustable height which allowed azimuth adjustment on the fly.

The new dual pivot mechanism is very clever in its simplicity, ability to be retrofitted to existing arms, user installation and exceptionally low cost of $150 retail.

That is very clever but what else would you expect from Judy? 🙃

[Joe Pittman]

I should add that the goal of ANY bearing, in addition to zero friction, is absolute rigidity. I have always liked gimbaled ball bearings for their high degree of rigidity. The SAT arms goal was stiffness/rigidity if I understand correctly.

Joel Durrands latest arm, which is a uni-pivot, also uses a dual pivot concept, but instead has two sapphire rods that slide against each other. This design is hard to beat due to the hardness and low friction of the sapphire-to-sapphire sliding contact, however, it is wacky expensive. I think VPI's new dual pivot can be tweaked to improve it's performance without a lot of cost.

[astrotoy]

Thanks, Myles. So for my Classic 3, I have two wands - one for my stereo cartridge and one for the mono. Do I need two kits, one for each wand? Also do you get the kit directly from VPI or through their parts distributor Music Direct or any retailer? Larry

[jonathanb]

Yes, at this time you'd need to buy two kits. While you'll need only one skate plate, you can't buy the clamps and plates separately yet. VPI has told me they are only selling complete kits at this time as demand for the dual pivot kit far exceeds supply.

[Asamel]

A few months ago when I asked a dealer about a 3D arm I was told that I'd have to send my table to VPI to do the upgrade. There apparently is a part change that is needed. Does the same go if I want to use the 3D arm as a dual pivot? Anybody know?

[Joe Pittman]

A few months ago when I asked a dealer about a 3D arm I was told that I'd have to send my table to VPI to do the upgrade. There apparently is a part change that is needed. Does the same go if I want to use the 3D arm as a dual pivot? Anybody know?

The Dual Pivot Assembly can be installed by the user. No special tools are required. And as far as I know, it can be installed on any existing VPI arm...

[jonathanb]

It's installable on any JMW tonearm. Other arms may or may not work.

[Stringreen]

Miles you (or some other poster) alluded to the stabilization of the arm via the dual pivot as a stabilization similar to the results that damping would have. In MY experiences, damping was very critical to the cartridge I was using...too much closed in/muddied the sound....but there was a magic point where it was helpful (at least on the metal VPI 10.5 arm that I had), using the Benz Ebony LP cart. Is there a similar too much/not enough adjustment with the Dual Pivot?

[MylesBAstor]

I never liked damping in the arms I tried. But this does not sound at all like damping. Damping no matter what I did say in the old ET, VPI or Graham always killed the sound. Lopped off the upper octaves and just smoothed things out too much.

And yes but I will discuss that after some more experimenting and making sure I am doing things correctly. I saw the update at VPI's, discussed the setup over the phone with Mat but the the instructions weren't quite ready yet. So just want to double check did everything correctly. Just want to add don't do what Mikey talked about in his review because this kit is different than what he reviewed. Andre and I discussed some things tonight and he astutely pointed out that the weight of the dual pivot piece that attached to the collar under the pivot probably adds enough mass to keep the pivot in contact with the thrust plate. That is in contrast to the version Mikey reviewed and I have here too where the pivot is mounted directly in the collar and need to adjust the CW so arm tips to that side to "preload" the dual pivot.Hope that makes sense.