general tonearm design question

Don't worry,Doug.No problemo.Feel free to mention the 2.2,it really would be silly for me,or anyone to get offended by a product comment.So long as the product sounds good,I don't care.The past is an embarrassment to me,so don't sweat whatever you feel like saying,at any time!!
My friend just got the Phantom,and it is superb.Being that we both have "flat platters",at all times,due to vacuum,the issue of the "true" unipivot 2.2 does not seem to be a big deal to me.I never see any twisting movement of sideweights when playing LP's.Yet,I think the Phantom is fabulous.It has it's own idiosyncrocies though!
BTW,yes,the Triplanar is not so bad either.-:)
Best!

Doug. Are you saying the azimuth on a uni changes each time you adjust the VTA? Wouldn’t a unipivot simply keep a consistent azimuth over an elevation on the record? I cannot recollect that I have ever had to adjust azimuth after I adjusted the VTA on any of my unipivots, and I frequently play with VTA adjustments (almost on every record).

Regards
Paul

Doug. Are you saying the azimuth on a uni changes each time you adjust the VTA?

No Pauly, I didn't mean to imply that at all. Sorry if it came through that way.

I was suggesting that IF an unstabilized unipivot relies on stylus/groovewall and cantilever/suspension pressures to help maintain steady azimuth, then:

a) this could make it more difficult for the stylus/cantilever to respond freely to subtle groove modulations and;

b) this would tend to make for constantly changing azimuth on WARPED records. If azimuth depends on the angle of the groove walls, and if that angle changes due to a warp, then... obvious conclusion.

Point (b) is virtually insignificant IMO. An arm with fixed bearings will maintain stable azimuth relative to the platter, but if the record is warped the azimuth relationship of stylus to groove will change because the groove is changing. I only mentioned it to counter the (silly) argument that someone once offered that a unipivot could compensate for warps by changing azimuth in real time.

Of course we should all have SirSpeedy's vacuum platter. Then point (b) would be non-existent!

Doug,I honestly don't know of "any" unipivot that relies on stylus/groovewall and cantilever/suspension pressure to help maintain steady azimuth,or balancing.That,alone,would be poor design,and would surely put a "TON" of pressure on the stylus/suspension.Who knows?Maybe I have more to learn,but I don't think my arm,or my friend's VPI rely on this.
They sure sound good though! -:)
BTW,without you knowing it,I am reporting that your EP-15a listing(Nsgarsh too) aided me in getting one!I included the Exact Power Ultra-Pure to go fully balanced.THIS combo is the the biggest improvement I have made to my system in a long while!Stuff like vta/azimuth/downforce changes are WAY more obvious with super clean A/C,and I'll bet many folks don't know how much more can be had!
Best regards!

SirSpeedy,

Glad to hear you're enjoying the EP units. Have you tried the EP-15a without the Ultra-Pure? I'd be curious to know how much additional benefit you hear from the balanced power.

BTW, upgrading the power cord from wall to EP-15 also makes a significant improvement. So does putting it on Rollerblocks. Strongly recommend you try both if you haven't.

Meanwhile, about the "Wobbly" Theorem:

I honestly don't know of "any" unipivot that relies on stylus/groovewall and cantilever/suspension pressure to help maintain steady azimuth,or balancing.That,alone,would be poor design,...

Well, I'm glad you said it first! ;-) But if there wasn't a problem (aka, opportunity for improvement), why did AJ Conti and Bob Graham go to such trouble and expense to give the Vector and Phantom additional stability? You've heard the benefits on the Phantom yourself: clearer, more resolving, less muddy, etc.

...and would surely put a "TON" of pressure on the stylus/suspension

Well, not quite that much. ;-) With a vacuum platter holding the record surface flat, the only impetus for an arm to roll comes from groove transients, which are pretty small events. The pressures being resisted are only significant to a mechanism as tiny and delicate as a phono cartridge. It might not matter to a low resolution cartridge, but to an Orpheus, UNIverse, XV-1S, etc., everything matters.

Who knows?

I admit my little theory is just a hypothesis. But consider the available evidence:
- a unipivot wobbles freely until the stylus touches down
- once the stylus is under full VTF, the arm becomes more stable
- nothing in the tonearm has changed to provide this stability
What other mechanism can we posit for the system's sudden increase in stability than assistance from stylus/groovewall and cantilever/suspension pressures? What else has changed?

Let's do what real scientists do with a hypothesis. Devise a test to prove/disprove it. (I'd do it but I don't have a unipivot lying about, so you're nominated if you're willing.)

1) With the armtube on the cueing support, nudge the finger lift upward with a given amount of force. "Measure" the arm's freedom to wobble by visually noting the amplitude of angular deflection and the length of time/number of cycles it takes to return to stability. Repeat a few times until you're confident you're applying the nudge consistently.

2) Cue the stylus down onto a blank (ungrooved) section of a non-spinning LP. Repeat the nudge test using the same upward force. Note the results.

3) Cue the stylus down into a groove on a non-spinning LP. Repeat as above.

Let us know how the arm's freedom to wobble in response to a given impetus changes under each condition. If my hypothesis has merit, the freedom to wobble will be greatest when the stylus is off the record, less when on the record and least when in a groove.

Doug