general tonearm design question

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

You could test unipivots for azimuth stability by throwing on (just said that to make Doug cringe ;--) an SQ Quadraphonic record. Its groove not only deflects the stylus left-right-up-down, it TWISTS it CW and CCW!
.

Hah! Great idea! Mozart wrote a piece called 'Notturno for 4 orchestras'. I have a London blueback copy in stereo, but I'm sure it would sound more like what he had in mind in quad. Surround sound ain't exactly new! ;-)

Doug,truthfully I don't hear anything in my friend's Phantom/Orpheus combo to make me want to change arms!Of course we have not done a side by side comparison,but I installed the Orpheus in his 2.2,and a dealer did it when the Phantom came( I know his system like my own).I,then,re-checked and voiced it to a more acceptable(to our circle of guys)level of performance.The Phantom is superb,but you are WAY underselling the 2.2!Old story,but NO problemo!!-:)
The Orpheus IS another story!I definitely like it WAY better than the Temper-v,which he had(I still do,but need more hours to justify a change).
Mind you,I really don't have much enthusiasm for the hyper technical(though I have NO reason to doubt your theories,which are usually well thought out,btw)comparisons,to prove something on paper.This does NOT mean you are not absolutely correct,but my 2.2(especially after the NEW Power Management System)is "really" giving me incredible performance!Could care less about the magnaglide as my arm NEVER tilts/rocks during play(really).I sense just a bit more air in the 2.2,with more weight in the Phantom(sort of like the superb SME-V,here).

I DO know what my Mercs,Lyritas,Deccas etc should sound like,and believe me if a unipivot sounded anything less than superb my friend Sid Marks,the LP maven(in spades) would never have sold his Air Tangent,and replaced it with a Unipivot design.Though I definitely liked the AT better.If there was a problem in my tracking,he would "destroy" me,and it is his dogged critical nature that has rubbed off on me,and gotten me in trouble on this site.Yet you are being a bit too picky,and trust me,I know not to tread too heavily with you,here!The performances,with all the other variables in place are really NOT all that big.
For that matter,the argument made by the reviewer,talking up this new arm called the SEPTUM(see the TNT website)has as much credibility,for "low parts count" as your argument against unipivots.He writes a very engaging design description,that makes alot of sense to me,but I am getting way to long in the tooth to argue anymore.My 2.2 is admittedly VERY finicky to set-up(that fluid again).Way more-so than the Phantom,which is less critical to fluid,but I like the latitude available(at least to me)with the 2.2's flexing of parameters.That is JUST me.Meaningless to anyone else!
I do have superb aftermarket cords on the EP stuff.The 15a came after the balanced Ultrapure,but it greatly enhanced the Ultra's performance.I am a big believer in fully balanced,so I never went the other way.INCREDIBLE combination!!!!!
Well,thanks for the communication,and best to you.