Unipivot vs Linear Tracking

Linear trackers are based on the theory that tangency is the most important feature of the arm and that the linear tracking arm perfectly mimics the geometry of the cutting head of the master, whereas pivoted arms inherently display tracking distortion. However, the cutting head of the master is applying great force with a blade while a linear tracking tonearm is "dragging" the whole arm assembly across the record with a few grams of down force, quite a different situation. You could say that linear trackers are triumph of execution over practicality if they are done correctly.
I spent some time playing with one of John Elison's spreadsheets from vinyl asylum, plugging in values for tracking error for pivoted arms. I find it difficult to believe that a properly set up pivoted arm, even a 9 inch arm, has enough error to significantly "hear" the tracking error unless the arm is not set up correctly. I tend to think the audiophile imagination "knows" there is some tracking error and runs rampant to fill in the blanks to believe that 12 inch arm and linear trackers are audibly superior "because" of the geometry advantages. If somebody states they can "hear" the superior qualities of a linear tracker vs. a properly set up pivoted arm, I would be very skeptical.
I tend to believe that if linear trackers and 12 inchers sound better, it would be for reasons other than the geometry, either superior overall execution of the arm or better cartridge matching or higher effective mass etc. It is hard for me to believe that the "fumble factor" involved in a linear tracker would make it a better choice in every instance. The linear tracker seems to have many design disadvantages and pitfalls compared to a good pivoted arm. I hate to invoke the dreaded DBT, but that is one that I would like to see the results of.

I would have to concur with Cjfrbw, I've played around with the RS-3 rotary headshell vs a standard fixed headshell and from just casual listening, I cannot say that I can hear a difference in terms of tracking error distortion. But this is only from a casual 45min session when I first got the unit. I can say that I did not take any step backwards either. I hope to spend more time with it in the future. It is a new toy that has no instructions, so it will be trial and error to learn more about this rotary headshell.

Cjfrbw,

you make some very good points. why a particular product sounds the way it does is always complicated. how would one elimiate all differencs between any two designs other than a pivot and linear tracking. the answer is not likely to ever occur. so you could never get to a point where you have sufficently isolated the issues to use DBT to prove it. even then, i don't personally believe DBT proves better....at best proves differences were proved to a particular person under specific conditions at a particular moment.

so we are left to assign characterisitics based on experience.....imperfect as that might be.

my personal perceptions about linear tracking on my tt may be as much as result of the eddy current direct drive motor, and the air bearing on that motor and the 60 pound platter. it may be the vaccuum hold down, or the 250 pound plinth. it may simply be the quality of build, and not linear tracking.

my opinion is that when you do go to the trouble to do 100% of all the things that can be done to make a tt perform optimally; one of those things is linear tracking.

The linear tracking arm is without doubt a better setup than any pivoting arm, but the friction of the arm when it travels has to be reduced to near zero. Most linear tracking arms use an air bearing which is complex and delicate, and the air compressor is noisy.

There is, however, another approach which is used by my Sony PS X800 turntable. The arm is moved by a servo motor, just like the arm which carried the cutting head when the recording was made. The movement speed is biased to match nominal groove spacing, and then that speed is varied to match the actual groove spacing as measured by any angle of the arm. The arm is not fixed perpendicular to the track, but can pivot slightly: the servo moves the pivot point. The servo is well designed and does not exhibit any of the problems that some folk fear (hunting, oscillation, etc). Tracking error is maintained at less than 0.05 degree. Note that the servo approach is equivalent to a completely frictionless bearing. There is no sideforce on the stylus...not even the tiny force needed to move an arm with an air bearing.

Personally I never went into my friend's home(the Air Tangent guy....Btw,his pump was highly modified,and the bass was amazingly good/deep/powerful...in case someone decides to "go on" about air bearings hurting bass)thinking about the business of "tangency" as it compares to a pivot,and "leaning" towards "wanting" to hear his set-up in "any" specific way!...

Or anything else,other than simply enjoying the plethora of amazing LP's he always surprises me with(an understatement).

I could care less about the technical aspects of the hobby(to a point)as it is with experience,and the "you just know it",from "that" experience which drives my own approach.....So,technically I am a little above clueless-:)

One thing I "DO" know is....a superb linear/air bearing arm(a "really" good one)just "lets" a great set-up "open into a listening room better"(to me)than anything else,which happens to be attached to the cartridge!....

Nothing too technical.Just simple,repeatable observations.Alot of 'em!

Yes,I definitely think that the issue of "resonant characteristics" is at play here(to whatever degree)....

The lack of any hard contact points(within the bearing),which is a bone of contention to me....This just "has to have some sonic signature"(whether unipivot,or fixed pivot)that is affecting the "flow of musical info",on a pivot of "any" type!!No matter how exotic the bearing material is....I definitely am theorizing here,but DO believe it,as one aspect/benefit of air bearing greatness.

That is "not" to say one cannot get "superb" performance from such designs,and "definitely" the "minutiae" of set up will definitely yield the "magic" we look for.....Btw,from what I have seen,many are all to easily fooled,because it is way to easy to get "good" as opposed to "great" sound.So they stop fotzing around with set up a little sooner than the "fanatics" do....

This I can understand,because of the "pain in the tush factor",with setting up to the "N'th" degree....I have been known to wear my tennis sweatbands during set ups,and I'm damn tired of it,to be honest.One reason why I "now" charge my friends two/five glasses of really good wine,for my setup services -:)

BUT, my ears tell me music is "more organic,more right" with a great air/linear design....Whether I am "thinking about" concentrating on the equipment in front of me,or not!...

For me,it's just the way it is!!

Best