What defines a good tonearm

Dear Mike,
You wrote, "anything not a unipivot will always be fighting itself to travel the groove correctly". I don't get that. Can you elaborate? IMO, the "issues" facing unipivot design are precisely those related to the possibility that the bearing allows movement in all possible planes. In a "perfect" pivoted tonearm, if one existed, some of this movement has to be completely prevented, e.g., you don't want the cartridge to "roll" on its axis with respect to azimuth as it traverses the LP. Yet this is precisely what happens with poorly designed and even some highly regarded unipivots. (I don't quite know how to classify the WT tonearms or the Schroeder, but I think of them as a variant of the unipivot. The WT tonearms do exhibit this instability of azimuth. Never saw a Schroeder in action.) Restricting tonearm movement to two planes, vertical and horizontal, is much more easily done with a fixed-bearing tonearm, not to say that is the only path to Nirvana.

Dear Syntax, In fairness to those of us who do like an idler turntable now and then and who also dislike the term "PRaT", I think the term was coined by Ivor Tifenbrun (sp?) with respect to the Linn LP12, which of course is a belt-drive.

hi Lew,

my perspective is that the most significant percieved and discussed weakness of a unipivot is actually it's biggest advantage, which is the freedom to wiggle. it is the micro and nano wiggling following the groove unimpeded that gives it the advantage over a fixed/gimbaled bearing pivoted arm which on the micro and nano level cannot follow the groove as well.

to take full advantage of the conceptual and theoretical advantages of unipivot is an engineering hill to climb. but along the way to the top of that hill i think the very best unipivots have already passed the best fixed/gimbaled arms.

i do think that 'back in the pack' it's hard to choose from different design approaches as execution is more significant than concept......and there are so many varibles in arm construction.

but at the cutting edge it's unipivot and then everything else.

So Mikelavigne, what do you think is the current state of the art in unipivot arms and why? And Lewm, the same question to you for fixed pivot arms. And is there an arm in either camp that you think gets it all wrong. These last few posts have been very helpful.

Part of the problem I see, as a hobbyist, is that we never get to hear what can ultimately be achieved by our systems. We only get what we think is the best our systems will provide and whether we like it or not. I guess that's why I do put some faith in reviewers like Fremer just because he has had the opportunity to hear the best, set up by the designer or factory tech, so he has some frame of reference as to what can be achieved, to compare to the item under review. Now of course, he has his biases, just like we all do, but he has a frame of reference that I could never have. So posts like yours are how I learn.

I am of course reluctant to start a new 'war' but our 'own' Raul and Dertonarm must have some very interesting ideas about this subject matter. They should be able to enlighten pros and contras of the unipivot, the usual steel bearings or the jewel kind of bearings. Not to mention the knife kind for obvious reasons.

Regards,

So Mikelavigne, what do you think is the current state of the art in unipivot arms and why?

ok. but first, a caution that i'm an observer of performance and maybe even process, but really no technical guy at all. like anyone that is around all this nice gear i have some level of understanding of cause and effect but only 'some'. so me telling someone 'why' something does something is of limited value.

all that said; the very best arms i have heard are the Durand Talea 1 and Talea 2 in my system, in other systems, and at shows. i would also add the Continuum Cobra to these 2. i've heard the Cobra 5 different times at audio shows.

i cannot say whether the Talea 2 betters the Cobra or vicsa versa as i've not heard them side by side. but i do hear similar type things from both, and those things are unique. so i'd say these are the current state of the art. with these 2 arms you hear the least arm distortion.

the music leaps from the grooves without added coloration, note development is more complete, micro-dynamics are un-fettered, bass is deep and tonally rich, you have a vivid clarity and delicacy, the music gets in you and is experiential.

the Rockport Sirius III linear tracker approaches close to these arms in some ways, is not as close in some ways, is slightly better in a few ways.

why do the Talea and Cobra do what they do?

i think they have the correct design concept, and have considerable techincal development and quality of manufacturing and assembly to be more optimal of the concept than other unipivots i've heard.

these are simply my observations of the situation and my conclusions.