What defines a good tonearm

Dear Manitunc, To respond to the closest thing to an answerable question that you have posed, with a unipivot there are issues related to not only adjusting azimuth but also maintaining a constant azimuth across the surface of an LP. The Graham and Talea unipivots have addressed this issue, but it is an issue nevertheless. With a unipivot one also has the question of the stability of the bearing. Excess vibrations disseminated from the cartridge could cause the arm wand to rattle, causing bearing "chatter". Many unipivots use some form of damping to eliminate or ameliorate this phenomenon. On the other hand, with a fixed bearing tonearm, there are issues related to bearing friction, maintaining constant friction over time, etc. Like someone else said, I have become convinced that execution of the design, not the nature of the design, is the major determinant of the performance of the tonearm. But this is pretty obvious, so I am not sure what you want to talk about in this thread.

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.

But it is the stylus tip that follows the groove, not the tonearm. If the pivot is not fixed, then energy transmitted to the stylus tip by the undulations of the groove wall, which is "music", can be lost via "wiggling". Ideally, the arm wand should be fixed in space at its distal end, IMO. Anyway, the point is moot where the very best unipivots are concerned, like the Talea, which blew me away at a local friend's house.

Dear Hiho, I was looking for your dog. Thanks. But be careful using the word "syntax", or you will conjure up Syntax himself, that man of mystery.

Dear Mike, Did you actually hear a difference between a Reed 2A and a Reed 2P? I thought the only difference between those two was the fine-ness of the VTA adjustment up and down.

Syntax, Thanks for the humor break. That is one of my favorite Monte Python bits.

Raul, What is the evidence that lowest possible friction at the pivot is a major determinant of goodness of a pivoted tonearm?

Lharasim, I am interested in linear trackers, but I am not interested in air pumps, filters, tubing, pump noise, etc, that inevitably go with them. Plus, if they are not perfectly adjusted in all planes, there is a kind of "chronic" tracing distortion across the entire LP. I agree they do sound "different" from pivoted tonearms, as a class.

This is a very intelligent, reasoned discussion. It seems we all agree on certain major points as regards the advantages and disadvantages of unipivot designs vs fixed bearing designs. And I like that Hiho mentioned the issue of azimuth adjustment (AA) when it takes place upstream from the headshell (cannot avoid also altering both VTA and the angle in space between cantilever and LP surface). But that would be the same for both basic types of pivoted tonearm. As far as I know, the only "modern" tonearm that permits AA at the headshell itself is the Reed, when ordered with the optional AA headshell. I hope you unipivot guys will agree also that it is the cartridge that needs to follow the groove and that Ralph is quite correct to say that if the tonearm per se were to respond to the groove undulations, there would be no music. What lies in between those two extremes is probably what actually happens with most unipivots. Still, I have to explain the ethereal quality of the Talea that I heard locally. It made me want one. Obviously, the Talea "works". In thinking about what I heard from it, I came to the tentative conclusion that in part I was responding to highly euphonic "imperfections" that I have heard before with unipivots in my own system. I think this is what Mike was trying to get at; there is a certain sense of freedom (still not a perfect word for it) associated with unipivots that is very beguiling. And that's perfectly OK in my book.

Dear Stevecham, You wrote, "A properly designed unpivot arm does not rock due to stylus tracking simply because the design has the stylus aligned with the pivot point". I completely agree with you, but who said that in the first place? I did not see such a claim being made here, but I may not have read all the posts. However, I cannot agree with all that you go on to claim; it seems to me that the interplay between skating and anti-skating forces, which can be neither perfect nor constant as the tonearm traverses the surface of an LP, could cause variations in azimuth as a unipivot moves. This cannot happen with a fixed bearing design. Granted, all the best unipivots use one or another of several strategies to mitigate this issue.

With a WT tonearm, which you may or may not liken to a unipivot, I have personally seen that azimuth changes dramatically over the surface of an LP. WT likes to say their tonearm has no bearing; that's the problem, IMO.

Halcro, You wrote, "Sounds like you are buying Raul's claim that anything which sounds good must be attributed to 'distortions'?"

In a word, no. Please don't re-interpret what I wrote. Further, IMO you are not even giving Raul's ideas a fair interpretation. He certainly never "claimed" that what sounds good must be therefore distorted.

I think we have converted a thread about what defines a good tonearm to a thread about what tonearms we like. It was a natural and unavoidable evolution. But then, we all agree there is no "best" tonearm to the exclusion of all others.

Raul, you actually answered my question by saying that you found there was such a thing as "low enough" bearing friction and that if you went lower, you found no audible further improvement. How low was "low enough"? Also, wouldn't the minimum acceptable friction be different for a high compliance cartridge compared to a low compliance cartridge? I think yes. And the beat goes on.

Yes, Franz. The tonearm is like the bumblebee. All logic says neither can fly, but both do. I would take issue with several of your presumptions in this last post, but I am too tired.... OK, one thing: do not waste your affection on a particular tonearm geometry over any other.