What defines a good tonearm

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.

Dear Mike: +++++ " 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. " +++++

IMHO the one that " rides " the recording grooves are the cartridge not the tonearm.
The main purpose of a tonearm ( even if you see it as " ridiculous ". ) is to hold the cartridge because the cartridge alone can't play.

What next?, that the cartridge could ride-free. Do you think that a bearing friction as low as 4mcg. ( like in the Technics EPA-100MK2 ) permit that ride-free condition?, IMHO certainly yes.
Which advantage has any unipivot against a fixed bearing tonearm like that one ? , IMHO none other than disadvantages: you speak of " the micro and nano wiggling ... " and is that micro/nano work the one that unipivots IMHO not solve yet.
You siad ( or Lewm. ) that the azymuth subject and unipivot rattle at bearing is solved and yes a priori is solved because many of us can't detect distortions that came from there. IMHO these to subjects ( azymuth changes and rattle at the pivot. ) exist there and were " controled " at some level but does not disappear and IMHO still have its own influence ( at that micro/nano level. ) on the cartridge/tonearm performance.

These two issues ( in a well fixed bearing tonearm design. ) just does not exist.

Now, IMHO things are a little more complex that only unipivot against fixed tonearm bearing designs. Let me put you some examples:

everyone knows the Telarc 1812 recording ( that I use through my whole test process. ) that not only has a high velocity recording levels but that those recorded HVL were mainly at the inner grooves part of the LP.
I own unipivots and fixed bearing tonearms. Well the B&O MMC2 cartridge mounted on the Grace G-945 ( an unipivot and removable headshell design ) with a 15grs. headshell " pass " cleanly the 1812 recording.
The Audio Technica AT-20ss mounted in the AT-1503MK3 ( a fixed and removable headshell design. ) pass the 1812 test with applomb too.

But, if we take the Colibrí on the Grace one or the XV-1 on the AT one: no one pass the 1812 tests .

These examples tell me that we are on the cartridge " hands ", it is the cartridge the one that " stay " or not in the groove and not the tonearm ( of course that the tonearm is important in this and other regards but it is only an " slave " that works for what the cartridge commands. ).

I don't have a Talea on hand or other today unipivot tonearm design but for my whole experiences and in deep tests about I can tell you for sure that with some cartridges one or the other tonearm will pass that test and with others just can't.

Now, IMHO other than those two subjects that I touched at the begin of this post other issue is that in some way or the other is more easy to design/handle on production an unipivot than a fixed bearing one.

Anyway, as Lewm and Stanwal pointed out: a good design with the right execution ( either design. ) works fine but I prefer a dead steady tonearm design that has not fight against its inherent unstabilities that cause tiny distortions ( normally is better to go " along " the gravity's forces, especially when what is happening at stylus tip and groove level (micro/nano) is so complex and full of " fierce " tracking forces and even temperature. ) but this is only my opinion and as you and other opinions the preferences are different.

Yes Nandric, our tonearm design is not an unipivot one.

Regards and enjoy the music,
Raul.