Curved and Straight Tonearms


Over the last 40 years I have owned 3 turntables. An entry level Dual from the '70's, a Denon DP-52F (which I still use in my office system) and a Rega P3-24 which I currently use in my main system. All of these turntables have had straight tonearms. I am planning on upgrading my Rega in the near future. Having started my research, I have noticed that some well reviewed turntables have curved 'arms. My question: What are the advantages/disadvantages of each, sonic or otherwise? Thanks for any input. 
ericsch

Showing 12 responses by lewm

Raul, After posting, I saw your earlier question to me, up the thread.  The chosen headshell offset angle and the suggested P2S distance do give a clue as to the intention of the designer regarding alignment geometry.  If you are willing to twist the cartridge (in the horizontal plane) in the headshell, then you can achieve almost any geometry with any tonearm, I agree.
Raul, I respect your opinion, but I don't necessarily do everything as you would do it.  For my 505, I do not use the Dyna spec; I use Stevenson.  Stevenson allows the cartridge body to be parallel to the long axis of the headshell and seems to sound fine.  Unlike yourself and apparently some others, I do not sit around fretting about tonearm alignment once the set-up is completed.  I just listen.  Some few years ago, I wrote on this forum that when I set up the 505 according to Lofgren/Baerwald, and as you must know too, the cartridge cannot be aligned with the long axis of the headshell (it must be twisted toward the spindle with respect to the headshell axis), and I heard some distortion that was troubling.  When I then re-aligned with Stevenson, to me it sounds better and the distortion I heard is now absent.  One must be careful about assigning cause and effect, but there was certainly a correlation between alignment and an audible distortion, in my case, in my system, to my ears.  I don't know why Clearthink is prone to hysteria, either.
One internet guru who refrains from posting here these days gave a qualified recommendation for Stevenson alignment, as follows: If your LPs are "vintage", meaning original pressings from the golden era of the late 50s and 60s, he saw a merit in using Stevenson based on the idea that those LPs have grooves nearly all the way to the label. Whereas he thought Stevenson might be avoided, if you are primarily listening to later production LPs, where there is on average a wider empty space between the innermost groove and the label. I don’t even know for sure that his assumption is correct, but there you are. For myself, I tend to use whatever alignment was in the mind of the person who designed that particular tonearm. So, for vintage Japanese tonearms that I own, I use Stevenson. Otherwise, not.

The obsession with tracking angle error causing inner groove distortion is interesting to me. Many of those who have listened to the few tonearms in production that are to be mounted such that the stylus underhangs the spindle and which have zero headshell offset angle are struck by the lack of such "distortion" (read reviews of the Viv Float or the RS Labs RS-A1), despite the fact that such tonearms generate very large tracking angle errors, especially out at the outer grooves and at the innermost grooves. Makes you think maybe tracking angle error is not the cause of the perceived (and/or measured) distortion.
Dear Nandric, Should I dip it in only the finest olive oil from Don Corleone?  I am loathe to disassemble precision devices that I may not be able to re-assemble properly.  In other words, my inclination is to let well enough alone.  I went through this dilemma with the L07J tonearm from my Kenwood L07D.  I was determined to upgrade the wiring and to create a continuous run from cartridge to phono stage, but I could not get the vertical piece of the arm structure to disengage from the horizontal piece, so as to get behind the one-of-a-kind Kenwood DIN plug and access the internal wiring.  I got it loose, but the two pieces would not give up their death grip on one another.  Rather than to risk total destruction of an irreplaceable item (as the bearings go rolling across my basement floor), I gave up. Discretion is the better part of valor, they say. Instead, I plan to run the new wire outside of the arm tube, totally bypassing the internal wiring.

Re position of the lateral counter-wt on the FR64S: I think I do have a copy of the owners manual, but I never consulted it as regards the lateral weight. I will do so now.
I am using 231.5, because I took a cue from The Tonearm, several years ago.  I even aligned it with the UNItractor, the official protractor of The Tonearm, also known to me privately as the Super Dennesen.  Using the FR64S template in the UNI, also supplied to me by DT. Thus I must be in Baerwald alignment.

Nandric, When I received my FR64S from Japan, the bearing was "stiff".  I actually followed the advice given, to leave it in the sun.  A few hours on our kitchen table in the direct sunlight coming through the window was sufficient to loosen it up.  Neither of our two sons tried to eat it. I've never had to do another heat treatment since then.
Genesis, I am using mine with a lightweight, non-FR, headshell, on which is mounted an Acutex LPM 320STR cartridge. I was prepared not to like this combination or to have a problem with bass response, at the very least, but I find that I do like it, and by this time I have been listening to it for nearly a year, off and on.  The bass has great definition within the musical envelope, with no hangover or spurious rumble. From what I have read, the FR headshells by themselves are quite heavy, and I assume therefore that they account for a significant fraction of the OEM effective mass of an FR64S.  I am also guessing that with my lightweight headshell, the effective mass is markedly reduced, although I haven't calculated it.  

Finally, the basis for Raul's criticism of these tonearms seems to be that they lack damping.  I have noted previously that in fact the pivot does seem to contain some viscous liquid that actually probably does provide a bit of damping. I infer this from the fact that at cold temperatures, the bearing becomes a bit stiff, overdamped in fact.  So, I think what might be going on is that Raul has a fact and an observation that he believes correlate. Fact: the tonearm has no damping (he assumes). Observation: He doesn't like this tonearm.  He is drawing a correlation between his listening experience and a principle of construction that may not be valid. We audiophiles commit this sin of attribution all the time. What is valid is his personal opinion that he does not like the FR tonearms, for whatever reason. I am fine with that. I wish he could stop by and hear mine.
Thank you for that input, Raul.
And thanks for your response too, Nandric.
I don't have the FR64S owners manual.  So I assumed that the lateral weight had to stay mounted on its post; I therefore have shoved it up against the pivot as far as it will go, on the assumption that my turntable is level AND that even in the extreme position, the lateral weight is doing something greater than zero to compensate for the J-shape, assuming that is a good thing to do.
I too wonder whether Raul's opinion of the FR64S has damaged its value, but since I am enjoying mine, I really don't care very much.  I would not want to be one of those who recently paid a premium for the FR66S, however, where the asking prices are up around $6-7,000.  But this is no reason for Raul not to express his honest opinion, his right to which I do defend. Nor do I doubt Raul's sincerity.
Nandric, I was just recently examining the shape of my FR64S.  Would you say it is more "J"-shaped than "S"-shaped?  That's what I concluded, J.  An S-shaped tonearm generally has two curves in it; the FR64S has one bend.  Either way, we know Raul hates it. He hates it with an intensity that seems inappropriate for an inanimate object.  I, for example, only hate certain politicians.  And yet, they pass for human.

How do you set the lateral weight?  I just have mine in close to the pivot.
So, who first promulgated that thought, Bertrand Russell or William Butler Yeats? In the Second Coming, written in 1919, Yeats wrote:
"The ceremony of innocence is drowned;
The best lack all conviction, while the worst
Are full of passionate intensity."

It doesn’t matter, really. We see evidence of the truth in these sentiments on a daily basis, emanating from the White House and its environs.


What "game" was changed by Rega pick-up arms?
I agree that the modern trend is definitely in favor of straight pipes.
Somehow, the OP's actual question about pivoted tonearms with straight vs curved arm tubes (or "wands") got completely lost as the discussion turned to turntable and speaker mass.  But most of the main points were made.
(1) As others mentioned, if the arm tube is straight on a conventional pivoted tonearm, then the headshell offset angle must be incorporated into the headshell mount itself.  As a consequence, many such tonearms bear headshells that are permanently mounted. This was a trend in design meant to maximize ridgidity from pivot to cartridge.  A curved arm wand (J or S) will generally have a higher effective mass than a straight one of equal effective length, simply because the linear length of tubing will be greater compared to the straight version. A curved arm wand will more easily accommodate interchangeable headshells of many different types and weights, because the offset angle does not have to be incorporated into the headshell mount.  There are all sorts of ideas and hypotheses about which is better, straight vs J or S-shaped, some of them having to do with resonance and some having to do with weight distribution across the S or J shape and whether one should compensate for that.
(2) Someone mentioned "very short" tonearms, like the Viv.  The Viv (and the RS Labs RS-A1 tonearm, which preceded it) is an entirely different animal.  Conventional pivoted tonearms have a headshell offset at an angle solely in order to achieve two points of tangency of the cantilever to the groove across the playing surface of the LP, using any of several standard geometries (Baerwald, Lofgren, Stevenson, etc).  The Viv and the RS-A1 have no headshell offset angle. Thus they can achieve only one point on the surface of an LP where the cantilever will be tangent to the groove, and generally the tracking angle error is greater for the Viv and RS-A1 than for conventional tonearms, at any other point on the LP.  The trade-off is in skating force.  The Viv and the RS-A1 will still generate a skating force (except for that one point where there is tangency to the groove, where skating force = 0), but the skating force is not affected by headshell offset angle, since there is none.  Conventional tonearms NEVER are free of skating force, because even at those TWO points where the cantilever is tangent to the groove, there is still a skating force due to the headshell offset angle. From my personal experience with the RS-A1, "straight: tonearms (meaning those with no headshell offset) can sound really good, better than you would expect given the much larger tracking angle error of this type of tonearm.