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
At your price point, you can consider going a refurbished Sota and start looking for a good condition Graham 2.2 arm or similar.  The Graham features VTA adjustment on-the-fly.  That is one of the biggest improvements in playback quality you can make.  You could also consider doing the same thing with a mid-priced Rega or other non-suspended table.  They may not be suitable for your installation, because it depends on how well isolated the table location might be.  Either way, you have a lot of excellent choices to consider.

Take your time, do as many auditions as you can, watch the postings here and most importantly, have fun!  Good luck & happy listening!
@yogiboy

Good points and a good article marketing the benefits of thin wall - a bit like the benefits of Rega light weight acrylic plinth and platters (in the case of Rega the sympathetic absorption of vinyl vibration is most effective when using an acrylic platter as the material is closer to the properties of the vinyl and like thin walled speakers we are expected to accept the argument that "more vibration" is "better as the material dissipates the energy")

So yes I am aware the thin wall speaker was initially designed for BBC for light weight and portability and then damped with bitumen to reduce the deleterious resonance effects and then the "magical" benefits of more resonance were discovered.

I buy the advantages of portability and light weight. I enjoy the fact my JBL PRX615M are great lightweight PA speakers (light cabinets with light neodymium magnets) that are easy to move around for my band.

However, I don’t buy their resonance arguments. Why use a bitumen damper if the resonance is not a problem? And I don’t accept the claim that the extra cabinet resonance is beneficial - all resonance should be avoided for ultimate fidelity as any resonance will change the timbre of the sound. And thick MDF built heavier speakers can have bitumen damping too - so logically when damped and heavily braced these should be even less resonant than a thin wall.

Of course "beneficial" could be construed not to mean high fidelity but desirable sound to listeners - a warmer tone perhaps or more euphonic sound - I accept that and I agree Harbeth have great mid range tone (it is more the lower frequencies that seem impacted by this thin wall type design - at least to my ear)

My two cents of course. Maybe I just prefer heavier TT and heavy speakers. Certainly you can get great sound from light weight designs: speakers like Harbeth or TT like Rega perform better than very many competive but heavier designs. However the necessary damping required tells me that designers must compensate for the tendency for light materials and thin walls to vibrate with their own characteristic resonances.
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.  
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