[Ericus Rex]

Seems like 9 out of 10 arms made in the '80s had S-tubes.  Now I can't think of a single current production arm that has one.  Is the straight tube just the 'flavour of the month'?  Or is there science behind the shift?

[AudioSoul]

   The Technics Sl-1200 is current production and has a "S" shaped tonearm. Although I hear it may be discontinued

[Uptown Audio]

Seems like 9 out of 10 arms made in the '80s had S-tubes.  Now I can't think of a single current production arm that has one.  Is the straight tube just the 'flavour of the month'?  Or is there science behind the shift?

The Ortofon arms are of the S shape with detachable headshell and are of very high quality. These are custom made in Japan with Ortofon's unique bearing design by the Jelco company who also make some of their own arms. The Rega tonearm design pretty much turned the analog world on its head and even companies such as SME who have traditionally made excellent S shaped tonearms (they still have one too I believe) have been making their newest arms with tapered arm tubes.

You don't really need an S shape, but you do need an offset angle from the straight tube design in which to mount the cartridge. You can either offset the headshell or you can offset the tonearm and use a straight headshell. There are plenty of designs that use either approach and neither is really superior in that the offsets accomplish the same thing. The S shape arm did have a couple of problems that the Rega arm addressed and so all modern designers are aware of it, whether they address it or not. That is that the tube in a conventional sense is uniform and so has a specific resonant frequency. That's not a good thing. They also had the problem of tolerances and fitting quality with the detachable headshell and that also causes noise through the resonance of the interface. If you have had the experience of mounting a nice quality headshell to a high-end Japanese or an SME arm, you would notice that they fit much better than those of the cheaper DJ arms, whether Japanse or Chinese, etc. it's not a country of origin issue but rather an issue of quality.
-Bill 

[toobluvr]

Moerch is current production.  Don't know if it's considered a true "s", but it sure ain't straight!

[Wayner]

A curved arm tube is hard to control tolerences at the bends. Straight is much easier.

Wayner 

[jsaliga]

I recently upgraded from a SME 3009 Series II (S-shaped tonearm) to a SME 309 (tapered straight tonearm).  To be honest, I liked the sound of both of them.  Most of the cartridges I owned were compatible with both.  The 309 is slightly lower mass than 3009 SII.  However, since the 309 is of a more modern design it has some features that make setup a little easier and somewhat more precise.  Other than that, I was happy with the performance of both arms.

--Jerome

[macrojack]

Looks like Jerome and Wayner combined to answer this question. If equal results can be achieved by doing something in a simpler, easier way, ultimately the more complicated, difficult, and probably more expensive approach will be abandoned. Hence, no mo esses.

[Uptown Audio]

Looks like Jerome and Wayner combined to answer this question. If equal results can be achieved by doing something in a simpler, easier way, ultimately the more complicated, difficult, and probably more expensive approach will be abandoned. Hence, no mo esses.

Actually, the best straight arm tubes, which are cast and tapered, as designed first by Rega and then adopted by SME, are much more complex and expensive. The research required to even make it possible was very costly and then the production process is also more complex and expensive. A homogenous, uniform tube arm whether bent or straight is the easiest and least expensive to manufacture. As far as the S shape goes, tolerance at the bends is not that critical. That is adjustable during final assembly of the arm and further, even if the final product was not 100% accurate, the cartridge mounting provisions always allow for adjustment to get the installation as close to perfect as possible for each set-up before actual use.

The S shape has also become unfashionable with the advent of more modern designs. Much as the S shape tube arm displaced earlier molded, cast, or formed arms of irregular channel shapes earlier. Each advanced the state of the art by offering new features and introducing new standards for performance. So as each design introduction offered  improvement, it became less attractive a proposition to use the older design styles.

While it's true that in many cases, simpler is better, as it is in terms of value when comparing a tangentially mounted tonearm to a linear tracking design, the design of the respective arms vary in terms of complexity within their own type and the more complex are often the better performing designs. For instance, even though I find linear tracking arms to be horribly inefficient and impractical designs, within this type of arm design, the more complex air bearing designs are better at doing what they are designed to do than the cog and belt diven oil bearing designs. I find the same holds true with the more advanced tangential arms. The better the design of the parts, in this case of the arm tube, and the more precise their fit, the better the resulting performance.
-Bill

[jsaliga]

The only point I was trying to make is that in this instance, design is somewhat less important than the implementation.  While the SME 309 offers some conveniences that the classic 3009 SII lacks, both are great performing tonearms when paired with a compatible cartridge.

--Jerome

[Wayner]

The Rega arm tube is investment cast. Not that complicated, really. It solves many assembly problems by combining parts. Then the arm tube gets machined in a CNC machining center. Very automated, less error, less parts. They could of just as easily cast a S-shaped arm if they wanted to, but why?

Wayner

[Ericus Rex]

So no one thinks there is a scientific reason for most arms these days being straight?  I.E. "Straight arms are better at ______________ which modern science has determined is better for ________ and S-arms cannot properly handle this new factor."  I had always assumed, like Bill, that the shift was due to appearance mostly.  You know, when I look at a Micro Seiki 505 with an S arm I think 'ah, the 80's!'  I don't think that when I see an SME V or a Graham.  I guess the Jury's still out on the ease-of-manufacturing part.

[Uptown Audio]

So no one thinks there is a scientific reason for most arms these days being straight?...

I don't think that it is just looks at all, I just pointed to the obvious of how they looked as example of how they were made and the technologies that were behind them. I thought that I mentioned that the S shape arm tube was in fact, just a tube, and so had a specific resonant frequency. The advantage of the Rega and new SME designs in their tapered shapes help to stop this resonance from propagating up the arm and back. That's a real scientific advantage. They have varied wall thickness and diameter which helps this but it also has another function. It increases the arms stiffness to mass ratio. That's another scientific advantage. It isn't that they are straight, it's that they are uniquely designed and manufactured.

These arms are without question more complicated and more difficult to manufacture. It is easy to say otherwise but let's see the arms from the smaller companies who cannot afford the huge expense of developing a good casting which are anything but tubes. Tubes are the easiest thing to make and the cheapest to use and most manufacturers just buy stock tubing and cut and bend it as they need it. Some use custom tubes but that is rare indeed. Any other shape is also going to be quite expensive to make or it just will not work as well. Dynavector for instance uses a rectangular structure for the main arm section of their tonearm and their tonearm is anything but straight. The individual components are all straight and rigid but the complex design allows a tremendous range of adjustments. This is an example of a non-tubular design that is not cheap and yet doesn't use a cast arm tube. It is quite the exceptional exception, of which there seems to one for almost every rule.

 

This doesn't rule out some unique and uniquely made arm shapes using other materials and methods. There are carbon fiber/resin arms of various shapes and even some more unique materials and shapes such as those found in the Continuum Cobra arm. Those can be about any shape that the designer wants whether it makes sense or not and really don't fit into the discussion of popular arm tube shapes as such. The most popular design for these is still tubular though just because it is easy to make and it is a strong shape. More companies are using synthetic tubes from fiber and resin now. One disadvantage of these is EMI/RFI shielding.



There are many straight arms that are horrible. Some of the cheap Stanton tables are equipped with straight arms that do not allow correct alignment of a cartridge, period. That's abysmal design and the tragedy of those things doesn't even end there. Many times, it is a case of getting what you pay for. Cheaper doesn't have to be worse but it is seldom better. The point being that it isn't about straight or curved, it's about design and quality.

The science isn't new; it's old school mechanical engineering. It does have some new twists which have just entered the market not because the concept was so new but that it just hadn't been implemented yet. Some of these arm ideals have been on many engineer's dream lists for a long time. The chief obstacle is cost. Basically no one cares about hi-fi sound, so the market is pretty small. The comparatively few really gung-ho audiophiles who would love to have a great arm may not have the money to buy them. So few companies can produce tonearms that have such advanced features at prices that we all can afford. Rega hit the mark on their design more so than any other maker. They did it by investing in a casting and then using that same arm tube casting on every arm that they make and then installing those on every turntable that they sell as well as offering the arms to other turntable makers who cannot develop better arms or even find them available elsewhere for less than the Rega. It is clearly great value and so has become the most popular tonearm in the world for use on hi-fi tables, regardless of the brand of manufacture. Only very recently has Rega made a cheaper arm for use on their budget table so as to be able to offer a product that sells at the same price points as tables made in less affluent countries, while still keeping production in their Essex factory. In fact, before they developed their own cast arm tube, Rega bought arms from a Japanese source and they were, wait for it... S shaped. It is just a case of economics. They were able to make the casting for their arm tubes because of their scale of production. It took a long time for it to pay off but they use the same tube on every arm so it worked out for everyone. The difference between the arms is then not the arm tube itself but the amount of prep and finishing which goes into them as well as the tolerances. The better arms get more machining and attention to get them more perfect and to accept better fits from the parts, plus they receive better parts other than the arm tube to form the complete product.

SME uses a casting also and it is very high tech and costs a lot more money. They obviously will not sell as many as Rega and so each arm is quite expensive although they are also excellent. I do prefer the 309 style cast arm over the 3009 tubular arm. It performs better. Both are quite nice actually and the original SME S shaped tube arms are no slouches either. I just sold a very fine Japanese arm which was based on the old SME design. One advantage of these styles is their interchangeable headshells. It's sort of a curse and a blessing actually as there are advantages to not having the interface there also. If the companies who make the S shaped arms use better parts and pay more attention to how they are finished, they could make some very nice arms. Again, that costs money and most companies just don't do it, they'd rather put the money in the bank than into your tonearm. There are still a few exceptions such as the new SME S shaped arm, although it appears to only be available in a 12" length, and the Ortofon tonearms. Both of these company's S shaped units are of very high quality. I am sure there are several more examples from smaller companies but at higher prices.
-Bill 

[Wayner]

I think the number one reason to create an S-shaped arm to begin with is to cancel vibration transfer up the arm tube. After all, it's called a tone arm, but we really don't want the tone to go up the arm, but rather the cartridge. We need the arm to hold the cartridge in a very ridged way controlling the geometry of the arc, allowing it to move up and down or side to side with little or no effort, but with zero vibration going up to the arm tube pivots.

Many straight arm manufacturers are now putting damping material inside the arm tube to further dampen the straight arm. The taper shape was also important to the straight arm to help cancel ringing and other wave transmissions. Some straight, none-tapered arm tubes also have a damping sleeve on the outside to reduce energy transfer.

Wayner

[Ericus Rex]

Thanks for all the great info everybody!  I do appreciate it.

Bill, I guess I just got hung-up on this line from you:  "The S shape has also become unfashionable with the advent of more modern designs."  That line supported my idea that appearance was ONE of the main factors.  Thanks for straightening me out with the follow-up, very informative post.  Wouldn't it be something if someone comes out with a dampened, tapered, cast S arm in the near future!  Maybe it's been done already but I dont' know of one.

Thanks again guys!

[Wayner]

Also, the "S" shape was a nice transition piece to disguise the cartridge's offset angle, that in the old days may have been interpreted as a manufacturing defect by the less then savoy. A perfect example of this is the AR-XA arm in which the fixed position headshell, was in perfect transition from the arm tube. Since that head shell had only 2 bosses to mount the cartridge, the included pointer and stylus seat set the way AR intended. So you could say, the S shape was around for looks.

Wayner

[Uptown Audio]

I wondered about the choice of words as I was typing. I thought it fit but it did make it sound as if it were more about looks. As Wayne points out again, it really is about looks though. The tube does have quite a bit of functionality and it was an improvement in that sense over older arms as a tube is structurally a very rigid shape in relation to its weight. The bends do have some effect on reducing the transmission of energy up and down the arm but it doesn't really stop it. Damping helps attenuate it further, so by having both an S shape and an internal or external damping material, you could control some of that. This has some drawbacks as pretty much everything is a trade-off. Both the S shape and the damping add material to the arm and so increases its mass without increasing rigidity. In fact, these measures can create some delay of energy release which blurs the sound. So you solve one problem and create another. If the first problem is really bad, then the solution might be more appealing.

The whole thing about the bend was really about getting the offset angle correct. That is getting the stylus to sit in the record groove as parallel as possible with the groove walls. Your adjustment is then just more or less to move the cartridge body forward and back in the headshell to get the overhang correct. In reality, it takes more than that and you use a protractor/gauge to align the cartridge. But the S shape tonearm makers were happy to just supply you with an overhang gauge that made it really easy for anyone to get it close. It also looked more square as the cartridge wasn't askew in the headshell. So that's where the "It looks better" comments come from.

The straight arms are never straight up to the end of the arm tube, the headshell must be angled to allow for this alignment. Otherwise things are very wrong. One of the biggest trouble spots for tonearms is the headshell and so a few makers have done away with them entirely. The less there is there to futz with, the better the design IMO. If you want real headaches, get an old Thorens or dual that had complicated headshells with integral wiring. Way over-engineered and wrought with problems these days. They worked well enough for most when new but were still a pain to mount cartridges to. Some were so odd that they had to have custom designed cartridges. Ortofon was happy to oblige and made cartridges for Dual. They even made some (quite nice ones actually) for B&O for their unique tonearms, which were straight tubes with a J bend at the cartridge end. The B&O style cartridges are now pure unobtainium however, frustrating many B&O turntable owners as they made some nice sounding and good looking tables.

   

-Bill

[Wayner]

The whole thing about the bend was really about getting the offset angle correct. That is getting the stylus to sit in the record groove as parallel as possible with the groove walls. Your adjustment is then just more or less to move the cartridge body forward and back in the headshell to get the overhang correct. In reality, it takes more than that and you use a protractor/gauge to align the cartridge. But the S shape tonearm makers were happy to just supply you with an overhang gauge that made it really easy for anyone to get it close. It also looked more square as the cartridge wasn't askew in the headshell. So that's where the "It looks better" comments come from.

-Bill

Yes, Bill, we are both on the same page! It certainly was an evolutionary process, as it should be. There comes a point where cost (usually in the form of higher labor) outways advantages of a particular design. I too love the Rega arm (RB300) and the more expensive SME's, tho they have more "gimmes". I have often wondered about an ultimate arm, one with almost no moving parts. Some have come very close. The Well Tempered arm hanging from monofilament comes to mind as it breaks from traditional design, tho I not sure how well it works.

In any event, Most of us realize that the tone arm is a very tasked device and the differences between success and failure may be small.

Good topic.

Wayner 

[Ericus Rex]

Definitely a good discussion!