Straight Tonearm vs. S-Shaped Tonearm

Very few, if any high end arms are bent.

True, and I doubt many would say the big players in arms wouldnt bend them if it were indeed better, they dont go about things in budget terms, nor do those who purchase them. Prefer what you like and why argue?, but some suggest Straight Arms are inferior and made because its cheap........I dont know how that debate holds weight based on the products offered today and the mission of those who make them as its about best sound at all cost, not best sound at low cost.
 
Radial tone arms can have dynamic tracking angle with 0 degree all the way.

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This is just an example.
I am sure I saw other attempts of integrating zero tracking angle into radial arms.
However, the audible effect of mistracking in traditional radial arms can be very hard to detect if at all.

"dolph"
 
So, as usual, it comes down to features that match the users preference and quality engineering and execution. I prefer swapping carts as I deem it needed. I also like to play various masses of headshells as I tune the response of any cartridge - so for me it's the J or S and I can mostly afford vintage S, so that's the way I swing. Since I still tape record, I find it easier to tailor the LP sound from pick-up rather than try to process down the line.

Others may want to mount only one cartridge for its life and deal with the sonic issues in other ways. For them an ultra-lite straight arm will be fine. It's not only audio performance, but work flow too :)
 
Radial tone arms can have dynamic tracking angle with 0 degree all the way.

1.jpg


5.gif


This is just an example.
I am sure I saw other attempts of integrating zero tracking angle into radial arms.
However, the audible effect of mistracking in traditional radial arms can be very hard to detect if at all.

"dolph"

I want one of those!
 
Why did we go to short straight arms? We know they are easy to design and cost much less to make. Lower cost, lower price, expands the market to consumers who could not afford, or want, the best.

Bean counters and profit motivated do not mind if we forget what we learned in physics classes.

Thanks for the intriguing post. I don't claim to know the physics of it as well as you do. But if what you claim to be true was indeed true, the high-end, cost-no-object tonearm world would be populated by S arms and/or J arms. But it's not. All the esoteric equipment (and everything that trickles down from it) is all straight.

It seems S arms still show up on DJ 'tables. Perhaps that is where their weight, rigidity and head shell interchangeability really is the best tool for the job.
 
It wasn’t a beautification project and the need to blow money that S and J-arms were invented for turntables. It was mysterious physics, magic, and a will to create better music for cartridges- but not in the way we would normally think.

For tonearms, longer is better. They have less vertical and horizontal tracking error like a car with a long wheelbase so in record warps we ride without jerking, more accuracy. With slower and less vertical and horizontal pivot bearing movements, they are quieter and have more dynamic range. And they are more forgiving of alignment errors. But if they are made too long then they have extra weight, flexing, and low resonance problems. In the microscopic world, it means a lot...


Sorry but IF the pivot point is the same, and the distance from the stylus to the pivot point is the same, the physics doesn't care whether the arm is straight or bent. As somebody pointed out earlier, the arm could be a pretzel, and the stylus would follow the exact same arc. Having more "stuff" doesn't trick the physics into thinking it's a "longer arm".

Granted, rigidity and mass could be different (depending on the diameter of tube and material) which would affect things. But the physics of the tracking angle doesn't change. For the same pivot point, and same stylus location, record warps are seen IDENTICALLY. Same rise and fall. Same angle change.
 
Thanks for the intriguing post. I don't claim to know the physics of it as well as you do. But if what you claim to be true was indeed true, the high-end, cost-no-object tonearm world would be populated by S arms and/or J arms. But it's not. All the esoteric equipment (and everything that trickles down from it) is all straight.

It seems S arms still show up on DJ 'tables. Perhaps that is where their weight, rigidity and head shell interchangeability really is the best tool for the job.

Exactly!
How anyone can say with a straight face all these companies are cheating us out of the best performance for the sake of the dollar boggles the mind.
These are folks that charge thousands for their offerings, and an industry as a whole that refuses to advance with the times (tubes still rule, Vinyl is still king) and the S arm was in the past aswell yet one of the only things they left in the past was that 1 design because its too hard, difficult or expensive to sell?
Simple fact is or has to be seeing how I am no design expert is that the straight arm is king for a reason, you can disagree but to say its because of market forces in a industry who could care less what anyone thinks or about price when folks line up or sit on a list to purchase items that cost as much as a home just doesnt hold up.
 
For tonearms, longer is better. They have less vertical and horizontal tracking error

S and J-arms are straight arms in disguise with an additional benefit. Stretch the S-arm and we see it is longer. Clever engineers took the straight arms then bent them to fit smaller boxes.

I agree that longer is better for tracking error. This is a consequency of the geometry. The longer the straight line distance between the arm pivot and the point at which the stylus contacts the record, the smaller the tangential error as the arm moves away from the null points as it plays the record.

I do not however believe that bending a one piece arm into a J, an S, or any other shape reduces tracking error.

All of the really high end arms that I can think of use a straight shaft and are 9" - 12" long. I believe that the primary reasons are that designers have to balance the following 3 factors:

(1) The effective mass of the arm has to be within a certain range so that it is compatible with the cartridges that it will be paired with.

(2) The arm has to be as rigid as possible to help minimize audible resonances

(3) The arm has to be as long as possible to minimize tracking error

For any given effective arm mass it is possible to achieve greater rigidity with a straight arm than with a bent arm, so they use straight arms.

For any given arm mass it is possible to achieve greater rigidity with a short arm than with a long arm, so they balance the rigidity or the short arm against the lower tracking error of the long arm and end up with arms that are in the 9" - 12" range.

Apart from aesthetic preferences:
- One benefit of a J or S shaped arm is that it is possible to achieve azimuth adjustment by twisting the headshell without affecting rake angle
- One benefit of an S shaped arm is that the horizontal bearing can be at right angles to the shaft which makes the machining a little simpler.

David
 
I agree that longer is better for tracking error. This is a consequency of the geometry. The longer the straight line distance between the arm pivot and the point at which the stylus contacts the record, the smaller the tangential error as the arm moves away from the null points as it plays the record.

I do not however believe that bending a one piece arm into a J, an S, or any other shape reduces tracking error....


Yes, if you move the arm pivot point out, tracking error improves. For any given pivot point, the shape of the arm is irrelevant as far as the tracking error.
 
Yes, if you move the arm pivot point out, tracking error improves. For any given pivot point, the shape of the arm is irrelevant as far as the tracking error.

Yup and if you make an arm like a pretzel as noted by someone earlier it makes no differene as point a to b is still X no matter how many detours in between.
 
It wasn’t a beautification project and the need to blow money that S and J-arms were invented for turntables. It was mysterious physics, magic, and a will to create better music for cartridges- but not in the way we would normally think.

For tonearms, longer is better. They have less vertical and horizontal tracking error like a car with a long wheelbase so in record warps we ride without jerking, more accuracy. With slower and less vertical and horizontal pivot bearing movements, they are quieter and have more dynamic range. And they are more forgiving of alignment errors. But if they are made too long then they have extra weight, flexing, and low resonance problems. In the microscopic world, it means a lot.


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S and J-arms are straight arms in disguise with an additional benefit. Stretch the S-arm and we see it is longer. Clever engineers took the straight arms then bent them to fit smaller boxes. But there is more.

Bent arms are more energetic in sound. Tonearms are small but influential organ pipes. Think of a muffler pipe; a long and straight pipe flexing and has low resonance, a burbling sound. Look under a car with a factory system and we see the pipe bends making it stronger and the sound is spread to higher and wider frequency range. Tonearms follow the same physics. Properly designed, angled at the right point to control resonance, and with the right materials, well designed arms can give a happy boost to the midrange. Drooping audio waves can be boosted by opposing lifted audio waves to make a neutral sound. Since many cartridges have a droop in the midrange, this is a happy mating. A bend or two can make tonearms passive amplifiers. Clever engineers.

Extra weight? Yes, but short arms are choppy rides. In longer arms, the combination of the cantilever, a heavier, movement resistant, tonearms and exceptional bearings makes a very smooth ride much like a shock absorber tonearm using a leaf spring cartridge. The arms are beauties to watch as the cantilever does the work and the tonearm floats.

Why did we go to short straight arms? We know they are easy to design and cost much less to make. Lower cost, lower price, expands the market to consumers who could not afford, or want, the best. One bend is costly but two? Wow, and both must be precise, perfect. Straight arms can be mass produced; there are no precise bends to worry about, less of a chance of defects, and faster assembly line manufacturing. Bean counters and profit motivated do not mind if we forget what we learned in physics classes.

Bent arms have many advantages.

All this time I thought I have "S" shaped tonearms when they are "J" shaped tonearms. Thanks for clarifiying the difference.
 
So, as usual, it comes down to features that match the users preference and quality engineering and execution. I prefer swapping carts as I deem it needed. I also like to play various masses of headshells as I tune the response of any cartridge - so for me it's the J or S and I can mostly afford vintage S, so that's the way I swing. Since I still tape record, I find it easier to tailor the LP sound from pick-up rather than try to process down the line.

Others may want to mount only one cartridge for its life and deal with the sonic issues in other ways. For them an ultra-lite straight arm will be fine. It's not only audio performance, but work flow too :)

It's not about tailoring a sound character.
This is for DJ's and people only listening to electronic music.

It's about getting as close to the Analog Reference as possible.

The Analog Reference being the sound originating from comming over the stage when the live event took place or the sound from when the master was made in the studio.

For this purpose, I found straight arms to be the best.

I compared Alphason HR-100S, SME 3009 and 4 other TOTL S/J arms with a simple arm like Rega RB 700.
All on the same Dunlop Systemdek IV TT having exact the same modifications and set-up.
Tested with 4 different cartridges in the price range of $1000 - $7500.
Benz Ruby 2 Open Air/Shelter 901/Lyra Olympus/Air Tight PC-1

I found them all to play very well.
However, there were significant lack of deep bass and room definition in the S/J arms no matter what cartridge.

The Room definition, 3-dimensional perspective, is to me one of the definite most important parameters to fool me to believe the music reproduced is close to the Analog Reference.

This is the reason I settled with a radial straight arm.

It might sound crazy but my choise of RIAA was based on the purchase of 8 RIAA's in the price range of ~ $1000 - $10.000
I chose Whest .20 psu/msu set of RIAA and power supply at ~ $2.500.
This was used for the above described test.
All of this was to make me decide arm and cartridge.
I don't buy stuff unless my ears approve.

"dolph"
 
The reason that most of the today-arms are straight, is that it´s easier to make a straight arm good. The ultimate tonearm is most likely straight. If theorizing, it would not be possible to make "the best" S-arm as good as "the best" straight arm.

But in the real world that is not what we are buying. We are normally buying arms that are full of compromizes, and it cannot be expected that a quite normal straight arm should be any better than an equally priced and carefully designed S-arm. There are other factors than the shape of the arm that will be limiting, we could think that if we hear a difference it´s the arm that causes this, when in reality it´s most likely other reasons.
For one thing one must have the same TT,cartridge and alignment to begin with.

Jelco still makes an S-arm that is very well regarded, and it would not be right to say that it´s not as good as a straight arm depending on shape.

/gusten

Adding: When I mention compromize, one major one is the dampening of the tonearm, in most cases there are not any adequate dampening applied to reduce resonances. How many tonearms have a dampening in order to reduce amplitudes from the fundamental cart/arm resonance?
 
Sorry but IF the pivot point is the same, and the distance from the stylus to the pivot point is the same, the physics doesn't care whether the arm is straight or bent. As somebody pointed out earlier, the arm could be a pretzel, and the stylus would follow the exact same arc. Having more "stuff" doesn't trick the physics into thinking it's a "longer arm".

Granted, rigidity and mass could be different (depending on the diameter of tube and material) which would affect things. But the physics of the tracking angle doesn't change. For the same pivot point, and same stylus location, record warps are seen IDENTICALLY. Same rise and fall. Same angle change.


Thank goodness someone posted this. His illogic was giving me a bellyache.
 
I agree...I was hoping someone would point out the difference between tube length and stylus/pivot distance. Also, short straight arms are used for scratch DJ turntables, because they are more immune to jumping out of the groove, or so I;ve been told...I don't scratch. Some new DJ tables come with interchangeable S/straight tubes depending on weather you will be scratching or just playing tracks. Many J arms are actually S arms in disguise...with the first bend within the confines of the pivot assembly. True J arms, like the SME 3009, have the axis of the counterweight and major arm tube portion in alignment. The bend at the headshell forces the center of mass to one side (cart axis is not aligned with tube/counterweight axis), which in turn puts unequal force on the bearings, which is remedied by the cute little cantilevered weights off to the side of the main one (not the dangly anti-skate one), which balances the arm as a whole. S-arms use the 'extra' bend to place the carts center of mass back in line with the bearings, but of course now the tube doesn't line up now...but physics doesn't care, so long as the mass is lined up. Some arms have only one bend, but the armtube doesn't come out of the pivot 180 degrees opposite the counterweight, thus making sure everything balances not only up/down, but left/right as well. these are the imposter J-arms...really an S with a super fast first bend right at the pivot...geometrically speaking. Of course, one less actual bend in the tube means it can be stiffer.
 
I doubt the center of mass is much of an issue except that the further from the pivot/joint, the more "effective mass" there is, or swing mass inertia. Numark was the company that brought back the interchangeable tonearm system, a much easier way than the old JVC method. The bearings getting different forces on them is also less of a concern than the joint angle when not aligned causing the diamond to angle side-to-side. I've been told this is extremely minor and the reason a great deal of arms don't align the bearing/counterweight to the cart, but us obsessive types can't help but feel a bit annoyed by it. The Numark ones, for instance, are this way...i.e. the joint is aligned for the underhung strait arm.
 
That is one hell of a bump there.

Bottom line, there is an optimum mass for the end of a tone arm and it is not much. Mucjh less than is achievable in practice actually. All it has to have is enough mass to resonate at a subsonic frequency when used with the compliance of the caantilever of the stylus.

Yes, this means a heavier tracking stylus needs a bit more mass behind it than a lighter tracking one. However, in practice the actual mass is ALWAYS more than enough.

Since the shortest distance between two ppoints is a straight line, it stands to reason that a straight tone arm will achieve a lower mass. This is desirable.

So we now have a tradeoff, a longer tone arm has less tracking error assuming it is setup properly. However a longer tone arm will have more mass.The S shaped tone arm, even if you want to call it J or whatevr, is not a straight line and therefore nothing but hype. It necessarily introduces unnecessary mass which is bad. It is simply a marketing gimmick. If any of the designers think otherwise, they need to go to a better school. Physics is physics. Period.

Then we come to those contraptions that correct the tracking error. One such device is depicted in an earlier post in this thread. Fine and dandy, and a great idea. No problem with it except for one. ANY such device necessarily adds mass to the arm, meaning to the end of the arm where it matters.

The Garrard Zero series suffers from that. They really are a great table, but all that mass brings on its own problems. Really, the mass is not all that bad in them. Think of the old ancient Garrards and other brands that needed a three pound weight on the back to balance. By those standards the Zero series was a dream comee true.

Very few records are perfectly flat, as such more mass at the stylus causes any warpage to produce more polluting low frequency outpur. Alot of this will be in the vertical direction which will be out of polarity (phase) at the speakers. If you have both woofers on one cabinet, it is not going to be "acoustic" suspension to that signal and the woofers may overextend (bottom out) with you not hearing a thing except that "click". Not good.

I have long advocates a "low blend" for phono inputs on amps to reduce or eliminate most of this probem but never got around to designing it. It is really not that difficult but if you don't want to use a huge, hum prone coil, there is more to it than say a high blend for FM stereo on weak sugnals. It is easy to get a little bit of suppresion, but the ideal would be to make the phono state totally monophonic at any frequencies below about 25 Hz. That requires a little bit more engineering and I can see why manufactirers wanted noting to do with it. Even harder making it switchable. There are always purists.

It is much easier to lower the mass of the arm and eliminate most of that noise at the source. It is also better for the cartridge, the stylus as well as its cantilever's suspension. Distortion is reduced, and when there is tracking error, less wow and flutter is produced by lateral movement of the head in relation to the record groove.

Bottom line there is no perfect soolution, even linear tracking. Linear tracking TTs DO have tracking error, it is just alot less. I worked on one not long ago which pleased me due to the fact that it did not require a P mount cartridge. That leaves alot more choices, and choices are good. Try to find a CD4 or MC cartridge in a P mount. As far as I know there are none.

I consider, engineering wise, the S shaped tone arm to be the equivalent of the "beauty rings" mounted on soeapers. Simply for looks and actualy of no use, or worse.
 
S arms at their best DO SERVE a function. You can not dismiss SME at less than your peril, remember those are Laboratory Reference standard tonearms in the disc mastering studios which cut your records, the QC and record label staffers at the record labels, and many quality minded broadcasting organizations, who sure know their engineering. Technics EPA arms are acknowledged by many as high quality, same for Jelco arms (they make an S arm). Even Rega used the S arm designed and built for them by Acos early on (before the RB series tonearms). Like all things, there are good and bad of each type. Engineering, geometry, and build quality including the materials and metallurgy crucial to the results we get. JURB, all bass response below 60 hertz on most stereo discs is already blended to mono due to trackability reasons.
 
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