Very few, if any high end arms are bent.
Radial tone arms can have dynamic tracking angle with 0 degree all the way.
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"
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.
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...
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.
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....
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.
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.
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.
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
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.