Latest first; to be continued as and when I get the time and the inclination....
10. Linear Offset only refers to the angle of the bearings to the arm tube.
I've seen this a few times recently. It assumes that a single bolt or screw is pushing the arm pillar against the back of the mount, such that if there is any clearance in the hole (which there must be otherwise the arm pillar would not go into the mount) then there is scope for the pillar to rock or tilt.
The clamping arrangement above is a point and line arrangement. If you have two screws then it is two points and line, which is more stable. The first Odyssey RP1 had shims, so this wasn't an issue, just a pain. The XG had two screws at 60 degrees. The later XG2 had one screw but two lines, as there was an arc cut in the mount, which was more stable. The later Gold Signatures had one screw closing a three line clamp which was better still.
8. Since we were on the subject in 7... Skating forces occur because the cartridge is at an angle to the armtube.
This is a nonsense. Skating forces occur because any tonearm with overhang, pivoted or otherwise, will have its stylus situated at a point where the stylus is being dragged at an angle to a line between stylus and tonearm pivot.
The skating force is directly related to this angle which is the horizontal tracking angle.
In fact, with a pivoted arm, even with zero overhang, there is a skating force, and only as overhang becomes underhang, does the skating force become zero and then go negative, tending to push the arm outwards.
The reason the cartridge is angled is because it has a cantilever and stylus which need to align with the groove in order to function correctly, because that mirrors how the record was cut, that is, along a radius.
As an aside, if a record was cut such that there was only vertical movement, and playback used a spherical tip, with no cantilever, then there would be no need for cartridge offset. It would simply be a matter of optimising overhang to minimise tracking error. However, there would still be skating forces.
7. Skating force is zero at the nulls.
Or, worse: skating force follows the typical graph of tracking distortion, starting high, reducing to zero, increasing then reducing to zero again, then increasing again.
Whether you prefer using an arm with or without anti-skate, skating force (whatever it may actually do) certainly doesn't follow the distortion plot as typified on the Vinyl Engine calculators. No question about it. Those graphs are the shape they are because they graph distortion, which is a positive number and zero at the nulls, as opposed to tracking error which is both positive and negative and zero at the nulls.
Variations in skating force are caused first and foremost, by the variation in arm pivot/ stylus/ groove tangent angle. which will vary by a couple of degrees of tracking error around the cartridge offset angle. In other words for a 9" arm, 23.5 +/- 2 degrees. Nowhere is that ever zero.
6. Damping sucks the life out of the music.
This is nonsense, and is repeated so often it has become a cliche.
Vibration is movement. So, other than the rotating platter, the cartridge cantilever (which is meant to vibrate in order to reproduce the signal on the record), or the arm, (which has to move to follow the groove), everything else should be stationary at all frequencies, that is, non-resonant, and not contributing spurious vibration to the record or cartridge.
Therefore, damping is both necessary and helpful. It helps control and reduce the resonances that occur in those parts that should not move, and to optimise the movement in the parts which should move.
Therefore, damping is both necessary and helpful. It helps control and reduce the resonances that occur in those parts that should not move, and to optimise the movement in the parts which should move.
If your system sounds worse with damping a component (eg turntable plinth), then previously it was adding a resonance which shouldn't be there. The "life" that has been sucked out of the music was never in the music to begin with, it was in the system.
It may well have improved your listening experience, and you prefer things that way, which is fair enough. However, that is another matter, nothing to do with damping.
5. An arm needs to be rigid.
This is a red herring. There are claims for this or that degree of rigidity in a tonearm as if this means it is free from resonance. However, the degree to which an arm resonates is dependent on the damping properties inherent in the overall design. Rigidity doesn't mean non-resonant. There is a large item weighing almost 14 tons a few miles from where I lived in London which most people would consider rigid, but it is definitely resonant. It is the bell, Big Ben. Whatever material an arm is made of and the manner in which it is used will decide whether or not its inherent resonances and colorations are to your liking.
4. Wooden arm tubes don't resonate.
This is one of the most nonsensical claims. Wood of course resonates as does almost every object at some frequency or other. The shape and species governs the degree to which it will do so. Guitar and other string instrument tops depend on resonance and are usually made of softwoods such as spruce, as it is light and strong, but can also be made from hardwoods like mahogany or koa. Different hardwoods are also used for the back and sides, and also contribute to the sound.
Using wood is no guarantee of success in a tonearm. Likewise, using metal, or any other material. As in musical instruments, it is how the material is used that is important, although in the case of tonearms, the design objectives are the opposite of a musical instrument.
Having said that, there are those who prefer some coloration in their hifi. Which is fair enough. There are no laws - just opinions and preferences.
3. Skating forces don't exist..
This is a nonsense. There is always, despite what some misguided souls believe, an inwards force with pivoted arms. That is just the way it is if you have two forces pulling in different directions at an angle to each other. It results in a force which acts, in the case of a pivoted arm, to rotate it towards the centre. End of story. Whether the resulting distortion is compensated by extra downforce, stiff tonearm wiring resisting the force, or whatever, it will always be there. You can use a longer arm, to reduce the effects, but it doesn't negate them.
2. Every arm has to be mounted in a specified position to the last fraction of a millimeter prior to aligning the cartridge.
This is a nonsense. It applies only to arms which cannot be set up by moving the base. All SME arms, all arms which are mounted on a pod, all arms which are on an arm board that can be swivelled or adjusted, all RP1s, all can be adjusted at the base. Consequently they can adjust for variations in cartridges more acurately than adjusting at the headshell. See SME geometry. The best option, which I have only ever seen used on my later custom arms, is to separate the adjustment of overhang and offset by using a fixed pivoted cartridge mount which rotates directly above the stylus, and have overhang adjusted at the pillar (ideally in a sliding base with a threaded adjuster).
1. There is a fixed or best geometry.
This is a nonsense. Geometries are based on records. You need to make this decision yourself regarding your LP collection. You will have to compromise unless all your records finish at the same radius. And to choose an extreme example, if all your records are 7 inch singles there is no LP alignment that will even come close to a correct 7inch alignment...
