@dover, good thing because the forces acting on the tonearm cartridge system ( they are imminently attached to one another) are very simple.
But since you Mention the Eminent Technology arm, it is a rip off of the Walker Proscenium arm. Both are arms in search of a cartridge that does not exist. The cartridge would have to have three times the horizontal compliance in relation to vertical compliance. Thus both arms exhibit much more distortion than proper pivoted arms. Air bearings are simple devices. You can easily buy a bearing and make your own air bearing arm more easily than you could make a gimbal pivot arm. Companies like SME or SAT could easily make air bearing arms but choose not to for good reason. The distortion added by tracking error is far less than what is added by an inordinately high horizontal effective mass. Linear trackers with motorized carriages are superior but difficult to design and build, far beyond a company like Eminent Technology or Walker. Better yet are arms like the Reed 5T and Schroder LT. Both arms have secondary horizontal bearings, one motorized the other magnetically guided that otherwise function as normal pivoted arms. They just stay tangent to the groove but, more importantly do not generate any skating force which is even more important from a tracking perspective. IMHO the Schroder LT is a brilliant design powered by the pull of the record on the stylus which transfers it to the cantilever, which transfers it to the cartridge, which transfers it to the tonearm and finally to the bearing platform pulling it forward while a magnet keeps the arm properly aligned. Brilliant. I wish I were that smart.
But since you Mention the Eminent Technology arm, it is a rip off of the Walker Proscenium arm. Both are arms in search of a cartridge that does not exist. The cartridge would have to have three times the horizontal compliance in relation to vertical compliance. Thus both arms exhibit much more distortion than proper pivoted arms. Air bearings are simple devices. You can easily buy a bearing and make your own air bearing arm more easily than you could make a gimbal pivot arm. Companies like SME or SAT could easily make air bearing arms but choose not to for good reason. The distortion added by tracking error is far less than what is added by an inordinately high horizontal effective mass. Linear trackers with motorized carriages are superior but difficult to design and build, far beyond a company like Eminent Technology or Walker. Better yet are arms like the Reed 5T and Schroder LT. Both arms have secondary horizontal bearings, one motorized the other magnetically guided that otherwise function as normal pivoted arms. They just stay tangent to the groove but, more importantly do not generate any skating force which is even more important from a tracking perspective. IMHO the Schroder LT is a brilliant design powered by the pull of the record on the stylus which transfers it to the cantilever, which transfers it to the cartridge, which transfers it to the tonearm and finally to the bearing platform pulling it forward while a magnet keeps the arm properly aligned. Brilliant. I wish I were that smart.