There is not one single high quality direct-drive turntable that I can think of that relies solely upon aluminum as an EMI shield. For one example, the Kenwood L07D uses a 7mm thick stainless steel platter sheet under the LP (~5 lbs of stainless steel), and in addition the coreless motor itself is totally encased in shielding. Also, do you think that belt-drive turntables which place the motor under the chassis usually adjacent to or even under the platter would necessarily be free of the issue with which you are so obsessed? Most of those motors in mid-price belt-drives are totally unshielded, though I am sure there are exceptions. Furthermore, belt-drive motors are running at much higher RPM than does any direct-drive motor, which might further enhance EMI radiated from them. But that is not my major theoretical objection to the average suspended belt-drive turntable, and you know it, because I have mentioned it before, but I had decided to keep mum on this thread for Sota lovers.
Typically, the chassis, including the platter bearing and the tonearm pivot are suspended, but the motor is anchored to the plinth. Thus when the suspension is activated, the platter and tonearm are isolated but the motor is static. This will inevitably result in stretching and relaxation of the belt, which will inevitably result in speed instability. That seems like a bigger more insurmountable problem than EMI and how to avoid it. The Doehmann and other very high end belt drive turntables do avoid the issue by mounting everything on the suspension, which is a MinusK in the case of the Doehmann. I owned both an AR turntable (at the beginning of my particular Oddysey in the 70s) and several turntables later a Star Sapphire Series III, with vacuum (1990s). As you know, I realized in retrospect that my SSS had significant problems with pitch stability. I went from the SSS to a Nottingham Hyperspace, an unsuspended belt-drive. Once I added a Walker Audio Precision Motor Controller to that turntable, I was made aware of where the SSS went wrong. I don’t want to rain on SOTA, because I believe they have taken steps to rectify this problem, although I am not sure exactly what. To be clear, I am sure the Cosmos and Millenium are fine turntables.
Typically, the chassis, including the platter bearing and the tonearm pivot are suspended, but the motor is anchored to the plinth. Thus when the suspension is activated, the platter and tonearm are isolated but the motor is static. This will inevitably result in stretching and relaxation of the belt, which will inevitably result in speed instability. That seems like a bigger more insurmountable problem than EMI and how to avoid it. The Doehmann and other very high end belt drive turntables do avoid the issue by mounting everything on the suspension, which is a MinusK in the case of the Doehmann. I owned both an AR turntable (at the beginning of my particular Oddysey in the 70s) and several turntables later a Star Sapphire Series III, with vacuum (1990s). As you know, I realized in retrospect that my SSS had significant problems with pitch stability. I went from the SSS to a Nottingham Hyperspace, an unsuspended belt-drive. Once I added a Walker Audio Precision Motor Controller to that turntable, I was made aware of where the SSS went wrong. I don’t want to rain on SOTA, because I believe they have taken steps to rectify this problem, although I am not sure exactly what. To be clear, I am sure the Cosmos and Millenium are fine turntables.