JRA and Gdg,

I have now completed an evaluation of the options for a 12” adapter for the SL1200, using my profesional CAD system and have decided that a design, which locks into the existing arm well and fits over the back edge of the Chassis is the way to go. The adapter plate protrudes 130mm out from the back edge of the SL1200. The arm centre is 25mm to the left of the arm-well centre and 165mm towards the rear. It will be manufactured from 25mm thick engineering quality alluminium bar stock. The mounting level for the SME arm slides will be 15mm below the top surface of the SL1200 chassis. The thickness of the rear mounting plate section will be 25mm.

The slot will be angled at 23.6deg to the theoretical angle of the line extended from the spindle to arm pivot point in order to maintain SMEs cartidge offset angle when adjusting for position. Given these dimensions, the top of the adapter plate, which protruded out to the rear will sit approximately 15mmm above the top of the chassis surface.

Now given that most of you will probably be using an arm of this quality with my new Platters, which sit approx 2mm above the existing platter. My question is for those who have a 12” arm, will there be sufficient clearance under the arm to clear the adapter plate when seated in it’s installed position.??

I make no excuse for the solidity of this adapter plate, it has to be, to avoid any resonances. To quote from a paper by SME the arm plate should be of the utmost rigidity to absorb any vertical vibration arising from the excellent stiffness of the arm design generally.