Advice for mounting a TT shelf on a wall

I couldn't be more appreciative of the comments/suggestions. The mounting bracket came in today and is as professionally made as I have ever seen. The finish is perfect, but most of all, the bracket is even better/stronger than it needs to be. So now, I will go out in the shop and choose among the wood slabs for something that will work well with this bracket. I like the idea about Herbies giant gliders. Saw them somewhere recently for sale.

 Attaching this bracket will have to be spot on as well. I want to get as close to the center of each stud as possible. And I am with the thinking that the mounting must make continuous as possible contact with the wall. I am still considering the height though. I still have time. 

You are correct about hitting the studs dead center. Use a stud finder to locate and mark the edges of the studs. Then hold the bracket to the wall with a level across the top surface and move the holes to the exact middle between your marks and adjust to dead level. Now use a pencil to trace the screw holes. Next use a small drill to create pilot holes in the center of the tracings. Drill slowly, moving the bit in and out and note whether you feel resistance and see wood pulp emerge from the hole as the bit is pulled away from the wall. This will confirm whether you are in the stud—no resistance, no pulp, no stud. If all holes are good do a final check by placing the bracket back on the wall over the screw holes. Are the pilot holes in the middle of each bracket hole? Is the shelf level side to side (also check front to back though this will probably be level and if not will require adjustment of you bracket platform unless you choose to shim the bracket which is not a good idea). If all good then select a drill slightly smaller in diameter than the mounting screws you will be using (not including the threads) and mount away. Use the largest screws that will fit through the bracket holes and see if you can place a washer between the frame and where the screw enters the hole—I had to sand off some diameter for the washer to fit in the hole. Start the screws by hand and them drive them home with an electric drill—not cordless you will need torque. You will need another set of hand at various points. We have moved 4 times in the past 20 years so my wife is now an expert assistant! Good luck!

Placing a turntable on a load bearing wall shelf will help deal with foot fall issues and some other low frequency events but it will not isolate the turntable and might possibly make things worse depending on the design of the turntable. A wall is one big sound board. If you place the edge of a stethoscope bell against the wall you will hear everything else that is going on in the house, the dishwasher, your kid's TV up stairs and even the truck rumbling down the street. Turntables that are suspension isolated will do fine. Examples are the LP 12, SME, Basis, Avid, Thorens and Sota models. All others need to be on an isolation platform. The best is the MinusK. 

Well, the shelf bracket is mounted, and I posted a photo of the temporary shelf for now. Man, this thing is heavy duty. Got it good and level too. I really do appreciate all the advice and reminders that were given. Will post another photo in my system page when done.