How to set SRA after determining true vertical?

As I have said before and nobody pays any attention. Probably becuase they think I'm wrong. Your record could care less about the cutting edge angle. What you want is maximum contact with stylus and grove. if you are lucky this will occurr when the headshell is parallell with the record surface.

When that happens you can then use the catridge angle as a tone control rocking it back and forth by raising or lowering the back of the tonearm. vtf can also change this angle. the more down force the more the cantilever will deflect. Stereo seperation is affected by antiskate and azimuth.what you want there is the the stylus riding in the direct center of the grove. easier for linear arms.

what's important then is the angle of the stylus not the angle of the cantilever. the stylus should be perpindicular to the rcord surface. If you took an xy graph and placed it on the record surface and placed the stylus at 0,0 or dead center and measured the angle in a 360 degree rotation you want 0 degree deviation all the way around.

Take a nail and dirve it into a board at a 90 degree angle about 1" from the end. You will see that the nail will be perpindicular to the surface. Now lift the end of the board 20 degrees. the nail is no longer at 90 degrees. you have two choices either bend the end of board 20 degrees or drive the nail in at 70 dgrees to compensate.

The cartridge and arm manufacturer do this for you as best they can. There are two variables they can't account for vtf and record thickeness. those two things must be accounted for by the end user. It might be easier if you chose the same cartrdge tonearm and turntable as the cartridge designer used.

Once you determinde the the arm is level by making sure the height of the arm is the same at the stylus, midlle and pivot hopefully the stylus is now perpindicular to the recocrd surface. You should be getting maximum contact with the stylus and grove as the cartridge manufacturer intended. My sme 4 provides a line through the middle of the arm for this purpose. You can then simply lower or raise the arm for different record thickness. Of course you should determine vtf before you finalize this process.

One additional variable is the mounting of the needle on the cantilever. If you examine a number of cartridges head on, you will find that the needles are not all set perfectly perpendicular to the cantilever or the headshell. Errors can be up to 3-4 deg. This is another reason why getting the azimuth and SRA right is not as simple as making the headshell perpendicular to the platter and leveling the arm etc. For azimuth, I would assume it is more important for the needle to be perpendicual to the record in the grove, than for the headshell to be parallel to the record surface. Anyone have any experience with this as well?

Zargon-the thrust of my argument is that SRA should be used to make the stylus perpindicular to the groove or record surface not necessarily mimmicking the stylus cutting head.
If I get you agree to that,I'm satisfied. How you get there is not that important. That will get you maximum groove contact and that is what you paid for.

I was just cautioning those who might not be sensitive to needle mounting variations. Their existence serves to strenghten the need to get SRA and azimuth close, and then make small adjustments either way while listening for the optimum setting. I really have no knowledge or opinion on whether the SRA should be vertical or 1-2 deg. forward, as Doug suggests. In my single case, it appears to end up vertical, but that is only one TT setup.