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?
How to set SRA after determining true vertical?
Here is a picture of a stylus with zero rake angle:
http://members.cox.net/nsgarch/SRA@%200.0%20deg.jpg
Since all modern styli are symmetrical in the x and y plane about the verical z axis, the tapered stylus and its reflection will make a perfect "X" when vertical (z axis perpendicular to the groove) and viewed from the side.
This condition is established by raising or lowering the tonearm pivot post. Once you find this point, and assuming you have a typical 9" tonearm (about 230 mm from pivot to stylus) then each 4 mm you raise the post from the zero
SRA point will apply one degrewe of SRA to the stylus.
A test setup is shown in these two pics:
http://members.cox.net/nsgarch/SRA%20setup1.jpg
http://members.cox.net/nsgarch/SRA%20setup2.jpg
Equipment includes:
a mini Mag-Lite flashlite,
a first surface mirror from old SLR cameras -- easy to find at photo repair shop)
a 50X pocket microscope
bean bags
Don't forget to first remove antiskate and set VTF.
.
http://members.cox.net/nsgarch/SRA@%200.0%20deg.jpg
Since all modern styli are symmetrical in the x and y plane about the verical z axis, the tapered stylus and its reflection will make a perfect "X" when vertical (z axis perpendicular to the groove) and viewed from the side.
This condition is established by raising or lowering the tonearm pivot post. Once you find this point, and assuming you have a typical 9" tonearm (about 230 mm from pivot to stylus) then each 4 mm you raise the post from the zero
SRA point will apply one degrewe of SRA to the stylus.
A test setup is shown in these two pics:
http://members.cox.net/nsgarch/SRA%20setup1.jpg
http://members.cox.net/nsgarch/SRA%20setup2.jpg
Equipment includes:
a mini Mag-Lite flashlite,
a first surface mirror from old SLR cameras -- easy to find at photo repair shop)
a 50X pocket microscope
bean bags
Don't forget to first remove antiskate and set VTF.
.