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.

.
128x128nsgarch
Raul,

Exactly right, "our best is only an approach". That is true of everything in audio of course. All the expertise, good will, time and money in the world will not turn a pile of wires and silicon into a violin.

But we keep trying, because it sounds so good when we take another little step closer...
Dear Doug: +++++ " But we keep trying, " +++++

Yes we do.

Regards and enjoy the music.
Raul.
Greg -- what a terrific website (you were referring to the article on Vinyl Microscopy?) My favorite part:

The animal (below) is a young silverfish with its extended cercae overlapping the closing bars of the final movement of Bruckner's third symphony. I mention this as it is not possible to tell from the photograph. There are few places in a Bruckner symphony where the sound of a diamond stylus colliding with a dead silverfish would be less welcome. The cadaver was removed by brushing with a carbon fibre brush.
Nsgarch, Dougdeacon,

This is a great post. This combined with the John Risch article enabled me to explore VTA positions that I would not have ventured to test before. I am now achieving stellar performance.

Dougdeacon's advice in setting SRA by listening is important. However, what I found the most valuable about this post and related references is that it' s very effective at getting a good starting point and idea about the range of arm psotions that can yield great sound.

Being a novice, I assumed that a parallel arm position was the best initial setting and that one shouldn't deviate too far from that. However, the best position I have found ranges from 1-2 degrees from vertical.

The arm is far from parallel in this range and I never would have ventured this far away from parallel had I not read these posts.

I also agree that listening to the bass perfromance and the HF detail are tell tale signs of optimal settings in SRA.

Thank you!

I hope more people can benefit from this.

Andrew
I'm right there with you, Andrew. The starting point has always been something of a mystery to me but this thread provides a very repeatable methodology.