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VTA and SRA?

Can anyone explain what the difference is? Or are they a horse of another color? Thanks!
128x128yogiboy
nsgarch's avatar
nsgarch
2,524 posts
 
They are absolutely NOT the same thing. I started the following thread right here on Audiogon -- long before M. Fremer figured it out by the way;~):
http://forum.audiogon.com/cgi-bin/fr.pl?eanlg&1140840022&openmine&Nsgarch&4&5&st0

Unfortunately, my IP doesn't support my picture files anymore. Sorry.
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dougdeacon
3,338 posts
 
Czarivey and Effischer,

Your posts are incorrect. For a basic understanding read the link posted by Mofimadness above, which is *almost* correct.

VTA and SRA are both viewed from the side of the cartridge (along the axis of the cantilever, as Effischer put it) but that's where the similarity ends.

VTA = the angle formed between:
1) the horizontal surface of the record and
2) a line extended from the point of the stylus through the axis of vertical rotation of the cantilever (this would be the same as the line of the cantilever, except for the offset provided by the height of the stylus).

VTA's range from 15-25 degrees, with 20 degrees being the industry standard since the mid-1960s.

SRA = the angle formed between:
1) a vertical line through the lowest contact point of the stylus and
2) the line of the stylus's contact ridge or edge.

SRA's on elliptical, line contact, micro-ridge and cutting styli tend to be 1-2 degrees forward from vertical, but there is no industry standard. A conical stylus can be said to have no SRA. Its spherical contact surface results in a single contact point, so there's no contact ridge or edge to measure.

As can be seen, VTA and SRA are very different.
lewm
13,171 posts
 
Here we go again.
And I was no fan of Ronald Reagan.
effischer
562 posts
 
I stand corrected. So, presuming I now understand this, SRA is a fixed relationship within the stylus itself and cannot be adjusted.
dougdeacon
3,338 posts
 
Read it again.

SRA = the angle formed between:
1) a vertical line through the lowest contact point of the stylus and
2) the line of the stylus's contact ridge or edge.

#1 never changes, but #2 can be changed in several ways.

The stylus's contact edge can be tilted forward or back by altering the height of the tonearm. It also changes as a side-effect of any alteration in downforce (VTF). Your own tonearm (listed as a Graham Phantom Supreme) has these adjustments.

You also change SRA (inadvertently) virtually every time you change LP's, since different LP's have different thicknesses.
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