Do You Have a Favorite Disk to Set VTA/SRA?

Whart,

Totally agree that "thick/thin" sound is consistent with the fundamental/harmonics timing differences one hears in more sensitive setups.

Also agree that this is cartridge specific:
1) A cartridge with a spherical/conical stylus does not really change sound at all with SRA adjustment.
2) Shelter 901 has an elliptical stylus, and it sounds "thick or thin".
3) AirTight Supreme has a "semi" line contact stylus. Not sure just what that means, but it makes sense that it would be more sensitive than a 901 but less sensitive than a true line contact.
4) High end Lyra and ZYX cartridges use a micro-ridge stylus, which provides the shortest contact radius of any stylus I know (short of a cutting stylus). It makes sense that such cartridges change sound in subtler or more detailed ways.

Interesting pictures of stylus shapes.

http://www.vinylengine.com/turntable_forum/viewtopic.php?t=22894

Chayro, great link, thanks! The pics/diagrams help explain what I was attempting to describe.

During the cutting process, the cutting needle lasts about 10 hours and then must be replaced. A worn needle cuts a noisy groove. Many people don't know this but if the cutter needle is set up right, the resulting lacquer cut is so quiet that no matter how quiet your playback electronics are, they define the noise floor.

As a result the cutter head must be removed and the needle replaced fairly frequently. Then it has to be reinstalled, aligned and then one goes through the process of getting it to cut correctly. This is the case regardless of the fact that the settings of the cutter head were previously recorded.

The issue is that every cutting stylus is slightly different. As a result, the 92 degree cutting angle can be regarded as an average and not an absolute as the mastering engineer is looking to get the machine to cut properly and is not aiming for 92 degrees. This means that every LP is cut at a slightly different angle. IOW its not just the thickness of the LP that is a variable. Even if they were all the same thickness to get ideal playback the VTA/SRA would have to be adjusted.

Hence the utility of the VTA tower pioneered by Triplanar. There are several arms now that use a similar design; if you really want to hear everything on the LP such adjust-ability is really handy!

Ralph,

Thanks for your expert insights from the POV of a cutting engineer, which do gibe with what I hear during playback.

Similar weight LPs from the same label and pressing plant do tend to have similar arm height settings, but it's only a tendency, a reasonable point of departure to begin fine tuning by ear.

I've always found the obsession with setting SRA to EXACTLY 92 degrees with a microscope amusingly arbitrary. You explained why that is so very clearly.