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VTF, VTA, SRA, and 92 degrees - question

I'm familiar with the logic that has been out there for a while about setting SRA at 92 degrees for what is considered the optimal styus position, based on a lot of analysis done by Elison and others. My question is, if VTF and VTA are set per cart maker's recommendations (let's discount Anti-skate for this discussion even though it would come into play), then wouldn't the SRA be automatically set optimally per the manufacturer's intention? Assume a cart that is built to the company's design parameters - no bent cantilever, no offset stylus etc.

Take a Benz cart for example. Many (if not all) of them specify a VTA of 20 degrees. So if VTF (and yes A-S) and arm height are set so that when all's said and done the VTA is 20 degrees, isn't that what it *should* be set at based on how Benz expects that cart to perform?

I ask because I set the SRA on my Benz to 92 degrees going by that camp, and when I checked the SRA it was at - guess what - about 22 degrees. That kind of suggests Benz expects the stylus to be at 90 degrees relative to the record. Isn't that how they've designed it? Don't I run the risk of having to compensate in other ways if the cart winds up exhibiting tracking problems at an SRA that does not support the specified VTA?
tonyptony

Showing 3 responses by atmasphere

atmasphere's avatar
atmasphere
11,615 posts
 
I am sure some of you have noticed that different records seem to need a slightly different VTA. The reason for this is two-fold; first the LP is a different thickness. The second is the the cutter stylus on the cutterhead that cut the lacquer for the LP may have been set at a slightly different angle. This is why two LPs of the same thickness on the same label may still need to have two different settings.

The cutter stylus has the job of cutting the lacquer. To do this it is shaped a certain way, heated to a particular temperature, set to a particular angle (cutter height) and tracked at a certain pressure. What works on one day in the mastering lab may not work the second day as the lacquer can be different, even if only by temperature (they cut easier on warmer days for example). So the mastering engineer has to be constantly aware of the condition of the stylus and keeping test lacquers on on hand to get immediate feedback on the effectiveness of his settings.

So this may not be as exact a science as you all might be thinking- it is as much an art. The 92 degree value is an excellent approximation, just as is getting the front of the cartridge to be perfectly perpendicular to the LP surface. This is why it is helpful to be able to adjust the VTA on the fly, like you can do with the Triplanar tonearm.
atmasphere's avatar
atmasphere
11,615 posts
 
^^ 'poor quality control'?? nah- certainly no worse than any other format. Most new LPs I see these days are really well done.
atmasphere's avatar
atmasphere
11,615 posts
 
QRP is doing some amazing work. We did a project through them recently and the final pressings were nearly as silent as the original lacquers (which is to say, so quiet as to rival digital recordings)!

It may be that the copy you got was warped, but that does not speak for all of them. IOW I was not joking. Warps have to do with heat during storage and shipping, not the process of making the LP. I buy a lot of LPs from indy labels, and it has been my experience that that they are usually excellent quality. But I live in Minnesota and that might make a difference with the warps.
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