Adjusting SRA using macro lens vs microscope

Here we go again. You'd think people who advocate pre-setting SRA to some arbitrary number would explain why we should bother.

Before asking HOW to do something, ask WHY to do it. What is the goal? Does a recommended method meet that goal? In this case the answer is an unequivocal "no". Setting SRA by eye is a waste of time, so asking which tools to use is pointless.

1. The only correct SRA is the one that conforms the playback stylus to the grooves of the LP you're about to play. This is the only SRA that matters.

2. Each LP's groove SRA is different. Everyone knows groove SRA varies with record thickness. What the set-by-eye crowd forgets, if they ever knew it, is that groove SRA varies MUCH MORE by record label, cutting plant and the era in which the LP was made. The SRA of a 180g Decca is nowhere near the SRA of a 180g Mercury, or RCA, or Erato, or...

3. Since each LP's groove SRA is different, any pre-set SRA is arbitrary. It won't bear any relation to the SRA of the next LP we spin.

4. Spending time or money pre-setting some arbitrary number that we have to change anyway is pseudo-science for the naive.

So, make the cartridge roughly level by eyeballing. That's as good as any other arbitrary number, it's where most manufacturers design cartridges to play, it doesn't cost any money and it takes all of 10 seconds. Adjust by ear from there.

Example:

Last Saturday I joined some other audiophiles to play with some gear, including an Ortofon A90. The A90 has the hardest-to-see stylus I've ever met. We wasted an hour trying to set SRA by eye per the manufacturer's inadequate instructions. After giving up in frustration we came to our senses, levelled the damn cartridge and began spinning LP's.

As I do with any good cartridge I adjusted arm height for each LP by ear. Even though I was in a strange system using tonearms I don't own, it took no more than 30 seconds per LP and cost zero playing time, since the tonearms were adjustable on the fly. The A90 is extremely sensitive to SRA, yet I dialed it in easily. Presetting it to ninety-something degrees, even if we'd been able, would not have helped a bit and trying to do it was a waste of time. You'd think I'd have learned by now... ;-)

Doug,

Thank you once again for being an informed voice of reason. This thread is a nice counterpoint to a thread in another forum entitled "Why Some Audiophiles Fear Measurements". It's not that some measurements aren't useful (they are), but it is human nature to attach a false sense of security to a measurement. An interesting take on this subject is "The Tyranny of Numbers" by David Boyle.

As Doug points out, does anyone think fixing SRA at 92.1 degrees really be any different than 92.0 degrees if you own a large record collection?

Doug, as you said Sat, you know that you can use the body of a Universe to start because you have looked at the stylus on a few samples and have concluded that the stylus does end up close to a starting SRA/VTA when you level the body.

I do agree with Doug that going to the effort to measure stylus angle with a microscope and some software is un-necessary. I also think a good 10x or 20x jeweler's loupe is sufficient along with good lighting.

I don't find Nsgarch's method that useful myself. This method assumes that the stylus is symmetrical, but almost none really are. There is usually an edge or facet that is the reference line and this would necessarily result in casting a non-symmetric image on the mirror. This method would never work on a stylus like the Replicant, but I would submit that few visual methods, if any, will work with the type of profile the the Replicant has.

We ended up leveling the body of the A90 because the stylus is shaped the way it is, and we had no other choice. I still want to know what reference point to use on that Replicant stylus to find the 90 degree angle referenced in the Ortophon directions and by Fremer. There is supposed to be some tiny, trailing edge facet that is the actual surface to consider, and maybe that does require a microscope to see. I would still not give up the step of actually looking at the stylus for most cartridges. I don't think I will count on a cart builder to set that angle with the body any more than I would expect the AZ to be perfect. I simply put the A90 in a category (almost by itself :-)) where usual methods may not apply.

All of my comments assume that the tonearm in use has the capability to make easy VTA adjustments.

So gentlemen, what did you think of the A90?

Richard, I didn't hear it committing any sins. The A90 is very respectable from my short time listening to it.