Stylus Force Guages - why extreme accuracy?

I am under the impression that, when setting up a phono cartridge, one sets the tracking force to the manufacturers recommended force, and then dial-in the final force by ear. If that is the case, then why are extremely accurate electronic stylus pressure gauges popular when the force is most likely going to change during final adjustment by ear? The Sure SFG-2, costing $25, has worked great for me to ball-park the initial tracking force before final tweaking. So, what benefit is the Winds ALM-01, costing $800, going to provide? Is it important to set the initial force to within a tenth of a gram, when that will change during final tweaking? What is the procedure those of you who own expensive gauges use for final adjustment by ear?
Maybe useful - after dialing it in by ear, you could remeasure and take a note of the exact force. Then as conditions change over the year - humidity, temperature, state of mind ;-) you could always run a quick check.

I guess if I had one, I'd play with it. And it appears that one can get a very accurate gauge for around $100 or so.

In my opinion, you can do pretty good with a 0.01g accuracy scale from Ebay (search 0.01g scale, mine has a stainless steel platform. More exactly, mine is item #190001314544) and a little jig such as this which can be made for a few dollars. The jig ensures the VTF measurement is made at the record's height, which is important and something that the more expensive, record-specific scales do. I also have a 50g (half capacity) and 100g (full capacity) calibration weights for my scale. After calibration, in fact multiple measurements taken on various parts of the scale are really within 0.01g, which is why I recommend that particular scale. In addition, my dealer used a Winds scale on my turntable recently, so I had a chance to compare the two methods. Mine was about 0.08g-0.1g different from his reading. However, after using the calibration weights on the Winds, it looks like it was off about 0.05g (at least compared to the calibration weights..), so I'd say they're really close. Close enough, that it could be due to the heights where the two measurements were made. The Winds scale was placed on top of a record, while my method measured the plinth to record height, removed the record, and then calibrated my jig to mimic the previous record height. I used a steel ruler to measure, and IMHO my method was a bit more accurate at measuring VTF exactly at the record level.

I hope this is helpful!
Most cartridge manufacturers have a recommended tracking force range, which allows for a bit of leeway plus/minus. I have used a Shure SFG-2 gauge for more than three decades, and have found it to be very accurate when checked against much more expensive digital gauges.

I am confused a bit by your comment about making final tracking force adjustments by ear. Are you referring to VTA (vertical tracking angle)? One DOES make final VTA adjustments by ear (after initially setting the tonearm to level), but I have never heard of making tracking force adjustments by ear. Seems to me that would mean there is no need for accuracy from the tracking force gauge.
Tracking force affects SRA, so adjustments by ear are important, right?:
I do VTA and VTF by ear. Use the gauges to get close. Ear for final dialing in....
Jfrech - Me too. Sdcampbell - may depend on your particular components, but on the tables and carts I've played with, lighter tends toward a more detailed sound and heavier toward a more romantic presentation. My by ear adjustments have stayed within the manufacturers recomended range but sometimes at the heavy end and other times toward the lighter.

Me three. Both VTF and VTA/SRA can be fine tuned by listening, assuming your rig and ears are interested of course. :-)

Lloyd Walker's well-written guidelines are worth reading:

FWIW, we also adjust antiskate, azimuth, impedance and even drive belt tension by ear. VTF changes are just as audible as changes to these other parameters.

Metralla's explanation is also why I have a .01g scale.

When the weather changes and/or I swap cartridges I want to dial in a baseline VTF quickly. On my tonearm I need to set VTF within .05g or so before I can use my fine VTF adjuster.

For me a .1g scale would be too coarse. If it read (e.g.) 2.0g, all I'd know is that I'm "somewhere" between 1.95g and 2.05g. With many cartridges a range that wide is so vast you might as well not use a scale at all. My main cartridge has a sweet zone for VTF that is .02g wide at most. Setting it up without a good scale could take hours, instead of minutes.
We've talked about this a number of times, and it appears that many seasoned audiophiles enjoy having highly accurate gauge in order to re-set the cartridge to a previously determined optimal tracking force. Reasons for this range from swapping cartridges and/or armtubes periodically to making VTA changes in arms that can have their tracking force thrown out inadvertantly in the handling process.

Then, there are folks like me (and possibly you) who don't have these needs and rely on fine tuning by ear with a gauge like the Shure just to get us in the ball park to start that process. I follow Lloyd Walker's turntable fine tuning advice for iterative adjustments of VTA and VTF to do my fine tuning. Then I adjust VTA for each different record weight, leaving VTF fixed. (The small VTA adjustments between 150, 180 and 200 gram LPs are very noticeable and absolutely necessary for my ear and my system, but they don't interact enough with VTF to warrant changing the VTF for each of these subsequent VTA teakings.)

Sdcambell, my experience has been that for setting up a tonearm/cartridge an iterative dialing process of changing VTF, then changing VTA, then changing VTF, is needed because of the interaction (just as Lloyd recommends). Thereafter, as noted above, I don't bother changing VTF when I adjust VTA between LPs because the difference truly is miniscule to unnoticeable at that point.
Anyone remember their college physics? How much of an error will be caused by having the stylus 1/2 inch higher or lower than the record surface? I doubt it is much, but haven't cracked my textbooks to do the calculation. Anybody?

Having one's stylus 1/2 inch higher or lower than the record surface would have a HUGE impact on sonics, namely, there wouldn't be any! ;-)

To respond seriously, we've discussed various explanations for the audibility of SRA/VTA adjustment several times over the years. An archive search will turn up several endless (and occasionally acrimonious) threads. There's no point going through all that again.

To summarize, no explanation has yet been posited that explains what people hear while satisfying the mathematically skeptical. Conclusion: the state of scientific knowledge still trails our experience of reality in this area.

If you're serious about researching this question, I'd recommend beginning with some archive searches here and at VA. You'll find enough material to keep you reading for weeks. I particularly recommend one article in the VA FAQ's, Jon Risch's "VTA once and for all". It comes closest to explaining what I hear, yet skeptics have expressed doubt that the degree of changes involved could be audible. They would prefer an alternate theory, but no more satisfactory one has been found AFAIK.

One long and inconclusive thread here was blissfully terminated by a practical post from Tbg. He wrote, "If you hear it adjust. If you don't, don't." Not a productive attitude for the scientific investigator, but a very productive one for the music lover/audiophile.
Nice reply, Doug. I think you captured it well.

Why not try it yourself and come back and let us know what you find out? Get a scale with some degree of accuracy and precision, say .01 gram +/- .005. Then take a reading at record level and one at 1/2" above (and below if you can). Keep in mind that by adjusting vtf you are changing the static location of the windings to the magnets. Biasing the circuit in a way. So it does not work against physics to suggest that minute changes in vtf can make a difference in the sound. This is probably not going to make any difference with some cartridges but it most definitely does with others. Now through in the mechanical action of the arm and bearings involved and you can see how there may be more or less resistance to slight changes in vtf from the stylus all the way back to the counterweight on the arm. It is all physics.

I don't think it is necessary to have a vtf guage that can measure to .01 in order to enjoy good playback, but it can be very useful with some equipment. And you don't need to spend $800 on the Winds. That $95 guage being sold here by ANS works very well.

I've had the pleasure of hearing Doug's rig. It sounds wonderful with any record. I have also heard the difference on some records when he makes minute changes to VTA. There is a very noticeable improvement. Not all pressings show this but the ones that do show it it very will. Granted this doesn't speak to vtf changes but I have no doubt that the table/arm/cart combo he is using is capable of showing what differences these slight changes can make.

"If you hear it adjust. If you don't, don't." That pretty much says it all.
An "audiophile" friend was amazed at my inability to hear the results of minor VTA adjustments. He attended my house to demonstrate, fiddled with the adjustment ring, and then proclaimed himself satisfied that he had found the optimum VTA. We listened for a while and then I noticed that I hadn't locked the adjustment ring in place. "You may have moved it a little when you were changing records", said my friend. "I'll have to go through the adjustment procedure again."

This time I stood at the turntable doing the adjusting while he listened at the other end of the room. But I never moved the ring - only made a pretence of doing so. Nevertheless he "heard" changes, rebuked me for my deafness, and was sure that his preferred position was identical to the one he had determined before.

I don't feel so bad about my inability to set VTA by ear any more.