I have to agree with this. But the problem is that most of us do not know how or have the means to measure this properly. I would love to see the cartridge manufacturers supply those SRA measurements and pictures. Great post
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The importance of VTA, SRA and Azimuth - pics
- Thread starter ack
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Thanks. Does Ogura have anything similar? I think my Ortofon A90 is using an Ogura stylus and cantilever??!? Am I right?
Hello ianm0,
This approach could work but it still does not take the requirement away of having to get a really good view of the stylus to take your measurement. I generally make my measurements at up to 450x magnification because that way I don't have to "hope" that the contact edges of the stylus are in the center of the shank. If you have a Shibata, SoundSmith optimized line contact stylus or some other unique design, there is no way you can use ~200x to get an accurate angle.
You are definitely correct that you need to take the photograph with perpendicularity to the cantilever (I am working on the WallySRA tool that addresses these issues). See this link for more on your point on the need for taking your photo properly: https://www.analogplanet.com/content/another-angle-digital-can-worms.
However, your approach doesn't offer you any freedom from the requirement on the INITIAL photographs you have to take to establish the relationship between the stylus and the cantilever. Once you know that angle, then you are "free" to use the cantilever angle to set SRA once the calculations are done.
One more thing: add between 0.25 and 0.45 degrees to your target cantilever angle to account for the impact on SRA by stylus drag.
It is interesting to know how sensitive SRA is to compression under VTF: Assuming a 6mm stylus tip to cantilever pivot point dimension, a TINY 0.15mm change in cartridge height will cause a relatively large 1.4 degree change in VTA/SRA. Depending upon the compliance of the cartridge, you could get a 0.15mm change quite easily from adding as little as 0.3 grams of VTF to your current setting.
Since cantilever deflection is NOT a linear function (impedance increases as deflection is increased), you CANNOT use VTF as a function (in addition to changes in cartridge height before and after application of VTF) to derive an SRA from a photo and data like the one you have posted. I'm not saying you were suggesting this, but someone might just wonder...
Above photo from Namiki site. Could be certain they got things right when it was taken. Now let's see photos I took and note how different the results are. I had to taken the average of the outcomes to match that from Namiki photo.
This shows how inaccurate amateur setups could be. Try measure SRA with USB microscope one day and redo the measurement on another with a fresh setup. The difference in the result could be quite astounding.
Note: I had my cartridge on the same platform at the same location, so hopefully the errors of each measurement cancel one another if opposite faces of the cartridge body are parallel with one another. Seems they have.
"a TINY 0.15mm change in cartridge height will cause a relatively large 1.4 degree change in VTA/SRA. " Can't agree with that more. I have long been a non-believer that a change of arm height by 4 mm results in a change of 1 deg change in SRA for a 9" arm. This is true only if the point/line of contact between the stylus and the grooves remains unchanged. If this point/line changes - the flexing of the cantilever also contributes to this change - the geometric conclusion 4mm implies 1 deg is no longer correct. Simply put, all bets are off. Change in SRA consequent upon changes in arm height and VTF depends on stylus profile. Actually I could hear the difference when my arm height changes of 0.1 mm for the Namiki microridge. Note: I have the luxury of a micrometer when changing VTA.
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That a ~4mm tonearm height causes 1 degree of SRA change on a 9" tonearm is roughly correct. However, as there is an offset angle not ALL of the 4mm height change impacts SRA. Some of the height change impacts azimuth as well. Calculator here: https://www.wallyanalog.com/sra-impact-to-azimuth-calculator"a TINY 0.15mm change in cartridge height will cause a relatively large 1.4 degree change in VTA/SRA. " Can't agree with that more. I have long been a non-believer that a change of arm height by 4 mm results in a change of 1 deg change in SRA for a 9" arm. This is true only if the point/line of contact between the stylus and the grooves remains unchanged. If this point/line changes, the geometric conclusion 4mm implies 1 deg is no longer correct. Simply put, all bets are off. Change in SRA consequent upon changes in arm height and VTF depends on stylus profile. Actually I could hear the difference when my arm height changes of 0.1 mm for the Namiki microridge. Note: I have the luxury of a micrometer when changing VTA.
Further, many arms are NOT neutral balanced which means that when you change tonearm height relative to the record surface you also change VTF which has its own affect on SRA due to cantilever deflection change.
So, when you change arm height at the pivot, you are also hearing changes of azimuth and VTF - not just SRA. This is why I am such an ardent proponent of isolating each parameter and measuring them independently of the other parameters. Analog playback is a multivariate system. A change to one parameter will always impact AT LEAST one other parameter.
Wait until you see what is coming down the road from me on zenith angle! That will blow some minds.
Do you mean SRA?
I routinely perform an intra-observer reliability regiment in my data captures. I never take just one photo. For SRA, I need at least nine images at varied magnification, illumination, polarizing factors and those nine results must have a confidence interval at 95% of no more than 0.25 degrees. I am building a database of all cartridges sent to me for analysis. I record 7 parameters for each and keep the results by brand and model.
The prototype WallySRA makes the measurements consistent, accurate and relatively fast. Still takes me a few hours per cartridge to be absolutely sure. When I am measuring someone's $20k cartridge and I know they will learn more about it than the manufacturer may know about that same specimen, I'd better be RIGHT!
I also make an SRA/Azimuth shim for interested owners made from same material used in ultra-dense engineering and dental applications so they never have to measure SRA and azimuth. Just slap it in after confirming level headshell with WallyReference.
Zenith measurements usually need about six photos to get statistically reliable results.
A while back I spent a lot of time using an USB digital microscope (a Dino-Lite AM4115ZT) to try setting SRA. It was almost impossible to get the lens perpendicular to the stylus and centered. Getting the round lens itself to a level plane was difficult. I tried putting a pencil lead behind the stylus and that helped a little but any slight whiff of air would move the lead. I tried putting an index card behind the stylus and that also helped a little, but it was very time consuming and I did not have full confident in a result.
I came to the conclusion that what is missing is a means to hold the small microscope firmly and to adjust it by very small amounts in three-dimensions. If the stand to do that is out there I'd like to know what it is. The slightest movement will move the scope in an unhelpful way.
Even after I got a picture, using the DinoCapture measuring software was dicey in drawing the left and right angles. There is not a straightforward way to establish a baseline that is perpendicular to a centerline running through the middle of the stylus in order to establish the angles are exactly on the same plane. It was easy to draw the angles incorrectly Different cartridges with different shaped stylii can have different angles on front and back.
Then doing it all again after tonearm height adjustment was somewhat hit and miss. That is what led me to return to setting SRA by ear. Somewhat time consuming but nowhere as fiddly and frustrating. Maybe my ears are better than my motor skills?
Only once did I achieve an quasi-acceptable result. That was with a Benz LPS.
J.R. I do thank you for all the helpful information you freely share with us and I am happy there is someone with your skill and motivation working in this space.
This is fascinating, J. R. Thank you for sharing information on this thread.
How do you account for sample to sample variation for the same cartridge model? I presume things may also change slightly when a cartridge is sent back for a rebuild/retip service.
Do you only go by measurements when setting up a cartridge or do you also confirm the set up by listening evaluations?
The other thing that always concerned me was how does one know the height of the stylus tip when it makes contact in the record groove? All of these photos, like Tim's above is on some reflective surface. Is that surface the thickness of a 150g LP, a 180 or 200g LP? Once in the groove, it is below the surface of the LP.
I had fun taking images of various stylus shapes with a USB microscope sitting next to my computer on a desk, but I rarely took it down to my turntable for images of the stylus when mounted on the tonearm. It was too difficult and tricky. I have gone back to setting SRA by ear.
Here are some images I took a while back. It is cool to actually see the shank in some of these.
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Thank you Lagonda. The first two are the MSL Signature Gold. The bottom two are the AirTight PC-1 Supreme. I currently own only vdH Colibris. I do not have any USB images of those, but the stylus does more closely resemble the images in post #204. It is just a tiny point coming out of a glob of glue. No facets or sharp edges that I can see through a loupe.
The only one i heard about using this measure to set VTA is Fremer, he wrote a couple of pieces on it in Stereophile, maybe his motor skills are better than his ears these days.
I think Ack who started this thread uses 92 degrees on his Ortofon A90, but that may have changed. He states it in the OP.
A simple question for those who advocate SRA/VTA setup by numbers and IMO somewhat questionable methodology, how do you know your numbers are any good without listening? What's your baseline if you don't know what to listen for?
david
david
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Things have changed quite a bit in here with the A90 in the last year or so...
Ortofon - whose claim to fame is very high quality control, above anything else - insists that with the arm set parallel and VTF to the recommended 2.3g, VTA will be correctly set (they never claim SRA will be 92 degrees, per se).
I have fought this claim for years by listening and measurements, adjusting the arm up and down, only to come around full circle and endorse their claim by pure listening. It has taken a significant increase in my system's resolution and accuracy to be able to do that, and at the same time, I have proven that my Dino-Lite USB microscope just isn't reliable enough to accurately measure, or I don't know how to measure accurately. Last I used the microscope was this past November or so.
What this also says is that, before, I was simply unwillingly trying to compensate for issues in the system elsewhere - like the arm and phono - rather than truly focusing on IMD reduction (and IMD is at the core of incorrect SRA). So the only true measurement here, for a layman audiophile who does not have an oscilloscope, is to use the Ultimate Analog Test LP's test track 9 discussed in various threads (I think also in here), and focus on IMD reduction that way. Then, with music tracks, the same results can be verified again; in fact, I did this very test one more time this past weekend with the Sheffield Drum Record, and identified the sonic differences one way or another - and once one can identify what to really listen for, then it becomes second nature. But it looks like it takes a lot of patience and experimenation to be able to do that.
The real breakthrough for me, as mentioned in the previous paragraph, was the arm, and specifically, anti-skating There were a number of discussions last year on this, and once this was dialed in and tracking distortion dropped by a wide margin, then it became a lot easier to tell IMD with SRA adjustments. So from my perspective, chalk one up for a high quality "proper arm" in one's analog rig.
I will agree again that THE RIGHT measurements if DONE RIGHT - assuming one has the chops to do them - is the correct way to START this journey, while listening is another critical part as well. But, extremely few of us have that ability to properly measure, which then leaves us with just listening as the only guiding light. The fundamental questions with that are: 1) what am I really, truly listening for; and 2) what other parameters are preventing me from doing it the right way. So I have come to the conclusion that proper cartridge and arm set up are much more difficult than I had originally imagined, involving a significant number of parameters.
Frankly, had I known that Wally Tools can properly measure my cartridge, I would have engaged them. Finally, kudos to Ortofon's high quality bar, at least for their higher end cartridges.
Live and learn...
Ortofon - whose claim to fame is very high quality control, above anything else - insists that with the arm set parallel and VTF to the recommended 2.3g, VTA will be correctly set (they never claim SRA will be 92 degrees, per se).
I have fought this claim for years by listening and measurements, adjusting the arm up and down, only to come around full circle and endorse their claim by pure listening. It has taken a significant increase in my system's resolution and accuracy to be able to do that, and at the same time, I have proven that my Dino-Lite USB microscope just isn't reliable enough to accurately measure, or I don't know how to measure accurately. Last I used the microscope was this past November or so.
What this also says is that, before, I was simply unwillingly trying to compensate for issues in the system elsewhere - like the arm and phono - rather than truly focusing on IMD reduction (and IMD is at the core of incorrect SRA). So the only true measurement here, for a layman audiophile who does not have an oscilloscope, is to use the Ultimate Analog Test LP's test track 9 discussed in various threads (I think also in here), and focus on IMD reduction that way. Then, with music tracks, the same results can be verified again; in fact, I did this very test one more time this past weekend with the Sheffield Drum Record, and identified the sonic differences one way or another - and once one can identify what to really listen for, then it becomes second nature. But it looks like it takes a lot of patience and experimenation to be able to do that.
The real breakthrough for me, as mentioned in the previous paragraph, was the arm, and specifically, anti-skating There were a number of discussions last year on this, and once this was dialed in and tracking distortion dropped by a wide margin, then it became a lot easier to tell IMD with SRA adjustments. So from my perspective, chalk one up for a high quality "proper arm" in one's analog rig.
I will agree again that THE RIGHT measurements if DONE RIGHT - assuming one has the chops to do them - is the correct way to START this journey, while listening is another critical part as well. But, extremely few of us have that ability to properly measure, which then leaves us with just listening as the only guiding light. The fundamental questions with that are: 1) what am I really, truly listening for; and 2) what other parameters are preventing me from doing it the right way. So I have come to the conclusion that proper cartridge and arm set up are much more difficult than I had originally imagined, involving a significant number of parameters.
Frankly, had I known that Wally Tools can properly measure my cartridge, I would have engaged them. Finally, kudos to Ortofon's high quality bar, at least for their higher end cartridges.
Live and learn...
There are no RIGHT measurements with such vague and dubious tolerances in production of everything involved in the playback chain starting with the cartridge itself all the way to the stamped vinyl that's produced with minimum standards. This is even before considering all the other variables relative to a playback system
!Setup difficulty is partially predicated on the tonearm too, many just aren't designed logically nor will they ever sound right no matter how accurate you try to be with your setup parameters.
david
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Well, Wally Tools has shown us I think that there can be proper measurements, even if the stylus/cantilever combo is way off, and he claims there is an SRA tool he's working on as well (looking forward to that). But just being able to get proper stylus/cantilever pictorial assessment and angle measurements (at a fee, or not), even if the measurements show really egregious build quality, is a great starting point, because one can then factor that information into how high or low a particular arm can theoretically sit, or even return the cartridge.
So I would not discount entirely the need for the right measurements, done right by a qualified entity (of which most audiophiles apparently are not). In fact, for the prices cartridges command nowadays, we as consumers should be requiring either more manufacturer data and proof, or make any purchase contingent upon sample review by a qualified professional - that ought to get the industry's attention and fix the quality problems, no? I know this is easier said than done, but since we are seemingly taken for a ride, what are we going to do about it...
So I would not discount entirely the need for the right measurements, done right by a qualified entity (of which most audiophiles apparently are not). In fact, for the prices cartridges command nowadays, we as consumers should be requiring either more manufacturer data and proof, or make any purchase contingent upon sample review by a qualified professional - that ought to get the industry's attention and fix the quality problems, no? I know this is easier said than done, but since we are seemingly taken for a ride, what are we going to do about it...
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