Pickup SRA - starting from a 500x microscope


I am not sure if my Lyra Atlas has the right SRA. Can other owners contribute? I have bought a 500x usb microscope, but it remains hard to find the exact angle. It is easy to get the angle of the record (or platter - I use a mirror), but very hard to get the angle of the stylus. I use the Cooling Tech software but it does not solve my problems. Trying to estimate the angle I cannot set the crosses sufficiently exact, and end up with values like 88, 90, 94 - varying all over the place.
I have only taken a few pictures so far, and could perhaps improve them. Tips and info welcome.
o_holter
It is fairly easy to mark the angle between the cantilever and the record. If the stylus had been 90 degrees on the cantilever, I would have no problem using this method. But this is what we don't know - right? Estimating the stylus angle vis-a-vis the record (or cantilever) is very hard and prone to subjective error, at least in my setup so far.
This is the definition of audiophile nightmare for me. One of many examples.
Should add, makes me thankful I am no longer one. Probably never was, but saw myself getting there. My sympathies.
Shoot me an email so I can forward you some photos of how to do this on a Lyra Atlas. They were made by Wally Malewicz and are quite easy to understand, basically measuring the angle in both sides of the stylus, then make a simple calculation.

Peter@pbnaudio.com

Good listening

Peter
Peter offers good advice. I have used some free software called ImageJ and it works great. Measures to within a hundredth of a degree. I usually take three to five measurements and average them. My current SRA on a dyna XV-1T is 92.08 - ImageJ is very accurate.
So interesting, for eons we set VTA/SRA by ear on the theory that sound should be the arbiter of sound reproduction.

In the last few years it has become fashionable and attractive to those that prefer an empirical solution to the issue rather than relying solely on hearing, to set VTA/SRA by eye or, more accurately, by degrees from a right angle to the groove surface. This is a method popularized by Malewicz and Fremer. If the surety of this method appeals to you, by all means follow the logic. But IMHO, having tried it, I believe that it is incorrect.

Just as the assertion by Mr. Fremer that small changes in VTA/SRA are negligible should be called into question and is easy to test by simply making very small changes in VTA and listening for any changes in sound.
Viridian,

I agree that small changes in SRA are noticeable, I do however subscribe to the idea that starting from a technical correct point is the proper way to go.

Good Listening

Peter
Peter, I have only the greatest respect for you and your achievements, but I believe that the modern theory is that an SRA of 92 degrees is not a starting point, but the correct end point. YMMV.
One problem I can think of with using the trusted ear method of determining the proper angle, any of the angles involved, is that you never know when you have achieved a local minimum, in terms of distortion. That is why a technical method should yield better results. Analogous to trying to determine the ideal best sounding speaker locations by ear. Technical solutions should yield better results than ye olde move a little, listen a little method.
I think Peter and Viridian are both correct but are differing in approaches. I use both. When I get a new cart or change carts, I set my SRA by ear first. That process takes a few days of listening and experimenting. I then check my SRA setting with a digital microscope. By ear I usually have it set around 91 degrees. I change the SRA to 92 degrees using the scope, but of course marking my original placement for reference.

So far, every time I have changed to 92 degrees using the scope, the sound dramatically improves - especially in transparency, air, decay and realism. I'm definitely in the SRA to 92 degrees camp.
Phil, I believe that Peter and I use the same approach, starting from approximately 90 degrees to the groove we fine tune by ear. Peter characterizes this as a "technically correct point" and I would describe it as a "convenient starting point", but we seem to be doing the same thing.

My point was simply that this recent method of setting SRA with a USB microscope often posits that 92 degrees to the groove is gospel. Nothing wrong with that and it seems to be most effective in your experience.
I have a Dino-Line AM3013T that i use to set up SRA for an XV1's and A90 and encounter the same difficulties as the OP using the software (DynoXcope) that came with the scope to determine the angles. If it was a matter of just pointing the scope at the platter/styli and and getting the rake angle with one "click" that would be easy.
I have a Sota Cosmos IV and getting the scope as close to the platter as possible to take a perfect picture is difficult to begin with (due to the plinth).

Once you have done that, using the DynoXcope software, you have to draw an horizontal and vertical line thru the centre of the styli to determine the rake angle. I had sent a few pictures i thought were at 92 degrees to Wally and he estimated one to be at 89d and the other one at 94d when i was convinced that i had hit the 92d mark. I found this exercise very frustrating.

Adjusting VTF, AS, Azimuth, overhang, zenith, is quite easy versus setting 92d SRA accurately with a scope. Unfortunately, for me using this scope and/or software gives me a rough estimation at best.
I agree Smoffatt, it definitely takes a lot of practice. I don't particularly like the Dinolite software.

One can use the following for a trial and see what they they think:

1. Pixelstix - this is great software (< $5) to get the baseline at 180 degrees. This is critical of course for SRA calcualtions. Its very difficult to sometimes get the camera adjusted so the base of the platter is exactly at 180 degrees. You get better and better with practice, but it helps to have a program that corrects the image to 180 degrees.

2. ImageJ - free and very accurate to drawing and calculatiing angles to the hundreth decimal point. Using ImageJ and taking the average of a few measurements will give you a very accurate reading.
Good thread at Audioshark.org with comments and pics of SRA. To see the pics you have to log in.

http://audioshark.org/all-things-analog-21/your-own-sra-pictures-6404-page2.html
Thanks for this Phil. Can you calculate angles with Pixelstix as well or do you just import your image into Pixelstix, correct the image to 180 degrees and then move it to ImageJ to calculate the angles? I will download ImageJ.

Indeed, for me getting a perfect 180 degree image to start with is very difficult.

Thanks for the link too.
Sly
SMoffat - You can use Pixelstix for both horizontal and angle calculation. Sorry I should have mentioned this sooner is another good 'horizontal' calculation program is Go Horizontal. Its costs less than $5 too and is even more simple to use.

I would go with Go Horizontal for the 180, and then ImageJ for the angle calculation. Pixelstix combines both but is more complicated to use.
Something to keep in mind is that all LPs are different- so the 92 degree SRA should be considered an approximation.

The simple fact of the matter is that the cutting stylus only lasts about 10 hours before replacement is required to continue doing low noise cuts on the lacquer. To replace the stylus, the cutting engineer has to remove the cutterhead from the lathe to do the job. Once done, it is then a matter of re-installing the cutterhead and getting it to work right again. That involves a number of test cuts until a number of the variables are worked out. These include stylus temperature, cutting angle, cutting depth and pressure (similar to tracking pressure, but cutting instead and somewhere between 60 and 70 grams is typical on our cutterhead).

The simple fact is that while you have to have a certain rake angle, in practice it might be 92 degrees and it might not. What it is will be whatever was required to get the cutterhead to cut a groove properly. As a result, all LPs are slightly different; 92 degrees is a good average.
Interesting that the OP is trying to figure out a method for setting the correct 92deg SRA on an Atlas yet the venerable Mr Carr at Lyra ( for whom I have the highest respect and admiration) is not a great fan of SRA.
A bemused Atlas owner !
Thanks for advice! I dislike it, however, when an honest question is turned into a stupid statement. Rpeluso writes as if I've left my ears behind - I have not. Going the visual way is a "nightmare". Well perhaps not though I trust my ears mainly. And Sunnyboy1956, where has Lyra said that SRA/VTA plays no role? It is more that they try to adjust for some margin, in my interpretation - but J Carr would be welcome to speak for himself. "Not a great fan" - who is? Karl Marx talked about the world of neccessity. Few audiophiles "want" to go into this SRA microscope testing business. The reason they do it, is to get the best possible sound from their pickups. Same with me.
Dear Mr Holter, my apologies if my comments appear to be derisive or dismissive of your efforts. That was not intended. As an Atlas owner all I was trying to suggest was that you can achieve great if not spectacular sound with your Atlas without obsessesing about SRA. I made no reference to VTA. SRA and VTA are not identical or even interchangeable terms. There are many who believe that the efficacy of SRA is overrated notwithstanding it's advocacy by MF. YMMV
All the best
Thank you Sunnyboy1956. I do agree with you (and with Rpeluso) that too much adjustment can become on obsession. On the other hand, a bit of it is a needed. Since you have an Atlas - where do you set the arm - up, down, or just parallel?

I do agree with you (and with Rpeluso) that too much adjustment can become on obsession...

Thank you for the joke of the year
"SRA and VTA are not identical or even interchangeable terms"

They are infinitely connected, one follows the other, no they are not identical but they will follow each other, if you change one the other will change too. So it ultimately a matter of where/how one chose to measure, in my opinion that would be SRA which is the point closest to the source.

I do however not subscribe to endless adjustments nor obsess over this, I usually just set it once and then forget about it till I change something on any particular setup.

Good Listening

Peter

It would be nice with a comment from J Carr or others of Lyra...
http://forum.audiogon.com/cgi-bin/fr.pl?eanlg&1398564021&openflup&5&4
Try this
Cheers
Hi O_holter. Sorry for not having seen this thread previously, and many thanks to the forum members who pointed it out to me. I very seldom visit this forum, and would not visit the Amps Preamps forum in the expectation of finding threads specifically about phono cartridges.

There have many threads about this same topic, and not only on Audiogon. For example, this one.

http://www.whatsbestforum.com/showthread.php?536-The-importance-of-VTA-SRA-and-Azimuth-pics

I have made relevant posts on page 13 and 14, maybe more.

FWIW, I know for a fact that LPs are not all cut at the same SRA, and the stylus used to cut LPs, being made of sapphire rather than diamond (for noise reasons), doesn't last very long. The chuck used to install the cutting styli allows a certain amount of freedom in adjusting the angle and how much the stylus protrudes, and not all cutting engineers have the same preference. Nor are the cutting stylii all made the same.

I have been told that that cutting engineers usually go for the setting that gives them the cleanest and quietest cut (test lacquers are usually cut before the real one). The cutting temperature also affects how easily and cleanly the stylus goes through the lacquer, so a number of interdependent variables are involved. Whether this results in a final cutting SRA of 92 degrees or not, depends on the cutting engineer, the individual cutting stylus, the lacquer blank, the master tape signal content (how much ampliftude, how much deep bass etc.), and more.

I also know that the photos of the same cartridge have been sent to the same expert on separate occasions (sometimes the same exact photo), resulting in different opinions on the SRA (too low, too high, just right). Undoubtedly visual assessment of SRA leaves room for individual interpretation (even by the same person).

The Lyra cartridges are made to deliver their best sound when the cartridge body is parallel to the LP. However, each cartridge has a slightly different optimal VTF (which changes according to the ambient temperature), and the proper VTF is critical to getting the cantilever rake angle and SRA right. At rest (no VTF applied), the Lyra cantilevers are designed to deflect downwards by about 3 degrees. Applying the proscribed amount of VTF (1.75g or thereabouts) should reduce the cantilever angle to 20 degrees, and the SRA to about 92 degrees. The recommended VTF range is only - +/- 0.05g, and this tight range is necessary to properly dial-in the cantilever, stylus and coil angles.

Today's tonearm designs pretty much guarantee that VTF will change as a function of the VTA adjustment mechanism. I trust that those who experiment with SRA are meticulous enough to check the VTF after each SRA adjustment, and readjust the VTF if it has changed? Note that the effective tonearm length and overhang will also change when the VTA mechanism is adjusted; these should also be remeasured and reset, otherwise the change in sound could be due to different VTF and different overhang together with SRA.

I don't think that the audiophile community (as well as tonearm and cartridge manufacturers) is yet at the stage where targeting a specific SRA angle is sufficient for optimal sound. I still think that it is best for audiophiles to adjust by ear, using the cartridge manufacturers recommendations as a starting point, hopefully re-check and re-adjust the VTF and overhang while the VTA adjustments are proceeding, and then use microscopes to find out what the SRA became. Put 10s or hundreds of such measurements into a database, and the information should begin to approach some semblance of validity that cartridge manufacturers can act on.

I also think that today's single-minded obsessiveness with SRA sends out the wrong message to cartridge manufacturers, because along with it comes the idea that cantilever rake angle does not matter as long as the SRA is 92 degrees. Although this is a case of reductio ad absurdum, there are cartridge models on the market with measured cantilever rake angles that are all over the place.

http://www.vinylengine.com/turntable_forum/gallery/image.php?album_id=97&image_id=16471&view=no_count

http://www.vinylengine.com/turntable_forum/gallery/image.php?album_id=97&image_id=16472&view=no_count

In reality, the vertical compliance of the cartridge increases in stiffness as a function of higher cantilever rake angle (calculate the sine of the cantilever rake angle), while the horizontal compliance does not change. What the cartridge should have is equal compliance in both the vertical and horizontal directions, and for this lower cantilever rake angles work better.

kind regards, jonathan
Isn't it amazing that when someone who REALLY understands all the technical issues and has a sound command of language, chimes in, it all becomes very clear?

Thank you, Jcarr for taking the time to provide such a thoughtful, logical and well written post. It seems to me that you've distilled this whole debate down into 11 words:
adjust by ear, using the cartridge manufacturers recommendations as a starting point

BRAVO!!!
JCarr, Did you see this post? http://forum.audiogon.com/cgi-bin/fr.pl?aamps&1424807026&openflup&17&4#17
Thank you, JCarr, much appreciated. Ever since I bought my first Lyra, a Clavis, I have adjusted by ear, and your text confirms that this is (still) the main way to go. Happily the microscope wasn't a big investment. Obviously, some find it useful, including Michael Fremer. I wasn't aware of the strong feelings (or obsessions) in this area. Now, I will go back to my traditional method. All measures set as suggested in the Atlas instructions. Then, lights off, on with some favorite music. Listen, try a tiny bit up, listen again, a tiny bit down, etc. When I no longer think about it, because the music grips me - thats where it stays. If I end up with a weird SRA, OK, I'll let you know!
Hi Ralph: No, I missed that post of yours, but it is a good one. Much of my knowledge of the LP cutting process comes from Takawa-san and his boys who were responsible for all of the King Super Analog series, and also Joe Harley, who has produced many a LP, but it is nice to be able to check my information against yours.

Guys, Ralph owns and operates an LP cutting lathe, and when he writes something about LPs and the LP mastering and cutting process, his words are based on first-hand experience!

BTW, I have absolutely no desire to dissuade anyone from using a USB microscope. As a firm believer in the importance of correlating objective measurements with subjective listening impressions (or at least seriously trying), I strongly encourage the use of azimuth checkers, digital scales, USB microscopes and anything else which can attach numbers to what we hear.

My prime suggestion in this case is that the ear be used as the principle guide, and the microscope used to translate the optimal setting into numbers that can be replicated or independently confirmed.

I'd love to see a database containing the SRA findings of hundreds of audiophiles. The greater the number of SRA reports, the more the outlier cases will be down-prioritized, leading to more meaningful results for us cartridge manufacturers. It would also be nice to have cantilever rake angles (which the microscope software should be able to supply) as well as the SRA, since the cantilever rake angle must also affect how the cartridge responds to the LP groove (as I wrote in my previous post).

kind regards to all, jonathan
Some months ago an audo friend of mine, visiting and listening to my system, adjusted my SME V arm upwards - he felt that the Atlas sounded better that way. It went as far up as possible, 6-8 mm in my case (Hanss T30 player). I thought, well perhaps he is right, at least it does not sound worse. Today I tried again, adjusting the arm down to parallel, listening, a bit up, listening again, and then up to the highest postion. Well yes, vaguely (my old non-golden ears), once more I did prefer the highest position, quite a bit above parallel. Now, what I should do (before I throw away my microscope), is to take some good pictures. Since my friend borrows it, they will come, later. Perhaps a core matter here, is that the Lyra pickups are made to be fairly - dare I say it - robust regarding VTA/SRA? In a sense, their "goodness" is their own worst enemy? I mean, if any of these adjustments had sounded BAD we would all have heard it, right, including Michael Fremer, who reviewed a lot of equipment with his Lyra Titan FAR TOO LOW on his LPs. I have a Meade telescope. It "clicks into place" when the focus is right. There is no question, one thing is RIGHT, all the rest is WRONG. My impression of Lyra pickups, unless you are really out of tune, there is seldom a WRONG, there is only a QUITE GOOD. And this often sounds mighty good too. So I am not sure if the "click into place" applies. Although I do believe in getting the best possible - going most of the way.
Hi O_holter. When you raise the SME pivot by 6-8mm, you are not only changing the SRA, you are also increasing the VTF, and reducing the overhang along with the tonearm effective length.

In order to isolate your findings to SRA only, you need to compare the VTF before and after raise and add the difference in VTF to the before raise position, or subtract the difference in VTF from the after raise position.

Also, you need to quantify how much the stylus position has moved and either pull the Atlas back a skosh in the before raise position, or nudge it forward a skosh in the after raise position.

I am not poo-poohing your findings at all, but good science demands that only one variable is changed at a time - even though you will have to fight the tonearm design to accomplish this.

Once you have confirmed the above and hopefully pinned the reason for the sonic improvement down to SRA increase and nothing else, I would be very interested in knowing what SRA and CRA (cantilever rake angle) your USB microscope reveals.

kind regards, jonathan
Thank you, JCarr. I will do it when I get the microscope back (may take some time). Very grateful for this help.
Let me assure everyone reading this, that I enjoy my Atlas a lot, each day - this is why I have used Lyra cartridges for almost twenty years.
If I can add my 2 paise worth. If the broad range for acceptable SRA is 90-95 deg, it doesn't require too much geometry to figure out that the cartridge body or tone arm underside will be parallel to the record surface. That's the starting point for most non SRA aficionados to start tweaking for optimal results. IOWs junk the usb microscope and NJoy the music.
Cheers
The angle at which the stylus is inserted into the cantilever varies greatly from sample to sample of even the best made and QC'd cartridge. This can be verified using a USB microscope. Setting the arm parallel to the record surface tells you nothing about SRA. Only a microscope does. By all means let your ears be your final arbiter if you so choose but having found 87 degrees and worse on some cartridge samples with the arm parallel to the record surface means the ear method sometimes will NEVER produce correct results. You need to know your starting point SRA and parallel to the record surface is false comfort. As for cutter head angles, the survey of cutting systems done nationwide by Discwasher's Jon Rich demonstrates that 92 to 94 degrees is the average range and that it MUST be greater than 90 degrees or the cut lacquer thread cannot be vacuumed away in real time, which is a necessity because the thread is highly explosive. Rich also published Intermodulation Distortion measurements at varies SRAs proving that 92 degrees is the average 'sweet spot'. If you wish to change for every record, see a shrink. By all means recheck VTF and overhang after setting SRA if you must but don't neglect setting SRA just because it might affect those other parameters! And here I just disagree with my friend Jonathan Carr: if you raise or lower an arm 6-8mm you WILL CHANGE SRA! On a 9" arm that would change it by almost 2 degrees. On the other hand those who hear differences between record thicknesses are blowing smoke since the difference in SRA will be a fraction of a degree. And Sunnykboy you are wrong and your post is JUNK. You obviously have zero experience here. Go measure a few dozen cartridges and you'd find some measuring 84 degrees and 87 degrees with the record parallel to the record surface. Stop passing along MISINFORMATION based on ignorance.
Dear Mr Graves
I really enjoyed reading your comments. Superb post. If SRA can cause such excitement, than surely all is well in this hobby that we love and enjoy.
Cheers
Thanks Grooves for the very informative post which I'm in total agreement with. I bought my USB Microscope after reading about the importance of SRA on AnalogPlanet and have been using this method since and always with better results.

Good Listening

Peter
I have worked more with my first pictures. As you can see, if I could copy them here, they are quite good, but not good enough to measure the SRA at a one degree level. My measures vary between 87 and 98 degrees, based on subjective ideas where to set the cross or measuring point, using various resolutions etc, trying to establish the angle of the stylus, the diamond itself. Establishing the record surface angle is easy. I am using Gimp, a good open source program that includes arc measurement, as well as the Cooling Tech software that came with the scope. I may be able to improve the photo quality, when I get the scope back, or I will have to buy something better. Distance and magnification are obviously keys to getting the best photos, and correct light plays a big role too. The pictures are embarassing - why is my cartridge so dirty.
Picture nr 3 at the top here:
http://forum.audiogon.com/cgi-bin/fr.pl?vevol&1337191142
I measured once more. With my SME V arm I am only able to raise the arm 2 mm or so from parallel. If it is higher, at the back, the rubber rim on the arm lift starts to engage the arm tube (even though it is at rest, not lifted), and there seems to be no way to adjust it down. This means I will have to use a shim under the cartridge, to simulate the arm going up, if needed. Since the whole idea with the SME V is structural integrity, no flexible connections, shims or whatever, I hesitate a bit. But if a good photo shows that the SRA is too low, I will have to reconsider. As it is, listening tests indicate that the pickup sounds best if the arm is raised as far as possible. Perhaps more is needed. Some owners (like M Fremer) had to raise their Lyra Atlas pickups more than I can.
You can adjust the arm lift down with the microscopic allen wrench supplied in your tool kit for the SME. Midway in the rubber strip there a tiny hole that the allen wrench is inserted through to engage a adjustment screw below, this is a VERY finicky and fragile adjustment so be very careful. Your SME Manual have instructions on this on page 20 paragraph 536, if you don't have them manual one can be downloaded from Vinyl Engine

Best of luck

Peter
Thank you Peter - but the arm rest is already fully down, or very close to it (if I could only find that allen wrench), so I don't think it will change much. Also the microscope is still on loan to a friend. Btw he has a big dog that likes good music, so I've been wondering perhaps he could train it to hear proper VTA. Just joking.
Your Welcome, the allen wrench is a .09MM and a set containing it is available Here

Remember even a VERY tiny adjustment at the base of the arm will result in a significant change in cueing height

Best of Luck

Peter
Thanks again! I have to get that wrench, it got lost.
To sum up: my Atlas sounds best as far up as I can get it, on my SME V arm on a Hanss T-30 turntable. I have measured, this is not very far up at the back, 2-3 mm or so from parallel. Perhaps I can get 1 mm more by adjusting the lift fully down. It becomes obvious that the SME V engineers did not include "off" cases - a needle and styles fairly close to the ideal angle is presupposed. If you have a poorly adjusted cartridge, you must use a shim, the high and low points of the arm adjustment create a quite narrow adjustment zone. BTW this type of compromise is typical of the SME V in other respects also. For example, structural integrity rules. So a shim is not the thing one wants, on this arm, with the shell integrated as part of the arm.

The point of the microscope is not to tell me, exactly what degree is my stylus. It can be off by an error of 1-2 degrees, or even more. The point is to give me a rough idea, where am I, compared to using the ears alone. Personally I am tired of people with golden ears who supposedly are able to adjust vta/sra by listening alone. I find that their magic may have worked last evening, but this morning I am not so sure.
September 2016 update
I have gone down to a more moderate arm position, just a bit up from parallell. I have done some more microscope tests but have mainly given up on the method, for now. I took two older Lyra cartridges to a shop that claimed to give good microscope analysis, but they did not deliver, beyond a vague message that they looked worn. In fact, one was worn, the other not.