tabarddn51
Super Member
IS IT ALL WORTH IT
Well from my efforts with my Shibata stylus, YES it definitely was worth the effort. There is more fine information retrieval, more space around the instruments & the bass, well the bass on my system is now to die for. So in my system yes, in your system it may be a different result depending on many, many factors, but you will never know until you try.
If you want more info, continue reading
Although many audiophiles have know about SRA for years, it has always normally been in the 'to hard basket” and was normally discussed by knowledgeable people under the VTA banner. However I have over a period of time come to realise & hear that the only way to set a cartridge up on a turntable is to adjust the cartridge/tonearm to the correct SRA.
Why is correct SRA so important. Well setting the SRA to the correct angle, experts much cleverer than me recommend it should be 92 deg's +/- 1 deg. This is to allow the stylus to best replicate the vinyl cutting head that allowed for the manufacture of the LP.
(However to muddy the waters further the cutting head angle has been changed around 1968 from 15 degs (Ortofon MC15) to 20 deg (Ortofon MC20). Now I have managed to come to grips with this subject & have adjusted my cartridge SRA accordingly to suit the post 1968 LP. After adjusting the SRA I find that the vast majority of my LP's sound very much better, but early released pre 1968 do not sound as good. Is there a solution for this. (yes easy adjustable VTA!! more later on this)
I believe the reason why SRA has been so hard for people to tabulate correctly over the years is because of the extreme difficulty it has been to measure it, until now. In the past we have only been able to take a photo or the stylus resting on a playing surface at the correct playing weight & extrapolate the SRA from there. This I can assure you from personnel experience is next to impossible even with the professional camera that I own shooting in RAW, (18 Mb of photo size) and a very good macro lens. Sorry it gets even worse, as the SRA can vary depending on the type of stylus profile the cartridge uses. From my deductions I have found the following to be true,
Conical/Sperical - Elliptical and Hyper-elliptical. Measure the SRA angle from the centre line of the Stylus profile.
With Shibata the stylus profile is touching the LP grove slightly towards the front of the stylus centre line.
Fritz Gyger the angle is measured virtually the back of the stylus due to that unique the stylus profile.
People in the past, including manufacturers, have simple advised users to make sure the arm is parallel with the platter & hope the manufacturer of the cartridge has done his job correctly. This approach has several disadvantages & will only get you the correct SRA if you are lucky. In my opinion this rule is incorrect for the following reasons.
a) This rule ignores the compliance of the cartridge, the compliance will predetermine how low the cartridge stylus sits on the LP when the correct tracking weight is applied. Thus some cartridges can sit lower than others depending on there compliance, this will mean that 2 cartridges with the same profile & same tracking weight but different compliance's will have different SRA settings.
b) The depth of cartridges from manufacture to manufacture varies a lot, from 12mm to 16mm.
c) Many, many tone arms cannot adjust there VTA..
d) The stylus cantilever angle to cartridge has a tremendous range which is confirmed by http://www7a.biglobe.ne.jp/~yosh/vta.htm with a variation of 12 – 36 degrees or greater just shown by this chart. However the chart does not advise how the stylus is set on these cantilevers so we are not totally sure of how this effects the SRA.
e) LP's vary in thickness from 1mm to 2.4mm so therefore theoretically require different SRA settings depending on the LP thickness being played. However I have found that as long as the SRA is set up say a the mid-point of the LP thickness at 1.6mm then the LP thickness variation can be coped with well within the +/- 1 deg when a 12 inch arm is used.
f) Adjusting the VTA to accommodate the 22 to 15 degrees LP manufacturing change would require an adjustment of the arm base by 28 mm for a 9 inch arm, slightly less for a 12”. This is well beyond the capability of most arms, but fortunately not my Temaad 12”.
So what to do.
Well I believe this subject is getting a fresh airing with many scratching of heads due to the fact that we can now buy USB Microscopes at a reasonable pierce of less than $100. You need at least a 5MP unit with 500x zoom. With one on these in hand & the computing power of any reasonably modern computer then the job is not that hard.
a) First determine, if you do not already know, what profile your stylus is. Fritz Gyger styli should be the easiest to set up as the SRA is measured at the back of the stylus. Interestingly of the Elliptical, Hyper-Elliptical styli seem to be the easiest as has quite a narrow contact bad running vertically up the centre of the stylus. All the other elliptical & conical styli also should be measured around the centre of the styli. Shibata is a little more difficult as it seems to change from manufacturer to manufacture, but basically measure a little in front on the stylus centre line.
b) Next you need to place a CD on top of of the platter. However this needs to be packed up a little as CD,s are 1.2mm thick & the medium thickness of an LP is 1.6mm. The easiest way to do this is just lay several sheets on paper on the platter & then place the CD on the paper. Yes I know paper varies in thickness, so you need to be able to establish how thick your paper is or measure it with a vernier. (buy a plastic verniers from a $2 shop)
c) Now carefully place your Stylus onto the CD.
d) Set your USB microscope up on it's stand so the centre of lens is parallel the stylus tip. Zoom in to the stylus, carefully adjust focus & take the shot.
e)Now process the image on your computer to .jpg and if the image of the CD is not horizontal you will need to adjust so it is. Then transfer the photo to your desktop.
f) Next open an Open Office calc sheet, it is a free download & in my opinion more flexible than XL. Now transfer the image from your desktop to the Open Office calc sheet. Here you need to be very careful that you do not change the size proportion of the image.
i) Now using the drawing application, draw a line horizontally across the image & vertically so that both lines cut through each other at the stylus point of contact with the CD. Next draw a line (in the example it's Blue) cutting through the centre of the stylus.
g) Now copy a protractor picture from the Internet, make sure the picture is sitting parallel. Drag it onto your calc sheet & align it with the horizontal & vertical black line. Next draw a line (in this case it is Red) through the stylus cetre axis to the 92 deg mark. And you will see how far your current set up is out. In this case the Stylus is sitting at about 101 deg's so the VTA needs to be seriously lowered, or you could shim the back of the cartridge down. The red line & blue lines should co-inside when the correct SRA is achieved.
h) Once you have made what you think is the required change, repeat the process. You will most likely need to do this several times to get the correct angle.
(SEE PHOTO)
Now how to fix the pre 1968 LP
The easiest way that I can figue out for most normal systems is to make up a platter topper to raise your LP up to nullify the angle change. This can be done as easy as stacking several LP's underneath the LP that is being played. How much do I need to increase the high will again depend on your cartridge compliance & I am still working on that one for my own system so more on that later.
Happy Fiddling & Listening.
Derek
Well from my efforts with my Shibata stylus, YES it definitely was worth the effort. There is more fine information retrieval, more space around the instruments & the bass, well the bass on my system is now to die for. So in my system yes, in your system it may be a different result depending on many, many factors, but you will never know until you try.
If you want more info, continue reading
Although many audiophiles have know about SRA for years, it has always normally been in the 'to hard basket” and was normally discussed by knowledgeable people under the VTA banner. However I have over a period of time come to realise & hear that the only way to set a cartridge up on a turntable is to adjust the cartridge/tonearm to the correct SRA.
Why is correct SRA so important. Well setting the SRA to the correct angle, experts much cleverer than me recommend it should be 92 deg's +/- 1 deg. This is to allow the stylus to best replicate the vinyl cutting head that allowed for the manufacture of the LP.
(However to muddy the waters further the cutting head angle has been changed around 1968 from 15 degs (Ortofon MC15) to 20 deg (Ortofon MC20). Now I have managed to come to grips with this subject & have adjusted my cartridge SRA accordingly to suit the post 1968 LP. After adjusting the SRA I find that the vast majority of my LP's sound very much better, but early released pre 1968 do not sound as good. Is there a solution for this. (yes easy adjustable VTA!! more later on this)
I believe the reason why SRA has been so hard for people to tabulate correctly over the years is because of the extreme difficulty it has been to measure it, until now. In the past we have only been able to take a photo or the stylus resting on a playing surface at the correct playing weight & extrapolate the SRA from there. This I can assure you from personnel experience is next to impossible even with the professional camera that I own shooting in RAW, (18 Mb of photo size) and a very good macro lens. Sorry it gets even worse, as the SRA can vary depending on the type of stylus profile the cartridge uses. From my deductions I have found the following to be true,
Conical/Sperical - Elliptical and Hyper-elliptical. Measure the SRA angle from the centre line of the Stylus profile.
With Shibata the stylus profile is touching the LP grove slightly towards the front of the stylus centre line.
Fritz Gyger the angle is measured virtually the back of the stylus due to that unique the stylus profile.
People in the past, including manufacturers, have simple advised users to make sure the arm is parallel with the platter & hope the manufacturer of the cartridge has done his job correctly. This approach has several disadvantages & will only get you the correct SRA if you are lucky. In my opinion this rule is incorrect for the following reasons.
a) This rule ignores the compliance of the cartridge, the compliance will predetermine how low the cartridge stylus sits on the LP when the correct tracking weight is applied. Thus some cartridges can sit lower than others depending on there compliance, this will mean that 2 cartridges with the same profile & same tracking weight but different compliance's will have different SRA settings.
b) The depth of cartridges from manufacture to manufacture varies a lot, from 12mm to 16mm.
c) Many, many tone arms cannot adjust there VTA..
d) The stylus cantilever angle to cartridge has a tremendous range which is confirmed by http://www7a.biglobe.ne.jp/~yosh/vta.htm with a variation of 12 – 36 degrees or greater just shown by this chart. However the chart does not advise how the stylus is set on these cantilevers so we are not totally sure of how this effects the SRA.
e) LP's vary in thickness from 1mm to 2.4mm so therefore theoretically require different SRA settings depending on the LP thickness being played. However I have found that as long as the SRA is set up say a the mid-point of the LP thickness at 1.6mm then the LP thickness variation can be coped with well within the +/- 1 deg when a 12 inch arm is used.
f) Adjusting the VTA to accommodate the 22 to 15 degrees LP manufacturing change would require an adjustment of the arm base by 28 mm for a 9 inch arm, slightly less for a 12”. This is well beyond the capability of most arms, but fortunately not my Temaad 12”.
So what to do.
Well I believe this subject is getting a fresh airing with many scratching of heads due to the fact that we can now buy USB Microscopes at a reasonable pierce of less than $100. You need at least a 5MP unit with 500x zoom. With one on these in hand & the computing power of any reasonably modern computer then the job is not that hard.
a) First determine, if you do not already know, what profile your stylus is. Fritz Gyger styli should be the easiest to set up as the SRA is measured at the back of the stylus. Interestingly of the Elliptical, Hyper-Elliptical styli seem to be the easiest as has quite a narrow contact bad running vertically up the centre of the stylus. All the other elliptical & conical styli also should be measured around the centre of the styli. Shibata is a little more difficult as it seems to change from manufacturer to manufacture, but basically measure a little in front on the stylus centre line.
b) Next you need to place a CD on top of of the platter. However this needs to be packed up a little as CD,s are 1.2mm thick & the medium thickness of an LP is 1.6mm. The easiest way to do this is just lay several sheets on paper on the platter & then place the CD on the paper. Yes I know paper varies in thickness, so you need to be able to establish how thick your paper is or measure it with a vernier. (buy a plastic verniers from a $2 shop)
c) Now carefully place your Stylus onto the CD.
d) Set your USB microscope up on it's stand so the centre of lens is parallel the stylus tip. Zoom in to the stylus, carefully adjust focus & take the shot.
e)Now process the image on your computer to .jpg and if the image of the CD is not horizontal you will need to adjust so it is. Then transfer the photo to your desktop.
f) Next open an Open Office calc sheet, it is a free download & in my opinion more flexible than XL. Now transfer the image from your desktop to the Open Office calc sheet. Here you need to be very careful that you do not change the size proportion of the image.
i) Now using the drawing application, draw a line horizontally across the image & vertically so that both lines cut through each other at the stylus point of contact with the CD. Next draw a line (in the example it's Blue) cutting through the centre of the stylus.
g) Now copy a protractor picture from the Internet, make sure the picture is sitting parallel. Drag it onto your calc sheet & align it with the horizontal & vertical black line. Next draw a line (in this case it is Red) through the stylus cetre axis to the 92 deg mark. And you will see how far your current set up is out. In this case the Stylus is sitting at about 101 deg's so the VTA needs to be seriously lowered, or you could shim the back of the cartridge down. The red line & blue lines should co-inside when the correct SRA is achieved.
h) Once you have made what you think is the required change, repeat the process. You will most likely need to do this several times to get the correct angle.
(SEE PHOTO)
Now how to fix the pre 1968 LP
The easiest way that I can figue out for most normal systems is to make up a platter topper to raise your LP up to nullify the angle change. This can be done as easy as stacking several LP's underneath the LP that is being played. How much do I need to increase the high will again depend on your cartridge compliance & I am still working on that one for my own system so more on that later.
Happy Fiddling & Listening.
Derek