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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

Showing 5 responses by philb7777

philb7777
401 posts
 
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.
philb7777
401 posts
 
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.
philb7777
401 posts
 
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.
philb7777
401 posts
 
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
philb7777
401 posts
 
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.
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