| jeff spall |
I have been looking at bias control and the kind of forces that operate and how to counteract them.
This is a complicated subject but my conclusion was that I needed and antiskate profile that, going across the record, started at a one value, decreased by about 10% as it approached the null points and then climbed again towards the end of the side. The amounts also need to be variable.
details here
So I’ve come up with a variation on the string-and weight that does just that. By varying the profile of the quadrant, you could create just about any profile wanted, including one that increases a little between nulls. It’s easy to adjust the values.
Basically, The radius of the quadrant is larger than the radius from the pivot centre, so the pull varies as it rotates.
Downside is that you can’t increase the radius of the pull to vary the overall antiskate force, so I make the weight hollow. To increase the force, add blu-tak or fishing weights inside the hollow weight. This is a bit fiddly, but the results are really good.
It's simple to make and set up, providing you can create a disc with a little groove for the thread. |
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| kevinkr |
Very interesting arm design and a thoughtful approach to the issues surrounding anti-skating.
I like the VTA adjuster set-up enough that it might inspire me to make something similar for my sme 3009 series II once I hone my machining skills..
More details on the arm? |
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| jeff spall |
Hi, thanks, I have a pdf write up on the thinking behind it at
http://www.audiomods.co.uk/regaNotes2.pdf
and a couple of up and running ones
http://www.audiomods.co.uk/armsinuse.pdf
I posted the antiskate because it's simple to make and I think might suit diy arm projects.
The vta just uses a NOS micrometer head whih are qite easy to get now the world's gone digital. If you want to do one I can send sketches of how it works.
I'm away for a week now, so if I don't respond, Im not ignoring the posts! |
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| kevinkr |
| The arm looks really nice and the explanations given regarding the mods are very thorough.. I'm quite impressed. I'd love to get my hands on one of those... Think I had better finish a few other projects first though...:D |
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| woodturner-fran |
Very impressive - lovely arm and I really like the neat, simple and elegant solution. Those always work best...
Well Done!
Fran |
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