Cartridge alignment in SME 3009 s2 improved - I'm confused!

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I just bought a new Shure V15 V cartridge for my SME 3009 s2 improved.

My 3009s2imp is manufactured in April 1976, serial# 212773

I no longer have the original protractor.

I have a question regarding the cartridge alignment null points.

There is a huge confusion on the web regarding this subject!!!

Here are some of the data that I have found in various scanned SME brochures or instruction manuals:

Original 3009 - single null point at 2 2/3 inches (cca 70mm)

3009 II - single null point at 60 mm (I've also found a document mentioning two null points - 60 & 111mm early version, 60 & 115mm later version)

3009 II improved early version - single null point at 60 mm (according to two null points document mentioned earlier - two points @ 60 & 117mm)

3009 II improved late version - two null points at 66 mm and 121mm

3009R - two null points at 66 mm and 121mm

I didn't know that there are earlier an later versions of 3009 s2 improved.
Which one is mine (April 1976, serial# 212773) ?

What null point settings do you recommend for it?

Thanks in advance,


PS I also have lost the original 1/16" hexagonal wrench.
Where can I find one? Here, we only have tools based on metric system...
do you understand how to achieve the 2 null points?
You are trying to achieve an angular error across the recorded surface that minimises distortion by introducing two null points with maximum error at the middle of side and at the two extremes of the start and end of track. Unfortunately the same angular error produces more distortion when tracing a track at a small radius and less when it traces at a large radius. This results in a minimum distortion when the angular error is small when playing end of side and a larger angular error when playing start of side.
Set up for 2 nulls and listen to a few records particularly at the end of side and probably at the start where you will have the worst angular errors which in turn generate the distortion you want to minimise.
If the end of side distortion is worst then move the small radius null in towards the middle i.e. change 66mm to 64mm or maybe a little less.
If the start of side is worst (less likely) then move the outer null out towards the edge. i.e. change 120mm to 123mm.
If the middle of side is worst then move either the inner null or the outer null towards the other null. If you are really adventurous you could try moving both nulls towards each other.
You can produce your own protractor and I have found that attaching a straight black cat's whisker across the front of the cartridge gives a better visual indication of angular errors than looking at the sides of the cartridge which are often hidden underneath the platform. If you adopt this you will need an array of parallel lines to the radial line through the null points. A few tangential lines through selected null points. On the radial you can pierce the various null points you want to experiment with. Start with 64mm and 120mm
If you want a starting (null) point I would recommend that you use the standard Baerwald null points which correctly given are 66mm and 120.9mm.Looking at the figures it seems that SME approximated these.Use a Garrot Bros. cartridge alignment tool if you can get one.
Two things; The 1/16 inch hex wrench. You'll have to get the next size up and file it down to fit. Not hard to do.
Secondly, with the alignment......I'll probable stop a bit of flack for this but is not essential to the geometry absolutely perfect. Now I am not a complete Philistine and I think you should try and get it as good as you can but having done that all the calculations in the world work on the assumption that the diamond is properly alligned on the cantilever of the cartridge. This is not necessarily the case and if it is out a couple of degrees then the perfectly aligned setup will be "perfectly" misaligned. When you've done the best you can with the geometry try and get hold of a good test record that allows you to optimise the orientation of cart' in the head shell. I'm not sure what's around these days but the old "Ortophon"(?) test record had a good track for this issue.
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