SL1200 Mk1 Cartridge Alignment Geometry - Help Please?

[ceejaydee]

Hello Folks,

I'm looking to set up my SL1200 Mk1 that I bought a while back with a new cartridge. but am having some difficulty finding an alignment jig or protractor to suit.

My 1200 is fitted with the EPA 120 tonearm but I am having some difficulty finding an alignment jig or protractor to suit as everything seems to suit the Mk2 and newer models which have a different tonearm length, pivot to spindle distance and overhang values to the earlier model.

I'm also not sure what alignment geometry to try as whilst I understand the concept of the various Loefgren, Stevenson and Baerwalds in terms of where distortion is on the record but don't which would work well with my MK1.

I suppose ideally I would appreciate the input and opinion of another Mk1 user or someone who knows their way around the subject to share what alignment method they use and the source of a suitable protractor if possible.

I've read the info on Vinyl Engine and had a play with the alignment calculator inputting my own data for the tonearm but am not 100% sure that what I am doing is right.

Any info or help much appreciated.

[Barry]

According to vinylengine, the two null-radii are likely to be at 58.8mm and 113.5 mm.

Looking at the information for the EPA120 arm, the quoted overhang corresponds to neither Baerwald nor Stevenson's geometry. Like a lot of Japanese arms, Technics probably have their own geometry, but unless you can find the value for the offset angle , the two null-radii cannot be calculated.

[Shovel_Knight]

Same geometry as EPA-101s. Effective length 220mm, overhang 14mm, offset angle 22 degrees. These tonearms use the same 52mm headshell flange to stylus distance as the rest of Technics tonearms.

[ceejaydee]

Thanks for the info chaps.
I was going to stick a Mk2 headshell in and play with the cart alignment but I'll have a play with the cart in the original headshell as there seems to be less room for tweaking so in theory there is also less room to get the alignment wrong.

[graham67]

Although basic these are super handy for techys.

https://www.ebay.co.uk/itm/283841977750

When I use this and check it with a.generic protector, it usually comes out spot on.

[ceejaydee]

Although basic these are super handy for techys.

https://www.ebay.co.uk/itm/283841977750

When I use this and check it with a.generic protector, it usually comes out spot on.

Thanks Graham,

I do have an overhang gauge which I had completely forgotten about and I've pondered a protractor for a while so will add it to my 'to purchase' list.

[Shovel_Knight]

Although basic these are super handy for techys.

https://www.ebay.co.uk/itm/283841977750

When I use this and check it with a.generic protector, it usually comes out spot on.

I agree, and they are more than accurate enough for cartridges with basic spherical or elliptical styli (e.g. Denon DL103)

[ceejaydee]

Found my overhang gauge so rather than wait for new headshell leads to fit to the Mk1 headshell and to get the ball rolling I have fitted a new cart - Audio Technica AT-VM95C to a new Technics Mk2 headshell that I picked up a good few years back.

I think a conical stylus will be a little more forgiving with a basic cartridge setup (ie. by eye)

For now I have just fitted it 'square' and after a tinker with the arm settings etc. I am spinning a few tunes and am really enjoying this turntable; I even enjoyed the setting up process as the using pinch screws for arm height, rest height etc. on the Mk1 seems so much more engineered than the convenience of the Mk2 and it suits my thinking.

Many thanks again for the input Barry, Pavel & Graham - it is much appreciated :)

[Shovel_Knight]

I'm glad you're enjoying your Mk1 Christopher, I like them as well! My personal feeling is that they were better built than the later models (although obviously not as sophisticated in terms of electronics).

[ceejaydee]

Helicopter pic :)

https://scontent.flhr4-2.fna.fbcdn.net/v/t1.0-9/97984354_3240349179355702_2439070511028764672_o.jp g?_nc_cat=110&_nc_sid=110474&_nc_ohc=Axlx-uWNfucAX9bFt9O&_nc_ht=scontent.flhr4-2.fna&oh=48be3cecbdef73e9ce2aa196768f8b1c&oe=5EE5090C

[Bacek]

Two choices.

1. Stick with original alignment and set tip distance to 52mm (using Technics gauge or other way) and cartridge parallel to headshell.
2. Generate your own custom template with software from here http://www.conradhoffman.com/chsw.htm

I guess more important than particular geometry is correct setting for one you choose.
I prefer those arc based templates because with careful handling they allow for more precise setting. Don't bother with exact null points positions. With generator you could optimize little bit alignment for set of records you have but not sure if this is worth of playing with. Except of tonearm parameters, generator takes radius where vinyl record starts and ends so for example you could have separate headshell with cartridge.

For custom calculations you will actually need pivot spindle distance which in case of your arm is 206mm (220-14).

You can observe what are effects of different geometries and inner and outer groove radiuses on tracking error on simulations here (you need to register first)

https://www.vinylengine.com/tonearm_alignment_calculator_pro.php?arm1=Arm+1&l1=ps&a1lv=206&a1=la&oh1v=&oa1v=&arm2=Lofgren+A&l2=ps&a2lv=&a2=la&oh2v=&oa2v=&arm3=Lofgren+B&l3=ps&a3lv=&a3=lb&oh3v=&oa3v=&arm4=Stevenson&l4=ps&a4lv=&a4=st&oh4v=&oa4v=&rs=12&rsv=&og=iec1&ogv=&ig=iec&igv=&cal=y&submit=calculate

27925

[ceejaydee]

I've been elsewhere for a while but many thanks Jacek for the reply :)