SME 3012 Alignment

[odey]

The given P/S distance of 294 is intended for the fixed cartridge mount headshell and effective length is nominal depending on the cartridge stylus tip to mounting hole distance. Adjustment is intended to be at the sliding base rather than the headshell.

Should you wish to use the slotted headshell instead of sme's fixed hole HS, then you're making the 3012 behave like a fixed mounting base tonearm.
You may need to determine the effective length of the tonearm using the average stylus tip to mounting hole distances of you favorite cartridges, from there you can compute for mounting distance.

excellent read here:http://odysseytonearms.blogspot.com/search/label/SME%20Geometry

[analogadikt]

The link should open now.

http://odysseytonearms.blogspot.in/search/label/SME%20Geometry

Regards,

[urbu dah lung]

It would be Stevenson, which always turns out to have the shortest o/hang.

The protractor is not much different from the Hoffman one i use (see picture in opening post).

There seems to be some magic about the 3012, i mismeasured the centre of the baseplate hole by about 12mm 

Maybe you have to change angel of tone arm tube;)

[wer]

Maybe you have to change angel of tone arm tube;)

Where did i put that hammer?   

[JayM481]

Maybe you have to change angel of tone arm tube;)

You don't want to mess with tonearm angels. They are subtle, and swift to anger. 

[Iron]

Werner, did you get any further on this? Please share your experience with us on this mystique of the SME 3012/II.

I am/have been struggling as well. So I'd like to contribute a bit of my experience, as I think, I had noticed a couple of things:

1. an original SME Headshell with a Shure V15/IV and ORIGINAL stylus (MR in my case) is exactly 52,5mm from the bayonet flange (this is not the case with an aftermarket HE-stylus).

2. to make this trick easier: the Technics cartridge alignment (overhang) gauge is using precisely this same distance, so you only have to adjust the cartridge with its stylus to the front edge. You only have to watch a certain variance coming out the (cheap) production, so please measure yours first.

Hey you fellow SME users, please check on this and share  I have not checked this on my arms yet, but update is to follow.

Cheers
Marco

[bluetomgold]

I've come across this too. I think the specified mounting distance is just wrong.  Not the end of the world as you can get away with it with the arm pushed right back, but still makes a bit of a bit of a mockery of the "reduced tracking error" theory of why 12" arms sound better...

[behind the rock]

All the older, and possibly the newer arms as well, specify pivot to stylus measurement to a point between the mounting screws ( Deja vu here) not to the actual stylus.  This means the true distance is somewhat more.  For most cartridges that is about 9.5mm but the Denon 103 is 7.5mm from stylus to mounting holes. Therefore although the sliding base is very convenient it does not mean accurate measurement of the embedded triangle of pivot to stylus and the notional right angle the stylus makes with the groove at two null points.  As I stated recently in another thread taking the 9" series ii improved serial #'s <439606 as an example where eff. length is allegedly 231.2mm and offset for that is 22.6 degrees with 15.86mm overhang and null points 60.4/117.3mm radius, its wrong, does not exist, a generalisation by SME. With a Denon 103 for example pivot to stylus is about 236.7mm and offset angle is 21.5 degrees or thereabouts for about the same levels of distortion and null points approximately.  I did all this years ago, I think it was a Baerwald alignment but I'm not sure. The SME view has been expounded on a tonearm site and labours the point about " square of the null points amongst other things. But, a triangle is a triangle and once you alter one of its parameters then all bets are off!    For spindle to pivot to be correct then so has the intrinsic triangle embedded in the pivot to stylus and associated parameters such as offset angle and chosen null points which help determine maximum distortion across the disc, allegedly.  Elliptical stylus are more alignment sensitive for best performance so correct alignment is probably more crucial for that type.

Andy

[behind the rock]

Werner, I just wrote a description on how to achieve a good alignment then I lost it! Doh! If you still have my home phone number call me and we can go through it. In fact I will PM you anyway with my number.

Andy

[behind the rock]

SME series ii alignment is Stevenson apparently for minimum distortion at the inner groove.

Andy

[Iron]

Dear fellow LH members,

hello WER, have you got any further on this? If yes, I hope you do not hold BEHIND THE ROCK with the answer 

I re-activate this thread, as the questions have not really been answered, at least not in the thread. I had and still have the same problems. I had my SME 3012/II aligned with a PS distance of approx. 305mm as well as with the current 297mm approx. in both cases overhang was more than 11mm. I find the alignment of this arm mysterious and always end up with data, which according to the VE website is not supposed to work.

So please, all you professionals out there, please give me a hand and measure your own mounting distance and overhang. But please, do not again come back to 294mm P/S and 11mm overhang and refer to several websites. This cannot work with the stock SME Headshell. So I kindly ask only the true SME 3012/II owners/users out there, to answer on this.

Cheers
Marco

[flood2]

Dear fellow LH members,

hello WER, have you got any further on this? If yes, I hope you do not hold BEHIND THE ROCK with the answer  

I re-activate this thread, as the questions have not really been answered, at least not in the thread. I had and still have the same problems. I had my SME 3012/II aligned with a PS distance of approx. 305mm as well as with the current 297mm approx. in both cases overhang was more than 11mm. I find the alignment of this arm mysterious and always end up with data, which according to the VE website is not supposed to work.

So please, all you professionals out there, please give me a hand and measure your own mounting distance and overhang. But please, do not again come back to 294mm P/S and 11mm overhang and refer to several websites. This cannot work with the stock SME Headshell. So I kindly ask only the true SME 3012/II owners/users out there, to answer on this.

Cheers
Marco

Hi Marco

The SME arms are designed according to a predetermined Linear Offset with a fixed offset angle defined by the arm bend relative to the headshell screw holes. Effective length and overhang are the variables which depend on the cartridge design (i.e screw hole to tip distance). Therefore there is a unique combination of pivot/spindle distance and overhang that satisfies the design value of linear offset and pre-determined offset angle. You achieve this by moving the arm base so the pivot/spindle distance and overhang are adjusted according to your cartridge.
In other words, effective length and overhang no longer have a specific meaning in relation to the arc protractor (which requires that you know the EXACT pivot/spindle distance and overhang for it to work. You will never be able to trace the arc AND achieve the nulls. Remember the specifications for the cartridge dimensions will have a tolerance to them and there are variances within that range with multiple samples of the same model.
The only reason SME publish those parameters is to indicate a specific data set that satisfies what the typical user will be expecting to use to compare arm lengths and alignment.

Due to the fixed offset angle, this also means that you don't really have the freedom to change the alignment nulls according to your preference or to accomodate a skewed cantilever (which is all too common). Hence an arc protractor is no use. The arms are made to a tolerance so the dimensions are never perfect (including the offset angle). You need to use the SME template or construct your own two-point protractor according to the SME published linear offset .

The Linear Offset is the arithmetic mean of the two null points so as long as you know this parameter, you can calculate a pair of nulls that satisfy the Linear Offset. To achieve the intended null points requires that you know the modulation envelope of interest.
Not to be pedantic, but the alignment commonly referred to (incorrectly) as "Stevenson" is actually one of 3 universal solutions proposed by Stevenson in his paper. The intention was to determine solutions that were optimal for playing all 3 record sizes.  1A favours an LP which is compliant with DIN specification and is the alignment used for the SME 309. 1B spans a modulation envelope from 145.3mm to 54.8mm. The linear offset is 88.66 which gives the familiar nulls of 60.3 and 117.1mm and is actually ideal for a 12" arm - You can play all 3 record sizes with less distortion than a 9" arm optimised for the typical IEC nulls of 66 and 121mm. However, if you don't need to play 7"s, then obviously 1B is not the best option for minimum distortion across an LP. 1C is biased more towards 7" playback but is generally inferior for LP and is not really that practical for most people.

I recommend that you use a 2-point method rather than an arc protractor.

[earsandeyes]

SME 3012 protractor can be bought here

http://www.ebay.de/sch/i.html?_from=R40&_trksid=p2050601.m570.l1313.TR0.TRC0.H0.Xsme+3012+protractor.TRS0&_nkw=sme+3012+protractor&_sacat=0

Originally SME 3012 Series 1 and Series 2 should work with 11 mm overhang, Series R with 13,2 mm.

In addition we should remember SME/EIA standard that defines the distance between needle tip and bayonet flange to 52,5 mm. Thus leads to a trick that makes alignment of SME arms very easy. You need to mount your cartridge in parallel to the middle line through the headshell and with a distance between needle tip and bayonet flange of 52,5 mm as it is done with SPU cartridges and in accordance to EIA standard. Afterwards you need only to move the SME arm in its pivot and check the overhang by pointing with the arm at platters spindle. That´s all.

A simple jig:

Then all new or other cartridges are a piece of cake.

The actual 52.5 mm depends on the movement of the needle under the tracking weight

Regards,

Michiel

[wer]

A simple jig:

Then all new or other cartridges are a piece of cake.

The actual 52.5 mm depends on the movement of the needle under the tracking weight

Regards,

Michiel

Is it really? If you have a slotted HS,  how do you assure that the cartridge is properly aligned?

[earsandeyes]

Perpendicular. That is one of the uses of the mirror together with a drafting triangle.
The use of the sliding vertical axis of a SME type arm is similar to twisting the cartridge.
I am of the belief that slots in the headshell are only there to compensate variation in design of cartridges as far as distance needle to bolts.
I use linear tracking arms as well and they make us of the same or similar distance from collar to needlepoint.
I do have a holes only original SME headshell (perpendicular by design) in which I used a Denon 103 and made that the reference standard for the setting of both a 3009 and 3012 tonearm.

Michiel