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SME arm alignment

I don't know, you buy an high end turntable and arm with precision mechanics, fine bearings, carefully chosen materials and damping, it can be adjusted in almost any parameter, the 309 even does azimuth, but you can not properly align the cartridge only get a close estimate. For what's it worth adjusting the stylus tip by 1mm maybe not sound much , but it actually throws the base of the arm out of position considerably, way more that 1mm. This means the different from an ideal arc is going to be way off at some points.
I am noticing that the cartridge tracks the end groves better than the start of the record, something I have not experience with other arm cartridge combos.
 
As I state above *do not* try to align the stylus a mm forward of the protractor. You will end up with distortion into many % at points over the arc. Use the protractor as intended and the offset error will be absolutely trivial. Far less than most folk achieve trying to bolt a cartridge without square sides into a slotted headshell. SME understood exactly what they were doing here. All pivoted tonearms are a compromise, the SME approach facilitates such easy aligning it gets closer to the ideal than most in practice.
 
PS Just to clarify: this infinitesimal offset error at the outer null on a Baerwald protractor isn’t really anything to panic about, it just means the cart will be ‘in’ at another point on the playing surface very close nearby. As I stated upthread unless you are prepared to faff about with page after page of complex algebra, which SME will certainly have done, it is not something to worry about. The inner null is exponentially more important due to the far tighter dimensions and lower maximum modulation of the record at that point.

Also remember pivoted tonearm math is such a compromise no one can even agree on the correct alignment anyway, there are at least six contenders, all placing the two null points at slightly different places on the playing surfaces.
 
Tony L said:
As I state above *do not* try to align the stylus a mm forward of the protractor. You will end up with distortion into many % at points over the arc. Use the protractor as intended and the offset error will be absolutely trivial. Far less than most folk achieve trying to bolt a cartridge without square sides into a slotted headshell. SME understood exactly what they were doing here. All pivoted tonearms are a compromise, the SME approach facilitates such easy aligning it gets closer to the ideal than most in practice.
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SME say in the instructions to view the cartridge from a different angle/position if the stylus to fixing distance is different than their assumption, so doing that that would be using as intended. It's just not clear exactly what they intend you to do. Thats all I really want to know.
 
You just sight it so the sides of the arm and headshell align perfectly with the protractor. You need to move your head around a little to adjust for parallax error and this gets a little harder with arms such as yours due to the tapered tube, but that is all you are trying to do. So hard to put this in words, I could show you in seconds. It is really simple, don’t over-think it! Just move the arm in the sled until it sits exactly in the protractor lines when the stylus tip is exactly on the mark. Job done. Bolt it down! Enjoy!
 
I think the confusion is in SME's wording. The SME headshell does not allow the cartridge to move. Just make sure you have it mounted square in the shell. SME then state that their basic assumption is that 'a' cartridge is made with a 9.5 mm distance from those mounting holes to the stylus tip. Ofc it often varies from maker to maker, and, knowing this, SME provided the sliding plate for the whole arm. If all cartridges were 9.5 they needn't have bothered, but ?

Whatever cartridge you fit, you always simply place the stylus on the marker dot and then slide the base until the arm tube lines up exactly parallel to the marked lines. That is all you do. I haven't seen the exact wording of the 'move your head' bit but I imagine they simply suggest you look from a few angles to check all is exactly lined up.
Millions of cartridges have been aligned this way, and all of them sound wonderful.
 
Having a slightly different stylus to mounting length will not stop you seeing if the lines are parallel. I can Cleary see the lines and whether they are parallel.
This is the wording
" Most cartridges have a stylus - fixing hole centre distance of 9.5mm. Correctly adjusted with these the outlines of the tone arm and protractor will coincide when viewed directly above the centre line of the tonearm. With others according to the position of the stylus, it will be necessary to view slightly to the left or right of the centre line."
 
Rockmeister said:
I think the confusion is in SME's wording. The SME headshell does not allow the cartridge to move. Just make sure you have it mounted square in the shell. SME then state that their basic assumption is that 'a' cartridge is made with a 9.5 mm distance from those mounting holes to the stylus tip. Ofc it often varies from maker to maker, and, knowing this, SME provided the sliding plate for the whole arm. If all cartridges were 9.5 they needn't have bothered, but ?

Whatever cartridge you fit, you always simply place the stylus on the marker dot and then slide the base until the arm tube lines up exactly parallel to the marked lines. That is all you do. I haven't seen the exact wording of the 'move your head' bit but I imagine they simply suggest you look from a few angles to check all is exactly lined up.
Millions of cartridges have been aligned this way, and all of them sound wonderful.
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The wording started with Series V, which is when the 'tonearm outline' alignment protractor came along. For single null point alignment, one can't do better than having the sight lines extend round the actual outline of the headshell and arm-tube all the way back almost to the edge of the record/platter. As such, one can be so precise that even one degree of variance can be perceived, hence the suggestion to compensate by looking down at a slight angle. The point being that the arm outline should be perpendicular to the printed outline all along its length. The difference (relative to where the offset would have been with 9.5mm tip to mount) isn't even worth discussing, as a simple bit of Euclidean maths will reveal; I can't be arsed as it's only 7:30 here and my 1st coffee hasn't quite kicked in yet.
 
What are you compensating for by looking at angle? This makes no sense, you can clearly see whether the tonearm is parallel to the lines already .
Lets just agree the wording is awful and causes confusion. I've been setting up turntables for 35 years with good results these instructions just make no sense.
 
spxy said:
What are you compensating for by looking at angle? This makes no sense, you can clearly see whether the tonearm is parallel to the lines already .
Lets just agree the wording is awful and causes confusion. I've been setting up turntables for 35 years with good results these instructions just make no sense.
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Your tip to mounting holes centre line is only 1mm off from what would have been the industry standard but never actually became such. Had it been 2mm off you'd have been twice as likely to notice a wee gap along one side of the protractor outline relative to that side of the tube; still parallel but seemingly shifted off to one side (i.e. simulating a parallax affect). Moving your head slightly to compensate might make you feel better, but listening to records is far more enjoyable. Have to agree that the wording could have been better.
 
Tony L said:
Assuming you get the centre in the right place there should be enough movement. Some turntables are pretty tight space wise, though the mounting sled movement is absolutely huge, at least +/- 15mm, and really all it is needed to do is compensate for the +/- 1 or maybe 2mm widely used by cartridge manufacturers.


Here’s a picture of my TD-124 & 3009 Series II. It is pretty tight, the mount is as far back as it can go on the armboard, and the sled still ends up past the half-way point with a typical cart, but even so there is more than enough movement given the tiny discrepancies between cartridges. On a Garrard the situation is usually reversed as the chassis is so large the arm mount needs to sit a little further away unless mounted right at the back, as such the arm tends to end up fairly far forward in the sled. It doesn’t matter, the movement range is huge and way more than would ever be needed. It is one of many things I really like about SME arms, the mounting position doesn’t need to be perfect the way it is on so many decks as it is an adjustable parameter. The level of precision required to drill an armboard exactly for a fixed pivot arm is beyond most people/dealers skillset and I’m sure often ends up wrong.
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I've seen some 124s where the SME sled is parallel to the armboard. That, I suppose, is what I was questioning.
 
As an aside, when John Palmer designed the arm mount for the Palmer2.5, he made that a swivelling block. You screwed the SME baseplate to that block, with the arm roughly central on it’s slide, and swivelled the whole block to do the alignment. Worked perfectly.
 
spxy said:
SME say in the instructions to view the cartridge from a different angle/position if the stylus to fixing distance is different than their assumption, so doing that that would be using as intended. It's just not clear exactly what they intend you to do. Thats all I really want to know.
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The headshell won't sit over the outline when viewed from directly above, but will project onto it when viewed from a slight angle. If you imagine your eye above the headshell looking down, you can move it in two axes, towards/away from the spindle, so radially, or along the line of the headshell, tangentially. If you can get the headshell aligned with the outline with a minimal tangential move of your eye, that's the best you're going to do and is what I interpret SME to mean.

Perhaps you should take a look with the arm near either end of its adjustment range, what optimal will look like should then become clear.

There are many wrong answers to cartridge alignment, but there is no correct answer. If you are really serious you have to measure the radii of the playing surface of the records you care about and do some sums.
 
And somewhere, there is a line between being really serious, and the effect being audible, and I'd love someone to do the work required to say exactly what that point is, in terms of measured distortion.
I have £5 that says it'll where the SME engineers alignment suggestions are.
 
Yank said:
I've seen some 124s where the SME sled is parallel to the armboard. That, I suppose, is what I was questioning.
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Because the sled is a means of adjusting overhang via changing pivot to spindle distance (rather than via changing effective length, which is fixed), the further away the sled is angled from the line between pivot and spindle, the less a given change of position between arm and sled will have upon pivot to spindle distance. IOW, the arm ends up moving at an oblique angle to the line between pivot to spindle, therefore, more travel along the bedplate is required for a given amount of overhang adjustment. This is the primary reason why SME wisely built in so much sled travel. Still there are some tight space squared to plinth installations where folk have run out of rearward travel before achieving 'dead nuts on'. Not that spot on overhang necessarily equates to perfection, mind.
 
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Craig B said:
Because the sled is a means of adjusting overhang via changing pivot to spindle distance (rather than via changing effective length, which is fixed), the further away the sled is angled from the line between pivot and spindle, the less a given change of position between arm and sled will have upon pivot to spindle. IOW, the arm ends up moving at an oblique angle to the line between pivot to spindle, therefore, more travel along the bedplate is required for a given amount of overhang adjustment. This is the primary reason why SME wisely built in so much sled travel. Still there are some tight space squared to plinth installations where folk have run out of rearward travel before achieving 'dead nuts on'. Not that spot on overhang necessarily equates to perfection, mind.
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Is there any perfection in pivoting tonearms? I can't see how perfection can exist. Even overcomplex arms that slowly turn the headshell angle must be introducing too much friction and vibration elsewhere?
If you want perfect, it'll be // tracking as far as tracking distortion goes?
 
Rockmeister said:
Is there any perfection in pivoting tonearms? I can't see how perfection can exist. Even overcomplex arms that slowly turn the headshell angle must be introducing too much friction and vibration elsewhere?
If you want perfect, it'll be // tracking as far as tracking distortion goes?
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Everything comes with its own baggage. I'll never forget installing a first gen Souther linear arm on a customers deck and subsequently throwing on the shops most warped record. As this marvel was billed as having the shortest tonearm ever, the result was as if we were listening through a Quad 44 pre-amp whilst someone rocked the tilt control fully to a fro with someone else playing silly buggers with the pitch control. Dull as shite on the crests and sharp as razors in the dips with a queasy inducing wow as constant. Was quickly told to go and find only the flattest records for when the customer came in to collect. Should have had a health and safety warning on the box.
 
In 1975 I replaced the big black ball tonearm on my TD150 with an SME 3009 S2 imp
Once I had fabricated an arm board I just followed the SME instructions
Dead easy.
I used this for years and never understood why so many people needed the dealer to fit their arms and cartridges
John
 
Tony L said:
He is technically correct. The reason being the pivot to spindle distance is not set in stone due to the moving baseplate, therefore the offset angle changes depending on position.
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Still not getting it. As it's possible to get the stylus/cartridge zenith perfectly zero at the desired null point by moving the arm pivot forwards or backwards what does the stylus tip distance have to do with it?
 
it will be fine at the single selected null point, in SME's case that is at the end of a record , but it will be out at the other null point nearer the start of a record as the arm to stylus tip length is different to the anticipated length.
 
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