Tracking error distortion audibility

Dear Peter: Your question IMHO has mre than one answer because there are mre than one factor involve.

If we take from the geometry point of view the 12" tonearm always will has advantage ( in theory ) over any other shorter tonearm. But unfortunately things are not so easy.

Looking to LOMC today cartridges the first " trouble " that we have is that the same cartridge, say a Titan i, will have a different resonance frequency with the SME 9" than with its " big brother ", this fact alone preclude a fair comparison ( and I'm not saying that the Titan is the best match for the tonearm, I take it only like an example. ) because that difference in the resonance frequency has its own " sound signature ".

Other subject that Dertonarm already point out: +++ the further away the cartridge is, the higher its influence on the mechanic resonance behaviour of the tonearm. +++++

and in my experience not only for the tonearm torsion resistance factor but depending on the tonearm build material, a 9" arm wand has a different " sound signature " than a 12" arm wand .

In the last three years that Guillermo and I been in our self tonearm designs we made ( and still do it. ) several and different tests and one of them was to have a shoot-out with the same cartridge, different ( same build material ) length on the arm wands, very near resonance frequencies between them ( due that we use different headshell weights ).
We do it with 9", 10", 11", 12" arm wands and we find that with the 9" is a clear overall advantage ( what we can hear )but betwen 10" and 12" seems to me that exist a " threshold "/land where it is extremly dificult to discern if there is a 12" advantage in the sound reproduction quality due to the stand alone length factor.
Our findings are very interesting because our propietary tonearm build material is almost neutral ( it does not have a " sound " ).

When the build material move away from " neutrality " then the differences are more " obvious ".

We are building a 14" and 16" other ones and we will see what happen, here the challenges are a little different.

I already posted on other thread that when you are in the audio item design ( any ) we learn a lot on the subject because we " live " every design day with the: why's, how's, where's and the like.
I hope to finish our tonearm project in the next three months.

What I learn/learned through the tonearm design help me to understand and learn too on the TT " behavior ", that's why in other thread I insist/push hard on TT build materials, this factor is definitive in tonearms and TTs quality performance more than any one can imagine.

Regards and enjoy the music.
Raul.

Dear friends: I'm sure that many of us some way or the other are understanding in a best way the whole tonearm subjects on geometry/set-up.

One additional point that I want to address is one in reference on what Axel posted:

+++++ " There seems to be a MAJOR discrepancy here with some other expert Forum members that maintain that the pivot to centre-pin distance is NOT of the ULTIMATE importance .... " +++++

that is a mis-understood because the pivot to spindle distance is very important parameter in the right and precise cartridge/tonearm set-up.
No one can change this distance free-will with out alter all the other tonearm parameters.

If any one of you analize the calculations examples that I posted you can see that that distance always change and not because a free-will decision but because is a consequence of the use of te Baerwald/Lofgren/others equations.

It is a incorrect/wrong practice ttry to compensate errors somewhere changing free-will the pivot to spindle distance or changing free-will the overhang. We have to remember here that if we change the effective length the equation calculations give us a new overhang/offset angle parameters and a new pivot to spindle distance.
We can't change " free " any of those parameters with out alter the others and we must know eactly the new parameters values. Many people that goes that wrong practice forgot all these and forgot that exist a new and different offset angle too.

Of course that any one can do it if they have its own tonearm geometry equations and if not IMHO those almost free-will changes give them higher distortions results, no doubt about.

Like Dertonarm say: here it is not what anyone of us " think "/feel/hear it is pure geometry/mathematics/physics where the best we can do is FOLLOW IT to be nearer to the recording.

Regards and enjoy the music.
Raul.

I'm wrong, what we are doing is an additional arm wand of 2cm over 12", that's all.

Raul.

Dear All, I do agree with Raul on most of what he said in his last post.
However - let me put it in a few "axioms":

1) offset, overhang and effective length do relate to each other and CAN be CHANGED WITHOUT changing the PIVOT-BEARING DISTANCE. Offset, overhang and effective length do change when you align to a different arc-calculation (say - change from Baerwald to Loefgren).

2) If you change the pivot-bearing distance you change the WHOLE GEOMETRY of the given tonearm.

3) you get the very best results with the recommended pivot-bearing (= mounting distance as specified by the manufacturer, because the whole geometry of the given tonearm builds on that one parameter.

4) whether you choose Loefgren, Bauer, Baerwald, Stevenson or whatever calculation for the alignment of the stylus (and these calculations are onyl aiming at the position of the stylus - not at the position of the tonearm !!) is INDEPENDENT from the geometry of the tonearm itself. These alignments can all be done at the headshell alone without moving the base (and thus the pivot-bearing distance). And they should be done without moving the base because that way you can be sure that the basic geometry of your given tonearm is as specified by the manufacturer.

I think we must clearly put a line here between the geometry of the tonearm WITHOUT a cartridge. This is the basic geometry of teh tonearm itself.
Then there is teh geometry of the stylus in a given tonearm. This is step 2. Here we have the option to align to whatever calculation does fit our needs best (for instance more modern pressings with long run-out-grooves or pressings from the early 1960ies with the inner grooves running close to the label - these need different alignments - one rather Baerwald - one rather IEC). Here we lay the position of the 2 zero-error points and the maxima and minima derivation. This 2nd alignment does have variations in the offset, overhang and effective length (not much, but some) - but NOT in the pivot-bearing (mounting) distance.

Hi, just a little aside from behind the curtain as it were.

SME in their misguided wisdom using the "ICE-standard" (that strangely exists for LP manufacturing at al, BUT not cart ALIGNMENTS, correct me if I'm wrong ) for their alignment happen to use Baerwald, hallo!

Now Baerwald is what most everybody and his uncle is using these days... and is constantly being referred to in this here circle, very good.

The other item that might shine some light on this pivot to pin distance issue, and SME's disregard for such importance is: The SME V (in fact all 300 series) are based on a mounting hole to stylus tip distance of 9.52 mm or better 3/8". Therefore 233.15mm stylus-to-pivot distance, and a 23.6350 offset angle.

Most carts I've seen/worked with are ball-park, give or take 1/10 of a millimetre. This means that the post is move by about that amount to correct for overhang for that specific cart. A difference in VTF alone will change this distance by some 0.01 mm.
Nobody seems to take note here, that when a hole of some dimension about 32 mm is drilled in a plinth to take a fixed pin/pivot arm arrangement, that 1/10 mm or even less is simply within tolerance.
Unless this is done in a tool shop with a highly accurate machining set-up.
So whilst I DO agree with the importance of it all, I surely disagree to get complete anal about this. Reality of arm fitment is most probably a lot worse than <0.1 mm.

Now I feel so much better :-)
Greetings,
Axel