Tracking error distortion audibility

Dear friends: Do you know why the tonearm denomination: 12", 10", 9", etc, etc? what those numbers means?

Well, as you all know is the tonearm effective length this is: the distance between the stylus and the center of the pivot/flucrum/bearing and IMHO this is the foundation of the tonearm calculations parameters.

When we want to design a tonearm ( between other things ) we first determine/think in those 12"-10"-9" numbers ( we are not thinking on overhang or pivot to spindle numbers. ) and is this " number " ( effective length + innermost/ outermost groove radius. ) the one that we introduce in the Baerwald/Loefgren/etc formula to obtain: overhang, offset angle, pivot to spindle distance and null points.

If we change the overhang ( like in the Graham example that " play " between Baerwald and Lofgren. ) alone then we are changing the " foundation " ( effective length ), so this practice is not correct, you can do it and you can do anything you want but that does not means is correct: is wrong.

Every time we change the " foundation " number ( effective length. ) change too the other tonearm parameters.

I'm not talking here if the sound likes you or not I'm only talking of what is right and what is wrong.

We can put an example using first Baerwald:

say 250mm on EL: offset angular, 21.949 degrees; overhang, 16.502mm; P to S, 233.50mm.

now 258mm on EL: offset angular, 21.235 degrees; overhang, 15.956mm; P to S, 242.04mm

Loefgren on 250mm: offset angular, 21.949 degrees; overhang, 16.967mm; P to S, 233.03mm

and in 258mm: offset angular, 21.235 degrees; overhang, 16.404mm; P to S, 241.60mm

Well, it seems to me that that tonearm effective length is in reality the foundation to calculate those critical tonerm parameters.

We have to take care on what we do because " sometimes " we achieve a different target that what we want.

Regards and enjoy the music.
Raul.

Dear all, to my knowledge the 9" and 12" denomination was introduced by SME with their original 3009 and 3012 tonearms (hence the names...3009 and 3012). Ever since then 9" and 12" is used to describe tonearms which do have an effective length around the 9" or 12" figure.
But they all do differ in their effective length - some are very close, hardly any is exactly the same as another.
Take a few 12" tonearms as example:

- SME 3012 - 307,34 mm
- MAX-282 - 282 mm
- FR-66s - 307 mm
- SAEC-506/30 - 295 mm

these are all named 12"-tonearms. 12" is 304.8 mm - so none of the above mentioned tonearms is really 12" in effective length.
Only the SME 3012 and the FR-66s are close to that measure. Same for the 9" SME 3009 which is VERY close with its 229 mm (the later 3009R has 231,80 mm.......).
Well - we can alter the effective length of any given pivot tonearm.
And we do.
We can do so easy and - in a certain and narrow range. We do this when we adjust/change overhang (and in the same procedure the related offset...) to achive for instance Baerwald or Loefgren based geometry. We had that topic already back in the thread about the "Oldskool tonearms".
Take again the Graham alignment tool.......... here you have a very good and clear example.
The base (= mounting distance) isn't moved at all. The change is done at the headshell by different overhang and offset.
The mounting distance is still fixed. You change overhang and offset to adjust to different zero-error points - not the mounting distance (at least..... you shouldn't....) - not the mounting distance P-S.
The mounting distance is the 1st and basic parameter of the calculation of any pivot bearing tonearm.

Dear friends: Anyone of you can corroborate what I posted here:

http://www.ispexperts.com/BaerwaldLofgren1.xls

Dertonarm: where can we corroborate what you posted?

Regards and enjoy the music.
Raul.

Dear Dertonarm: I'm not talking on the name of the tonearms model but real: 12",11", 10" or 9" ( inches ) effective length.

Regards and enjoy the music.
raul.

Dear friends: I think that the Graham is a real 9"=228.60mm tonearm, well here are the results on Baerwald:

offset angular: 24.128 degrees; overhang: 18.173 mm and P to S: 210.43mm

Lofgren B.

offset angular: 24.128 degrees; overhang: 18.690mm and P to S: 209.91

As you can see the offset is the same and the other two parameters are different ( including the pivot to spindle distance. ) where the effective length is the same.

regards and enjoy the music.
Raul.