STP distance. Is it critical ?

Dear Nandric: ++++ " But we all
are trying to get the stylus on those null points. But if
we use,say,SME V with holes and ...." +++++

I can't understand what you exactly men with the V.

SME V was designed with Baerwald geometry, its null point are right " there " .

If your tonearm is mounted with the precise STP distance then you have not any single problem to achieve the SME null point.

Please let me know what I'm missing here.

regards and enjoy the music,
Raul.

Dear Smoffat: Everything is almost critical in cartridge/tonearm set up depending what you are looking for.

In a cartridge/tonearm set up you can't change the effective length: the distance from stylus to tonearm pivot center.

All the geometry calculations/equations were made with this effective length parameter with a fixed/permanent value and inner/outer most grooves distances.

Baerwald, Löfgren or Stevenson set up calculations take all those three values to obtain mainly : overhang, offset angle and STP distance.

You can find through the net all these geometry calculators where the only parameter that you need give to the " Calculator " is tonearm effective length to have all the set up parameters.

Even you can choose between DIN or IEC standards or even you can make tyny changes on the inner/outer most distance values.

In all cases you will have all the parameters need it to cartridge/tonearm set up and you can use any one of them with your Phantom and decide which works fine for you or wich one you prefer.

With any of these kind of geometry set up calculations the tonearm can be placed anywhere if you respect the effective length at null points.
Yes 1.0mm-2.0mm makes a difference and not for the better.

As Syntax point out: " Analog reproduction is precision. "

Regards and enjoy the music,
Raul.

Dear Nandric: I already email you an example of equations used to find out tonearm design geometry parameters where you can see/read that the input/variables for those equations are these " numbers ": effective length and inner-most and outer-most values.

The STP distance comes by: effective length minus overhang.

IMHO a tonearm designer define first if he want a 9" or 10" or 12" effective length tonearm ( he does not cares about where the stylus in the cartridge comes, it does not matters: the cartridge designers has almost no standards about. Every one is almost different where the stylus comes in the cartridge. ) and not the STP figure that is only a result after knowing the other parameters through the equations, in specific the overhang.
At least this is the way how we start our self tonearm design.

Maybe there are other tonearm designers that goes through STP parameter but I doubt. Like I posted maybe I can be wrong but this is MHO.

Regards and enjoy the music,
raul.

Dear Smoffat: According to Baerwald ( IEC ) calculator for an effective length of: 235mm the precise STP distance is: 217.36mm and with DIN standard: 218.41.

The differences in DIN against IEC is not only with the STP value but there are differences too in the offset angle and obviously overhang.

Regards and enjoy the music,
Raul.

Dear Smoffat: Are standards from International Enginnering and from Germany ( Deutch ) inner/outer most distance groove that are two values necessary for the calculations.

Your Phantom manufacturer specs seems Baerwald IEC and I assume that your Mint LP protractor too. So just follow it.

Each different set up geometry calculations made differences in the percieved system sounds. So, if we have the tools, we can test either equations with either IEC/DIN standards and through listening decide which one match our priorities.

Here you can download Baerwald/Löfgren B calculators:
http://www.enjoythemusic.com/freestuff.htm

you only need to make click with your mouse in: Donload Now ( at the bottom of the page ).

Baerwald is Löfgren A in that sheet. The original values in the calculator inputs are IEC standard, you can change to DIN standard changing the input inner most value: 60.325mm by the DIN innermost value: 57.5mm

If you only want to use the calculators with IEC standard then the only value that you have to introduce is the tonearm effective length at the calculator input, then you make click in the CALCULATOR word ( in white at the center. ) and appear at the right ( green color side ) the output parameters that you need to the set up.

It is more easy to use that my explanation.

regards and enjoy the music,
raul.

Dear Bpolleti: You can make any " move/movement " you want with a pivot tonearm and always will have worst results that if you respect the different geometry set up equations where what you can change are the most outer/inner groove distances, the tonearm effective length must be the same.

If you move the pivot to spindle distance at random you have almost " nothing " but higher distortions..

A pivot tonearm always was and is designed with a precise effective lenght in mind/target not pivot to spindle distance, at least I don't know any pivot tonearm designer that his main tonearm target was the pivot to TT spindle distance but I can be wrong.

regards and enjoy the music,
raul.

Dear Bill: Now that I read both of your posts I think we are talking almost the same.

All those different set of equations were made to optimize/put at minimum the tracking error somewhere but to bring at minimum the tracking error means that we have to choose in what part of the LP recorded surface grooves we want to do it because we can't do it all over the recording LP surface.
So always is a trade-off choice.

The interesting for me in this whole subject is that in almost any pivot tonearm we can change those equations parameters and with the same cartridge see what happen and what works better in the audio system.

Now, IMHO for we can heard/hear differences in quality performance due to this geometry changes it is a must that in each time we test it the cartridge/tonearm set up were made almost perfect.
The analog medium is so imperfect that in this subject we have to be " perfect " to achieve a valued information.

Regards and enjoy the music,
Raul.