STP distance. Is it critical ?

Smoffat, making a couple of assumptions about the tone arm you can see what the results might be by using the calculators available at VinylEngine. Let's assume that to set up for Lofgren's A (Baerwald) alignment with an effective length of 235mm and spindle-to-pivot distance of 217.5mm that the corresponding overhang would be 17.5mm with an offset angle of about 23.4 degrees. (If you know the actual offset angle/overhang you can get more accurate results.)

The calculator will indicate the effect of moving the tone arm +/- 1mm of the specified STP while maintaining the specified offset angle and effective length of the tone arm. (Overhang is changed by +/- 1mm to accomodate change in STP and keeping effective length constant.) The graphs display the resulting tracking distortion.

If your STP distance is 1mm closer at 216.5mm ("Custom"):

http://www.vinylengine.com/overhang_shift_calculator.php?el=235&oh=17.5&oa=23.4&ty=s&n_oh=18.5&submit=calculate

If your STP distance is 1mm farther at 218.5mm ("Custom"):

http://www.vinylengine.com/overhang_shift_calculator.php?el=235&oh=17.5&oa=23.4&ty=s&n_oh=16.5&submit=calculate

However, you may be able to accomodate the needed change in offset angle by rotating the cartridge within the headshell slots. For example, if you change effective length by 1mm to 234mm (STP is 1mm too close), you may be able to achieve Lofgren's A (Baerwald) alignment by rotating the cartridge so the offset angle is now 23.5 degrees. The alignment will be very close, depicted as "Original"/"manufacturer":

http://www.vinylengine.com/tonearm_alignment_comparator.php?m_el=234&m_oh=17.5&m_oa=23.5&compare=i&submit=calculate

Tom

Thank You all for the info you have provided. To make it simple, i will ensure that the STP distance is dead on BEFORE i attempt to align the cartridge (A90) with the Mint LP.
Thanks again.

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.

Forgive my ignorance Raul but, what is IEC and DIN and the difference between both.
Which should i use.
My tonearm is Graham Phantom II and Ortofon A90.

Thanks

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.