STP distance. Is it critical ?

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.

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