How much difference if the tonearm is mounted 5mm

Hi Lewn,
Your response totally makes sense to me. Here is what had happended.
when i mounted the tonearm 212mm S2P the cartridge could not reach the crossmark on the Dr. Feickert Protractor, it seams like the slots are too short. Two days ago, I mounted it at 207mm, the cartridge can touch the crossmark now, but the offset angle is off at about 20 degree to get allignment correctly. As of now, all i can think of is the arm problem since I have used the Protractor before with the Vpi jmw and the Triplanar vii u2 with no problem at all. Please give me your opinion.
Thanks, and I used Baerwald, i will try Stevenson to see if it is any better.
Calvin

Lewn,

The problem  with 'trusting' the given dimensions for spindle to pivot is that it is expected that everything else will just automatically falls into place (dimensionally).  Well, that isn't always the case.  What you are trying to accomplish is for the stylus tip to correctly trace a given curve line.  BTW:  All tone arms with a cartridge mounted will make a perfect circle it they were being used to draw with.  You want the stylus tip to follow a section of that circle (part of that curve), in which the record is going to be placed on.  The setting up of the spindle to pivot distance only ''assumes'' that the stylus tip is then going to follow this curve.  It just might if you only use the head shell that was or is provided by the tone arm manufacture.  That is because he has provided those head shell ''slots'' to be in a position that would allow you to mount a cartridge so that it will follow that curve.  Use some other head shell and those slots might be in the wrong place.  I use the Mint LP Tracker or sometimes referred to as the Best Tracker as my cartridge set-up device. If you were to 'hold' that stylus tip onto that curve line, and you had the cartridge mounted in a head shell with very long slots, could you not move that pivot point in or our (closer to or farther away from the spindle), without moving that stylus tip?  Yes,moving it out 6 feet would change the curve but we are not talking feet.  Not even inches.  We are talking 5 milimeters.  The change in the curve would be even smaller that what the difference is between the Stevenson and the Baerwald.  Not to even mention all the other variable alignment protractors that are out there!  I find it more important to decide what head shells you wish to use, and then set up for it.  Not the other way around and have your hands tied sort of to speak, being forced to use what ever head shell (slot position), that the manufacture decided upon.  I like Magnesium for head shell material, and I like to have adjustable azimuth.  Most tone arms do not provide this Azimuth adjustment feature.  My Graham arm does, but neither my JVC 7045 or my Lustre GST-801 do.  I do not want to shim head shells, so I have chosen the Sumiko's, or cheaper yet, the 'Zupremes'. 
   There is no industry standard as to where these head shell ''slots'' are suppose to be.  This is sad but true.  
    The JVC 7045 tone arm came with its own head shell.  I marked a dummy arm board (made out of plywood), per the spindle to pivot dimensions given and drilled it.  I then mounted the arm, the provided JVC head shell with a cartridge installed.  It followed the Mint tracker curve perfectly.  I then remove the JVC head shell and mounted a head shell with a cartridge that was not a JVC head shell only to discover that I could not get the cartridge to slide far enough back in the slots to trace this curve.  I tried several other brands of head shells that I have with cartridges mounted in them and none of them would allow me to position the cartridge so that it would trace that curve line.  So where is the problem?  Is it the spindle to pivot distance dimension?  Well, if you only use the supplied head shell from JVC, then the answer is 'No'.  But if you wish to use head shells supplied by other manufacturer's then the answer is 'Yes' . That spindle to pivot dimension is wrong.  I did finally drill my arm board but I didn't use the supplied dimension given on the drilling templet.  I drilled the hole so that my cartridges sit in the center of the slots when they are mounted in one of these Sumiko's.  The stylus tip traced that Mint Tracker curve line perfectly.  I don't know nor do I care what the spindle to pivot dimension is.  I only care that it traces the curve correctly.
Regards,

Lewm,

I should also mention that the supplied head shell from JVC also is usable after my drilling.  But instead of the cartridge being mounted in the center of their slots, the cartridge is now mounted near the forward most location of their slots. All other brands of head shells allow the cartridges to be mounted some where around the center.  Some more forward, some more towards the rear.  But all will follow the Mint Tracker curve perfectly.
Regards,

Dear Dangcaonguyen:  """  I mounted the arm 5mm shorter than manufactor reccomedation. The result was terific.  """

IMHO what it's terrific down there are only " terrible " and high distortions not real music information.

Many years ago Löfgren makes a huge research and found out what after him was the flagship of a tonearm alingment ( you can search google for those white papers to understand the meaning/foundations of the theory. ) where vintage and today tonearms has each one tonearm specific alignment parameters.

What define those critic parameters ( overhang and offset angle ) is the tonearm pivot/bearing to spindle distance where for each PTS distance exist one and only one offset angle and overhang. Each time that STP distance change these two parameters change to aling correctly the cartridge in the tonearm.

Look, the difference between the Löfgren and Baerwald alignments with the same PTS distance is less than 0.6mm in the overhang where the offset angle stay the same in both alignments proposals. In this example the whole tracking error ( pivot tonearms. ) is different all over the LP recorded surface.

Here you are talking of 5mm!!  with out changing the offset angle!!!, so the tracking error goes up in exponential way"""" and that's what you are hearing.

Those gentlemans that gave you the advise to change the cartridge position through slots do not understand yet from where come those parameters values ( equations on the white papers. ) on overhang and offset angle.

Now, here you can read all referent to mount VPI different tonearms an you have to mount any cartridge on them through the VPI dedicated protractor and if you are in doubt then contact directly to VPI:

http://www.vinylengine.com/vpi-tonearm-geometry.shtml

and here you can read about calculators when you need a different PTS distance, overhang or offset angle:

http://www.vinylengine.com/tonearm_alignment_calculator_pro.php


or you can downland this calculator that gives you all you need to know about and know how distortions goes with changes in any tonearm/alignment parameter or alignment kind:


http://www.enjoythemusic.com/freestuff/BaerwaldLofgren88.xls


Regards and enjoy the music,
R.

I

I'm sorry Raul, but I do not listen to 'white papers' so I do not know what they sound like.  I listen to records and know what I 'hear'!  
What you state about there only being one correct number for overhang and offset angle  of any particular tone arm length is true.  But that doesn't meant that the person who came up with those numbers on my JVC templet are the correct ones!  Nor does that meant that the numbers for set-up in the tone arm in this thread are the correct numbers because they are ''only'' numbers printed on a form.  Nothing more, nothing less!  The proof is in how it traces after set-up.  Not how it measures in regards to some printed number on a form!  The arm in question was not actually measured so how do we know what its 'overhang and offset angle' should be?  You 'assume' that its length is what is stated on the templet.  You 'assume' that the dimensions stated on the templet is correct. You 'assume' that to drill this hole for the arm to mount into will be correct.  Sounds to me like you are ''assuming'' far to much and not doing enough 'actual measuring!  After drilling, it either tracks that Mint Tracker correctly, or it doesn't.  That is all, and nothing more.  If to do so, some other number had to be used to drill the mounting hole distance from the spindle for the arm, so be it.  The point is to track the curve line.  Not ''what does it measure''?
Regards,