Dear Rauliruegas, all I did was displaying the geometrical facts. I don't know why you are so mad about this and why you have so many problems accepting these technical parameters which were and are used in analog playback in the past 6 decades.
Again - take the Graham and your comparism between Loefgren / Baerwald:
With the supplied Graham alignment tool you do adjust for either Baerwald or Loefgren. You do so with the detached armwand only and you do all adjustment at the headshell only. When the adjustment to either geometry is done,you fix the armwand to the - never moved... - armbase. So it is quite obvious, that the spindle-bearing pivot (=mounting) distance is not moved.
I think the big missunderstanding is that there are always 2 (TWO) geometrical calculations in tonearm playback.
a) the geometrical calculation of the pivot tonearm itself
b) the calculation of the arc with its 2 zero-error points.
b) can always bealtered by changing overhang and offset.
In doing so, we change the effective length and set the positons of the 2 zero-error points to different degrees on the arc and further apart or closer together to acommodate to LPs with longer run-out-grooves (IEC standard 1983) . The mounting distance remains the same.
Lets have a look at the tonearms you are using in your home system:
SAEC WE-8000, MAX-282, GST-801, AC-4400, IT-407, AR-1M - all these toenarms do not offer any possibility to change the mounting distance. Their bases are fixed. But you can nevertheless adjust tehir geometry to Loefgren/Baerwald or any other other arc-geometry - WITHOUT changing the mounting distance at all.
Same for Dynavector, EMT, Ortofon, Koetsu - the huge majority of tonearms does not feature a slide mounting base....... once you have drilled the mounting hole - thats it.
You can not change the mounting distance on these at all!
They are all fixed.
For good reason.
The sliding mount of the SME does lead into the erratic idea that mounting distance can be changed freely. This is a geometrical error.
Bob Graham used the SME slide mount because that mount was widely available and because it enables the user to adjust the mounting distance precisely to the manufacturers specs.
Again - take the Graham and your comparism between Loefgren / Baerwald:
With the supplied Graham alignment tool you do adjust for either Baerwald or Loefgren. You do so with the detached armwand only and you do all adjustment at the headshell only. When the adjustment to either geometry is done,you fix the armwand to the - never moved... - armbase. So it is quite obvious, that the spindle-bearing pivot (=mounting) distance is not moved.
I think the big missunderstanding is that there are always 2 (TWO) geometrical calculations in tonearm playback.
a) the geometrical calculation of the pivot tonearm itself
b) the calculation of the arc with its 2 zero-error points.
b) can always bealtered by changing overhang and offset.
In doing so, we change the effective length and set the positons of the 2 zero-error points to different degrees on the arc and further apart or closer together to acommodate to LPs with longer run-out-grooves (IEC standard 1983) . The mounting distance remains the same.
Lets have a look at the tonearms you are using in your home system:
SAEC WE-8000, MAX-282, GST-801, AC-4400, IT-407, AR-1M - all these toenarms do not offer any possibility to change the mounting distance. Their bases are fixed. But you can nevertheless adjust tehir geometry to Loefgren/Baerwald or any other other arc-geometry - WITHOUT changing the mounting distance at all.
Same for Dynavector, EMT, Ortofon, Koetsu - the huge majority of tonearms does not feature a slide mounting base....... once you have drilled the mounting hole - thats it.
You can not change the mounting distance on these at all!
They are all fixed.
For good reason.
The sliding mount of the SME does lead into the erratic idea that mounting distance can be changed freely. This is a geometrical error.
Bob Graham used the SME slide mount because that mount was widely available and because it enables the user to adjust the mounting distance precisely to the manufacturers specs.