Multiple arms, multiple cartridges and geometry?

Halcro, thinking you may be able to work this backwards. ie allign MA505 to your chosen common allignment. Remove the headshell and put it on one of your other tonearms. Move P2S for that arm so that it follows the arc that the MA505 used then record the new P2S for future referance. Just a thought but not sure if this would work due to the differences of offset and overhang between the arms you use.

Hi Halcro,
you said:

How then.......can I have different geometries for each arm if I don't wish to re-align a cartridge within its headshell depending on the arm in which its installed?
Surely......I must select a single geometry for all my arms so that the cartridges fixed to their headshells....are truly interchangeable?

I see you are still pursuing this quest. Previously I posted regarding a similar issue you asked about

...It looks to me that swapping headshells between arms would require them to be set up initially with oneheadshell/ cartridge combination which remained set once the first arm was done, and which was then used to set the remaining arms with adjustment achieved at the bases of the others, assuming they were different arms.

The alignment chosen would have to also be the same for each set up, irrespective of the arm design, but the arms could be different lengths. Then any cartridge/ headshellcombination could be set up to suit these alignments without moving the bases. This would depend on the headshells having slots, though the initial headshell could have holes as long as the arm used was designed to the chosen alignment.

So headshell swopping only works with arms of the same alignment. where one cartridge is used initially with one arm then that cartridge is used to set the mounting distance for the rest.

You could also set for Lofgren B, using the same headshell/cartridge by setting an arm closer to the spindle, thus increasing overhang by around half a millimetre (depending on effective length), as the cartridge offset remains the same using an adjustable base.

For other non LofgrenA arms you would have to know the offset angle and whether you could achieve a suitable alignment with a cartridge already mounted correctly for LofgrenA by adjusting the mounting distance only.

Have fun...

John

Yes Ecir and John,
I'd forgotten your earlier response on this subject John.......but reverse engineering seems to be the way to go?
I will try it and see if it works on all my arms with all my cartridges?
Thanks...and keep tuned :^)

Henry

My opinion is that if you care about really precise alignment according to any single one of the standard geometries (you pick), and given that your tonearms all have different recommended P2S, effective length, headshell offset (which may or may not be true, but from your system photos it looks to be true), this cannot be done. "This" is defined as mounting each cartridge in a headshell such that any headshell/cartridge can be used with any of your tonearms without further tonearm-specific adjustment to achieve proper alignment.

OK........have just spent the day checking my arms and cartridges :-(
Who said that "Analogue starts with anal"?
Apart from one of my ZYX Universe cartridges mounted in the DaVinci 12" Grandezza and one of my Empire 4000D/III Gold cartridges which is fixed into the Continuum Copperhead tonearm.........all my other cartridges are fixed into removable headshells which have been aligned using Dertonarm's UNI-Protractor with the Fidelity Research FR-66s template and arm mounted at 295mm S to P.

I inserted some random headshell/cartridge combinations into the Micro Seiki MA-505s mounted at the recommended 222mm S to P distance and checked the alignment against the UNI-Protractor with the MA-505 template inserted.
The alignments were almost perfect......but a correction to 223mm S to P distance.....DID make them perfect :-)

I next inserted some random headshell/cartridge combinations into the FR-64s tonearm mounted at the recommended 230mm S to P distance......and lo and behold.......perfect alignment :-)

Moving onto the SAEC-308N with a recommended 235mm S to P distance......I could not make any headshell/cartridge combination align with the correct point?! At the furthest headshell slot.....the stylus point was always 3-4mm too short. Four different headshells were tried with the same result?!
I remember this happening with my Grace 940G tonearm as well....with only one headshell able to stretch to the correct distance?
I then remember what Daniel had written to me about the 235mm distance when he sent me TWO templates for the SAEC-308N......one at the 235mm S to P distance...and another at 225mm S to P??

It is indeed, but it results in a rather "sub-optimal" overhang of 5 mm only.
The resulting tangential curve is catastrophe.
The overhang has to be prolonged.
My template (at 225mm) results in effective length 251.1 mm.

So I moved the armpod to give the alternate 225mm S to P dimension......but of course all my headshell/cartridge combinations did not work!?
The off-set angles and overhangs were totally wrong :-(
They required massive twisting of the cartridges in the headshells to be aligned correctly and only the Yamamoto wooden HS-1AS and Micro Seiki headshells allowed such extreme twisting?
So I selected about 4 or 5 MM cartridges in these headshells...and aligned them according to the UNI-Protractor with the 225mm template.

Ahhhh........the sound....the joy....the bliss!!

So the net result is this:-
I have two tonearms (the Copperhead and DaVinci) without interchangeable headshells.
I have three tonearms with interchangeable headshells which accept any of 20 of my cartridges pre-mounted in their individual headshells...with correct geometry.
I have one tonearm with interchangeable headshell capability (MA-505s).....which has five dedicated headshell/cartridge options ready for instant insertion.

I'm like a pig in mud.....only cleaner.