Uni-Protractor Set tonearm alignment

Dear Halcro: I don't think you noted yet. Several of my hedashell removable tonearms design have the manufacturer overhang spec at 15mm, I choosed on porpose due so many tests cartridge/tonearm combinations I have. This similar overhang characteristic help me to mount with almost none change any cartridge in any of those tonearms.

Yes, this is not exactly what you are talking about but an idea that could help.

Btw, now that you and other people are so in " deep " about cartridge/tonearm set up through accurate protractors seems to me adequate for you and every one that want to " explore " and learn on the subject to make a simple ( no money need it.! ) experiment:

- in one or two of your cartridge/tonearm combinations move the cartridge 1mm forward ( no protractor need it. ) and mantain the same cartrridge/headshell offset angle. After re-set the VTF and VTA/SRA and if you want azymuth and antiskate ( not need it for the experiment but if you want to be more " even " with today set-up. ) push the playback " button " and listen for a while.

After that and if you have the time and patience move the cartridge an additional 1mm forward and the same process but moving the cartridge 1mm and 2mm rearward.

Compare what you listened on those four different set ups against each to other and against what you are listening in your rigth now set ups.

IMHO this is a un-expected ( because the quality performance ) experiences where we could learn what is happening down " there ", I mean on playback against no-play status.

All of you that decide to " explore " in this " jungle " will be appreciated what you experienced.

Thank you in advance.

Regrads and enjoy the music,
Raul.

Jazzgene, 'to bad Thorens ain't what it used to be'. I agree but there are many of those 'old one' second hand still demonstrating the value of simplicity in design: good platter, good bearing and an simple motor. Despite of
this fact the Uni-Pro on them looks to me like a King on
a donkey.

Regards,

Dertonarm:

You said:

If a phono protractor really is universal, it must automatically align regardless of the given mounting distance.

I would agree with you in that, but I would disagree with you when you say that

Setting the mounting distance is done before aligning the tonearm. It is a "conditio" already set before starting the alignment.

This is only necessary when using a protractor which requires it - like yours - because, as you say,

The UNI-Pro does follow the smart idea of Francis Dennesen and adapts to whatever P2S a given tonearm is mounted.

As is the case with the Dennesen, arms with adjustable bases and fixed headshell mounts are awkward for your protractor. So it can´t really be called universal, as it only caters for arms with adjustment for effective length and offset at the headshell.

In most cases the tonearm is already mounted when one starts to align the tonearm/cartridge

All arms are "mounted" prior to alignment, but, as you are aware, not all arms have the pivot to spindle distance fixed at a specific measurement, but have the facility to adjust this, as in any arm on a pod or adjustable arm board, or the SME, and arms like it.

It could be argued that a more universal version of the Dennesen would have adapted it to allow its use with arms such as these, as well as with different alignments.

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Raul,
Could you please elaborate on this? I don't understand what you are trying to do by moving the cartridge forward or backward. Are you asking us to listen for different amounts of distortion from a cartridge that is no longer aligned properly? Thanks.

Dertonarm:

you said

If however the user does wish to align the given tonearm exactly to the geometry (especially the offset angle) the tonearm was designed with, then knowing the P2S and setting it precisely (IF possible ...) is important.
Important only if one wants to avoid an additional breakdown torque and thus another source for skating force in a pivot tonearm with a fixed offset cartridge mounting.
With tonarms like the Schroeder, Reed or Talea however we won't run into this problem at all.

Didn´t you suggest starting an antiskate thread?

But since you have brought the subject up, in what way do the Reed, Talea and Schroeder differ from other arms?

The Talea and Schroeder appear to have a facility to alter the effective length,(as does any other arm with a slotted or movable headshell) and they have a facility to alter the headshell angle. What is the difference between this and altering the angle in a normal headshell?

The Reed has a normal slotted headshell except for the model with its little azimuth adjusting device.

What´s the difference? I would honestly like to know.

And I am intrigued to know what are these mysterious additional breakdown torques which the above arms don´t have.

Unless you can explain where else it comes from, the only torque acting to rotate the arm inwards is generated by forces acting on the stylus in reaction to downforce and friction. More downforce, more friction; more friction, more inwards torque. No downforce, no friction.; no friction, no torque.

Using more downforce doesn´t make the inwards force disappear, just that the force acting downwards is enough to allow the stylus to track without distorting. The imbalance of forces on inner and outer groove walls hasn´t gone.

John
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