Tracking error distortion audibility

Dear Berlinta, the choice of an inner (2nd) zero close to the label makes sense too, if you own a large collection of early classical stereo LPs made by Mercury and/or Decca (to name the 2 major labels who hadsome of the most daring cutting engineers...) in late 1950ies and first half of the 60ies.
Ask hundreds of collectors of valueable vintage LPs.
Here we often have run-out grooves sometimes starting within less than 8 mm before the paper label. Especially with some of the most dynamic recordings. And then the large final tuttis are very close to the grooves end.
Its not all singles.......

There never was a "norm" from IEC and the AES for the stylus - mounting holes ?
Well - there was and is one.
The fact that so many manufacturers do not obey to it, doesn't mean there is none.......

Anyway - these are windmills....... I won't make the same mistake as Galileo did. I leave the discussion in this thread for good - this step will surely get some applause, as it leaves the field to others to shine........ and increase their sales.

Dear all, after we have now learned that finally all parameters of the tonearm geometry are variable, nothing can stop us now entering analog heaven.
If any of you will still suffer inner groove distortion....... well, don't worry that happens. Move your tonearm, rotate the cartridge. If it distorts now at the run-in grooves? Hey - be flexible. Times may be hard, but modern.

Hello Peterayaer,
An arc protractor works perfectly for one specific effective length only. This requires the cartridge to be moved (i.e. in the headshell slots) to match that length as precisely as possible. Any arc protractor designed for a particular arm cartridge combination(-your question above) should have taken actual measurements as a base for fabrication. Unfortunately, as described by Jonathan Carr, the sample to sample variation in cartridges(screw hole to stylus distance) often exceeds what could be seen as an acceptable tolerance (= below human eyesight limitations), resulting in grounds for error even if the same arm and cart model are used.

But the Null points on an arc protractor are valid regardless of the arc itself. It is only the circle segment line which needs to be re-drawn.

Cheers,

Frank

Dear Dertonarm: The understanding and know-how in almost any analog audio subject is a matter of in which level/point of any audio subject learning curve we each one are.

In an open forum and due to different experiences at different level ( good or wrong ) is too dificult that everyone of us agree totally, specially in an almost " new " stylus set-up.

Through these related threads on the subject I'm still learning things that could help in my tonearm design.

In my last post I speak about my mistakes/errors on cartridge/tonearm set-up over the time, well the last one was during one of the tests on my tonearm design:
" changing and testing an arm wand ( different build material ) by error ( I'm testing on prototype unit ) the arm wand was out of position on " length " distance and I put the same headshell/cartridge ( that already was checked on overhang ) with out checking again the stylus position in the pro-tractor because I can't " see " my arm wand position error.

Let me tell you that the error was not 1mm but almost 4mm( maybe more, I did not measure. ): Well that arm wand build material was so good that even that the set-up was totally wrong the sound was even better than with the other different arm wand and this fact impede me ( at that time/moment ) to know about the mistake

When I take in count of the error I fix it and the performance improve. "

One tool that help to take in count that error was to hearing my record tracks that i use like references.

But this error help me to understand ( I'm not saying is correct ) about that threshold of hearing with that kind of errors and of the importance not only of a tonearm build material but about its whole quality.

There are many subjects around that make so complex the whole tonearm/cartridge set-up. What is true is that we must to be really precise/scientific on the tonearm/cartridge set-up to obtain in a " better/best " way what is in the recording.

Anyone can do what they think/want but that does not means that always is rigth, is different with different distortions that are usualy higher than follow an orthodox method.

Of course that everyone is free to take the Lofgren/Baerwald and others work and put on the trash can. We live in a " democratic "/free world.

Regards and enjoy the music.
Raul.

Hello Axel,
Believe me, I'm anal about cartridge alignment...
If the generator isn't mounted dead center inside the cartridge housing and you can't shift it by 0,3mm, then you'll have to rotate it and slide it forward or backward, depending on the generator being closer to the right side or the left side of the cartridge body.

BUT, the magnitude you described will cause an error so small as to make it near impossible to correct for it reliably and repeatably.

As an example, let's assume your cartridge generator is so far offset(sideways) that it causes the actual offset to be reduced by 0,5°(a larger figure than what can possibly result form generator displacement). Your eff. length is shorter than "normal"(let's say, by 0,3mm), if you have that cart mounted in an arm with fixed holes.

Here's what you get(SME V specs as a base):

Unaltered:
eff.L.: 233,15mm, Null points 66 and 121, average distorsion 0,42%
Now it gets interesting: distorsion at 61mm(inner groove area): 0,54%

Reduce the offset due to shift by 0,5°:
eff. L.: 233,15mm, Null points 71,4 and 111,8mm, average distorsion 0,389%
Distorsion at 61mm: 0,95%%

Additional compensation of eff. length due to shift, -0,3mm:
eff. L.: 232,85mm, Null points 71,8 and 111,1mm, average distorsion 0,393%
Distorsion at 61mm: 1%

Draw you own conclusions...

My take on this: Most people can make out a 0,3mm difference when aligning a cartridge. VERY few can tell the offset angle(sometimes referred to as "zenith") being off by any less than 1-2° !
It's the inner groove area where this really comes into play.

Cheers,

Frank