What is you tonearm’s Maximum Distortion?

@rauliruegas 

Well, don’t tell to me but directly to the SAT designer.

I do not have an issue where mark sets his null points and I do not believe he would fudge the inner groove radius to 75mm in the calculations to avoid showing the sharp increase in distortion once you get closer than 75mm.

 The OP P2S 225.. was asking for better numbers and the SAT ones gaves it.

Sure... if you use a little harmless parameter manipulation and substantially shift away from a standard set of inner/outer groove numbers you can get vanishingly low numbers.  

" I have found no point in listening to the last track ... "" that's at least untrue because the higher distortion happens only with the LP that has groove modulations  up tp 60mm ( inner groove )

This is akin to saying that a silent groove has no distortion.   JR @wallytools makes a compelling argument and has collected data to support a trend in newer records and audiophile reissues to basically leaving the last track off each side to avoid the issues with the inner groove.  He offers a protractor with dual alignments to take this into account and makes it very clear what his goal is.  The key here is he gives all of the information and lets the end user select what best fits their listening style.  Taken to the extreme I could even see a second arm being added to a setup to allow for two different alignments to match JR's observations.

Btw, have you an alignment with no trade-offs?

Nobody does.  I actually believe that there are far too many variables that cannot be set accurately enough to get any specific alignment and simply getting two null points on the playable surface is no small task.  I want to be clear that I am not being critical of anyones alignment goal.  Everyone is allowed their own choice of compromise.  My problem is presenting manipulated numbers without disclosing the manipulation to justify someones choice.

 

dave

 

 

While I do hear some inner groove distortion sometimes, I am grateful to the last track for giving me a bit more listening time per side.

As we see here in the graph below 👇

The Löfgren B has lower distortion all over the record surface except in the end just before lead-out starting. But we also know that a 12" LP always start at the same diameter but the 60 mm at the lead-out is something that they recommend that we stop to cut information closer to the label than those 60mm. The issue and problem is to:

1. Find appropriate track to put as the last one. On that A/B side. When the resolution is lowest there.

2. Because of the above we would like to make so that side A and B ends at the same radius. In other words it is not wise to end one side at ~80/90 mm and the other side at 60mm. If we could rearrange the track order so both of the sides end at 70 mm instead. For better fidelity.

3. Many 12" 45 rpm ends further out than 60mm and has a big area lead-out.

4. Do we push the envelope to go closer to the label than 60mm then we get issues with some auto stop or automatic return mechanisms in automatic TT.

So in short lead-in is more or less always at the same place but the same can not been said regarding lead-out, it is far from all 12" discs that end at 60mm when many ends future out for some of the reasons above. With that insight it is less of importance to optimize at just 60mm like Stevenson do in the graph below.

 

It seams that the consequences and penalty for having that aim is that having the lowest distortion from 60 to 65mm (were Löfgren B crossing Stevenson) is that Stevenson has higher distortion then Löfgren B from 65 mm and more or less the whole way until the start and lead-in of the disc!

That is a high price to pay and is only benefits if you has overture 1812 with canons at the end between 60 to 65mm or bolero and other crescendos in that area in many of your favorite albums may have.

 

Otherwise Stevenson is in my opinion something nobody should use. And maybe there is a reason why Lofgren calculated and created a second and improved version after his first attempt.

 

 

Here we see that this record side is actually close to 60mm:

And as you see it is those 5mm I "sacrifice" with my Löfgren B:

 

So it is not a huge "sacrifice" if now the lead-out starting at 60mm.

Or in other words someone that prefer those 5 mm to have the LOWEST distortion on the record has actually "sacrificed" and choose a higher distortion from those 65mm and the whole way to the start of track one!

Hi guys,

Debates on this level of refinement (which alignment pattern to use or which tonearm offers lowest tracing distortions) are really insignificant compared to zenith error tolerances in the cartridge industry. Your zenith error should be known and corrected before any of this inquiry will deliver results. The average zenith error in the last few hundred cartridges I’ve analyzed is a hair over 2.5 degrees. If we look at the dataset with Gyger replikants removed, that number goes up substantially. Industry assembly tolerances are so far beyond the differences between Loefgren, Baerwald, Stevenson, etc that the debate and inquiry offers limited “yield” until zenith correction is satisfied.

I don’t mean to rain on you fellows. There still may be value in this inquiry but it can’t benefit us until we’ve first managed the elephant in the room.

I am still in development with a tool to correct for zenith error in the field so it does not require sending to me in the lab. Technically, the WallyZenith allows for it already but the correction involves using your ears in a rather tedious process of listening for best results. The tool makes it very easy to know where you are and return to any previous position with a high level of accuracy.

You might ask why I bothered to put alignment variations in the WallyTractor in the first place then. Simply: I redesigned the WallyTractor before I came to realize how poorly stylus/cantilever assemblies are made and mounted.

In a product development process I had to do repeated static and dynamic repeatability tests for zenith error in which I repeatedly aligned the cantilever by 0.5° increments. We were able to confirm that these attempts were accurate though I do believe 0.5° is likely my limit of resolution when aligning a cantilever. One of the engineers on our research team who has a fantastic analog rig and is a VERY discerning headphone listener insists he can hear 0.5° zenith error differences on his pivoted tangential tracking arm. I have not blind tested him on this but I’d say that I’m not worried about resolving below 0.5° accuracy based upon what I’ve seen in Matlab and Abaqus with respect to fine changes in zenith error.

The tracing error difference between Loefgren and Baerwald is less than that. So is the difference in tracing error between a 9” arm and a 12” arm.

@intactaudio : " manipulated numbers without disclosing the manipulation to justify someones choice."

" your proposed alignment simply "

 

and way before you posted the graphics I posted to you:

 

 

" that is the SAT tonearms alignment. "

Btw, was ridiculous/false/untrue/lie that in your graphic instead to write SAT use it my name when the alignment came from SAT and I posted to you before that graphic and you knowed.

 

" I do not believe he would fudge the inner groove radius to 75mm in the calculations "

 

that’s only your ignorance because you showed with this kind of statements that your knowledge level on the SAT tonearm is near zero. Your problem not mine.

 

""" Everyone is allowed their own choice of compromise """

 

Yes, that’s why exist the custom key in the calculators.

 

@optimize thank’s for your expert explanation.

 

Btw, intactaudio you posted that with the SAT the distortion level goes at 60mm to 2%. Well could be that your speakers goes even way higher that that figure and no compliant about. The phono stage you are using ( I think you are using it ) develops a huge distortion level with that high swing of 3db deviation in the RIAA inverse eq. and I can understand with out compliant because it’s what you are using and that makes more harm that the SAT alignment. Incredible that you made a " film of drama " on this issue.

 

In the other side all SAT owners are fully satisfied with Mark tonearms. I listen 3 times to the SAT and it’s really good and I think that @mijostyn did it and like it too.

 

I think that if your main undisclosed attitude is to hit me then you are wrong in that specific alignment issues that as I told you I’m only using it and whith not the kind of critics like you other than exactly the same opinion that @optimize about Stevenson A alignment.

 

So I appreciated if you take off my name in your posted graphics due that no belongs to it.

 

R.