Fun with vinyl measurements

[Thomas_A]

It is good to have a control condition. Although you have a within-subject design, an external control would be a different record. If you get the same increase in HF levels from a record without 'grainy patches', it would argue against your causal attribution.

I would not have any chance to look for those grains - my microscope will be a bit complicated to use for records. What I know is that frequency response test records have been exceptionally stable so far.

Start point was that Ray found record damage from an AT MR/ML stylus, especially this record with demanding tracks. I can't really see that much other than grains being shaved away. There seem to be no loss of HF content - but the opposite.

 

[JP]

Side is 20 minutes, next play was played 1-2 minutes after finish. Temp was 22°, a bit more humid 57% inside. Basically the same results as first experiment...with some minor diff.

Elastomer self-heating will cause minor variations.

 

[Thomas_A]

Elastomer self-heating will cause minor variations.

Yes, being thinking of that. But first experiment was made with a 6th play long after the first five. There is no "return" of response. I will doa 6th play tomorrow.

 

[JP]

There seem to be no loss of HF content - but the opposite.

I can’t recall which paper, but Shure noted mistracking could result in vinyl being piled at the top of the modulation, resulting in increased amplitude. Several papers also note that typical visual “damage” seen on grooves don’t necessarily cause any meaningful change in playback.

 

[Thomas_A]

I can’t recall which paper, but Shure noted mistracking could result in vinyl being piled at the top of the modulation, resulting in increased amplitude. Several papers also note that typical visual “damage” seen on grooves don’t necessarily cause any meaningful change in playback.

I certainly see that grains on leading edges of modulations gets shaved off pulled up on top of modulations. So not only the stylus is digging deeper on leading edges but pulling dirt up on the hill tops as well.

 

[sqrl]

I would not have any chance to look for those grains - my microscope will be a bit complicated to use for records. What I know is that frequency response test records have been exceptionally stable so far.

Start point was that Ray found record damage from an AT MR/ML stylus, especially this record with demanding tracks. I can't really see that much other than grains being shaved away. There seem to be no loss of HF content - but the opposite.

A control record would be played on the same occasion - randomized plays between Telarc and control - and sections analyzed at the same groove diameter. Mind you, you would need to blind Ray, so at least 2 copies of each record with only one played. Then, is the assessment of grainy patches qualitative or quantitative?

 

[Thomas_A]

A control record would be played on the same occasion - randomized plays between Telarc and control - and sections analyzed at the same groove diameter. Mind you, you would need to blind Ray, so at least 2 copies of each record with only one played. Then, is the assessment of grainy patches qualitative or quantitative?

Well this would take quite some records and sending. My first question now is whether the shaving off gets more even between L/R. First record was played with 14-15% AS and there was more shaving off in the right channel. So this is semiquantitative at the moment.

I can play may third record using my original HE stylus to compare to the JICO SAS.

A note is that increases in level occur where there should be no music, just noise. So a control play will come tomorrow.

 

[Thomas_A]

Elastomer self-heating will cause minor variations.

You were right.

 

[JP]

You were right.

Once a year. Thankfully it’s not January.

 

[Thomas_A]

So a follow-up on this topic. I got two more copies of this record and remade the analysis (thread at VE). It will also be sent for microscopic analysis when I played also side 1.

Lorin Maazel & The Cleveland Orchestra - Mussorgsky: Pictures At An Exhibition / Night On Bald Mountain" Telarc record. Record was US washed. Played side 2 five times in a row and recorded them. VTF 1.4 gf at tip, brush down, AS 10 %. Looked at three sections with higher modulations to see changes in the high frequency range.

Section one, L/R, first and fifth play shown:
View attachment 555173View attachment 555174
Not much to see other than there is some changes at HF. So here is the difference analysis with first play as reference. Track 2-5 vs 1, L/R
View attachment 555175View attachment 555176'

Same for section 2:
View attachment 555177View attachment 555178
View attachment 555179View attachment 555180

Section 3, the very last and high crescendo of side 2.
View attachment 555181View attachment 555182
View attachment 555183View attachment 555184

So there is a general increase in level of HF during the first plays. The only hypothesis I have is that the stylus is cleaning up the grooves, especially those grainy patches.

Just to finish this story off with a single figure. It is a section played on side 1 of the Telarc record. First played 5 times in a row, with the rise of HF seen in previous plots. Then repeated another day with 5 more plays in a row. Comparing the plots of play 5 (with 1 as reference) and play 10 (with play 6 as reference), gives the same type of curve. All things points to a warming up of suspension during long play, affecting compliance and output. If it was permanent damage of grooves, I would see a continuation of that gradual degradation. Also, play 6 did not continue from where play 5 ended, but the level dropped.

So like speaker voice coil heating during heavy play, we seem to have a case of stylus/suspension heating playing demanding tracks. Case closed.

like

 

[Balle Clorin]

Since the Ortofon 50-100 um tracking tracks showed uneven channel distortion, I decided to try the similar Clearaudio tracking test record. This is what I got at varying Antiskate settings

The impact of antiskate or not on crosstalk is small

Note that the left channel is largely unaffected, which tells us that even the highest antiskate setting is not enough to make the inner track mistrack…

When we normalize for radius and Amplitude we get this plot

Down to 9% antiskate force ( 1.5 AS for 1.67 VTF) we have no increase in right channel distortion up to 80um( red curve), With no antiskate we see a slight increase in distiorton at 70um, 60um ss OK without antiskate. Maximum antiskate 18% (AS 3 vs 1.67 VTF) gives no mistrackingt in either channel
For low modulation 50-60um it seems to be a reduced distortion in R at lower AS from 15% to 0%. 18% is lower than 15% …


Without level and radii compensation it looks like this

 

[Balle Clorin]

More fun with a web app

https://vinyl-tracking-test.streamlit.app/

 

[Balle Clorin]

For no need for measurements to hear the terrible speed stability here, it actually makes me seasick.
If it is the record used or turntable I am not sure

 

[Thomas_A]

For no need for measurements to hear the terrible speed stability here, it actually makes me seasick.
If it is the record used or turntable I am not sure

Is it the same record shown but different ones played?

 

[Balle Clorin]

Sound if from different records/ pressing , visually same showing.
The first one is terrible to listen to , terrible wow of record or platter

 

[Balle Clorin]

Very good about skating force.

 

[Thomas_A]

So to the ever odd question of horizontal tracking angle measured as "inter channel phase" between channels using a JICO SAS MR/ML stylus and the Sperling 1 kHz test record. It has not been easy to set both overhang or zenith to get something that would match up at zero phase shift at the null points of a protractor. @Balle Clorin made an updated version of the phase measurement tool, and I made first an initial measurement of the current set up. Also the cartridge zenith was adjusted such that the cartridge is twisted a bit CCW in the head shell. Then I got this below. The optimal alignment points were according to my Moerch protractor, green dotted curve, and the experimental result in dotted right.

So the curves a similar but do not match. I increased overhang a tiny bit but still kept the slight CCW twist in the head shell and got this:

Pretty close. Now arise the question, since I twist the cartridge a bit, s my stylus mounted with zenith off a bit or is the test record recorded with a fixed zenith error? Since it is the whole cartridge that is twisted a bit, it is a combination of stylus skewness and diamond rotation. So I my scope and tried to get a glimpse.

It is not easy to measure if there is a deviation, but from the best I can see, there is a ≈2 degree twist of the stylus, with left channel "leading" and right channel "lagging". That would match with my need to twist the stylus CCW to get the curve above matching with the null points. This indicates that the Sperling record may not be cut with a fixed zenith error, as previously discussed, but rather close to zero error. Still remains the mystery why @Balle Clorin gets negative phase values at null points, regardless of stylus twist or overhang.

 

[JP]

Cutting stylus is aligned by eye, after all.

 

[Thomas_A]

Cutting stylus is aligned by eye, after all.

Well, then those cutting engineers are probably quite good at aligning!

 

[JP]

It's probably a standard distribution, and I'd think a few degrees would be best-case.