Fun with vinyl measurements

[Thomas_A]

idk where to put it either don't have an integrated amp topic..it is of "integrated" dsp design. dsp was added to other models mine not mine is pre-dsp model.

Still the wrong thread.

 

[jspinks321]

Still the wrong thread.

I like what you describe lol sorry lol..Its ufo but thats closer to say its an integrated amp.

 

[Dberryco]

Anyone with a smartphone can do a RPM check. While my strobedisk is very stable at correct speed i get +0.24% on the app . The app also show similar w&f variations a recording of A test record.

How can you use a smart phone to check the RPM? Or what app specifically?

 

[somebodyelse]

wrong thread, maybe?

Maybe, but it's a consistent problem. A bit of something that may be sort of on topic followed by a chunk of off-topic content and a couple of guitar-related photos - often almost identical between threads. Once or twice is a mistake, but this many times is beyond coincidence.

 

[Labhound]

How can you use a smart phone to check the RPM? Or what app specifically?

I've used this one for IOS: RPM - Turntable Speed Accuracy

 

[sqrl]

Maybe, but it's a consistent problem. A bit of something that may be sort of on topic followed by a chunk of off-topic content and a couple of guitar-related photos - often almost identical between threads. Once or twice is a mistake, but this many times is beyond coincidence.

AI agent on the loose?

 

[Balle Clorin]

I was thinking of your plot in post 3004. There the Merolemez angle result is decreasing when shimming down VTA (?)

I did a check today of my setup and made a small adjustment of the azimuth (at tonearm base):
Terrific script by the way...


Before:
View attachment 542010

After:
View attachment 542011

My initial measurements when stylus was new:
View attachment 542013


Now there are many confounders here. Suspension is affected by temperature and humidity (summer heat now, tried to cool down but still 24.4°C, against my normal temp of 22.0°C), and I also have increased the VTF to 1.6 (with brush), meaning effective VTF is 1.4. So I need to repeat this when temperature goes down.

Have other experiments on the way but I don't want to redo alignment due to the above experiment... it is a long time experiment....

Here is the Merolemes at different VTF that of course change VTA, VTA change affect the minimum angle for the Merolemez record.
Lower VTA increase VTA and moved minimum point closer to central 90 degree azimuth

Extrapolating VTF to 0.6g gives 24.2 degrees VTA which gives minim at track 6/11 or 45' groove wall or 90 degree azimuth
At spec VTF 1.5g VTA is measured by the script to 22.6 degrees vs spec 23 degrees. Not bad considering the my script measures running VTA which is lower than geometrical stationary, not sure which VTA AT specify
Assuming a 10mm distance form til to pivot point ( Obray 6mm rod +4mm) gives compliance 33CU vs spec 35

 

[Thomas_A]

Here is the Merolemes at different VTF that of course change VTA, VTA change affect the minimum angle for the Merolemez record.
Lower VTA increase VTA and moved minimum point closer to central 90 degree azimuth


View attachment 552178


Extrapolating VTF to 0.6g gives 24.2 degrees VTA which gives minim at track 6/11 or 45' groove wall or 90 degree azimuth
At spec VTF 1.5g VTA is measured by the script to 22.6 degrees vs spec 23 degrees. Not bad considering the my script measures running VTA which is lower than geometrical stationary, not sure which VTA AT specify
Assuming a 10mm distance form til to pivot point ( Obray 6mm rod +4mm) gives compliance 33CU vs spec 35

View attachment 552179



View attachment 552193

Interesting and I think the direction of change is correct. My wonder VTA change with shim gives the same as VTA change by VTF. A lot of work though.

 

[Thomas_A]

So with the help of Ray Parkhurst, some high resolution images of inner grooves of the record Telarc's "Lorin Maazel & The Cleveland Orchestra - Mussorgsky: Pictures At An Exhibition / Night On Bald Mountain". Shown also in the Humminguru thread but here with higher resolution. This record have a high crescendo in the end of side 2, and also have cutting/pressing errors in shape of grains and ridges at the very sharp modulations. It was played at 1.4 gf effective stylus pressure Shure V15V JICO SAS/B with ≈14% antiskate, five times. Studying the grooves more carefully, I can see that the right groove (which up in the pictures) grainy patterns are shaved off more than the left groove. This could mean that the antiskate force is a bit too high at 14%. This despite that the typical 315 Hz tracking test shows distortion/mistracking in the right groove before the left groove. I have ordered two more records and will redo the experiment with 1.5 gf effective VTF with brush down, and 10% AS, to see if the grain wear pattern evens out.

A zoomed in part:

Since the pictures are too large, they are linked to my dropbox.

Dropbox

www.dropbox.com

Dropbox

www.dropbox.com

Dropbox

www.dropbox.com

Dropbox

www.dropbox.com

 

[Jimi Floyd]

So with the help of Ray Parkhurst, some high resolution images of inner grooves of the record Telarc's "Lorin Maazel & The Cleveland Orchestra - Mussorgsky: Pictures At An Exhibition / Night On Bald Mountain". Shown also in the Humminguru thread but here with higher resolution. This record have a high crescendo in the end of side 2, and also have cutting/pressing errors in shape of grains and ridges at the very sharp modulations. It was played at 1.4 gf effective stylus pressure Shure V15V JICO SAS/B with ≈14% antiskate, five times. Studying the grooves more carefully, I can see that the right groove (which up in the pictures) grainy patterns are shaved off more than the left groove. This could mean that the antiskate force is a bit too high at 14%. This despite that the typical 315 Hz tracking test shows distortion/mistracking in the right groove before the left groove. I have ordered two more records and will redo the experiment with 1.5 gf effective VTF with brush down, and 10% AS, to see if the grain wear pattern evens out.

A zoomed in part:

View attachment 552407

Since the pictures are too large, they are linked to my dropbox.

Dropbox

www.dropbox.com

Dropbox

www.dropbox.com

Dropbox

www.dropbox.com

Dropbox

www.dropbox.com

Just to start the debugging phase, those grainy areas appear on this record only or on a majority of records? Do we have pictures of before-any-play available as well 1 play, or 10 or 100?

 

[Thomas_A]

Just to start the debugging phase, those grainy areas appear on this record only or on a majority of records? Do we have pictures of before-any-play available as well 1 play, or 10 or 100?

According to Ray, it is not only on this record, but this one seems to be quite dense on this one especially the crescendos in the end of side 2. Looking at the middle of side one, which is quite modulated as well, but it is not end of record, so modulations not as dramatic, it is cleaner (below).

Ray have posted quite many pictures of this record unplayed and played many times.

Dropbox

www.dropbox.com

Dropbox

www.dropbox.com

Dropbox

www.dropbox.com

Dropbox

www.dropbox.com

 

[Balle Clorin]

A script for tracking/anti skate is not really needed, this is easily done by ear. But I asked Claude to make one anyway.

Maybe it can be used to tune antiskate. It used the 50-100um Ortofon test tracks

 

[Thomas_A]

I will test the groove wear pattern vs antiskate force. 14% seems to give more on right groove. 10% AS experiment coming.

 

[mackat]

Today, I measured an Audio-Technica AT-25 and got an unusual distortion pattern nearly identical to that commonly seen in Nagaoka cartridges:

This is very unusual, and I am hoping it might help explain why this unusually high distortion in this specific shape shows up.

Compare to the following Nagaoka measurements:

My other AT-25 stylus does not show this distortion pattern (used in a TK10ML body as it's not a good channel balance match with the body it came with):

Nor does the TK10ML stylus.

I believe both AT-25's to be unused or very lightly used. The stylus on the problem unit seems to be higher compliance than the other.

I enlisted Claude's help in trying to help me figure this out, and I've attached a shortened summary.

I'm not an engineer, and a lot of this is beyond my understanding, so some info may be incorrect.

I'm happy to provide files if anyone would like.

Two findings.

The hump's shape is a measurement artifact. There's a resonance at ~21.5 kHz. SJPlot rates each harmonic against the fundamental without correcting for what the system does at 2f or 3f, so when the harmonic product lands on that resonance it reads as distortion, then falls off once the product moves past it. Hence a hump that peaks and turns over. Confirmed two ways: H2 through H5 all peak at frequencies multiplying out to 20 to 22 kHz, and the silent groove at the end of the file shows the resonance directly as a +4 dB bump in the noise floor.

The level underneath it is real. The correction is only about 5 dB, leaving roughly -14 dB of genuine second harmonic at 10 kHz. Every distortion peak sits at an exact integer multiple of the sweep, so it isn't the resonance ringing.

The one solid clue: the second harmonic is vertical, appearing in antiphase between channels across 1 to 8 kHz. But dedicated lateral and vertical tracks show the same vertical 2f either way, which rules out the obvious contact-angle explanation. Still open.

Also worth noting: the electrical resonance is at 48 kHz here (85 mH, 130 pF) and contributes about 1 dB at 20 kHz, so loading isn't the story.

Two things anyone measuring cartridges might find useful: if a cartridge's response is still climbing at 20 kHz, its 10 kHz H2 figure is inflated by roughly the response difference between 20 kHz and 10 kHz. And a few seconds of silent groove gets you the response above 20 kHz that the test record's sweep can't reach.

 

[Thomas_A]

Today, I measured an Audio-Technica AT-25 and got an unusual distortion pattern nearly identical to that commonly seen in Nagaoka cartridges:

View attachment 555116

This is very unusual, and I am hoping it might help explain why this unusually high distortion in this specific shape shows up.

Compare to the following Nagaoka measurements:

View attachment 555112

View attachment 555113
View attachment 555114

My other AT-25 stylus does not show this distortion pattern (used in a TK10ML body as it's not a good channel balance match with the body it came with):

View attachment 555115
Nor does the TK10ML stylus.

I believe both AT-25's to be unused or very lightly used. The stylus on the problem unit seems to be higher compliance than the other.

I enlisted Claude's help in trying to help me figure this out, and I've attached a shortened summary.

I'm not an engineer, and a lot of this is beyond my understanding, so some info may be incorrect.

I'm happy to provide files if anyone would like.

The Ortofon test record could help here to see up to 45k.

 

[JP]

It's not a measurement artifact. While the level of HD will be boosted by the resonance, that's the real output of the cartridge.

 

[Thomas_A]

So with the help of Ray Parkhurst, some high resolution images of inner grooves of the record Telarc's "Lorin Maazel & The Cleveland Orchestra - Mussorgsky: Pictures At An Exhibition / Night On Bald Mountain". Shown also in the Humminguru thread but here with higher resolution. This record have a high crescendo in the end of side 2, and also have cutting/pressing errors in shape of grains and ridges at the very sharp modulations. It was played at 1.4 gf effective stylus pressure Shure V15V JICO SAS/B with ≈14% antiskate, five times. Studying the grooves more carefully, I can see that the right groove (which up in the pictures) grainy patterns are shaved off more than the left groove. This could mean that the antiskate force is a bit too high at 14%. This despite that the typical 315 Hz tracking test shows distortion/mistracking in the right groove before the left groove. I have ordered two more records and will redo the experiment with 1.5 gf effective VTF with brush down, and 10% AS, to see if the grain wear pattern evens out.

A zoomed in part:

View attachment 552407

Since the pictures are too large, they are linked to my dropbox.

Dropbox

www.dropbox.com

Dropbox

www.dropbox.com

Dropbox

www.dropbox.com

Dropbox

www.dropbox.com

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:

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

'

Same for section 2:

Section 3, the very last and high crescendo of side 2.

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.

 

[JP]

What’s the dwell time between plays?

 

[Thomas_A]

What’s the dwell time between plays?

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

 

[sqrl]

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.

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.