Fun with vinyl measurements

[RayKay]

@ElectricWarrior,

If I may, I’d like to posit the idea that not only is there a sliding friction for the stylus on vinyl but, the stylus/vinyl interface also exhibits sticktion. Stylus sticktion would account for at least some of the difference seen between the two videos.

In the second video, VTF pushes down on the cantilever suspension and causes the stylus to move forward as the cantilever rotates upward from the VTF bearing down on the suspension. Stylus sliding friction adds a pulling force on the suspension, which ends up deflecting the cantilever upward and the stylus forward even farther.

In the first video, VTF pushes down on the cantilever suspension too, but stylus sticktion inhibits the stylus tip from sliding forward and allowing the cantilever to “stretch itself out”, so to speak. I believe that in this scenario, forces would also resolve into a lateral component that would cause some sideways deflection. It would be informative if you could repeat the same video sequences except with the camera viewing the cartridge and cantilever head on to see if there is sideways deflection.

These effects would indeed hamper alignment accuracy through having some effect on effective length, but might also skew the cantilever sideways and directly add an angular error to the procedure which may be worse than a small change in effective length.

Thoughts?

Ray K

 

[Balle Clorin]

maybe posted before but a good reference How to test cartridges Hifi World

Cartridge tests

Frequency response of a modern Moving Magnet pickup cartridge, an Ortofon 2M Red.FREQUENCY RESPONSEWHAT IT TELLS USPickup cartridge frequency response is a good guide to tonal balance and

www.hi-fiworld.co.uk

 

[ElectricWarrior]

@ElectricWarrior,

If I may, I’d like to posit the idea that not only is there a sliding friction for the stylus on vinyl but, the stylus/vinyl interface also exhibits sticktion. Stylus sticktion would account for at least some of the difference seen between the two videos.

In the second video, VTF pushes down on the cantilever suspension and causes the stylus to move forward as the cantilever rotates upward from the VTF bearing down on the suspension. Stylus sliding friction adds a pulling force on the suspension, which ends up deflecting the cantilever upward and the stylus forward even farther.

In the first video, VTF pushes down on the cantilever suspension too, but stylus sticktion inhibits the stylus tip from sliding forward and allowing the cantilever to “stretch itself out”, so to speak. I believe that in this scenario, forces would also resolve into a lateral component that would cause some sideways deflection. It would be informative if you could repeat the same video sequences except with the camera viewing the cartridge and cantilever head on to see if there is sideways deflection.

These effects would indeed hamper alignment accuracy through having some effect on effective length, but might also skew the cantilever sideways and directly add an angular error to the procedure which may be worse than a small change in effective length.

Thoughts?

Ray K

Sideways deflection can certainly happen, especially with high compliance cartridges. Conrad Hoffman posted some pictures over at vinylengine: https://www.vinylengine.com/turntable_forum/viewtopic.php?f=19&t=16849&hilit=arc+template&start=12
I currently only use medium compliance cartridges and haven't observed it myself yet.

I think it's best to keep tracking force low when using a protractor and to set the overhang a little shorter. Approximately 0.5mm for a medium compliance cartridge iirc.

 

[Balle Clorin]

My midwinter holydays has officially started in my home. And there will be a break in my Hifi testing. I will be testing other things, like the home made » Julesild» and this years Aqua Vitae.Happy holiday to you all.

 

[Thomas_A]

My midwinter holydays has officially started in my home. And there will be a break in my Hifi testing. I will be testing other things, like the home made » Julesild» and this years Aqua Vitae.Happy holiday to you all.

View attachment 498560

God Jul!

 

[Balle Clorin]

God jul til deg også!

 

[narud]

was there ever a consensus on what degree shim to use with sas styli for optimal distortion? do we know what angle the pats audio shims are? set up the arm level and then use the shim?

 

[Thomas_A]

I plan to do some systematic tests in a week or two.

 

[Balle Clorin]

was there ever a consensus on what degree shim to use with sas styli for optimal distortion? do we know what angle the pats audio shims are? set up the arm level and then use the shim?

Level arm, Pats audioparts shim gave me 6 degree. Not sure what other Jico SAS are, by my Shure V15-4 is 28-30 degree

 

[narud]

Level arm, Pats audioparts shim gave me 6 degree. Not sure what other Jico SAS are, by my Shure V15-4 is 28-30 degree

i thought they were all built with that overly large angle? i havent measured mine, but to the naked eye, the 4 that i have dont look any different to yours. i ordered some pats shims. thanks for the heads up. i dont really notice any increased distortion as is, but what fun would vinyl be without another thing to over analyze and be critical of?

 

[Balle Clorin]

If anyone can do a calculation on VTA effect on friction during play it would be nice. Say 1.5 g VTF, compliance 20 and friction coefficient 0.3. Perhaps ≈ 1 degree effect?

I asked an AI model and got 0.93 degree change with VTF 1.5, compliance 22, friction coefficient 0.3, cantilever length 6 mm, VTA static at 25 degrees.

Wallyscope has. YouTube video on dynamic,moving SRA.. and a webinar too. The result was 0.9 degree less SRA with spinning record

 

[Balle Clorin]

About VTA correction , see show Wam engineering have corrected this Hana by 9 degrees to get to a VTA target of 18degree , taken from YouTube on my TV, video 6 in a series
Calculating backwards This gives an original VTA of 27 degree on Hana Unami Red. But if this is a Obray boron 18 degree VTA would give SRA of 88….

 

[Thomas_A]

A first attempt investigating VTA effect on crosstalk using the Shure V15V with JICO SAS/B. It has something like 28-30° VTA as is which is too high according to standards (20° nominal with range 20-25° for modern records).

I tested it with 0 shims and three small papers from playing cards to shim it in the back. Upon remounting I aligned it and used the same vertical tracking force, 1.44 g. I did not bother with fine adjusting azimuth but I think this experiments shows the point anyway. Test records were Meroloemez azimuth test track, Ortofon test record (sweep and 1 kHz), CA-TRS1007 (sweep and 1 kHz signals).

I go first with the 0 shimming and Merolemez. Minimum values were at 42°/43° at around -41 and -39 dB while the ideal angle 45° showed moderate crosstalk at -28/-26 dB.

Shimming about 6° gave this result. Minimum values were now at 44° and the 45° showed -39/-35 dB.

Could this be replicated also with the Ortofon 1 kHz test record? Yes. Crosstalk was lowered significantly after shimming.

0 shims:

3 shims:

I do not give values here but it is obvious that the crosstalk was reduced significantly after shimming.

Ortofon sweep 0 shims:

Ortofon sweep 3 shims:

CA-TRS1007 sweep 0 shims:

CA-TRS1007 3 shims:

Not so much effect on the CA-TRS1007 at this shimming.

2nd harmonic was also measured on the CA-TRS1007 1 kHz tracks:

0 shims (L/R values):
L/R track: -47.4/-39.8 dB
L+R: -44.7/-44.0 dB
L-R: -38.2/-37.1 dB

3 shims:
L/R track: -50.2/-44.3 dB
L+R: -43.1/-43.3 dB
L-R: -50.1/-48.3

Biggest difference in the L-R track (expected) with 12 dB lower 2nd harmonic.

 

[narud]

A first attempt investigating VTA effect on crosstalk using the Shure V15V with JICO SAS/B. It has something like 28-30° VTA as is which is too high according to standards (20° nominal with range 20-25° for modern records).

I tested it with 0 shims and three small papers from playing cards to shim it in the back. Upon remounting I aligned it and used the same vertical tracking force, 1.44 g. I did not bother with fine adjusting azimuth but I think this experiments shows the point anyway. Test records were Meroloemez azimuth test track, Ortofon test record (sweep and 1 kHz), CA-TRS1007 (sweep and 1 kHz signals).

I go first with the 0 shimming and Merolemez. Minimum values were at 42°/43° at around -41 and -39 dB while it was the nominal 45° showed moderate -28/-26 dB.

View attachment 499958

Shimming about 6° gave this result. Minimum values were now at 44° and the 45° showed -39/-35 dB.
View attachment 499959

Could this be replicated also with the Ortofon 1 kHz test record? Yes. Crosstalk was lowered significantly after shimming.

0 shims:
View attachment 499960

3 shims:
View attachment 499961

I do not give values here but it is obvious that the crosstalk was reduced significantly after shimming.

if im understanding correctly, shimming is really the most beneficial with these jico sas stylus assemblies that have the cantilevers assembled at this oddly large angle? benefits are reduced imd and better crosstalk? ive got some pats shims showing up today so im looking forward to getting my shure v15vx body with sas/s remounted.

are there any other carts using this 28-30 degree vta? was there ever an explanation from jico as to why theyre building them this way?

 

[Thomas_A]

if im understanding correctly, shimming is really the most beneficial with these jico sas stylus assemblies that have the cantilevers assembled at this oddly large angle? benefits are reduced imd and better crosstalk? ive got some pats shims showing up today so im looking forward to getting my shure v15vx body with sas/s remounted.

are there any other carts using this 28-30 degree vta? was there ever an explanation from jico as to why theyre building them this way?

There are many cartridges with too high VTA. Most of the ATs seem to be around 23° though. I am to sure why though. SRA and VTA are linked so why they are like that is unclear.

 

[Balle Clorin]

The Wally Tools guy said on YouTube that the reason makers use too high VTA is to reduce sibilants and improve tracking. I cannot confirm, but how does your shimmed SAS track compared to unshimmed? My shimmed tracks +16db on Hifi news test record but not 18, when asking Jico I got a vage answer about unknowns distortion effects and that more VTF would help on a steep VTA

 

[Thomas_A]

The Wally Tools guy said on YouTube that the reason makers use too high VTA is to reduce sibilants and improve tracking. I cannot confirm, but how fours your shimmed SAS track compared to unshimmed? My shimmed tracks +16db on Hifi news test record but not 18, wham asking Jico I got a vage answer about unknowns distortion effects and that more VTF would help on a steep VTA

No real difference on the Ortofon tracks. I will do some distortion checks tonight.

 

[narud]

just got the sas/s shimmed. distortion looks a bit reduced on the plot. i wouldnt know how to run all the tests you guys are doing. seems to track the hifinews 300hz tracks as well as before. needle drops of music at the end of a side dont show any difference in frequency response.

 

[Balle Clorin]

Biggest difference in the L-R track (expected) with 12 dB lower 2nd harmonic

Which means we have aNother test track for VTA,… did not think of that one before, maybe the L+R could be useful for HTA.?

It is pretty clear from the tests here that VTA has little effect on frequency response, but significant effect on distortion… what people subjectively hear and claim to be more or less bass or treble byraising lowering VTA by arm end, therefor may be more distortion effects than frequency response changes, at least for these micro line styli

 

[Thomas_A]

Which means we have aNother test track for VTA,… did not think of that one before, maybe the L+R could be useful for HTA.?

It is pretty clear from the tests here that VTA has little effect on frequency response, but significant effect on distortion… what people subjectively hear and claim to be more or less bass or treble byraising lowering VTA by arm end, therefor may be more distortion effects than frequency response changes, at least for these micro line styli

A pure vertical signal (L-R) should give increased distortion when VTA/VMA is not matched (as also Yosh summarised and have in his Excel-macro). This would be the same with LTA that you did with the 3150 Hz CA test record using a lateral cut groove (L+R). LTA error is however too low and distortion is swamped by other distortion components, but phase might be the way to go. I find myself struggling with geometry when the VMA angle makes the triangle tilted so that the projected walls are no longer at 45°/45°. Only the same angle of the stylus will "see" 45°. The high VTA gives an out-of-phase x-talk signal, which I guess it means that it sees less than 45° (fits with the Merolemez). This may have to do with generator symmetry as well, but in my case the lowered VTA got closer to the ideal. I may try an additional shim to see if I can get perfect 45° match on the Merolemez test record.

What could happen if crosstalk gets too bad is that it affects the signal in the frequency extremes, since there is where crosstalk is poor. Adding more crosstalk by wrong VTA and/or azimuth could theoretically affect those parts of the spectrum. But I suspect you need quite bad crosstalk (in the range of -10 to -15 dB). Also, VMA varies with frequency (a cutter thing) so one needs to choose.

A last thing with "sibilance" is that it may affect tracing of HF at the end of the record if the stylus is not perfectly fit. It may be SRA-related, but I am yet not sure how much SRA can vary before it is noticeable in tracing HF. There are not many test records for that with test signals, other than the fricative test.

Not sure if the VTA and crosstalk has been discussed much. Most things are with the "tonearm height/VTA" and bass/treble, which so far seems to be myths.