Fun with vinyl measurements

[Balle Clorin]

I was thinking of running the VTA tracks but since they are lateral there is no logic running them. A vertical 1 kHz track makes more sense distortion-wise. Have you tested those (eg 1 kHz vertixal on AP)?

Since this experiment will take significant effort in re-aligning the cartridge after each shim it will take some time to do. Hoping for some time after Christmas.

TheVTA tracks on Tacet and AP are stereo, they should have been vertical to show VTA affects. I cannot se info about them being lateral- if that were they should ba calked Zenith track, not VTA , I ran them with 22 to 29 mm VTA tail end on my SME V, could not detect any impact on IMD%

 

[Thomas_A]

TheVTA tracks on Tacet and AP are stereo, they should have been vertical to show VTA affects.

Yes,

your script gave below. The diff one will be the same as the base (341 Hz) so it will be 100%, only sum which was 0.57-0.59% for Tacet.

Left:
f1 @ 341.397 Hz ↦ 0.02 dBFS
f2 @ 659.770 Hz ↦ -0.01 dBFS
diff@ 341.397 Hz ↦ 0.02 dBFS → IMD% = 100.3333%
sum @ 1001.161 Hz ↦ -44.56 dBFS → IMD% = 0.5924%
a2_diff = 7.9070e-04 a2_sum = 4.6688e-06
3rd-order:
2f1+f2 : freq=1319.589 Hz, dbfs=-50.19, coeff=1.9228e-09
2f1-f2 : freq=17.594 Hz, dbfs=-51.04, coeff=1.7441e-09
2f2+f1 : freq=1660.841 Hz, dbfs=-65.49, coeff=3.3144e-10
2f2-f1 : freq=1001.161 Hz, dbfs=-44.56, coeff=3.6916e-09

Right:
f1 @ 341.396 Hz ↦ -0.17 dBFS
f2 @ 659.769 Hz ↦ 0.05 dBFS
diff@ 341.396 Hz ↦ -0.17 dBFS → IMD% = 97.4331%
sum @ 1001.172 Hz ↦ -44.81 dBFS → IMD% = 0.5715%
a2_diff = 7.0927e-04 a2_sum = 4.1601e-06
3rd-order:
2f1+f2 : freq=1319.506 Hz, dbfs=-46.87, coeff=2.3889e-09
2f1-f2 : freq=17.507 Hz, dbfs=-50.37, coeff=1.5971e-09
2f2+f1 : freq=1661.103 Hz, dbfs=-68.87, coeff=1.8478e-10
2f2-f1 : freq=1001.172 Hz, dbfs=-44.81, coeff=2.9506e-09

 

[Balle Clorin]

F1+F2 is what matters I think

 

[Thomas_A]

F1+F2 is what matters I think

Yes, in the Tacet case. But I wonder what it says re: VTA change. What VTA test signal is the AnalogMagic?

 

[Balle Clorin]

Stereo L and R 60hz and 7khz , and later tracks are 200:4000 and 250:8000

 

[Thomas_A]

Stereo L and R

Ok but what are the frequencies?

 

[Balle Clorin]

See above, strange you saw the post before I posted the full sentence…

 

[Thomas_A]

See above, strange you saw the post before I posted the full sentence…

Ok, so quite different from the Tacet. The AP is similar, but both are stereo/lateral cut. I can only see a vertical cut test signal useful to look at distortion vs. VTA.

 

[Thomas_A]

According to Yosh spreadsheet, and VMA/VTA diff of 10° (20°/30°) gives 2.53% H2 at 10 cm radius, 5° difference gives 1.25%, and 1° difference gives 0.25%. I am not sure if it would be possible to do any meaningful read-outs of the records as yet; the Tacet record gives 1.41%/1.71% H2 vertical which in theory would mean a 6° mismatch between VMA and VTA (I have around 25° VTA now). One could only hope that other distortion components of the AP and CA-TRS1007 is low enough so that any pattern will show. But it will be the same "problem" as looking at lateral tracking angle distortion; risk of being swamped by other stuff.

 

[Balle Clorin]

CBS str-112 has a vertical modulated IMD VTA track.

You may also try a L R to mid-side conversion to get he vertical modulation from a stereo track. TACet is stereo I think, certainly , not vertical.

So L-R= vertical modulation component. L+R -= lateral mono

 

[Thomas_A]

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.

 

[Balle Clorin]

a video of cantilever angle when spinning or not.. any USB microscope would do..

Or this math plus compliance

 

[Thomas_A]

a video of cantilever angle when spinning or not.. any USB microscope would do..

Or this math plus compliance

This is one calc from AI. One problem is that rotational stiffness is the correct figure to use (unkonwn) and that friction u probably is lower.

 

[Balle Clorin]

I think maybe AI missed on the vertical component , that I expect would be sinus or tangens to the stationary VTA

The horizontal friction pull in not the same as vertical push as used in AI calc above

 

[Thomas_A]

I think maybe AI missed on the vertical component , that I expect would be sinus or tangens to the stationary VTA

The horizontal friction pull in not the same as vertical push as used in AI calc above

My manual calc gives a bit more between 1-2 degrees at given data. Still though there are missing data of rotational compliance. Tip displacement does not happen like described.

 

[Balle Clorin]

I think vertical compliance is a good enough approximation

 

[Thomas_A]

I think vertical compliance is a good enough approximation

Yes. But calculation is from a linear displacement when it should be angular. So I need some more chat.

 

[ElectricWarrior]

here's a video comparison: dropping the stylus onto a stationary record vs a spinning one

 

[Thomas_A]

here's a video comparison: dropping the stylus onto a stationary record vs a spinning one

It's a bit tricky to do accurate VTA measurements (+/- 0.5°) even with just static VTF, and dynamic will be even more difficult (unless you have an accurate test record for VTA). That said, all calculations I've made with the help of AI all give similar results. I am not confident that calculations are correct though, but around 1° lower VTA from a static one is reasonable correction value.

 

[ElectricWarrior]

sounds reasonable.

I originally recorded this to see if it makes much of a difference for the effective length. after all, one will align the cartridge on a stationary protractor and then use it on a spinning record..