Fun with vinyl measurements

[USER]

One idea: not sure if it is possible or not, but is there a way to have Chat GPT come up with an "auto-centering" mechanism based on the polar plot? I'm wondering if that would make more test records usable.

 

[Balle Clorin]

That would be about what I do on my Excel W&F plot:
Take the plot values and make a low pass filtered column/value . And subtract that from the unfiltered value. So the result is the same as a high pass filtered value, showing all Noise and higher frequency variation. But that may not be what you wanted?

Less than 0.55hz would be removed too…

 

[Balle Clorin]

At last somethings seem to match between theory and practice. AnalogMagik V2 33.33rpm record and my own script… Intermodulation track 60:7000hz

 

[Thomas_A]

Shims 1.5, 2.5, 3.5, 4.5, 6.0, 7.0 and 8.0 degrees and AP test record vertical 1 kHz; Shure V15V JICO SAS/B .

Here is the CA-TRS1007 results with lateral and vertical H2 and H3, left + right channel.

8° shim:

Effect on frequency response at 7 degree shim, Ortofon record. I've not seen this before. It seems to loose a bit more >35 kHz in R channel. Which may be due to SRA mismatch.

 

[Balle Clorin]

Wow, 2harmonic on Vertical modulation works!
Will be interesting to see if another cart gives a minimum…before trend reverses

 

[Thomas_A]

Wow, 2harmonic on Vertical modulation works!

Lot of work here. I have 8.0 degree as well but not sure if i do it. I'll see.

 

[Balle Clorin]

I guess if cutting angle is 18 degree , shimming the Jico so much would cause cartridge pins to hit the record..

 

[Thomas_A]

I guess if cutting angle is 18 degree , shimming the Jico so much would cause cartridge pins to hit the record..

7 degree still fine. Will test 8 as well later tonight. Floor ball now!

8 degree added to measurements.

 

[Thomas_A]

I'll probably make this a web app like sjplot, but in react/js so it's interactive - would be good for the decomposition plot.



View attachment 517796

Is this python?

 

[JP]

Is this python?

Yep

 

[sqrl]

VTA (cantilever angle) and channel separation on MP-700



Cartridge shimmed 1.5°. Green (below) and red (above) angles relative to cartridge as supplied at 26° (blue).

 

[Thomas_A]

VTA (cantilever angle) and channel separation on MP-700

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Cartridge shimmed 1.5°. Green (below) and red (above) angles relative to cartridge as supplied at 26° (blue).

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Yes, VTA affects crosstalk as well as distortion. It is quite clear. What is the shimming capacity of the Nagaokas?

 

[sqrl]

Yes, VTA affects crosstalk as well as distortion. It is quite clear. What is the shimming capacity of the Nagaokas?

~3°

 

[sqrl]

Same method for 2nd Harmonic Distortion





Static SRA is 92° at a 23° cantilever angle, so it's possible there is a curvilinear relationship, but can't test that without bottoming out the cartridge.

 

[Thomas_A]

Shims. supplied separate or in kit of 16 shims 0.5-8° and two flat 0.5 and 1 mm shims. There are four holes, so they can be used either as VTA or azimuth shims (or built together in combination). 0.5 and 1 mm flat shims are added if additional space is needed for cartridge.

 

[sqrl]

Shims. supplied separate or in kit of 16 shims 0.5-8° and two flat 0.5 and 1 mm shims. There are four holes, so they can be used either as VTA or azimuth shims (or built together in combination). 0.5 and 1 mm flat shims are added if additional space is needed for cartridge.

View attachment 518458
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I quite fancy a piece of emmental just now for some reason.

 

[sqrl]

Nagaoka MP-700, shimmed by 1.5°; 6 and 7mm mats + tonearm height, 0mm (VTA/cantilever angle; 23.25° and 23.50°). Average antiskate (%) at 1.5g VTF plotted against frequency sweep (SJPlot .csv output), n=4-12 measures per group.



Best channel separation is at ~13% (0.75), although this is reversed at HF by a small margin. Zooming in, a tiny advantage in the 0.5-0.7 dial setting range versus 0.8-1.0 (n=12 per group).



~12-13% average tends to correspond with the Wallytools recommendation, for 10% at the outer grooves, at which the inner may be 3-4% higher.
The QR-2010 test record would be a further check: the inner sweeps have a lower groove radius.

 

[frank is here]

Please be aware that you may also need a shim for the top of the headshell to allow for the angle of the bolts or you are entering into another can of worms re torque /tension of bolts....yes there is such a thing and yes it affects the sound...test it....

 

[Thomas_A]

I have thought about any possible problems with the bolts being a bit tilted. I have used both rubber and plastic washers which work fine.

 

[mackat]

Somehow, I keep missing TRS-1007's

One just went on Discogs last week for $3.43...sigh