Fun with vinyl measurements

[Thomas_A]

Channel balance may be affected if crosstalk is very poor such as at frequency extremes. I think.

 

[Balle Clorin]

From http://pspatialaudio.com/cart_compensation.htm?utm_source=copilot.com

 

[Thomas_A]

A crosstalk is a loss of energy but if it is -30 dB you loose very little. Unless in frequency extremes where crossstalk is large/uneven.

 

[Balle Clorin]

One channel may have in phase crosstalk that adds to the signal , while another out if phase will subtract. Probably why Tacet test record has in phase and out if phase pink noise track that illustrate this effect

 

[Thomas_A]

One channel may have in phase crosstalk that adds to the signal , while another out if phase will subtract. Probably why Tacet test record has in phase and out if phase pink noise track that illustrate this effect

One can look at the frequency response at the 10-20 kHz region when channel balance sometimes diverge. Problem is that VMA is frequency dependent and there is no way to have perfect match over the whole frequency spectrum. I would say if there is perfect adimuth and VTA/VMA match at 1 kHz let it be. Cartridge suspension can be a bit asymmetric at 10-20 kHz as well.

 

[Balle Clorin]

FINALY, THE SPERLING TESt RECORS SHOWS ITS PROMISE. 1khz stereo track from 146mm to 57mm radius 22 minutes 33 rpm. EDIT(compared to Shure TTR-109 at 5 cm/s the level is 6db lower, or half , that is 2.5cm/s)

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We can actually see the interchannel phase difference caused by the HTA varying across the record..,, but that is NOT reflected in the distortion, that has a steady increase towards the centre- cuaseby reduced wavelength i suspect. VTA ajusted cartride -6 degree, VTA is 22 degrees when recorded

Heavy smoothing

 

[Thomas_A]

Do you know what level it is recorded? You have a min/max of ≈1.7°. You do not have zero crossings so cart need perhaps 0.5° twist.

 

[Balle Clorin]

-10dBu whatever that means EDIT ( compared to Shure TTR-109 at 5 cm/s the level is 6db lower, or half , that is 2.5cm/s)

To have zero diff at 120.9 null I need to turn phase diff 0.9 degree, have to converte that to alignment degrees, … and I get 2 degrees..or 0,5mm lateral at cartridge corner

 

[JP]

I’ll have to go back and re-read old papers, but I never really read HTA effects as harmonic distortion. It can understand it with certain contact geometries, but not universally.

Got in to Melbourne yesterday for tennis, so will be quite occupied the rest of the trip. New Zealand was stunning.

 

[Balle Clorin]

It’s seems to me that every classic paper on cartridge alignment stateHTA error must be minimised to minimise harmonic distortion..
But the Løfgren,Bearwald was while conical existed as the only option , and Stevenson possible while elliptical were present.

My plots are with Microridge,,, and cannot see any effect of HTA change on distortion… just as Korf blog found.

 

[ElectricWarrior]

Tracking distortion is the same for any stylus shape. It's caused by the cantilever tracking the groove from an angle.

The Korf blog results were pretty much as expected. Dominated by tracing distortion.

 

[Balle Clorin]

But If the distortion is caused by tracing angle error why does the distortion not respond to the tracking error variation indicated by the inter channel phase difference ( proportional to HTA error) in the upper plot?

It seems like the HTA effect is overshadowed by other factors like wavelength( inner grooves shrink), VTA or something else..

 

[JP]

So now with a conical, elliptical, hyper elliptical.

 

[Thomas_A]

-10dBu whatever that means

To have zero diff at 120.9 null I need to turn phase diff 0.9 degree, have to converte that to alignment degrees, … and I get 2 degrees..or 0,5mm lateral at cartridge corner

When you twist remember you get + in one channel - in the other. So a 0.9 diff will be fixed by 0.45.

 

[ElectricWarrior]

But If the distortion is caused by tracing angle error why does the distortion not respond to the tracking error variation indicated by the inter channel phase difference ( proportional to HTA error) in the upper plot?

It seems like the HTA effect is overshadowed by other factors like wavelength( inner grooves shrink), VTA or something else..

The peak recorded groove velocity of a test record is probably not so high. If we assume it’s 5cm/s and apply RIAA correction, tracking distortion would be only ~0.23% for Löfgren A at 215mm PTS. That should be easy to overshadow.

 

[Balle Clorin]

So now with a conical, elliptical, hyper elliptical.

Korf did that in his blog.

More Clues from THD

korfaudio.com

The Trap of Mental Experiments

korfaudio.com

 

[JP]

Phase, not HD. In general it’d be good data to give insight to magnitudes, followed by some calculations of where the HD contribution sits, remembering how distortion sums. It may never be measurable.

I don’t follow Korf as he has a habit of setting out to prove his conclusions rather than being exhaustive. His treatment of effective mass is quite a disservice to the analog community, as one of several examples.

 

[Balle Clorin]

The peak recorded groove velocity of a test record is probably not so high. If we assume it’s 5cm/s and apply RIAA correction, tracking distortion would be only ~0.23% for Löfgren A at 215mm PTS. That should be easy to overshadow.

The recording level in the Sperling TLP-1 is 6db lower than the Shure TTR-109 which is 5cm/s…stereo , and I recorded flat no RIAA

 

[Thomas_A]

The recording level in the Sperling TLP-1 is 6db lower than the Shure TTR-109 which is 5cm/s…stereo , and I recorded flat no RIAA

so that would be 2.5 cm/s. You would need below -60 dB for all other distortion components to see tracking distortion.

 

[Balle Clorin]

many Thanks, So that is the explanation then. HTA distortion is below other distortions and noise. Vinyl engine or was it Yosh that has an excel sheet to calculate distortion vs HTA and level, need to dig that out when I have time. The cartridge gives 1.25mV on this 2.5 cm/s track. Recorded at 40db gain


HTA error distortion theoretical TLP- 1, 1.25 cm/s. too low variations to be detecteble compared to the "general "distortion level of 0.3-1%
The record is simply at too low level to produce HTA error distortion clearly. But Phase difference between channels can still be used to check alignment nulls= phase changes sign.

For HTA error distortion to get above my test distortion I would need 15cm/s which is almost 10db above the standard 5cm/s level and 16db above the current test record level...mistyped legend below . 1.25mV at 2.5cm/s