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Fun with vinyl measurements

Balle Clorin said:
View attachment 312323View attachment 312322Something very strange is going on when I play the recorded file of my turntable inCooledit and loop OUT to IN physically and observe in the T-100 app. I then get this view- no low FFT frequency content no WOW - ABOVE

During recording from TT I get this

WOW is visible, Why is it not visible when I Loop the recording? It is WOW in the file I see it in Audacity WF add-in
Click to expand...
Do you have a HP filter in the out-in-loop? (You also have different methods in the screen shots)
 
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in AU you can set point parameters.
 

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Thomas_A said:
Do you have a HP filter in the out-in-loop? (You also have different methods in the screen shots)
Click to expand...
Not that I know of, trried another sound interface Tascam 144mk2, same result. The wow part becomes filtered out It seems. The WF values depend on the volume too , but in Audacity the FFT show that the source file has wow, it just vanishes when I playback in loop. Tomorrow I will try playing from one pc into another, in theory PC 1 becomes the source in place of a TT + RIAA
 
And from one pc to the other, still the same variation of w/f on output setting? It seems not to be an issue with the T-100 where spec says that input can be anything from 3 mV and up.
 
With 2nd PC as source the w&f values are no longer affected by signal level /volume. Seems like looping out-in on one PC only leads to erratic values, maybe my PC is not up to the multi-tasking
 
Balle Clorin said:
With 2nd PC as source the w&f values are no longer affected by signal level /volume. Seems like looping out-in on one PC only leads to erratic values, maybe my PC is not up to the multi-tasking
Click to expand...
Could be HP filtering. Increasing output would make more LF signal pass through.
 
Explanation
In the digital domain, there are two algorithms for analyzing W&F: (1)Zero-crossing, (2)Hilbert transform. The zero-crossing method is relatively straightforward. It is less sensitive to signal distortion, but it can’t provide deeper information such as W&F spectrum. The T-100 app uses the second method which is the Hilbert transform. It can provide deeper information, such as the W&F spectrum in the advanced W&F display. However, the downside of the Hilbert transform is that it is quite sensitive to distortion(s) of the input signal. Nothing is perfect...

So, what you have seen is presumably a result of potential distortion in the input signal. While this is an undesirable side-effect, it can also be an indicator of potential problem(s) in the audio path, as distortions are often level related. Hope this helps.
 
Balle Clorin said:
With 2nd PC as source the w&f values are no longer affected by signal level /volume. Seems like looping out-in on one PC only leads to erratic values, maybe my PC is not up to the multi-tasking
Click to expand...
You can just record the out-in loop with test signals low in frequency to see whether there is HP filtering.
 
Balle Clorin said:
Yes , need to investigate , may be belt vibration?
Click to expand...
So that is the Gyro? Belt and the platter mass forms a resonant f, you can test if that is around 7 Hz. Seems a bit high for a 3 kg platter? What is your arm-cart resonance?
 
Balle Clorin said:
The Denon DP-51F

View attachment 312672
View attachment 312673
Clearaudio test record. 3150Hz
Click to expand...

Hm. Comparing to your Gyro, the 0.56 Hz wow is at 0.112-0.125% here vs 0.24% for the Gyro file. I tested my USB microscope to align/center the run-out groove of the Tacet record for better centering, and it seems to work quite well (similar to a "manual" Nakamichi TX-1000 centering method). I will also buy the T100 software do some (hopefully) interesting experiments next week.
 
On my Gyro the wow is <0.1% often 0.08 unweight wow with Shaknspin . The Denon is down to 0,05% at best

How do you senter with microscope?
Denon on phone app
IMG_0187 2.png
 
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