Thank you for the nice pictures Cor.
I hope I can show the effects of VAG setting with a few Audacity screenshots.
It will show it is hard to know when the system gets saturated because the signals differ quite a lot with different VAG settings. That is one of the reasons to make a bunch of recordings with different gain settings.
I will show you pictures with two recording on 384Khz samplerate one with VAG set to 1F and ons set to 08 the signal was injected directly into the audioboard using a 100nF capacitor and good shielded cable. The signals injected are 25, 35, 45, 55 and 65 Khz
This first picture shows the wave forms, you can easily see a lot of difference in the signals the lower, set to 08 is much stronger.
next is a picture showing the spectrogram.
You will notice a difference in signal strength, harmonics but to the right you see a huge difference where there is no signal.
The next pictures shoe the spectrum of a portion of the 45Khz signal.
You will notice the 1F recording as lower signal in the 1st harmonic (fundamental frequency) but also the 2nd and 3rd harmonics are stronger.
The picture below is the recording on 08
Where te 1F had a signal of about -11.4 this recording has a fundamental frequency at about -5.3dB
The last pictures show a contrast measurement using a portion of 45Khz signal in contrast to the silent part.
1F
08
The struggle now is to find the best settings per samplerate, fnrunately Cor has a very nice way to do good analysis but.... Best signal to noise ration does not always mean we have the best signal to harmonics contrast so what choice do we want to make.
I do not like the harmonics in my recordings but unfortunetely there just are harmonics to deal with. Even is you cant really see the in the waveform Audacity will show them.
I had my best looking recordings sofar on just 176.400 but one can see the best setting for the lowest harmonics is near 1F (1D maybe or even just 1F or should we pick 1E to be in the middle.)
Anyway lots of data to interpret and lots of choices to make. Whatever values are chosen it will probably never be completely perfect but hey what fun is this audiochip and how much fun is this nice little detector.
Every time I use it, I am amazed by the sounds it picks up.
Kind regards,
Edwin