- Messages
- 6,503
So some background.
Mel-spectrogram:
In short:
So Here's what I did:
First I normalised the audio files in the DAW, to minimize digital level differences (not the same thing as balancing signals using your ears!)
Then I took a mel-spectrogram of each file. I then converted the data from power-spectrogram to dB.
For each modeller signal, I added it to an inverted version of the real amp signal; essentially a polarity inversion that you would do with audio in your DAW, but against the mel-scaled spectrogram>dB representation.
And these charts are what you get.
Effectively, for each frequency band.... the closer to zero you get, the more accurate the modeller signal is to the original signal. Where the colour is pink or red, those are the biggest differences compared to the original signal.
So from a high-level macro view, I observe two things:
- The Kemper has consistent differences in the low frequency range.
- During the palm-mutes in my riff, the Kemper suddenly snaps back into "very accurate" from 15,000hz down to about 7500hz.
- But on the open notes in the riff, this doesn't happen. There are quite a lot of differences on those notes.
- Also on the palm-mutes you do see interspersed red chunks throughout the frequency range. This also happens with the QC.
If we zoom in on the lower frequencies:
It may look like a load of noise. But I'm seeing some patterns in there that are quite interesting.
There are far fewer dark red chunks on the QC lane (3rd lane if it wasn't clear) than the other two. Below 1000hz. So let's zoom in there....
So look at frequencies 0 through to 500hz. The colour-banding here should tell you about the accuracy of the signals versus the real amp.
The Kemper has a much higher base level of pink and red in the 0hz to 500hz, across the file. This shows that in that frequency range, the Kemper is less accurate than the QC.
So now for IK ToneX. Unfortunately I made the Kemper VS QC clips in 2021, and don't have the DI anymore. So this is a completely different riff. But it has loads of palm mutes, strummed chords, and ghost notes and such.
Ignore the amp line at the top - actually no, don't. What that is showing is that the inverted amp and amp data completely cancel each other out (constant stream of zero's in every single band) which means my analysis is doing the right thing.
There *are* differences of course. But fewer instances of bright red and super dark blue.
This isn't exhaustive. Can't be taken as a truth because of the limited dataset, but IK ToneX seems to be more accurate than both the Kemper and QC, on the surface of things.
Mel-spectrogram:
In short:
IE: It is a spectral representation of an audio signal scaled against the mel-scale, which more closely represents how human hearing perceives frequencies.
So Here's what I did:
First I normalised the audio files in the DAW, to minimize digital level differences (not the same thing as balancing signals using your ears!)
Then I took a mel-spectrogram of each file. I then converted the data from power-spectrogram to dB.
For each modeller signal, I added it to an inverted version of the real amp signal; essentially a polarity inversion that you would do with audio in your DAW, but against the mel-scaled spectrogram>dB representation.
And these charts are what you get.
Effectively, for each frequency band.... the closer to zero you get, the more accurate the modeller signal is to the original signal. Where the colour is pink or red, those are the biggest differences compared to the original signal.
So from a high-level macro view, I observe two things:
- The Kemper has consistent differences in the low frequency range.
- During the palm-mutes in my riff, the Kemper suddenly snaps back into "very accurate" from 15,000hz down to about 7500hz.
- But on the open notes in the riff, this doesn't happen. There are quite a lot of differences on those notes.
- Also on the palm-mutes you do see interspersed red chunks throughout the frequency range. This also happens with the QC.
If we zoom in on the lower frequencies:
It may look like a load of noise. But I'm seeing some patterns in there that are quite interesting.
There are far fewer dark red chunks on the QC lane (3rd lane if it wasn't clear) than the other two. Below 1000hz. So let's zoom in there....
So look at frequencies 0 through to 500hz. The colour-banding here should tell you about the accuracy of the signals versus the real amp.
The Kemper has a much higher base level of pink and red in the 0hz to 500hz, across the file. This shows that in that frequency range, the Kemper is less accurate than the QC.
So now for IK ToneX. Unfortunately I made the Kemper VS QC clips in 2021, and don't have the DI anymore. So this is a completely different riff. But it has loads of palm mutes, strummed chords, and ghost notes and such.
Ignore the amp line at the top - actually no, don't. What that is showing is that the inverted amp and amp data completely cancel each other out (constant stream of zero's in every single band) which means my analysis is doing the right thing.
There *are* differences of course. But fewer instances of bright red and super dark blue.
This isn't exhaustive. Can't be taken as a truth because of the limited dataset, but IK ToneX seems to be more accurate than both the Kemper and QC, on the surface of things.
