Kemper Profiler MK 2

[Sascha Franck]

This test very literally tells you exactly which frequency areas had the largest differences.

Interesting (possibly over my head, though) and that's likely how things should be done in capturing comparisons - until the very moment when we have a capturing process that is truly nulling (in that case anything else is moot).
OTOH, as said, I don't think the general consensus of capture quality ranking is something to argue about much, so maybe it's not too relevant to improve the null testing.

 

[DLC86]

Well, corresponding to the human hearing still doesn't necessarily mean too much in terms of "relevant for guitar amplification".

Huh?

which means i can construct a null-test result with very audible garbage on the low end, and still have it measure better in LUFS than a NAM plugin.

That seems to be a non-sense. If it is "very audible" it can't measure better in LUFS.

 

[Sascha Franck]

Huh?

The human ear can ideally listen to frequencies that are well above (and also below) anything relevant to guitar amplification.

 

[Deadpan]

The thing with Kemper’s accuracy is that it doesn’t need null tests or any kind of visual representation to hear how far off it is, because you can hear it when listening without much trouble. Those kinds of things are more helpful when it’s impossible to distinguish and you still need to split hairs. Kemper just tends to have audible giveaways in comparisons, ToneX and NAM also have differences but they can be harder to notice.

Point is they are all imperfect. The difficulty in telling where the differences are does not determine if those differences matter to the player or even if the differences are less or More desirable.

 

[Deadpan]

From here:

The null test being perfect may insure that the capture is identical to the source and that there is NO sonic difference.

The null test being less than perfect DOES NOT mean that there IS a sonic difference from the capture to the source.... but it COULD mean that there is.

I still maintain that it doesn't matter. Good tone is good tone. I have heard profiles that I like better than the original amp (as an example).

Still, I wouldn't be surprised to see Kemper's new algorithm get much closer to a perfect null test. It seems that doing such a thing makes a certain part of the market very happy.

The null test being perfect only says the frequency content of both samples are exactly the same.

 

[Orvillain]

The null test being perfect only says the frequency content of both samples are exactly the same.

That is not true. Not in the way these guys are measuring it. In order to compare the frequency content, you have to convert to the frequency domain.

 

[DLC86]

The human ear can ideally listen to frequencies that are well above (and also below) anything relevant to guitar amplification.

Palm mutes can easily produce content down to 20 Hz and you just need an RTA to see that a distorted guitar easily reaches 20 kHz...
But even if that was true, in which way does that make a LUFS measurement useless?

 

[Sascha Franck]

The difficulty in telling where the differences are does not determine if those differences matter to the player or even if the differences are less or More desirable.

Well, but that's irrelevant.
See, I'm as firmly in the "what sounds good is good" camp and I don't give a toss about accuracy at all as soon as things work great.
But here we're talking accuracy - and it's totally irrelvant whether you or I don't need it.

All I'm doing is questioning the worth of the nulltests as we know them.

 

[Sascha Franck]

But even if that was true, in which way does that make a LUFS measurement useless?

I'm not saying it's useless. But it's not showing the entire picture. Or rather: It actually *is* showing the entire picture and that's why the focus of where accuracy is truly relevant might be missed.

 

[DLC86]

1+2 = 3
2+1 = 3
6 / 2 = 3
1+1 = 2

The first three are the same. The last one doesn't match.

When comparing a capture to the real source, without any variables changing you would hope for X or Y to be exactly the same. If they're not, then this shows difference. Difference results in a sonic different, at whatever scale you choose to analyse.

Now whether that is important to you or not is a completely different question, and is almost not even within the realms of the science of empiricism; it is more akin to feelings, emotion. We're not making any claims about that when we do null tests.

Null tests are simply a way of comparing two signals to see if they match, and if they don't, to reveal where they don't match. That's it.

Another way to say this is that when you do a null test and the bass region is off, it is you who determines whether that is worse or better. Not the null test. The null test simply shows you what is true.

Essentially there are two questions at play:

1. Are there differences?
2. Do they matter?

Null tests answer the first one.
They cannot answer the second one. Only a human can do that.

Additionally, I agree with Sascha. Analysing a null test based on your metering in the DAW is really roughshod, and isn't the appropriate way to do it. The appropriate way is to perform the null within the spectral domain, just as I did here:


This test very literally tells you exactly which frequency areas had the largest differences. To this day, no one has ever replicated my comparison, or even talked about it very much at all. Most I've had is a few guys just laugh at it. Very strange.

But to my mind, when it comes to replicating the sound of a real amp, the hierarchy is:

NAM
ToneX
QC
Kemper

I like your approach in that article and it is surely a valid way to look into the accuracy... but do we have a real benefit in finding out which frequency bands show the most difference if, as already said, the LUFS measurement already gives us values "normalized" to our own perception?

 

[DLC86]

I'm not saying it's useless. But it's not showing the entire picture. Or rather: It actually *is* showing the entire picture and that's why the focus of where accuracy is truly relevant might be missed.

But with this statement you're implying that there's something wrong with the weighting used by LUFS (which is not perfect nor universal but, afaik, the best thing we have currently)... Unless you're saying that accuracy is more relevant on things that are less relevant for our ears, in that case I wonder what those things are. Isn't the whole purpose of capturing/modeling to let us hear the same tone as X amp?

 

[Sascha Franck]

but do we have a real benefit in finding out which frequency bands show the most difference if, as already said, the LUFS measurement already gives us values "normalized" to our own perception?

I would happen to think so. The problem possibly being that different persons with different needs may rate different frequency bands as important. Yet, if you had a nulltest splitted into, say, 4-5 (rather broad) bands, it might tell you more than a single full frequency nulltest.
But again: All that is hypothetical, I have no idea whether the final outcome would be a different ranking (likely not).

 

[Humbug]

This test very literally tells you exactly which frequency areas had the largest differences. To this day, no one has ever replicated my comparison, or even talked about it very much at all. Most I've had is a few guys just laugh at it. Very strange.

This is interesting and, of course, miles over my head. I considered laughing, but instead I'd like to ask if there's a "...for idiots" guide available somewhere?

 

[Sascha Franck]

Unless you're saying that accuracy is more relevant on things that are less relevant for our ears,

No, not for our ears. But for guitar applications. I mean, pretty much all electric guitar sounds are capped well below 10kHz already (not brickwall capped but still a whole lot), so any inaccuracies happening above, say, 5kHz might be less relevant than inaccuracies happening at 1kHz.

 

[Lysander]

That seems to be a non-sense. If it is "very audible" it can't measure better in LUFS.

It is not. The standard K-weighted curve rolls off steeply below 100Hz, all the way down to -30dBa. That's a lot of volume in a very audible range, which which LUFS won't properly reflect in the context of a null test.

And this is not academic, either. One thing that Leo does really well is playing his null test results clips for different devices; I recall at least one measuring better in LUFS than a competitor, and having an absolute shit sounding spectrum in test.

 

[Orvillain]

I like your approach in that article and it is surely a valid way to look into the accuracy... but do we have a real benefit in finding out which frequency bands show the most difference if, as already said, the LUFS measurement already gives us values "normalized" to our own perception?

LUFS gives you a normalized value as you say. But it doesn't give you specifics.

It's like the difference between using a flawthrower to solder a capacitor into a pedal, versus using a soldering iron.... that's your dBFS versus LUFS.

Converting to the frequency domain is like having a magnifying glass to assist your soldering iron.

LUFS == perceptual loudness
Spectral analysis == adding a billion eyes to your face, each one with x-ray vision, so you can be the biggest, baddest, hard as fuck Dark Souls end of level boss.

 

[Orvillain]

No, not for our ears. But for guitar applications. I mean, pretty much all electric guitar sounds are capped well below 10kHz already (not brickwall capped but still a whole lot)

Only once you add a cab, and even then, there can still be valid energy above 10kHz.

 

[JiveTurkey]

Saddites is favoring a test that favors the person paying him to make videos? So surprising!

 

[Sascha Franck]

Only once you add a cab, and even then, there can still be valid energy above 10kHz.

I'm not saying it's invalid. All I'm saying is that it's likely somewhat less important than some crucial midrange for most people. Which is why I think a frequency splitting nulltest would tell more.

 

[DLC86]

No, not for our ears. But for guitar applications. I mean, pretty much all electric guitar sounds are capped well below 10kHz already (not brickwall capped but still a whole lot), so any inaccuracies happening above, say, 5kHz might be less relevant than inaccuracies happening at 1kHz.

If you're comparing two samples that are both capped any difference there can't be shown as a huge difference cuz the starting level is already low.
If they are completely different and the level at those frequency is -50 dBFS, the LUFS measurement for those frequencies can't be higher than -50 LUFS (it will be lower actually)

It is not. The standard K-weighted curve rolls off steeply below 100Hz, all the way down to -30dBa. That's a lot of volume in a very audible range, which which LUFS won't properly reflect in the context of a null test.

You mean like human hearing?