Rex
Dignified but Approachable
That's the test signal. If you got rid of it, you'd have no test.@FractalAudio I see! Can you explain what is the 10kHz peak exactly though? Is it technically possible to get rid of it?
That's the test signal. If you got rid of it, you'd have no test.@FractalAudio I see! Can you explain what is the 10kHz peak exactly though? Is it technically possible to get rid of it?
No. Aliasing is dependent on the gain. That test had obviously had less gain. I would've matched the gain to "Brand K" as on that particular device the controls do not mimic the real thing so changing the controls would introduce inaccuracy.
Maybe I'm not understanding your question, but how would someone test aliasing, which is a digital artifact, in an analog amp?Can you actually post details of how you went about this test so folk can try it for themselves? I ask because I know a few people have tried this with the Helix against the actual amp being modelled, and none of them get the results you have here. In fact, in every case the modeller follows the noise curve of the original amp within +/- 1.5dB all along the spectrum with a couple of exceptions.
Kind of sounds like you're insinuating Cliff is not telling the truth...In keeping with the old adage...if it's repeatable, it's science. If it's not, it's pseudo-science...or marketing material.
That's been the gist of every post he's ever made.Kind of sounds like you're insinuating Cliff is not telling the truth...
No, he's saying gain levels are different between the 2012 and 2018 tests. Perhaps consider your reading comprehension before you suggest someone of expertise is posting meaningless stuff.Hang on a minute...so you're saying that the gain was different on the units (but the aliasing depends on the gain), so the results are meaningless? The signal paths also appear to be different, hence the ground loop on the Axe tests...
Could you share the data you have? Would enjoy looking at it.Can you actually post details of how you went about this test so folk can try it for themselves? I ask because I know a few people have tried this with the Helix against the actual amp being modelled, and none of them get the results you have here. In fact, in every case the modeller follows the noise curve of the original amp within +/- 1.5dB all along the spectrum with a couple of exceptions.
Can you actually post details of how you went about this test so folk can try it for themselves? I ask because I know a few people have tried this with the Helix against the actual amp being modelled, and none of them get the results you have here. In fact, in every case the modeller follows the noise curve of the original amp within +/- 1.5dB all along the spectrum with a couple of exceptions.
Maybe I'm not understanding your question, but how would someone test aliasing, which is a digital artifact, in an analog amp?
Kind of sounds like you're insinuating Cliff is not telling the truth...
No, he's saying gain levels are different between the 2012 and 2018 tests. Perhaps consider your reading comprehension before you suggest someone of expertise is posting meaningless stuff.
Could you share the data you have? Would enjoy looking at it.
Just googled "noise curve", no reference outside of environmental studies. What are you referring to with this term?
As has been pointed out above, the alias issue refers specifically to the effect of a DIGITAL amp model and what is input into it creating aliasing noise based on the CPU capacity, converter filtering and sample rate. The comparison as I understand it has nothing to do with comparisons between the actual amp modeled by different brands, but merely used the same amp model and its gain structure and similar settings between brands as a reference, and to then input the same signal to see how much aliasing results in different modelers.
Did I miss something? Is there something else missing from the comparison test? If you send the same input into 2 different JCM 800 modeler brands with controls set basically the same and get different amounts of aliasing noise, how is this unscientific given two modelers will never be exactly the same in their implementation of both the model itself and the digital architecture?
Read the thread. The 20k Peak has been explained.
It does measure aliasing, just not in isolation. And that can still be useful for evaluating aliasing in a comparison provided other factors aren't as significant variables. In particular, the major difference between the Axe-Fx II vs III graphs does seem to me due to aliasing, and I don't have to know the isolated aliasing portion of each graph to make that observation. My assumption is that base-noise level of II and III are similar enough.No, I'm saying that the tests in the OP don't measure aliasing, unless something has been done to completely isolate the effect of aliasing (which it plainly hasn't) from any other effects. TrueRTA is a spectrum analyser, not an aliasing analyser.
Please message me the linkI will as soon as I can, yes. Still waiting for a full useful write up, and this forum won't let me post links at the mo anyway.
Is this also displayed in the Helix measurement data you have? Link please~Oddly, the more accurate the modeller, the more noise you'd see - if every component in an amp is modelled perfectly, then the overall model will display just as much noise outside the original signal as the original amp did, and that wouldn't be aliasing.
What drop after 10 kHz? 10 kHz is the test signal, it's meant to drop afterwards for this test.Yes, but it doesn't actually answer my question : if it is (desirable 2nd-order distortion or not) related to that drop of signal that doesn't happen with real amps. High gain amps don't drop like that after 10kHz. I don't know if the III drops, but the I and II do.
How do you know the ~9 kHz undesirable stuff you hear is due to aliasing? You'd have to know this for sure to demand a sweep performed outside of 9 kHz range.Also, I didn't see any explanation as to why, if there was an undesirable aliasing peak at 9.3kHz, this chart would show it instead of it being hidden by the input signal. Is my wish to see a same chart with a sweep performed outside of the 9kHz range worthy of a funny facepalm picture as well? Cliff.
I've always heard so far in FAS products, like in any modelers, an undesirable fizz in the 9 kHz range, it was around 9.7 kHz in the Ultra, now 9.3kHz in the ax8. It's getting quieter and quieter though. Not talking about IRs, the amp alone (or drive block, or anything that distorts enough).