"Behind" note buzz.HELP!!!

Ok, that being the case...

In the OP's clip, you can hear the sound over single notes. Even in Cliff's example, the start of the strum is only one note and you can hear it. So what are the one note sections modulating against that make this IM distortion?


A guitar string does not produce a sine wave but a bunch of frequencies (harmonics) and therefore never only one single note.
 
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...with every single firmware release (15? 20 of them?), apparently something has been corrected or made more authentic...more exact. So apparently something wasn't responding exactly like a tube amp. A conundrum as to how both things can be true but apparently contradictory.
Both things are true: the Modelling is very accurate, but there is always room for improvement. The IM aspect of the modeling is very accurate.
 
A guitar string does not produce a sine wave but a bunch of frequencies (harmonics) and therefore never only one single note.

That makes sense. So if we were to hook up a signal source with a pure sine wave instead, we shouldn't hear this kind of IM distortion?
 
Both things are true: the Modelling is very accurate, but there is always room for improvement. The IM aspect of the modeling is very accurate.

At the risk of poking the bear, that doesn't seem to be what Cliff is saying when he says it responds just like the real amp. ;-) I agree with you that there is room for improvement, and that (I think) is what is being suggested here.
 
A guitar string does not produce a sine wave but a bunch of frequencies (harmonics) and therefore never only one single note.
This. For example, string vibrating at a fundamental frequency of 1000 Hz produces harmonics at 2000 Hz and 8000 Hz. Those two frequencies intermodulate to produce a tone at 6000 Hz, which is not a harmonic of the fundamental frequency.

Correction: it is a harmonic, but not an octave harmonic. And still intermod.
 
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No need to get defensive. I like and use the AFX. But I have heard this exact claim ("responds just like a real amp") made with every single firmware release since I bought the unit several years ago. And yet with every single firmware release (15? 20 of them?), apparently something has been corrected or made more authentic...more exact. So apparently something wasn't responding exactly like a tube amp. A conundrum as to how both things can be true but apparently contradictory.

Maybe I'm reading too much into other peoples' motivations, but at least for me when I have tried to bring this up, it has been with the motivation to help out...either to improve the modeling because I don't hear this in my amp, or to improve awareness of what to do about it if a person found it objectionable.

The onus is on you to prove your amp doesn't do it. I posted clips proving that the amp the OP was using behaves exactly like the model and yet that wasn't enough for you. Put your amp in isolation, mic it up and put your money where your mouth is.
 
The onus is on you to prove your amp doesn't do it. I posted clips proving that the amp the OP was using behaves exactly like the model and yet that wasn't enough for you. Put your amp in isolation, mic it up and put your money where your mouth is.

I'm not headed back to the studio for a bit, but I agree that's fair. I'll see what I can do. I am prepared to eat crow!

That said, I'm also not saying that it isn't authentic for any amp, just perhaps not all. And that even if it is authentic, it might be the kind of thing that some users would like to avoid...analogous to 60Hz hum from transformers, or microphonic tubes, etc., or that they would just like more direct control over it. And you've been extremely helpful in the past with that kind of suggestion.

For your clip, what guitar, amp, cab and mic were you using, and can you give a rough mic placement? If I can, I'll try to duplicate that in the studio as well.
 
I'm not headed back to the studio for a bit, but I agree that's fair. I'll see what I can do. I am prepared to eat crow!

That said, I'm also not saying that it isn't authentic for any amp, just perhaps not all. And that even if it is authentic, it might be the kind of thing that some users would like to avoid...analogous to 60Hz hum from transformers, or microphonic tubes, etc., or that they would just like more direct control over it. And you've been extremely helpful in the past with that kind of suggestion.

For your clip, what guitar, amp, cab and mic were you using, and can you give a rough mic placement? If I can, I'll try to duplicate that in the studio as well.

The OP said he was using the Blues Jr model so I used a Blues Jr. I used a 57 on the cap edge off axis. It's interesting to note that only one person so far has ventured a guess as to which was the amp and which was the model.

The "buziness" of IM is a function of the clipping hardness. As I stated before you need to determine whether you are getting power amp or preamp distortion. In general preamp distortion is softer but not always. It depends on the circuitry. You can reduce the clipping hardness with the Preamp Hardness and Power Amp Hardness parameters. This ONLY changes the shape of the virtual tube though. The final clipping behavior is also dependent on the surrounding circuitry which the user has no control over. For example a JCM800 preamp actually clips pretty hard because there is no bypass cap on the last triode's cathode. Therefore there is a lot of local negative feedback on that stage which makes the resulting transfer function "harder". In contrast a 1959SL Plexi has a bypass cap which softens the transfer function.

Power amp clipping behavior is dependent upon the amount of global negative feedback. The less feedback the softer the distortion. That's why "Class A" amps have softer clipping as they have no negative feedback. Fenders, otoh, typically have 3-6 dB of gain reduction which makes the power amp clip harder. Therefore you can reduce negative feedback to soften the clipping behavior if your distortion is coming from power amp overdrive.
 
..... I have heard this exact claim ("responds just like a real amp") made with every single firmware release since I bought the unit several years ago. And yet with every single firmware release (15? 20 of them?), apparently something has been corrected or made more authentic...more exact
I get what you're saying ..... but to add a little perspective ..... I wish someone from Marshall/Mesa etc had come along and offered free regular upgrades/improvements to my amps back in the day ....

Every authentically modelled amp block in the AxeFX with all those component parameters exposed can also be easily tweaked to be something way beyond the original's capabilities without your arse ever leaving your seat or your wallet being raped.

Outstanding bit of kit really.
 
First of all, Cliff thanks for the explanation above. As you mentioned earlier, understanding more about the real amps and how they behave helps. I know squat about the Blues Jr.!

I get what you're saying ..... but to add a little perspective ..... I wish someone from Marshall/Mesa etc had come along and offered free regular upgrades/improvements to my amps back in the day ....

Every authentically modelled amp block in the AxeFX with all those component parameters exposed can also be easily tweaked to be something way beyond the original's capabilities without your arse ever leaving your seat or your wallet being raped.

Outstanding bit of kit really.

Maxdown, and everyone else for that matter, please don't mistake my questions, critiques, objections, bug reports, and so forth as anything that they're not: I agree with you wholeheartedly that this is a fantastic piece of kit, and I regularly say so and thank the makers for each new firmware. I also think that some input/critique that has come along in the past has called attention to things that were corrected in the firmware, or were able to be worked around by using the right tweaks. That's all I'm after here, and pretty sure that's all the other people in this thread who aren't saying "that sounds perfect" are trying to accomplish, too.
 
The "buzziness" of IM is a function of the "hardness" of the clipping circuit. The first thing you need to do is determine what is distorting: preamp or power amp. Power amp distortion is typically harder than preamp distortion due to global negative feedback. If you are using a modern amp model, i.e. something with a Master Volume, then there is a very good chance you might be overdriving the virtual power amp. In this case simply lowering the Master Volume will reduce IM.

If it's preamp distortion then you can reduce Preamp Hardness or experiment with the Preamp Bias to change the distortion character.

The Axe-Fx II is extremely accurate. Understanding how real amps work will allow you to adjust things to achieve your ultimate tone.

To the OP: what amp model are you using? I will post a clip of the actual amp vs. the model and prove that the real amp does the same thing.


I just have to say that THIS is why I love the Fractal Products.... What other company's owner/developer respond like this? Hell, they probably wouldn't respond at all! He not only responds, but provides solutions and examples. Thanks for making this one of the best purchases I have ever made.
 
I just have to say that THIS is why I love the Fractal Products.... What other company's owner/developer respond like this? Hell, they probably wouldn't respond at all! He not only responds, but provides solutions and examples. Thanks for making this one of the best purchases I have ever made.

It is hands down one of the most impressive aspects about this whole Axe-Fx community. It makes it easier to be spending large amounts of money on all these awesome products knowing that it is supporting a company that truly seems to care about the customers.
 
Well..... Cliff actually has the fact he's right and can prove it on his side..

If one where to speak ill of say, a L6 POD, saying it doesn't exactly match a real amp, what would the owner of the brand (Peavey these days ???) even be able to claim ? They couldn't do an exact side by side audio clip showing the statement is false....basically they just have to say "yeah its not, what you going do about it" and go back to counting their money.
 
The OP said he was using the Blues Jr model so I used a Blues Jr. I used a 57 on the cap edge off axis. It's interesting to note that only one person so far has ventured a guess as to which was the amp
1. Axe 2. Real Amp.
 
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