Anyone Want to Test This Beta Firmware

[NeoSound]

In my tests the coloration is always unpleasant as it boosts the mids and, more importantly, reduces the low-frequency resonance which lessens the "knock" and "thump". This is when using a solid-state power amp. When using a tube power amp the resonance gets magnified.

Redundancy!? Double tap idea?

If we use this method in the beta fw and shoot the perfect ir - then we are essentially doing the same thing again coloring the sound (to a lesser degree) when we use our amplification system, so my question is if we do the same or similar process again only for our amplification system (as long as its capable of full range reproduction) with a reference mic
shouldn't we have a corrective ir that can be placed at the end of the effects chain in all patches that will compensate as long we don't switch amplification systems? Seems to me even the best frfr could benefit?

 

[erockomania]

Redundancy!? Double tap idea?

If we use this method in the beta fw and shoot the perfect ir - then we are essentially doing the same thing again coloring the sound (to a lesser degree) when we use our amplification system, so my question is if we do the same or similar process again only for our amplification system (as long as its capable of full range reproduction) with a reference mic
shouldn't we have a corrective ir that can be placed at the end of the effects chain in all patches that will compensate as long we don't switch amplification systems? Seems to me even the best frfr could benefit?

Any amp will color. It's the nature of the beast. I don't understand why folks would want to circumvent that. Are we chasing reality here or "perfection". Many would argue the perfection is in the imperfections created by the amps and speakers. Embrace it.

 

[Boogieman]

Redundancy!? Double tap idea?

If we use this method in the beta fw and shoot the perfect ir - then we are essentially doing the same thing again coloring the sound (to a lesser degree) when we use our amplification system, so my question is if we do the same or similar process again only for our amplification system (as long as its capable of full range reproduction) with a reference mic
shouldn't we have a corrective ir that can be placed at the end of the effects chain in all patches that will compensate as long we don't switch amplification systems? Seems to me even the best frfr could benefit?

You might be conflating a couple of concepts. The technique Cliff is providing simply removes any amplifier artifacts from the final speaker/cab IR. What we want is a "faithful reproduction" of the speaker/cab combo without any other influences co-captured. Guitar speakers (and their cabs) have ugly responses: this approach simply captures the ugliness more accurately.

The fact that most amplifiers have their own non-ideal responses is not a problem in the playback through our better IR. In most cases, we love our modeled amp's odd response and interaction with the speaker impedance as it provides the unique character of the various amp types. What we should strive for is faithful reproduction of each component in the chain, amp, speaker/cab, microphone/preamp. The fact that each component has their own non-ideal idiosyncrasies is what makes all of this so cool when played in different combinations.

Remember, accuracy in capture for our purposes does not mean flat response ;-)

peace
boogie

 

[NeoSound]

Any amp will color. It's the nature of the beast. I don't understand why folks would want to circumvent that. Are we chasing reality here or "perfection". Many would argue the perfection is in the imperfections created by the amps and speakers. Embrace it.

But isn't the perfect reproduction of that imperfection exactly what modeling is about? hence the speculation on reproducing the amps without additional color

 

[erockomania]

But isn't the perfect reproduction of that imperfection exactly what modeling is about? hence the speculation on reproducing the amps without additional color

I understand. The problem is that every amp is different. My recto is different from every other one I've ever tried. My Uberschall did not sound like my buddies and sounds nothing like the Uberschall in the Axe. There are new revisions of each amp with tiny details changed, all speakers, even exactly the same model from the same year, are different to some extent, all mics are different, all tubes are different... etc... There is no perfect replication of any amp. There is only a perfect replication of one very specific amp at one very specific time. Adding a touch of low end, mid or top will not make it sound any more or less like the amp in question. In fact, it might just sound closer another production of the same amp. My point is, dial with your ears... you can make up for anything you hear that might be "different" or imperfect. The is no perfect and there is no "wrong" at this point of the game... there is only slightly different.

We are getting to a point where we are simply chasing our tails, in my estimation. 1703 is fantastic. I think the final frontier will be a dynamic cab IR that will display the same nonlinearities of real cabs in real rooms. I'm sure Cliff will figure that one out much like he figured out the dynamics of power amps. Then we are in for a real treat. The game will be changed forever.

 

[Rex]

Any amp will color. It's the nature of the beast. I don't understand why folks would want to circumvent that. Are we chasing reality here or "perfection".

We are chasing both. When you remove the influence of the amp you used to capture the IR, you free the Axe's amp models to exert their own influence. The result is truer to the real amp.

 

[barhrecords]

Any amp will color. It's the nature of the beast. I don't understand why folks would want to circumvent that. Are we chasing reality here or "perfection". Many would argue the perfection is in the imperfections created by the amps and speakers. Embrace it.

Accuracy in the impulse response itself + non-linear algorithms in the Fractal.

The sound is a combination of the convolution of the speaker impulse response plus the power amp and other algo's in the Fractal.

 

[nicolassal]

Holy Shit! Do you ever sleep, Cliff? Happy New Year and happy holidays! Awesome stuff!

 

[erockomania]

We are chasing both. When you remove the influence of the amp you used to capture the IR, you free the Axe's amp models to exert their own influence. The result is truer to the real amp.

What does that really mean when no two amps are exactly the same? I fully understand we want true or "real" but in the grand scheme of things it really only means it will be true to the particular amp Cliff used. Also, aren't you basically eliminating the trueness of the model as soon as you mod something? My point is that I'd imagine the same tones could be accomplished either way and many of the tones we get are NOT realized in the real counterpart anyway. I'll concede that the corrected "baseline" amp might be slightly truer to the particular amp used to model. To some that might matter. To me it doesn't as I pretty much don't leave any amp stock and most other deep features/mods will likely make that trueness irrelevant. Then again this feature could easily prove me wrong in the coming months

 

[Rex]

What does that really mean when no two amps are exactly the same? I fully understand we want true or "real" but in the grand scheme of things it really only means it will be true to the particular amp Cliff used.

It means it will be true to the amp model you selected from the 200 available, uncolored by somebody else's power amp that was originally used to capture the IR.

Also, aren't you basically eliminating the trueness of the model as soon as you mod something? My point is that I'd imagine the same tones could be accomplished either way and many of the tones we get are NOT realized in the real counterpart anyway.

True. But in this case, you're in complete control of your departure from accuracy. Your knobs aren't being bumped by a cab IR that behaves differently from the actual cab itself.

Maybe that doesn't matter to you. No harm, no foul. Just don't use the reference IRs. On the other hand, if you don't care about this level of cab accuracy, then your workflow will be entirely unaffected by this, because you'll still be tweaking the same stuff. You'll just wind up at different settings.

 

[JOHNNYROCKIT]

So Cliff,... Let me see if I got this straight...


All power amps produce their own particular unique set of frequency distortion characteristics of varying degree that are specific to that particular amp.


This reference amp used in making an IR embeds its' own unique frequency distortion characteristics into the IR...


The amp model types in the Fractal, each have their own unique set of frequency distortion characteristics. This distortion is part of what gives each type of amp its personality and voice,... which is most desirable.


When used with a particular modeled amp type in the Fractal, the captured IR with it’s embedded unique frequency distortion characteristics obtained from the ‘Reference’ power amp, consequently ‘adds’ them to the Fractals’ amp types naturally occurring frequency distortion. Right?


Conclusion; The 2 unique relative frequency distortions are now compounded.
(not in a desirable and pleasant way).


Due to this compounding, the possibilities toward varying degrees of frequency losses due to
phase cancelation are highly probable.

This compounded distortion, based on the above mentioned would most defiantly also produce a
variety of exaggerated or by contrast, under-exaggerated frequencies, uncharacteristic to that
particular Amp and speaker type.

The way I see it, this distortion issue would make dialing an amp in extra laborious and detract from
it's response, feel and realism.

I’m no expert..... Just my 2 cents

 

[mnemonic]

In my tests the coloration is always unpleasant as it boosts the mids and, more importantly, reduces the low-frequency resonance which lessens the "knock" and "thump". This is when using a solid-state power amp. When using a tube power amp the resonance gets magnified.

Kind of tangentially related to this thread, but this post inspired me to take another look at the Ownhammer IR's I've been using. I just started using the ones shot from an EL34 poweramp without giving the Solidstate poweramp IR's a second thought. I loaded up the Solidstate versions of the mix IR's I've been using and wow! Much bigger difference than I expected!

I was starting to think that the Ownhammer cabs were a bit scooped sounding, but it seems it was just in the poweramp coloration. The IR's shot with the Solidstate poweramp have noticeably more mids and less low resonance. I'm now blending the Solidstate and EL34 mixes, which seems to be the best of both worlds for me.


Learn something new every day!

 

[joegold]

So I haven't had time to try the new IR Capture Utility's feature and I don't even own a suitable direct box yet so I'm just trying to think this through in the meantime.

I'm assuming there won't be a gain staging issue here, based on the instructions in the Release Notes but...

The signal coming off the mic preamp that goes into Input 2 L will be line level, right?
And the signal that comes off of the direct box that goes into Input 2 R will be mic level, because that's the type of signal that most if not all of these types of direct boxes send out, right?
I.e. Input 2 R doesn't need to also see a line level signal, right?

Also...
When shooting my previous IRs I've always had to use a passive XLR to 1/4" adaptor because the Outs of my RME Babyface are line level XLR (unless I want to use the headphone outs, which I don't want to do, right?).
That's the right way to do it, right?
I.e. I don't need a transformer in line or anything fancier than the passive converter cable, right?
And I'll also need a similar passive XLR to 1/4" adapter cable to take the mic level XLR signal coming out of the direct box so I can plug it into the Axe's Input 2 R jack, right?

If I've munged any of that up I'm hoping someone will correct me.

 

[Rex]

...Let me see if I got this straight...

Sort of.

Every speaker cab has a non-flat impedance curve—in other words, the cab's impedance is different at different frequencies. This varying impedance is in addition to the cab's actual frequency response.

Every power amp is affected by the impedance of the cab its connected to; the power amp itself will have a different frequency response because it sees a different impedance at different frequencies. And that changes the way the cab sounds.

The purpose of an IR is to capture the frequency response of the cab, not the frequency response of the power amp. That's because the Axe's Amp block already simulates the way the power amp reacts to a cab's impedance curve (that's what the SPKR page in the Amp block is all about). In other words, the Axe already models the way a cab's sound changes when the power amp reacts to the cab's impedance curve.

So we want to get rid of the influence of the power amp that was used to capture the IR—let the Axe's virtual power amp work its magic instead. That's what this new IR capture method does.



The release notes only talk about distortion to point out the fact that you no longer need a clean signal chain to make a good IR. Using this new capture method, the Axe will pick through any distortion to get the information it needs to create an IR.

 

[FractalAudio]

So Cliff,... Let me see if I got this straight...


All power amps produce their own particular unique set of frequency distortion characteristics of varying degree that are specific to that particular amp.

This reference amp used in making an IR embeds its' own unique frequency distortion characteristics into the IR...

The amp model types in the Fractal, each have their own unique set of frequency distortion characteristics. This distortion is part of what gives each type of amp its personality and voice,... which is most desirable.

When used with a particular modeled amp type in the Fractal, the captured IR with it’s embedded unique frequency distortion characteristics obtained from the ‘Reference’ power amp, consequently ‘adds’ them to the Fractals’ amp types naturally occurring frequency distortion. Right?

Conclusion; The 2 unique relative frequency distortions are now compounded.
(not in a desirable and pleasant way).


Due to this compounding, the possibilities toward varying degrees of frequency losses due to
phase cancelation are highly probable.

This compounded distortion, based on the above mentioned would most defiantly also produce a
variety of exaggerated or by contrast, under-exaggerated frequencies, uncharacteristic to that
particular Amp and speaker type.

The way I see it, this distortion issue would make dialing an amp in extra laborious and detract from
it's response, feel and realism.

I’m no expert..... Just my 2 cents

Yes, you are understanding it better than most it seems. I wouldn't necessarily say the compounded distortions are undesirable, they are simply less accurate. There wouldn't be any phase cancellation issues though. The typical result we've observed with solid-state amps is that the IR has more midrange than it should. With tube amps the IR has less midrange than it should. I'm not quite sure why the solid-state amps have more midrange but I suspect it's something to do with the amplifier topology and feedback method. We've measured the output response of various amps and the solid-state amps have a loss of response at the low-frequency resonance and at the high frequencies. In some cases this loss has been as much as 3 dB which is substantial. Regardless, it doesn't matter whether there is more or less mids. The fact is that the amplifier response is not flat when connected to a reactive load when ideally it should be.

Let me try to explain it better:

1. The ideal cabinet IR is one that is a perfect representation of the voltage response of the speaker. IOW, if we could build a power amp with infinite damping factor, perfectly flat frequency response, zero distortion and connect it to the speaker with cables that had zero resistance the IR captured would be "pure" and uncolored by the power amp because the power amp is pure and uncolored.

2. No power amp is perfect. Some come close ($$$$$) but most have finite damping factors, imperfect frequency response and various amounts of distortion. This imperfection leads to inaccuracy in the IR, typically around the low frequency resonance and in the high frequencies. The amount of inaccuracy is dependent upon the power amp used. The goal is to eliminate the inaccuracy caused by the power amp.

3. This new technique removes the coloration of the power amp from the measurement thereby creating a "pure" IR. The technique obtains the actual frequency response at the output of the power amp (which should be flat but is not) and applies the inverse of that response to the captured IR. There's a little more to it than that as there is distortion removal and some other signal processing but that's the important part.

 

[FractalAudio]

Sort of.

Every speaker cab has a non-flat impedance curve—in other words, the cab's impedance is different at different frequencies. This varying impedance is in addition to the cab's actual frequency response.

Every power amp is affected by the impedance of the cab its connected to; the power amp itself will have a different frequency response because it sees a different impedance at different frequencies. And that changes the way the cab sounds.

The purpose of an IR is to capture the frequency response of the cab, not the frequency response of the power amp. That's because the Axe's Amp block already simulates the way the power amp reacts to a cab's impedance curve (that's what the SPKR page in the Amp block is all about). In other words, the Axe already models the way a cab's sound changes when the power amp reacts to the cab's impedance curve.

So we want to get rid of the influence of the power amp that was used to capture the IR—let the Axe's virtual power amp work its magic instead. That's what this new IR capture method does.



The release notes only talk about distortion to point out the fact that you no longer need a clean signal chain to make a good IR. Using this new capture method, the Axe will pick through any distortion to get the information it needs to create an IR.

You explained it better than I did.

 

[USMC_Trev]

So does this render the current batch of ultra-res cabs obsolete?

 

[Rex]

You explained it better than I did.

Nah...just from a different perspective.

 

[FractalAudio]

So does this render the current batch of ultra-res cabs obsolete?

No, why would it?

I'm beginning to regret this. It seemed pretty intuitive to me.

 

[Rex]

So does this render the current batch of ultra-res cabs obsolete?

Nope. The current batch of UltraRes cabs still sound just as good as they always did, and they still smoke just about everything that's out there. This new method (@Cliff: needs a name; maybe TrueCapture?) is an improvement, but it'll be a while before there's a bunch of them.