Anyone try using UA Ox Stomp for their cabs?

marsonic said:
I meant basically the whole kemper.

Adding accurate nonlinearities to what IRs do is very close to profiling.
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Not really.

The Kemper's nonlinearities are far from accurate.

The Kemper uses a generic waveshaper with a compressor on the output and an expander on the input. The expander is simply the inverse of the compressor. The side-chain of the compressor is a bandpass of sorts so it compresses and distorts midrange signals more.

It then finds the output frequency response by driving the DUT at a high level. IOW it's trying to find the post-EQ in a Wiener-Hammerstein model. It then subtracts a "generic" speaker response from this to obtain the "cabinet". It then lowers the drive level until the DUT is in it's linear region. From there the input EQ and gain can be found.

It does attempt to determine the bias point for the waveshaper and the bias excursion but the waveshaper is very basic and it doesn't even appear that it even attempts to change the shape of the waveshaper. Every profile I've ever examined has the "Tube Shape" set to the same value. I believe the waveshaper is just a simple (x-k1)/(x+k2) function.
 
FractalAudio said:
Not really.

The Kemper's nonlinearities are far from accurate.

The Kemper uses a generic waveshaper with a compressor on the output and an expander on the input. The expander is simply the inverse of the compressor. The side-chain of the compressor is a bandpass of sorts so it compresses and distorts midrange signals more.

It then finds the output frequency response by driving the DUT at a high level. IOW it's trying to find the post-EQ in a Wiener-Hammerstein model. It then subtracts a "generic" speaker response from this to obtain the "cabinet". It then lowers the drive level until the DUT is in it's linear region. From there the input EQ and gain can be found.

It does attempt to determine the bias point for the waveshaper and the bias excursion but the waveshaper is very basic and it doesn't even appear that it even attempts to change the shape of the waveshaper. Every profile I've ever examined has the "Tube Shape" set to the same value. I believe the waveshaper is just a simple (x-k1)/(x+k2) function.
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Wow...that's really interesting.

Okay, I'll rephrase: if they could accurately model nonlinearities from measurements similar to the way you take linear measurements of FR for an IR, they could use the same black box to profile an amp. But, apparently I was significantly wrong about what the Kemper itself is doing.

(...which makes sense, because I've only played one once, didn't like it or the idea of profiling in general, and haven't looked into it because I don't care...)

Do you know if the other profilers work similarly? (Again, I don't care about profiling, just curious)
 
marsonic said:
Wow...that's really interesting.

Okay, I'll rephrase: if they could accurately model nonlinearities from measurements similar to the way you take linear measurements of FR for an IR, they could use the same black box to profile an amp. But, apparently I was significantly wrong about what the Kemper itself is doing.

(...which makes sense, because I've only played one once, didn't like it or the idea of profiling in general, and haven't looked into it because I don't care...)

Do you know if the other profilers work similarly? (Again, I don't care about profiling, just curious)
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I don't know much about any of the other profiling products.

If you want "nonlinear IRs" you need to use something like Volterra kernels. I've experimented with this and, in fact, the Speaker Drive and Speaker Thump parameters essentially create higher order Volterra kernels based on various amp parameters.

The harsh reality is that speakers are pretty darn linear. Things like cone cry are design/manufacturing defects and shouldn't be modeled IMO. There is some low frequency distortion and we model that but a classic, linear IR is the gold standard for replicating the sound of a speaker. Armchair pundits like to pontificate about "IRs are the weak link, blah, blah" but they're typical internet loudmouths who have little to no expertise and would fail a double-blind test every time.

Now, thermal compression is definitely a factor and we model that quite extensively. As you play the voice coil heats up and its resistance increases. The radiation resistance does NOT change, however, so the resulting acoustic output decreases. There's a lot more involved when simulating a tube amp though and I can't disclose that stuff because it's proprietary.

Another factor is the actual speaker impedance. It's a function of displacement. Again, we model this extensively. As the speaker moves in/out of the magnet the Bl product changes and therefore the inductance and various other electrical parameters change.
 
All very interesting. I couldn't come close to replicating the work, but I get most of what you're saying.

Honestly, I just hope that you don't go down the route of shoving an AI someplace it doesn't belong. I'm quite happy where fractal is at.
 
FractalAudio said:
These things are obviously subjective.

Using objective tests I've found nothing inherently superior. The aliasing performance is quite poor and the frequency response is inaccurate.

I dug through my computer and found this aliasing test:View attachment 127937

The blue is the Axe-Fx III, the green is the Dream. The spikes in the Axe-Fx are power supply ripple (since we model an AC power supply). Note the peaks are at 120, 180, etc. Multiples of 60 Hz.
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They only oversample to 192 and then filter. That’s been their style for years. Unfortunately it brings in aliasing
 
Rogerthat said:
They only oversample to 192 and then filter. That’s been their style for years. Unfortunately it brings in aliasing
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Wait, really? Yeah...that's not enough.

So....to put that in context, the 32x oversampling thing I posted would have been oversampled to 1411.2 kHz (original audio was 44.1kHz).
 
The IRs in the OX seem to have the same length as the dynacabs in the Axe III. The room IR is super short too but still sounds great mixed in.
 
On the one hand, I envy you’all being able to discern these nuances with your ears. On the other hand, I can’t figure out what it is you’re chasing. Fractal gear plays, feels, and sounds every bit as good as my original vintage amps and speakers. That’s my comparison, and this is at stage and venue volumes.
 
Rogerthat said:
https://www.soundonsound.com/sound-...ct-processing-bandwith-their-uad-plug-ins?amp

A lot of their algos are the same as their plugs. I think their amps sound good but I never use a lot of overdrive.
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They're actually talking about more than one thing there. Idk if UA didn't answer the question or if the writer didn't explain it.

Oversampling the distortion is what prevents aliasing. 192 doesn't actually buy you that much frequency headroom over 20kHz (about 2 octaves). If you're using something that causes strong 4th harmonics or higher, you still get aliasing at 192.

Band limiting is still the correct decision, but that's also about IMDs caused by ultrasonics, which you don't want to become audible. Everything is brand limited, and yes, most of it well below 96kHz (nyquist for 192kHz sampling).

The thing about low frequencies being harder to process at high sample rates seems like it's kinda specific to their sharc DSPs. Other DSP chips and computers can deal with the compromise well, though at some point, it also takes so long that you have to turn up you lr asio or coraudio buffer.

It's probably a personal thing, but oversampling something that distorts to 192 is too low for me personally.
 
The cabs from UA sound no better than anything else IMO. Having said that, their room parameters seem to elevate the sound over what I can achieve with anything else. I would love this kind of stuff in the Axe, especially the ability to EQ the room sound.
 
Here is my 2c from the persective of a pretty average Fractal user demographic, I suspect (ie: mainly a bedroom/home studio player)....

Firstly, for context, I have owned AxeFx itterations for a long time and absolutely love them. They output to Atomic CLRs and sound great. I then wondered what all the noise was about "real" amps being "better" than modellers, so I was fortunate enough to be able buy a Two Rock CRS (and shortly complemented it with a Marshall SV20).

The Two Rock and Marshall are also wonderful and, as has been debated endlessly with no need to conflate here, a tube amp into a cab does feel different than a modeller into a FRFR. I acknowledge and appreciate the reasons why.

I have improved as a player, in terms of technique, by the inspiration afforded by both the AxeFX and the traditional amps in their different ways.

But.....

Purely as a result of my own inability to effectively use the plethora of paramaters provided in my AxeFX by the genius of Cliff, I had noticed that I reached mostly to the real amps more and more. This because I just couldn't seem to find "the right cab" in the Axe, or tweak the controls to voice any IR - including dynacabs - to something I liked more. I stress this wasn't an apples and oranges unfair comparison between a "miked FRFR" sound and an "cab in the room sound", because I know they will always be different in that respect to a certain degree. Again, like most people in my user demographic, I play my amps attenuated and not pushing much air......but still I began to prefer the sound of them over the sound that I could achieve myself from my AxeFX.

This, I have no doubt, is a failing on my part to be able to leverage the paramaters, and not because the Axe can't achieve it.

I confess frustration at the feeling I was wasting all these potential fantasic modelled amps because of what I felt was the missing piece of the sound (due to my own inability to dial it in) lying somewhere in the cab block.

Enter the UA Ox Stomp!

My gosh, I haven't turned my AxeFx off all week!!

It has literally transformed what I already knew was a masterpiece product into something that an AVERAGE USER LIKE ME could get to sound like the masterpiece product I knew it always was!

And there, I believe, is the point : the combination of the two technologies, irrespective of their independent approaches, simply sounds great and that great sound is very easy and intuitive to achieve by someone like me!

@FractalAudio, if I had to give reasons, I could probably settle on just one major player :
  • Room mics - primarily one simple mix knob on the UA unit being easy and a powerfully transformative blend control to the post-amp sound.
....if I turn this dial to zero, I'm back to feeling "something is missing - I don't like it". I've had so much fun this week trying every type of amp in the Axe with suitable cab pairings in the Ox Stomp. Within minimal time, in every case, I had a smile on my face at the new sounds coming out of my Atomic CLRs as I blended in the room mike parameter!

Conclusion :

I'm selling the real amps.

For me, the UA £380 pedal has transformed my ability to use Cliffs masterpiece and extract out the goodness that lurks inside it.
 
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Jon Fenton said:
Room mikes - primarily one simple mix knob on the UA unit being easy and a powerfully transformative blend control to the post-amp sound.
....if I turn this dial to zero, I'm back to feeling "something is missing - I don't like it"
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Would you be willing to share some clips recorded into your DAW (i.e. not a phone mic recording)? I'd be curious to hear the same dry clip (using the looper) run 1) through the room mics in the UA and 2) using a short room reverb after the UA with the room mics off.

I always have at least a small amount of reverb going (except when tracking a dry part), which may explain why I've never felt anything is missing from my Fractal tones compared to my analog days.
 
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Jon Fenton said:
Room mikes - primarily one simple mix knob on the UA unit being easy and a powerfully transformative blend control to the post-amp sound.
....if I turn this dial to zero, I'm back to feeling "something is missing - I don't like it". I've had so much fun this week trying every type of amp in the Axe with suitable cab pairings in the Ox Stomp. Within minimal time, in every case, I had a smile on my face at the new sounds coming out of my Atomic CLRs as I blended in the room mike parameter!
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Did you try messing with the room parameters in the cab block? Also, FullRes IRs?
 
Saarang Narayan said:
Did you try messing with the room parameters in the cab block? Also, FullRes IRs?
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I think, with respect, the point that I was trying to make is being missed. I tried IRs in the cab block, along with different adjustments there. Most likely it was my inabilty to succeed, but I subsequently found a more pleasing and easier result with my real amps - the frustration then becoming that I had lost out in 300 others in the AxeFX!

Now, for me, at least, the Ox stomp has reversed that situation, mainly on account of a single parameter ("room mic") being blendable with one single control (notwithstanding you can obviously also change the mikes and repective EQs themselves etc).

It is definately different sounding to the AxeFX room parameter etc, at least as far as I was able to achieve with that section of the Axe cab block.

There obviously are other features of the UA unit which also give a contribution, but the room mic section was overwhelmingly powerful in influence to the overall sound - all from turning a single knob.

It is on this basis that I say it can appeal, not any basis of a deficiency in the AxeFx. If folks find that they have no issues with getting the sound they like out of the AxeFx on its own - great!

I was just highlighting how I have found the combination of the two products from an average (in more ways than one!) user point of view, rather than an under the hood tech spec analysis.
 
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Jon Fenton said:
I think, with respect, the point that I was trying to make is being missed. I tried IRs in the cab block, along with different adjustments there. Most likely it was my inabilty to succeed, but I subsequently found a more pleasing and easier result with my real amps - the frustration then becoming that I had lost out in 300 others in the AxeFX!

Now, for me, at least, the Ox stomp has reversed that situation, mainly on account of a single parameter ("room mic") being blendable with one single control (notwithstanding you can obviously also change the mikes and repective EQs themselves etc).

It is definately different sounding to the AxeFX room parameter etc, at least as far as I was able to achieve with that section of the Axe cab block.

There obviously are other features of the UA unit which also give a contribution, but the room mic section was overwhelmingly powerful in influence to the overall sound - all from turning a single knob.

It is on this basis that I say it can appeal, not any basis of a deficiency in the AxeFx. If folks find that they have no issues with getting the sound they like out of the AxeFx on its own - great!

I was just highlighting how I have found the combination of the two products from an average (in more ways than one!) user point of view, rather than an under the hood tech spec analysis.
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I understand what you're saying. And I'm glad you found something that works for you. That's the important part. I don't think very many pieces of gear are inherently special: there's technically better and technically worse, and there's more inspiring and less inspiring....and you being happy with it is the most important factor of all.

But...if you want to, search the factory cabs for the word "room". There isn't a room mic capture for everything, but there are for some. It was a big deal for me. It's the closest thing to reverb that I don't hate (not to dismiss Cliff's reverbs...I hate all reverb effects including Fender and aftermarket real springs, legit 4' tall physical plates, Lexicon, Bricasti, FabFilter, Valhalla, etc.), and it is a key to the puzzle as far as I'm concerned.
 
marsonic said:
I understand what you're saying. And I'm glad you found something that works for you. That's the important part. I don't think very many pieces of gear are inherently special: there's technically better and technically worse, and there's more inspiring and less inspiring....and you being happy with it is the most important factor of all.

But...if you want to, search the factory cabs for the word "room". There isn't a room mic capture for everything, but there are for some. It was a big deal for me. It's the closest thing to reverb that I don't hate (not to dismiss Cliff's reverbs...I hate all reverb effects including Fender and aftermarket real springs, legit 4' tall physical plates, Lexicon, Bricasti, FabFilter, Valhalla, etc.), and it is a key to the puzzle as far as I'm concerned.
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You hate reverb? I can’t imagine what that is like, I absolutely love it in all forms. I probably love it too much tbh, I over-do it a lot of the time 😬.
 
kplooksafterme said:
You hate reverb? I can’t imagine what that is like, I absolutely love it in all forms. I probably love it too much tbh, I over-do it a lot of the time 😬.
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Yeah, pretty much. I mean....it's necessary for some guitar sounds (surf rock, miserlou, etc.). But, as a general rule, I prefer delay to create space in a song. There's always something that sounds like flutter echo to me in basically every reverb that I can't stand. As soon as it's loud enough for me to hear it, I want it off. A really good room sound, when the room doesn't exhibit flutter echo, is the exception. But, I haven't found a plugin or effect that does it. I'm sure there are IRs out there for convolution reverbs that work, but it isn't worth searching for to me.

It's kinda funny, I thought I found a spring reverb sound in the fractal that I actually liked a few weeks ago....there are parts of the sound that I like...but, when I set it up to "test" it blind, once I was playing with anything else (backing track, etc.), I couldn't tell whether it was on or not.
 
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