I saw a YT video the other day talking about the UA amp in a box pedals. The guy basically said that cab sims in all of the modelers have a basic problem that the UA pedals don’t have - that being that the cabs will not break up no matter how hard you hit them with the amp. Thus, infinite headroom. His claim was that the UA cabs react like a real world cab where they break up the harder you hit them.
So, the question here is - is this true with QC cabs?
I think QC cabs are static ir.
This can be a request for future update.
I guess if you used the capture process to capture a cab rather than using an IR, that should capture the dynamic response?
Not something I’ve ever thought about or wanted personally - if speakers are distorting, something is wrong.
My Fractal AX8 has a “speaker drive” parameter in the stock cab blocks but they’re not IRs and I never found the function very realistic. They should have called it a “crappy” parameter. Maybe it works better on their newer gear.
Correct me if I’m wrong, but I would have thought you don’t want a cab to break up through over-power. That’s ‘permanent damage to the speaker’ territory - not consistent, repeatable overdrive. It would sound like trash…
If it was a desirable outcome; why for example is a Mesa 4x12 capable of handling 240W, when ‘big’ amps are 100W…?
I guess the answer to your question is yes, cab sims in modellers (or at least in the QC) can’t break up. To me, that is a good thing, because I have never heard a speaker breaking up that sounds good. But I am happy to learn if you can share some examples of people who actually do that on purpose.
II would be nice if they transform them in modelling territory.
Computing impedances Curves, k factor on poweramp, the speaker movements that influences the Dynamic response…etc etc
Amd not only static ir.
Probably this Is the next Frontier of modellers.
This aspect is not necessary for people until you have it… because after that there is no going back ahah
I don’t know what YouTuber was saying this, but I side with everyone else here that speaker cabinets should not break up.
Perhaps what the YouTuber intended to say was that the UA amp-in-a-box pedals have a dynamic response, in the sense of better emulating the “thump” of cabinets when driven at high volume; not necessarily meaning that there’s break-up in the speakers.
I’m not convinced there’s a problem with static IRs either, but that’s just me.
Breakup, medium or severe at 99% can be unpleasant, Shure.
But modelling not.
If you play One month with speaker shaper of softube (not only One day), if you return on static ir the First comment Is
“'OUCH!!!”
Then all return to normality… But…
If speaker breakup would be modelled correctly it should sound as unpleasant as a real speaker breaking up. Because a good model of a real thing sounds like the real thing 
My real world test with getting cabs to “clip” is that it sounds terrible. I’m not sure why anyone would want this.
I think you and the YouTuber were trying to say that there is some dynamic response when you hit a speaker hard, as well as the air movement inside and outside the cabinet. It’s not breaking up, it’s called speaker distortion, and it happens with every speaker when you push it to its limits.
I know that UA also has that option also in the OX box to emulate that, and they also have it on the new pedal mentioned.
I didn’t find that doing anything better to the results I have got without using that feature, but I recently found out this plugin - Bogren Digital IRDX Core, that emulates that effect. You can download it and try and see if you like it.