IR producer here! You've been warned.
Every physical 4x12 Mesa cab sounds a little different. I've had four in my studio this year. Here's a clip I posted before. I didn't mention it then but these are all 4x12 Mesa cabs and they all sound different:
The new pack that I'm working on with Misha was chosen because it was the meanest and most metal sounding scooped Mesa cab out of the bunch. We wanted to go full on brutal djent with this one.
So even if I did a pack out of all four I would end up with four different sounding packs. That's just how it is. I'm not sure what the difference would be if different IR producers shot the same exact cabinet. Would we agree on the mic positioning etc? Would we agree on the capture methods? I would say that it all comes down to mic placement. Everything else you can have an opinion on but will only affect the IR maybe 5%. Mic positioning will be the majority of the tone.
Like
@York Audio mentioned I've also always done everything 100% raw. The process of shooting IR's includes about a dozen different gimmicks and processes for all of us so there's no "one correct way of doing things" but all that I do is to ensure that I have the most authentic capture. Nothing is there to "make the IR's sound better than the cab actually does". If you counter this kind of IR marketing, please look away. We're dealing with digital modelers so to make everything sound as real as possible keep things as raw as possible.
I drive my cabs with 100w tube amps and I drive them loud which might be one of the things that separates me from some of the other IR producers. Marshall cabs are driven by Marshall amps... Mesa cabs by Mesa amps etc. Even I am not sure if it makes a huge difference but I want to make sure that the cabs are "in their natural environment".
IR producers have different approaches and that is IMO one of the best parts about having different IR producers. Many IR producers allow you to virtually mic up the cabinet in post and give you different brightnesses. This is not my approach. I feel like my job as an IR producer is to give you the mic position that you "should be using".
I feel like this is my job. I have a microphone robot... hell you can buy microphone robots these days so you don't have to build one like I did. If I wanted to, I could systematically shoot all available mic positions on a 4x12 cabinet. We would end up with thousands of IR's and... people would be confused and asking for the best positions to use, so I'm saving everyone's time and giving you the best positions. I usually have around 16 mic positions per mic per cab and even that is too much for most people. That's 16 mic positions hand picked from around 200-400 mic positions depending on the mic. These 16 positions are not a systematic brightness sweep.
A fundamental part of my approach is that you shouldn't use mic positioning as a presence knob. You have a presence knob on the amp so use it for that. This is probably one of the biggest things that separates ML Sound Lab from most IR producers.
@keymaker posted an OH vs ML comparison at one point and here's the Mesa comparison:
I like this comparison because it's unclear even to me if the differences are because of the cabinet or our approaches. I like mine better; I think mine is more pleasant in the highs and is tighter in comparison. You can hear the tightness especially in the ending riff. But I'm 100% sure Kevin likes his better because it's growlier and more aggressive. That's the beauty of having different IR producers. We all have different tastes and approaches and I think we should just celebrate the fact that IT IS SUPER EASY TO CREATE PROFESSIONAL SOUNDING GUITAR TONES THESE DAYS. Man... 15 years ago when I recorded my band's album through a Boss GT-6 this would've been a dream come true.