Which one?
@eric_divers if you’re just gonna be practicing in a bedroom, I think all of this is lost in the sauce lol.
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Now extrapolate all of that to a guitar cab, and I think you’ll get what Eric was saying (and what I’m about to reiterate).
Something like an AxeFX is an amazing tool, and if you bypass the cab simulation and run it into a clean poweramp and a guitar cab, it will do a damned good job getting you there. I’ve met Cliff a few times at a get-together run by a different site I’m a member at, and I remember spending some time with the then-latest firmware, a Carvin poweramp, and my (at the time) Recto 2x12 cab. I forgot what I started with but after hearing what I was playing Cliff flipped it over to a blackface amp of some sort, and if I hadn’t known it was an AxeFX, I 100% would have immediately asked what I was playing through, because it was THAT good.
But, importantly, when you’re running an Axe direct, that’s not what it’s trying to do. I was listening to an Axe in the room throguh a 4x12 cab, and had I pulled up that same patch straighrt into my dAW without the speaker/cab seciton bypassed (IIRC the Axe has a master control that lets you shut this off for all your patches when running through a regular guitar cab), it wouldn’t have sounded anything like that, by design.
An AxeFX doesn’t try to replicate a guitar amp “in the room.” Rather, it replicates a recorded guitar signal chain, which means 1) your sound is being filtered by your choice of microphone, and 2) its also “listening” to the cab from a TOTALLY different position, not ten feet back and six feet off the ground, but probably within an inch of the grill, right in front of one of the speakers, and that’s a very, very, very different listening position.
I can try to capture the “in the room” sound of my amp and compare it to a mic’d up version of that sound if it would help (honestly, an iphone is pretty good for this), but trust me, they’re really two different beasts. It’s nothing about the volume a cab is running at (IRs can be made with a certain amount of speaker excursion occuring, and I suspect the best ones already are) or some weird directionality thing with the IRs, so much as the fact that you’re listening in two totally unrelated positions.
But, that’s my TED Talk on amp modeling - it’s not that one is “better” or “worse” than the other, but a half stack in the room with you ISN’T an expertly mic’d recording of a half stack, so we shouldn’t expect one to sound like the other.
(a corollary here is one of my standard bits of advice for anyone who hasn’t had much experience micing cabs before is, at low volume, first stick your head down near the speakers and listen to what the mic is going to be hearing, and make sure your amp is dialed in to sound it’s best there, and not from your usual listening position).
TBH, I wonder how much of this is simply volume.
One of the songs on this album I’m just wrapping up, the solo was very Billy Corgan influenced and I had a good take but it just sounded too “clean” to me, and I wanted some of that “amp blowing up” vibe. So the other week I took advantage of having the house to myself on a work from home day, and wound my Roadster WAY up, and did three takes. One of them was keeper-quality and ultmately replaced most of the first half… but it also wasn’t REALLY “blowing up” like I’d envisioned, and that amp was so fucking loud I wasn’t going to turn it up even more. But, what it DID do, was some of the sustained notes had a little more harmonic stuff going on, it wasn’t quite tipping over into uncontrolled feedback, but there was some extra mojo happening that wasn’t there in my “speaking voice level” DI takes I’d done during my daughter’s naptime, probably, earlier, that was evident even in Amplitube, but also when I then ran the DIs back through my Mark at “sane” volumes.
So, all that said… I do wonder if you took an AxeFX, ran it through a poweramp and 4x12, and turned it up LOUD, if that “tube interaction” you were looking for would be there. I’m honestly not sure, but my hunch is maybe.
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My plexi has a damn good master volume. And I’m using a hot plate on the super reverb. Both set to room levels, I really don’t like high volumes most of the time. It could well just be the cabs bringing the mojo, not necessarily volume cause you can run your FRFR monitors loud.
I found a foot and a half approx mic placement from the speaker to work great for cleaner tones, it’s fuller but not suitable for hi gain.
I’ve only done a little experimentation with room mics and only in the context of high gain. I found a SM57 on the grill and a WA87 (I don’t have real Neumann money, I’m afraid!) maybe 3-4’ back gave an instant “80s shred” sound. Which I hated. 
I do like two close mics though.
I’m using a 57 as well, it works well for the distance I mentioned, I held off recording quite a while thinking I need an expensive room mic till I tried it. I think another 57 behind an open back cab blended should give you some interesting options.
The most valuable piece of advice i’ve received about sound is to lift the speakers off the floor. It really is a game changer imho, and you wouldn’t have to crawl so low for getting in line with the cab.
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Did a quick dirty take with not much regard for where the mic was positioned beyond the distance from the cab. I may need to get a proper room mic yet.
edit: I bypassed the attenuator and cleaned my ears up, it’s a different amp 
I don’t know if I can record at that volume as I’m not used to it! Will give it a shot just to hear the difference.
edit2: Not able to get the sm57 to translate well with this sort of tone. I think I need to figure out a better mic or get a zoom field recorder type of thing thats cheap and can record a room better than a near field mic, plus my power is so dirty, I’m waiting on an isolation transformer to see if that cleans up things, was trying to make another NAM profile but something has changed in my power situation and even the NAM Profiler complained about excessive noise.
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Here is my summary view of modelers at the time of this writing, where I will postulate about the Axe-FX3 that I’m somewhat familiar with.
- The “modeling” of the speaker cabinets + microphones is likely terrible. Anybody just using one FIR filter is capturing just one operating point of a speaker (that is highly nonlinear), e.g., one direction at one volume. If they had multiple FIRs with the speaker being driven differently, they could create an excellent model, but to my knowledge, they’re NOT doing this.
- An FRFR speaker can only sound like the original cabinet in one listening direction at most (and this is in the range of the FIR where they sampled), excluding actual room reverb, and other than this, it will be quite different than the original cabinet.
- The “modeling” of the amps themselves is not exact. The reason that this holds is that the chipsets that are inside the Axe-FX3 don’t have the horsepower to run something doing circuit modeling in realtime, so there is no way that they’re accurate like SPICE would be. That said, I suspect the devices have various empirical curves and lookup tables that their developers derive offline. An empirical curve-fitting approach, if done carefully, should produce something that sounds good.
- I strongly suspect that if somebody took a real tube amp and the “model” of that amp and drove them with the same settings and dry signal, the outputs would be noticeably different, particularly at the edges — unusual settings or dynamic extremes. I wonder if anybody has tried this.
- “Amp in the room” is a real physical phenomenon — chest vibration, room modes, microphonic feedback of a cranked speaker in a confined space, and so forth — but the people invoking it are usually conflating the modeler with their monitoring setup and volume level. A modeler cranked through sufficiently large speakers at sufficient volume should shake one’s chest just as well, but not really sounding like the amp and cabinet it is “modeling.”
Perhaps “modeling” really means “inspired by.” This is not to trash an Axe-FX3, I own one and like it.
my entire point above is that this is probably not true UNLESS you’re not matching the IR to the cab.
That is to say: drive the amp with same settings and dry signal, and use an IR created from the same cab and mic position that you’re using to mic the “real” amp signal, and it’s unlikely the differences will be noticeable.
Just because I want an analog setup doesn’t mean I hate modelers!
I mean, numerically exact? Might be. Have you ever listened to the direct out of a tube preamp and the numerical simulation of one? they both sound awful, I bet I couldn’t tell the difference.
I disagree. A good IR is very difficult to distinguish from a close-miced cab. There are plenty of albums where people have used, say, an Axe-FX and everyone ooh-ed and aah-ed over the tone, having no clue it wasn’t a miced-up tube amp.
This much I agree with.
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In theory, sure… but, while you’re welcome to TRY to lift my 112lb 4x12 with a pair of 70lb heads sitting on top of it off the floor, well… ToT era Petrucci might be able to do it, but I look more like Rock Discipline era and it’s not gonna happen. I’m ok kneeling down and bending over. 
Not necessarily - some is bad, some is really very good, and the technology has been around long enough that it’s fairly mature. And since an IR does capture the change in response as amplitude changes, while you can’t easily change speaker drive without changing IR, you’ll at least get an appropriate capture of the way a speaker drives when maximum amplitude is at a certain level and an internally consistent degree of speaker incursion if the IR was captured with a cab up load enough for some of those nonlinearities to be present. Speaker incursion isn’t really any different from poweramp distortion from the perspective of nonlinear, and somewhat frequency dependent, changes in response (even if they sound very different), and we’ve done increasingly great jobs of modeling that.
Yes. Youtube is full of these comparisons. It’s tough though because unless you exactly replicate the cab and mic setup from the IR, the best you can really do is bypass cab/mic emulation and run both the real thing and the model into the same cabinet, otherwise even tiny differences in mic positioning and from instance to instance of even the same model cab will exceed model-vs-real differences.
Not really. Sure, some of it is the “feel” of the sound in the room, and while turning up a FRFR speaker cabinet will help, unless it also has 12" speakers it’s going to feel a little different.
But the primary difference is, a modeler isn’t TRYING to sound or feel like an “amp in the room” (unless you’re specifically running a “room sound” IR, which a buddy of mine who owns a bunch of great real amps but also has used Axe and Kemper devides for a long time now did specifically hunt down to make the modelers a lot more comparable to a half stack).
If there’s one thing you take away from this conversation, it should be that 99.9% of the IRs on the market are capturing the response of a close mic on a speaker cab, and the “amp in the room” sound is essentially a full frequency flat stereo “capture” of a distant mic, from 10-20 feet back. Listening (with often times a “filtered” sounding mic with its own color) 1" from a cab, and listening 240" from a cab, are going to sound totally different.
They’re not supposed to be interchangeable solutions; one’s a recorded tone, the other is a live ambient sound of a loud instrument in a big acoustic space.
I’m a little fuzzy on what SRV did here, but IIC, “Texas Flood” was a pair of SM57s, positioned one probably where you have it, and the second basically touching it, parallel, but pulling it backwards slowly until phase cancellation basically just took out the highest “fizzy” part of the tone.
I’m listening on a shitty one-earpiece headset on the trading desk here at work so I can’t really opine on the tone, but near as I can tell it DOES sound great, and you’ve clearly been doing a very deep dive on SRV’s inflections, because this sounds eerily close to what I remember from his albums.
EDIT - here you go:
Older Unidyne 3 abeled SM57, 45 degrees off center, within 2-3" of the speaker cone (he’s doing all the demos without a grill, so I’d say in practice probably pretty close to the grill?
I haven’t done anything other than head-on micing in a long time, I should give it a shot again to make sure nothing about off axis is really working for me these days that didn’t back in the day. Another thing worth trying though if you can get a pair of 57s is the so-called “Fredman” technique, head on and off axis, with the edges of the capsules touching. Definitely more of a swedish melo-death metal thing, but an erffective mic technique is an effective mic technique, and this could work well for SRV type styff too, giving it a little more body than off-axis alone.
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It looks like the IR conversation revolves around “static” IRs but how about the so-called Dynamic IRs?
My experience with them has been far superior than traditional IRs which sometimes I’ve been able to get close enough with EQ alone.
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That’s great info Drew, thanks! I shall try it.
And thanks for noticing, deep dive indeed!
I have half a mind to build a mini brick and mortar cab room
edit: tried the close miking from the vid… I’ll keep experimenting.
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Ah, perhaps we could replace the word good with appropriate. For example, do you want to be like most users and run the speaker at very modest volumes? Absolutely, make an IR for this! Or, if you’re YJM and you’re running it in your basement at extreme volumes? Absolutely, make an IR for that! The point is, these are two different IRs, and that’s why the modeling is so weak IMHO with the cabinets.
Alas, that’s the problem, when people make the IR they apparently do things like exponential sine sweeps, but they have a particular volume that they run the speaker at. So the resulting FIR will be accurate there, but not necessarily elsewhere. Again, if you’re a jazz cat at low and moderate volumes, that will be quite appropriate. If you want to be face-meltingly loud, it will be inappropriate. So, “it depends.”
No, I don’t mean random people saying, “oh, it sounds the same to my ears,” I literally mean test equipment and comparing numerical errors. I don’t think I’ve seen this anywhere, even once, but I know that the “model” will not be within fractions of a percentage, it will be all over the map.
Yes, I think that you’re exactly right. For example,
Finally, I haven’t read Farina’s paper yet, but I’m somewhat curious about the topic, so I’ll share it here in case somebody wants to read it and learn more about the topic (sine sweeps).
Bolded part - why should that be the case? Do guys making IRs just not play rock and are unaware that speaker response is part of the “sound” of a guitar.
There’s no reason, if you’re a professional VST/IR producer, to only model speaker cabs quietly, and I’m curious why you’re so sure this has to be the case.
So, I haven’t tried a “scientific” test, and again, cab/mic choice and positioning are a massive wildcard that, unless you’re running into the same cab and mic, make this impossible… and if you’re running your models throguh a cab and mic, that defeats the porpose of using a modeler.
But, when I switched to a new computer, I grabbed Amplitube 5 in part because they’d worked with Mesa on a number of “official” amp models, including of my Mark V (I’m sure I could have found a good enough version of a Mark IV lead tne elsewhere, but the ability to also model the rest of the channels accurately was a huge selling point). And, I started by creating a number of patches, using the same mics in pretty close to the same positions on the same cab that I actually use, and “typical” amp settings for me.
I then reamped some of the DIs through my real rig and compared them, and playing them back out of phase, I got some weird phase artifacts. That to me suggests Amplitube actually got fairly close - it didn’t null to zero, but some nulling was occurring.
End of the day, I think amp modeling has gotten very good… but, the point I keep trying to make that you keep missing, is that a modeler isn’t even TRYING to replicate the “amp in the room” sound, so they’re really not apples to apples comparisons if that’s where your interest is. It’s trying to replicate the sound of a recording of a real amp.
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I just updated fractalaudio’s icons fulltertone library and gave it a shot, setup a rig, they have this new room thing that is very cool. Honestly I’m pretty smitten with it, it maybe just smoke and mirrors but it’s convincing enough and I’m having a blast practicing with it.
Having the real components really helped me dial the rig in. The fuzz is programmed incredibly well. The stock cab selections left nothing to we desired. I’m using first gen KRK rocket 5 that were just bassy enough to be fun to listen to across the entire room.
What do you guys think?
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I suspect that these IR people are musicians or studio engineers leveraging existing software that was built, from the ground up, assuming that the system is linear; this is not a bad assumption for many forms of music, but less so in guitar.
The fundamental problem is the user software loads just one IR.
Why would a studio engineer or a guitarist ever assume a speaker is a linear system, though? I don’t know if you’ve ever stumbled across Slipperman’s “Distorted Guitars From Hell” treatise, but he spends whole pages about finding the sweet spot where speaker excursion begins to occur.
I’m not going to quote it for, um, reasons (this is very colorful) but this is an absolute gold mine of intel on getting a good amp sound to tape:
Anyway, broken record, a modeler isn’t trying to sound like a guitar amp in the room, it’s trying to sound like a recording of a guitar amp, and we can’t expect the former to sound anything like the latter. This isn’t apples to apples, it’s apples to hard cider.
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I still remember some of his (derogatory, accurate) descriptions of guitarists and their guitars. What a great post that was.
Oh it’s amazing, haha. I forget if it was speaker incursion that separated the men from the boys, or one of the seventeen or so other things he went on about, but honestly the more I do this the more I’m grateful I discovered this when I did.
EDIT - it was:
“In short: You KNOW at what Master Volume setting the speakers start to ‘excurse’ and where the ‘cabinet involvement’ starts. This is the point at which we start to separate the boys from the men.”
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Have a question about these IRs.
I presume they are recorded with the power amp pushing the real speakers with optimum power to get the speaker working? I skimmed over some of that doc, did it mean that you need to also monitor at optimum SPLs?